AYA II DS, DIY edition

As announced a few months ago, we have another run of AYA II.

This run, marked as DS, includes one update with respect to AYA II 2014: synchronous DEM clocking circuit is more completely integrated, so now it is not optional but an integral part of the AYA II project. By using the BCK signal from TDA1541A input, this circuit operates properly i.e. synchronously, regardless of the selected source.

PCB layout is updated to suit this change, and there are also several other minor changes on PCB, in order to facilitate mounting of possibly different parts.


The AYA II DS is sold out.

189 replies on “AYA II DS, DIY edition”

  1. Hello Pedja,

    God news for the DIY community and even the non skilled ones with already populated kits !

    I linked the news on DIYA as some wished to were here during the

    (Did you have time to try some varaitions with passive parts like the scenario which sounded good at home with me ? By the Way, it’s great this batch give even more possibilities for trying parts 🙂 )

    Many thanks


  2. Thanks, Eldam!

    I appreciate experimenting with different capacitors setup, and I would definitely suggest everyone to try your recommendation, and remove local cap from TDA pin 15, and replace main 1500 uF FM cap there with 1200 FC // 330 uF FM. Further tweaking might depend on the system.

    BTW, if you are agreed with this, it is still not to late to add the footprint for 330 uF cap to parallel C2, so people can try this without soldering that cap beneath the board.


  3. No thanks to you to allow us to share your great design in a friendly DIY way. I enjoy to listen the AYA 2 2014 edition nearly everyday 🙂

    Yes of course, add it if you believe it worths it;the more versality the better: each can choose on a easier and faster way what flavor he likes best in relation to the rest of the devices, amp, speaker, etc !

    It’s more easy to putt without soldering an other cap on a second aera to listen to with it, without it, with an other one, an other value, etc ! And solder it after the listening tests or come back to the genuine which is great & neutral !

    I use myself just one smd not three anymore as explained already in the blog and all my simple tips are given to everyone… It was only possible thanks to the great design of your regs which are making the TDA1541 sounds great with of course all the layout around! the simple tips I talk about are just salt & Pepper and I’m very happy you liked it.



  4. Hi Pedja,

    I have 2 PCBs for a dual mono build yet to be populated from the 2014 order, what would the shipping cost be for 2 transformers only? (To brisbane, Australia)

    I had thought about a battery psu for it all but dont have the time to integrate all of that neatly at the moment so in interest of getting the build moving I have regretted not having ordered the transformers previously.


  5. Eldam,

    So it will be included, with credit given to you in the assembly manual. 😉


    Battery supply can sound very good, and I can’t complain in that regard, but it can be impractical as well. And, in my view, in this case we simply have too many supplies to think about it.

    Regarding transformers, another “Add to Cart” button was added above, so it is now also possible to order transformer(s) only.

    And, speaking about transformers, people often ask about required power… These are 50 VA units, and each secondary is rated to 0.7 A. Actually, everything above 0.3 A per secondary would be fine for AYA II, however it is usually not convenient to put all the required windings to the smaller core.


  6. Hi Pedja, as you want, you’re a gentleman !

    Btw : for this tip, one has to populate only the smd C303 (not the others 2 smd).

  7. Here is some information about transformers, that may help when choosing between EI and toroid.

    The first, for those who missed it, two year ago I posted this article on differences and main (dis)advantages of both types here:
    PSU transformers: EI vs. toroidal, and more

    It is not really possible to narrow down things this way, but as a most rough approximation: if you have less than about 10 cm of space between transformer and circuit board, and there is no shield in between, then toroid might be better, otherwise you can consider EI. Transformers sold with this project have no shield, can or hoods included or attached.

    Transformers dimensions are as follows:

    EI height is 66 mm, and its outer dimensions are about 70 x 75 mm, with mounting holes spaced at about 62 x 55 mm.

    Toroid height is a bit less than 35 mm, and mounting hardware adds a few millimeters more, so the mounting screw (one, that goes thorough the center) is 40 mm. Its diameter is about 80 mm.

  8. HI All

    Trying to get my BOM ready for when I receive the boards and transformers so I need to know if these parts are “acceptable” please:


    item#4: 100nF SMD1206 -> Rubycon MU series – acrylic metallized
    item#6: 1uF SMD1206 -> Rubycon MU series – acrylic metalled
    item#8: 3n3F SMD0805 -> Panasonic ECH series – PPS
    item#9: 100uF Rubicon ZA -> OSCON SEPC
    item#13: 1nF -> EPCOS PP metalised (or should I stick with Kemet PP?)


    As I don’t have the board I’d also like to know if all the semiconductors are SOIC footprint?

    Thanks for any help!

  9. Hello Brent,

    Rubycon MU looks like new thing. I have no experience with them, and I can’t seem to find detailed information about their dielectric, but they are apparently offered as polymer alternative to ceramics. So, ceramics size SMD package, without distortion associated to ceramics, which of course makes them more suitable for analog circuits. This is still not enough to predict really anything, but they might worth a try.

    Anyhow, C105/205 are not critical. OTOH, local TDA1514A decoupling is way more important, but it will depend on the rest of the setup, and it is usually the best to start without those three caps at all.

    Item #6 is again not critical.

    Item #8 – yes, it is fine.

    Item #9 – yes, mostly fine.

    Item #13 – for me, styrene is much preferred here.

    As for semiconductors, apart from TDA1541(A), all the others are SMD. Q104 is TQFP, others are SOIC.


  10. Hi all, Hi Pedja,

    I received some asking on my DIYAUDIO private mail about my last mods on the second run of AYA 2 2014 since the good news of the third launch called DS edition was annouced here by Audial.

    To pursue the great DIY sharing spirit of Audial I drop here my last mods if anyone want to try it as it’s very simple and give a good option to the stock BOM. Free to Audial to putt it if wanted as an option in the DS edition BOM. Or even critic it if thinking the result is not good as I think (have only my system to benchmark;)! Anyway it’s simple to try before as it has less caps and few different ones.

    C3 : 1200 uF Panasonic FM + (in parralell) 300 uF Panasonic FC or 1500 uf Panasonic FC

    C6/C7 : 1500 uF to 3000 uF Panasonic FC (try both value and keep the best sounding result on your system)

    C305/C308/C302 : unpopulated (see the comments in this thread above)
    C303 : populated with the BOM value; but C306/C309 : unpopulated (great improvment on my system)

    C401/C402/C403/C404 : unpopulated

    I/V resistors : Rhopoint 8G16D : 1K Ohms (Farnell)

    C407/408 : polystyren but in tin foil version (Farnell)

    I don’t use output caps after the oaps as I trimed them at 0V drift.

    As you can see, it’s a very easy mode to try when you are in the assembly phase as it’s less caps :). The exact reference of caps is important (or try yours 😉 and voltage of caps are the same as the BOM )

    Best regards


  11. We were asked to extend the offer for another week, so yes, at this moment we can still accept the orders. We are going to remove the payment buttons on Monday, 16 November (forenoon, Central European Time).

  12. IS there a reason why the “general circuitry” ie. everything outside the signal path needs to have carbon resistors? does it affect sound at all if these were substituted for carbon which is more accurate tolerance?


  13. In my view, supply resistors are not that critical, both regarding the type and absolute value tolerance, so feel free to use whichever you find convenient.

    Speaking about this, absolute value tolerance is also not very important at signal path too. The exception is I/V conversion where, if you use AB, it is good to measure and match the pair between several samples. AB are now very old, and it is not uncommon to find 7-8% difference between the samples of nominally the same value. You can not really go wrong here either, however it is important to understand that these resistors set the output voltage, and that 7% difference will result in 0.6 dB different levels of two channels.

  14. Found this on the hificollective site and thought it useful given Preda’s earlier comment re their tolerance.

    Allen Bradley RESISTORS special treatment method:

    As stated Allen Bradley resistors are carbon composite, being made of an organic material they do have the tendency to absorb water from the atmosphere. This absorption can increase the actual resistance of the component, hence the slightly higher than normal tolerance published on this page. To fix this simply remove the water from the component and seal it. The best method is to place the resistor/s on a baking tray, set your oven to 80 degrees centigrade and leave in the oven for 8 hours. The secret is to remove the mositure slowly if you rush it it will become noisy in circuit. Once cooked seal the body of the component in Shellack (preferably the flakes) to stop any further water absorption. At the end of this procedure you will have a much lower noise, more closely tolerance resistors. Special thanks to Colin Cornish for this excellent tip.

  15. Hello, found a whole lot of email in my spam folder from this site:-)
    I am concerned about Pedja’s comment regarding tolerances for these resistors. Even 5% is a bit much for this role isn’t it? Unless we buy a whole bunch, treat them, then match them its a bit hit and miss. Bar a group buy and matching, are there any other resistors at either http://www.hificollective.co.uk/components/resistors.html or
    http://www.partsconnexion.com/resis_main.html that would be a good fit for this critical part? Eldam your our parts guru:-)

  16. I guess the 5% (0.4 dB) difference in channel levels will be between hardly audible and inaudible.

    However, my notice above applies only to vintage Allen Bradley resistors, which resistance has drifted (mostly increased) during decades.

    As for regularly produced resistors, practical tolerances are in fact better than nominal (worst case) tolerances, so taking into account that the nominal tolerances are always 5% or better, matching will not bring any real benefits. Of course, I am aware of how many audio people were and are obsessed with parts matching, but… the good sound is simply not about that.

  17. Assembly manual was just sent to e-mail addresses of all AYA II DS users. In case you missed it, please check your spam folder.

    We will start shipping the boards and transformers the next week, and kits about the middle of December.

  18. With slight delay, the shipping is now starting.

    There were several separately ordered transformers, and they are all sent today. Unpopulated boards, with or without transformers, should be all sent by the end of this week. And then the kits, by the end of next week.

  19. Hi Pedja, thanks for the update. I am surprised by that 0.4db is hardly audible. I thought it would be. I need to make a bom soon, but its getting into crazy season:-)

  20. You are welcome, Patrik, and thank you too.

    Please let us know as your project progresses.


  21. Hi, the board is arrived yesterday, thanks Pedja.
    Now I have a few questions yet. I just use the I2S input Feed from Amanero which power supplies I need to connect on board?
    Is it possible to use the power supply from Coax/SPDIF part for the Amanero?

  22. Thank you, Aron.

    Yes, it basically is possible to use that supply for other unit(s), with no shortcomings, provided it is not used to feed existing on-board circuit(s). Of course, you would have to check the current consumption of the external unit.


  23. Thanks Pedja, I got 8/10 on 0.5db, this is detectable. I got 4/10 on 0.2db, and to be honest I guessed and was not sure of any. I expect imaging, soundstage etc may be influenced by 0.4db so I will try for a better match on these critical resistors. But thanks for this link, its real to me now and I understand what it actually means:-)
    I will research this, maybe Riken, Eldam tells me they have changed and not as good as the old ones. Will they fit on the pcb? The smallest size is 0.5W.

  24. One more thought on 5% resistors, the max possible difference is plus and minus 5% of the value, this is actually 10%. Anyway, Im sure this is very mathematically unlikely, but possible.

  25. Luke,

    My Aya 2 2014 is only with carbon résistors everywhere as Pedja’s BOM advices.

    As usually I made severals dozen hours of tests about caps but few with résistors. I just tried to swap the AB of the BOM around the oap, bought at HifiCollective by good Philips Metal and Takman carbon ! For I/V: I always leaved with wirewound Rohpoint in all my experiments (with // styroflex tin foil cap of the same BOM value).

    Difference were huge is the favor of the AB by far (more natural tones according to my tastes). I was surprised myself to hear so much différences. I saw also some older versions of the AYA were with some red English résistors. I believe if Pedja come backed to AB is not for Nothing. There is a fort dependency according to me between caps & résistors to find the best equilibrium (objectivly you can make a dac sounding tot)ally different and even waste a good design with the bad parts.

    You should try the Riken as well, (sweet highs most of the time). I did’nt. As there are only two AB, you have 4 combinations only from the full AB, mix AB/RikEn, Full riken !

    But the equilibrium is dependant of the rest of your system : my speaker are clear Crystal, and some of my friends joke the sound changes also with air humidity (lol!). Each system has a different tonal balance as well. Sometimes more transparence is not better… as noticed some experienced guys like Hiraga !

    Just one advice : don’t solder the parts you plan to change for tests : try them unsoldered, it’s good enough for tests. Just take care of shorts, and give you chance of a burning time for caps and several listenings not the same day. Always with the same tunes.

    Say us after what you will keep 🙂

  26. Red resistors you see at some AYA II pictures are PRP. They were indeed used in some initially produced samples of AYA II, but I have given up of these, as I found them ultimately too bright.

    The thing is, it is not easy to find something actually better than Allen Bradley. Despite of their relatively low price they are simply superior to about anything available around, in about any aspect. The only objection might be about their somewhat fragile tone, but I am not sure if I would trade their advantages for this. Wire-wound resistors can sound, well, more sublime, but this does not necessarily applies for every system.

    Rikens were used in The Model DAC (2007), but they were also replaced by Allen Bradley in all the later Model S DACs (2008 onwards).

    Anyhow, 0.5 W Riken should be possible to install in the AYA II DS, certainly as R415/R416 and R419/R420, and it might be harder but still possible to fit them to R417/R418 footprints too.


  27. All the orders are processed (most of them were shipped by the end of December), and surplus board are now available.

    We can supply transformers with these boards too, lead time will be one or two weeks. Also, some of these boards are partially populated, mostly their PSU and S/PDIF parts, but I would prefer to ship them completed, i.e. in the working condition.

    So, anyone interested in these items, please send your inquiry by using contact form, or e-mail address you will find below the form.

  28. Hi Eldam,

    maybe a slightly stupid question, but how did you test all the different caps without soldering them, or did you solder? For me the pcb seems to be a bit too fragile for that. On the other hand, bores are to big in diameter in order to have tight contact without soldering.

    By the way, my plan is to make my own I/V resistor using resistive wire, wound bifilar around a piece of broomstick, soldered at the end to coppper wire and fixed by beeswax 🙂

    Others are or will be Takman and ABs.

    Looking forward to hearing it 🙂

    Cheers Ernst

  29. Hi Ernst,

    Indeed you will be bored if you solder. contacts are good enough for test phase ;)… it’s not all the caps; it’s just some caps! and if you follow what I wrote you even don’t need to solder some : so easy to test then Pedja Rogic BOM with the 100 uF near the loads.

    For the résistors I use little copper pipe berylium/copper for vias you can find at Mouser (sorry forgett the ref !)

    Many tried to make their wirewound resistor with no better results than a Rohpoint resistor 516G. Pedja Rogic said the weaker value avaliable at Farnell was enough as I/V giving 1.5 V RMS if I remember. Why bother to make it yourself, and the footprint is narrow, so… Rohpoint is the way imho (Farnell only).

    In each case you have to test both the Allen for this position and the Rohpoint. It is not said the wirewound will sound better in reltion to your whole system or the front end you choosed.

    Following exactly the Pedja Rogic’s BOM is the guaranty of a good result and musical equilibrium. The -15V tip I gived seems good enough for him and he writted going further (with the whole list of mod I gave) is a question of taste/system.

    So to summarize : it’s easy to test mine as it’s less caps then going for the genuine BOM without soldering the caps involved. Just take care of shorts and never putt or swap a part without switch off the dac : don’t try to save time with that 😉

  30. Eldam, thank you again. Which tin foil cap from Farnell did you use for C407/408? Cannot find anyone.

    Cheers Ernst

  31. To experiment with parts… I guess the problem is how to remove the solder from the holes, once you remove the part itself.

    Instead of getting into the hot air or rework stations or pumps, a simple home sewing needle with diameter that matches the hole can be handy, and I guess everyone has something like that at home anyhow. So, you just melt the solder by the iron, and push the needle through the hole, and wait for a few seconds for solder to cool down. Then you can remove the needle, and solder will remain out of the hole, probably shaped that way so you can remove it by tweezers.

    With normal soldering iron tip, and temperature between 320 and 330°C, this way you will not damage the board by changing the part for 4 or 5 times. And probably more, but up to that point you will likely make your decision.

  32. Ernest,

    I sourced these ones : FSCEX serie; 1000 pF 1% / 250 V ; they are sold by 5 ! n° Farnell when I bought it 952-0651

    They seems to be directional (I don’t say polarized) as they have a marking : blue circle, but I never chooed a sense ! I don’t know where is the beginning of the foil and the end, I assume the marking informs on it ?!

  33. Hi all,

    there is something confused. Pedja, in the assembly manual you wrote:
    “C3 : 1200 uF Panasonic FC + in parralell 300 uF Panasonic FM, instead FM 1500 uF Panasonic”

    Eldam wrote at 04.11.2015:
    “C3 : 1200 uF Panasonic FM + (in parralell) 300 uF Panasonic FC or 1500 uf Panasonic FC”.

    FM and FC was changed?
    What is the right setup?

    I have here Rubycon ZL, and have good results with it, someone of you have used the ZL?


  34. Hi,

    The right setup is the genuine AYA 2 2014 : Panasonic FM 1500 uF / 25V (if you have the 15V secondary, need more voltage tolerance if you have a 16V secondary. I advise eberyone to listen the genuine BOM to have the genuine sound and choose yourself what setup is going the best in your whole hifi system!

    For the rest and your question, my bad : The initial setup I given was 1200 FM + 300 FC ; but I tried both (1200 FC + 300 FM), etc…

    I also tried Rubycon ZL here and they miss Something in the bass region according to my hifi system.

    As Pedja Rogic was friendly to add a second cap aera I suggest to try in order : (assuming you didn’t populate the 100 uF near the chip and you onl populate the 0.1 uF advised (and not the two others 0.1 uf : very important point and you still can populate them later to try both setup).

    first listening :1200 FC /50V alone (or 1500 FC /25V, I prefer at ears subjectivly the 1200 uF / 50V but it will miss an extra of filtering and life in aging ! Hey it’s AC just before !)

    second listening : 1500 FM /25V uF alone as genuine BOM.

    From here you may find an important difference ! At least in my system it was very different. FM & FC are different beast !

    Third listening: 1200 FM / >=25V + 300 FC / >=25V

    Fourth listening : 1200 FC / >=25V + 300 FM / >=25V

    Choose your poison, but the time wasted in extra part to test it worths the cost imho.

    If you just want buy 2 caps (but hey caps are cheap !), go with 1500 FC to respect the capacitance value the swap to try the original 1500 FM ! In the analog section you will adapt the tonal balance from there with what I wrote the 04.11.2015.

    It worths the try imho ! It will cost a little more in parts to try the both BOM… but so few. And all dépends of the numeric front end you have

    Don’t forgett Audial via Pedja Rogic allowed us this possibility at more than a friendly price (cost price)for DIY communauty to make those tries. I believe this is an encouragement to test, but to have a point of reference, one has to listen to the genuine Audial’s conf of course.

    So my bad for the typo !

    best regards, Eldam

  35. Good morning 🙂

    Pedja, I would like to add an i2s input to my DAC, means I want to have a BNC connection right from the rear side of the housing to the pcb; so to speak the same as you did in your Model S.
    I think you mentioned earlier but I didn’t get it really. So which connection ist preferable, 75 or 50 Ohms cables and plugs? I think, you use cables BNC to U.FL. I would really be happy about a recommendation for these? Type, supplier?

    Thanks in advance.


  36. Hm, just saw, that you don’t use adaper cables but direct to pcb soldered BNC plugs. So sice wwe do have the U.FL dingies on the PCB, I have to use adapter cables for routing it to chassis. Maybe anyone has got an idea, which parts to use. U.FL to BNC chassis mounted plugs are difficult to find. U.FL to SMA are easy to aquire.

    So probly I’m using these. Does it make any difference if they are 50 or 75 Ohm versions?



  37. As Patrik said, R219 is 100R, and it is SMD 1206.

    Also, R217 is mistakenly listed in the parts list as 1/4 W leaded resistor, and this one is also SMD 1206.

    Both will be corrected in the upcoming assembly manual revision, which will be sent in the next 10 days or so.


  38. Ernst,

    U.FL connectors are always 50 Ohm (SMA is 50 Ohm too), which I guess solves some of your doubts. In my view it is always preferred to have one cable, and not to use extensions of any kind, if possible.

    Please also note that, if you want to have properly terminated line, you will have to add the end termination resistors somewhere.


  39. Hi Pedja

    Thanks for this wonderful dac. Been filddling with e caps & also had some
    mail exchanges with Eldam. He sure know quite a fair bit about your dac
    Pedja. Followed his advice & I started removing caps step by step & as
    I did I found the sound to improve but off course this would not work had it
    not been for the well design regulators plus galvanic approach that you’re
    using on the Aya Pedja. To cut a long story short . The dac now is very
    transparent & organic sounding dare I say its at least 30% better over stock
    & all this just through a couple of simple tweaks. My recollection of the TDA prior to AYA ll was its bass & mid range but never had I thought that this oldie
    can be so damn good. Unbelievable. Pls seek out Eldams advice cause you
    don’t know what your missing until you try it. My differ in the cap recommendation instead of Pana FC , Im using BG standard. Perhaps the BG might be the magic of what Im hearing now. In anycase Im sure the Pana FC will get you to at least 90% of my result. Thanks again Pedja & Eldam


  40. Thank you very much Jaffrie,

    I’m sure you can winn a little more by removing the Silmic and the 100k shunt resistor if your pré or amp has a DC blocking cap : this is my current setup !

    Defintly use FC on the -15V ; and on the analog side the FC 3300 uF/25V (exactly this ref) is advised to beginn from there with the FM 1500/16V : it gives very different thing so depend on the rest of your amp/speakers ! I’m not so surprised BG 1000 uF and more gives good result as well : certainly darker soundstage as fleshy & organic sound !

    Where are you using the Black Gate please ? -15V or analog 5V ?

    Panasonic FC according to my whole hifi gives better result than even the moderner FG & FK I tried also !

    What did you think of the standalone 0.1 uF PPS thrick ? Surprising no ? I believe it is due maybe to the internal ground scheme of the chip ! I don’t know I have no electronic background ! It seems power shematic of the AYA 2 does all the job : fast, clean, quiet :)….

    Happy you like it 🙂

  41. Hi Eldam,
    i wouldn’t touch those -15 caps ya coz it came from your hardwork. Lol in any case Im very happy with how the dac sounds like now. Might try out a higher voltage Silmic coupling caps to see if sound improves.. Btw Pedja why such a high value coupling caps for the output ? Whats the cut off corner frequency ?


  42. These are the speakers that I’m using. Very transparent. You can hear changes made very


  43. Jaffrie,

    It is beautiful. I am also listening to the electrostatics, so we might have similar preferences. 🙂

    Capacitor cut off point is given by the equation F = 1 / (2 * Pi * C * Z), which means that it is determined by the impedance it “sees”.

    In this case, the impedance is practically purely resistive, and it is the sum of the DAC output impedance at one, and R421/R422 (typically 100 kOhm, but it can be significantly increased if necessary) in parallel with downstream device input impedance on the other capacitors side. The DAC output impedance is the sum of the output series resistor and OPA861 “emitter” impedance (8 Ohm), so it is typically 130 or 140 Ohm, and negligible in comparison, and hence it can be neglected.

    So, practically speaking, in most cases, when used with (pre)amplifiers with input impedances between 10 and 50 kOhm, the impedance seen by the output coupling capacitors mostly boils down to the (pre)amplifier input impedance.

    The equation above will tell you -3 dB point, and it is fine if you move this point one or two octaves below audible range.

    So, with 10 kOhm (pre)amp input impedance you can use 2.2 uF or even less, and the higher the impedance, the less capacitance you will need. The reason I am using such a high value is to make it compatible with low impedance shunt potentiometers. And while your potentiometer is such nicely accessible, once you may want to try that option too. In my experience, that is how every potentiometer gives its best.

    As for Silmics voltage, my experience with capacitors was that the lowest possible voltage usually works the best – it was one of discoveries we came across back in Gramofone days.


    This capacitor is not that critical, and that is why this part is not specified. You can not really go wrong with it.


  44. Hi Pedja
    i have now attain the ultimate from AYA after mucking around with the tweaks. Originally when I first fired up the dac, music was presented in a very organic manner everything was there but 2 things were troubling me. There was a darkness to the sound & the tempo was a little slow but now it no longer is this way. As for the high value silmic at the output I think it’s evil but then again if I change the value or use a different cap it will offset the balance of the dac. Haizzz might try a 10uf BG N to see. Last nite I told myself no more tweaking but? Had own & also auditioned many dacs over the years but I would dare to tell all the disbelievers, there really isn’t many dacs out there that can compare with a tweaked AYA regardless of price. Hey Eldam thanks again for sharing your experience & sorry due to different taste buds I had use diiferent values & components to voice the Dac to my liking. Cheers guys & happy diy

  45. Hi Pedja
    Silly question, how do I ground the dac to a 3 prong earth connection ? Can I run a wire from ground of pcb to the earth connection & if yes which is the best place on the pcb to tap ?


  46. Hi Jaffrie, thanks, you’re welcome. This is the spirit of the tweak, the last setups to adapt to your own taste and whole hifi/system/room behavior is fine. All deserves to sharing spirit of Pedja Rogic.

    Without Black Gate also, I believe the unique 0.1 PPS + the Panasonic FC and some adaptation with the Panasonic FM will give the possibility with on shelves parts to mod the DAC for most of people with enough versatility due to the very good shematic of the Audial Layout. Easy to test firs as it’s less caps !

    In the manual If I remember there is, if needed, the description on how connect the pcb tp the earth. But the better, if the local electricity rules laws agree in your country is to connect the earth to the metal case of your dac at the feet of the dac plug. You must isolate the Gnd of all the inputt plugs (RCA, BNC, USB,…) from the metal cabinet.


    PS : Mr Rogic and Mr Jaffrie : send me please your electrostats, that are better than my speakers, I have to check my dac on it :)!

  47. Hi Jaffrie, thanks, you’re welcome.

    Without Black Gate also, I believe the unique 0.1 PPS + the Panasonic FC and some adaptation with the Panasonic FM will give the possibility with on shelves parts to mod the DAC for most of listeners with enough versatility. Easy to test firs as it’s less caps ! But sure I too like Black Gates caps ! Some testimonials from Pedja Rogic on the 2014 AYA II edition blog as well If I remember !

    Earth connection : In the manual If I remember there is, if needed, the description on how connect the pcb tp the earth. But the better, if the local electricity rules laws agree in your country is to connect the earth to the metal case of your dac at the feet of the dac plug. You must isolate the Gnd of all the inputt plugs (RCA, BNC, USB,…) from the metal cabinet.


    PS : Mr Rogic and Mr Jaffrie : send me please your electrostats, that are better than my speakers, I have to check the AYA 2 2014 on it ;)!

  48. Hi Eldam
    Thks yes when in metal box I know what to do but now its just on a plywood. Am going to test a AC filter to see if it works. Hence

  49. Symetrisation traffo seems to work very good as well 🙂
    why to filter if you don’t need to plug the earth for security ?

    Ah, I understand, I believed you were talking about security issues only !

    You can also putt your traffo in a second box in aluminium and stay with the Aya pcb with Plywood.

    You can also add copper walls Inside the wood cabinet as writted in the manual 😉 Keeping the distance between the secondaries and pcb at the distance Pedja advised !

    I don’t know if it’s better to keep the aya 2 from external EMC or putt the traffo in aluminium case to protect a little the aya pcb from traffo vibration and “radiation”… Permalloy casing staying a dream for big wallet.

  50. Hi Eldam

    Am always curious so wanting to try cleaning up the AC via filter before going in to the transformer. I build a Jon Risch filter that was incorporated into one of my amps years ago. Must say it work pretty well but the set back of that design was that you needed a 100 watt bulb to load the filter.

  51. Hi Pedja,

    Without a chassis now, can I just run a ground wire from C2 to the
    earth connection instead just for testing.


  52. One more Aya dac II DS plays music! Maybe this is my last dac i build, this is so good. Actually i don’t know what i want more than this? So smooth and detailed at the same time. Hard to explain more that this dac gives me goosebumps all the time in my system. Thank’s Pedja for the opportunity to let my build this great dac!!

    Have a few more tweaks to try if i want. For now i use FM 1200 at C3 and FC 330 at C3b and nothing at C302-C303. Eldam you have populated C303!?

    I bought a few different resistor brands for try at output. Right now i use green kiwame. I have and soon will swap to Allen Bradley but can’t really imagine how and what more i’ll get with AB’s? Fun and interesting swap.

    Maybe as i can read from you Eldam and Jaffrie it’s worth trying to tweak more and don’t use caps at c305,C308,C401-C404? If i’ll try this should i remove anything at backside? And what should be populated at backside? More that populate C303 again and have C306 and C309 unpopulated?

  53. Kiwame is a little warm sounding from my experience. Not sure how it sounds like for i/v though. Perhaps you can do an AB & share with us your thoughts Patrik. What equipment are you using ?

  54. Hi Patrick, this is the -15V PPS cap only which has to be populated in my tweak ! It deserves a try but you must unpopulate the 100 uF before it ! ANd also imho the two others one (-5/+5v).

    If those radial caps are populated, take care as the vias are very tinny and fragile ! Don’t risk the dac if no experienced yourself with such a task (I wasted a pcb already ! Advice of Pedja Rogic with needle works good, but you should be carefull and patient when processing like this).

    PPS caps are fragile, the more you heat it the more capacitance fall, so you should to be rapid when removing it, and better to have a capacimeter to measure it after !

    Yes, defintly try the AB… better than KIWI résistors.= imho!

    What is your front end ? SPIDF, USB ? from Aya 2 ?

  55. @ Jaffrie, almost diy straight through:) The only not diy is my Squeezebox Touch. My diy things R2R volume control, Firstwatt Aleph J and bookshelf morel speakers and cables.

    @ Eldam, i have populated the tweak parts really high so it´s easy to cut them and then they are as new again. Not perfect way to have them populated like this but for test i think it´s ok. The smd parts is another thing though. Don´t want to risk anything and maybe i´ll stick with the resistor tweak and populate C303 and solder down the radial caps.

    For now i´ve only tried Spdif but have populated every part for Usb use also.

  56. Good idea to solder high the parts ! I even don’t sold mines as the inner vias are conductive ! When I’m fine with my definitive setup, I solder !

    Patrik, a little off topic, I don’t know if you know it, I assume you do but it’s always good to repeat often with SPIDF:)

    – your spidf as your plug on your drive has to be 75 ohms : difference are huge when the plugs and cable are not matched. Sound of 75 ohms are not all the same, but the simple TV cable works fine, no more than 15 cm wire will give better result than 1 meter length !

    A complete list of my tweak is in this thread above on the 04-11-2015 with the BOM.I can’t comment partial tweak of it!

    Imho, in your case, the most important is to use the AB résistors first over the Kiwame.

  57. Hi Patrik
    As Eldam said I too use spidf . Bought some belden 75 ohm coaxial & terminated them with BNC connectors of 75 ohms as well. Dont bother with rca plugs. Noticed that your using lots of Nichicon FG ya . You might have to tweak some what around the dac. FG sounds a little too tilted up for me too much highs


  58. Yes i use 75ohm’s BNC connector and one Canare crimped BNC 75ohm’s Cable. Actually it is nichicon MW and not FG. Don’t know the difference though? Maybe i should try others now when it’s easy. I have some 100uf 16v KW lying around that i could try. Or can you suggest something to try? Or should i try to squeeze in some 100uf 6.3v Elnas even that lead space is little more?

    Also tried USB yesterday with my laptop windows 10, Foobar and Asio4all! Haven’t tried this before but this was also very good, maybe even better than spdif! Have to AB test this more🙂

  59. Nice Patrik finish it up let run in for a couple of
    days then slowly tweak from there.


  60. Nice work Patrik. Finish the dac let it run in
    & slowly tweak from there. That way you’ll hear
    either improvement or degration as you start to
    tweak. The AYA is really very well designed.
    You’ll hear changes that you make. As for caps
    talk later ya. After burn in you can start with
    Eldam’s recommended supply cap for the -15v first.


  61. Hello Pedja, Hi all,

    the next AYA is ready…famos thank you Pedja for that sharing…

    The sound improves great 🔊🔊🔊

    Pedja, at this moment i don’t use AC1, i have soldered, should i do something at this?

    Next project is I2S to PCM and simultanious mode at TDA1541A…


  62. Hi all,

    I would like to ‘deposit’ publicly my congratulations to Pedja, an another Aya had seen the light.

    I’m driving it with an Amanero, too.
    Maybe will post it later, i had directly placed, piggy backed it on board of the Aya, over the empty space of unused input sections.

    I had some adventures with my TDA chip, will do some testing later.
    But it sounds very promising, and I’m still at the initial phase..

    Ciao, george

  63. Thanks, guys. 🙂

    Yes, you could simply leave unused secondary to float, and the only important thing is to secure its leads from accidentally connecting around – and what you did is certainly one (and good) way to do that.

    I am all the ears.
    (For those who do not know, George’s tests are always interesting.)


  64. Jaffrie,

    If you do not already use safety earth (“protective ground”), I would not recommend to add it to the system because of the mains filter either. There are different scenarios regarding earth connection shortcomings and (rare) benefits, but with mains filter it is essential to lower the noise between two poles (hot and neutral), and so long as we talk about conventional passive filters, this can be done as a classic common mode low pass LC.

    Once you possibly start to use safety earth, you can add the caps from each pole to the earth ground.

    But in my view, the earth is (or should be) there for safety, and for no other reasons.


  65. No more tweaking for me🙂 Thank’s Eldam, Jaffrie and Pedja again! After a few days with the green resistors
    there was a little to much laid back/soft sound as you said Jaffrie. Actually i don’t like tweaking to much, it’s complicated and not easy to desolder and solder again and have a nice job done after that!
    So i decide to go all the way at the same time and have now AB resistors, no caps at C305,308 and no caps at C401-404. Also populate C303 and nothing at C306,309.

    I like it very much as it is right now. Before i listen to critical i’ll give it a few days more.
    A chassis is also on it’s way to put it in🙂

  66. Thank you for the thanks Patrick 🙂

    Something not risky is once you are happy with this is to choose the equilibrium you prefer with C7 & C6. But before it worths as you made this config to be sure you have a FC cap in the combo advised for C3 & its litlier mate. It adds the low snap with the C303 you already populated.

    I found yesterday than the equilibrium could change with the grade of the chip (a Gentleman sent me a single crown TDA1541A two days ago:)). Its extra clarity, lower distorsion and better dynamic and less projected sound is good with FM cap which fill the mid range.
    I envy very much the guys whom had the Taiwan grade TDA given with the populate kit which is equal to a double crown !

    about my little tests: but caps I already advised as an alternative to test, the FC 1800 uF/35V for C6&C7 gives something very interressant too in relation to the system you can have (fuller than the Fc 3300/25V but less snappy in he mid-bass…) just a matter of taste & rest of hifi system equilibrium. Différences are important enough to test it in relation to the others FC & FM values already talked imo. But don’t know in relation to the DS edition (mine is the 2014 non DS edition)

    @ Aron,

    I’m looking forward to read your own tests as Pedja Rogic said. I’m daily pleased with the natural tones of the AYA… and the greater lisibility of the single crown I have (big orchestra of jazz or classical are WOW !)

    Is it not important to remove R421/R422 if no output capacitors as your photograph (or at least lift the red wires?)

    Nice cabinet 🙂 Marantz or old Philips CD players ?


  67. Hi Eldam,

    i have no output capacitors as you can see at the photo. The red wires connect R421/R422 with output signal. I think it’s ground and important, isn’t it?

    You have good eyes, the cabinet is from old Philips CD-150, but i have one another for the nice AYA DS, it’s only to test 😉

    Have you news about Input stage i2s to PCM to run the TDA1541A at simultaneous mode?
    A solution such as JLsounds USB to PCM converter, maybe he can make once for us AYA-people or maybe Pedja can do once for us?


  68. I just talk of the red wire on the signal path which are at the place of the caps. The red wires of your main RCA plugs if they are the return Gnd MUST be connected to the Gnd of the Aya board like you did already.

    But imo the the resistor which are a 100K shunt from the signal path to the gnd should be lifted as you have no capacitors and there is already an output impedance ! But I’m a poor technician, better to ask to a cursed electronician to know what a serie 100 ohms résistors with a shunted 100K do ! I’m certainly wrong as nobody noticed that !

    My understanding is the JlSounds boards is not suited for the TDA1541A chip, it will not work… and it’s a good idea to match the impedance like you did with your USB board with 50 ohms plugs and coax wires. In the DIY way there is an “I2S to PCM” board which works but the question is :does the divider (74xxx chip) output in the DS which feed the DEM clock is ok with higher speed clock than the one planned for the embeded front end of the AYA ? You may ask to Pedja, it’s above my poor knowledge…

  69. Since Eldam strongly recommended Rhopoint as I/V resistor I wanted to get them for my DAC. Unfortunately Farnell doesn’t list the 1K5 type; so Eldam uses 1K. I use a EL84 Amp without a preamp, so I need 2 V rms for 1.5 Watt outputpower – enough for my 100db/W speaker, but it shouldn’t be less. So the 1K resistor is not for me! I tried a lot in getting the resistor from another source, but I was not successful – until today. I just went to Rhopoints webpage and made an inquiry. The result was, they are willing to send me 2 piece of them for a very moderate money (4 pounds per unit plus shipping to Germany (9 pounds) 🙂

    Nice surprise!

    Cheers Ernst

  70. Dear Ernst,

    I would ‘congregate’ with you, if they will to send more..
    Still looking for complete the dac, presently using it with passive IV. With satisfaction, though..

  71. Aron,

    These resistors are there to pull-down the DC voltage at caps output to 0 V. This is a sort of the standard, that ensures clickless connecting to the (pre)amplifier while devices are powered up. So if your output is DC coupled (with all the caution), there is no use of them, and DC will drift for some milliVolts anyhow.

    I have no plans for making either I2S or simultaneous data protocol standalone source for now. But who knows, maybe once…


  72. Good morning Joseph,

    unfortunately I had ordered them before I read your post. By the way, at the same time I found another source for them: Schuricht (https://www.distrelec.de/) does sell them as well, though a tad pricier.

    I’m just waiting for delivery of the Rhopoints and Shellack(for the ABs to be laquered). This means I have only 3 resistors per channel leftover to solder onto the boards. Everything else is done; the PSU works as it should. The single voltages are perfectly close to the nominal values 🙂

    So I should be able to fire it up within just a few days. I’m really looking forward to hearing how much this DAC in combinantion with Ians FIFO stuff betters my very musical Monica DAC, which is powered by a few discrete regs.



  73. Hi guys
    I’m almost done with my build and was contemplating the output stage options: go with Predja’s as is; try Eldams (nothing :)) alternative, or try maybe a more expensive output cap like a Jupiter copper foil cap.

    Any comments on either would be appreciated. FWIW what would be a suitable size cap to replace the yours Predja?

    Thanks for all the comments and help so far guys – much appreciated.

  74. Hi Brent,

    Pedja talked about that already in the other thread before this one : AYA II 2014. IMHO, every DS edition builders should also read this build thread before : full of tips 🙂

    You need to know the input Z of the next stage (pre or integrated amp). The more Z, the less the DC capicitance. I believe there is also a note on the manual if I remember. With a modern pre of 47K ohms input or 100 ohms, les than 0.2 uF may suffice.

    But also the caps add Something… so the choice should be the one which sound right in relation to the whole system balance.

    Of course you need to has good measurement and Stream to zero volt to be near micro volts drift and your pre to have a DC blocking cap at the input to avoid a DC blocking cap in the AYA II output.
    If a cap there are a lot of good caps and the result dépends as well of the result without it, so from the main analog caps and/or not (if unpopulated) the 4x 100 uF. You should proceeds with what you have.
    If possible : no caps ; then caps with the right value depending on the next stage input impedance. One of the best is Black Gate N serie, (but a rarity), Silmic 2 are good, foil caps as well if you need a low value. Sometimes, for a reason : a little correction, you may prefer an output cap : no universal answer here, you have to test by try&error to find the equilibrium which match with your ears & whole system. It is not the most expensive cap always the best, although you can not go wrong with BG N bipolar serie if you can find ones and from the good capacitance !


  75. Thanks Eldam

    Took your advice and read all the previous posts. Checked and my pre-amp has a “100kΩ shunted by 220pF”

    So according to your post and Predja’s I should be looking at 0.2uF right?

    Or direct as per your tweak. Saw you blew the OPA’s when trying your- how can this be avoid?

    Also with the current series 47uF caps as per BOM – will this have a effect on the sound?

  76. What I advise is always to go to the manual and original BOM as Pedja Rogic knows what he is is doing about good music reproduction ! As you notice, I’m just an enthusiast who share modest cheap tweak, just because I spent some time and found the tweaks good enough to be given to Audial or shared here on the blog. There is unluckilly no definitive answer to your question, and I just share my feeling here.

    Well I believe if you make no short when you trim to zero volt, it’s ok with the oaps ! Every one should have a spare pair just in case off the day the oaps will be out of stock.

    The larger capacitance value at DC is to go lower low-end (lower high pass). but with 100k I believe 0.2 uF should be good enough. If I’m wrong Something will correct the input.

    The bigger result for sound adjustement will be about the two main power cap of the analog stage. Advised to try first the signature of the BOM. Then if you have the BG standard Jaffrie uses is imho good if you have these capacitance values. I use myself since I have a FIFO front end :Panasonic 1800 FC/35V ! Very good with silked dome tweeter. if a compression driver, an ESL or metal dome or a too much climby treble, you may prefer the ones I advised before or the FM 1500 uF/16V. Without FIFO, I find the 1800FC/35 V 5 mm pitch to be awinner.

    Really dépends of the whole hifi. But to summarise : cheap to try before the 3 sorts of main analog reservoir smoothing caps as they are cheap and Worth to be tried (other dozen and dozen I tried already), then trey without DC, and ultimally with a DC if you feel it can please you (sometimes I like a good Amphom aluminium in oïl). I bet with the FC 1800/35V, the little demoniac character of it (what a snapp!)may match well with a DC blocking after the oaps. (notice here the 100 uf are not used on mine and I use the Allen Bradley but rohpoint for I/V). It will be always less transparent and clear with dc caps, but franky the goal of ultimate transparency is a common trap ! that’s the tonal result which is important as the non listening fatigue and you are the only one which can setup this in relation with your test on the hifi you have :).

    But always try the BOM, Audial is famous to have natural sounding devices when I read the tests here and there, my own taste can not be yours 😉 But for the low price of my tweak (but the Rohpoint I/V) everybody enough skiled should try with taking care of not damaging the board with re soldering)


  77. Thanks Pedja yes will add the caps for hot & cold when I try out the filter. btw Pedja have you ever compare the Taiwan 1541 to an S1 ? Had I known it was as Eldam said as gd as Double Crown I would have pick up a pc to try

    Hey Eldam whose that gentleman, heard that the S1 is worth the price of gold right now. Lol

  78. what is it that you prefer in the Taiwan chip Pedja n is there really a big diff between the S1 ?


  79. S1 is fine, but I honestly did not find it very special, in comparison to many other “regular” samples.

    Taiwan made samples are great for their smooth tone, authority and resolution. They may vary somewhat between particular samples, but are generally better than other series, S1 included.

  80. Hmmmm my S1’s is way above the stock Tda. i would tend to believe all S1’s are more consistant in comparison.
    Anyway my AyA DS is optimum for me now so not more tweaking. moving on to the next chain of replay

    thks again PedjaDZ

  81. Brent,

    In this case, with 100 k preamp input impedance, you should also consider the resistance of R421/R422, as they are effectively in parallel with preamp input impedance, so technically speaking 100 k is not negligible. For this reason you may increase their value to say 470 k. But even if you leave everything as is, and use 0.2 uF, you will have something like -3 dB at 15 Hz, -2 dB at 20 Hz, and -1 dB at 30 Hz. If you increase R421/R422 to 470 k you will halve these roll offs, and -3 dB point will drop down to 10 Hz.

    The good thing with such a low capacitance approach is that you can use for instance some old polystyrene caps, which are usually great, and which, if you do not already have some, are not any expensive.

    Either option above should work fine, but of course, if capacitance value is not an issue, you can simply “play safe” and use higher value.


  82. …..Soldered in the last parts today, I/V resistor, laquered AB resistors and a few other minor important parts. Then I soldered the supply cables and plugged in the u.fl plugs to the pcm board. Plugged the pcm board to the reclocking board, the reclocking board to the isolator board, the isolator board to the fifo board, the fifo board to the xmos usb thing. Checked again the voltage after the opamps. Everything looked ok. My heartrate meanwhile was pretty high. Wasn’t sure if I shouldn’t start with DAC only for the first time and only i2s in the beginning. But my decision was already taken. So I went up to my main system and connected everything. Pfuhh. Nervous!!! Heartrate very high and a big dumpling in my throat.

    It worked!!! Couldn’t believe it. Great sound, great sound. Thanks Pedja, thanks Eldam! I am really happy!!! 😀
    I attached a pic of my DAC, so you might understand my surprise when it worked directly.

    Now running in and thinking about an appropriate case. But this is not too important now.

    Cheers Ernst

  83. Excellent, it didn’t work immediately for me… great!

    Do you switch off the spidf/usb of the Aya II 2014 DS when you use the Iancanada front end ? Wgat cho ?icer of caps combo for C3/c3b

    and good BG N for DC output (you really have to try Pan. FC 1800/35v, sure it will be very good with the BG N you have after) ; the little black reg of mravica, pink Takmann carbon on the Aya… 🙂

    Nice picture…. modern Art ;)… and above all : good music 🙂

  84. Eldam, everything is as after your proposal. Just two things differs. Had no 1800/35,so I used FC 2200/35. Second difference is Blackgate N. They have been around for such a long time, I had to use it. Even it would work without in my system.

    I have neither the spdif nor the USB input installed, only what is needed for the relays. And the u. Fl plugs.
    Since I want to use the DAC for movies as well, the FIFO delay time is annoying. My plan is to bypass the Fifostuff by using an i2s switch from Twisted Pear after USB Xmos. One goes to Fifo and then via PCM board to AYA Dac, the other branch goes to second AYA DAC input, which is i2s. So I will be able to avoid the delay while watching movies and use perfectly both inputs. A switch will actuate both, the relays and the OTTO.

    When I have time, I’ll post a cleaner pic.

    Cheers Ernst

  85. Wondefull cap than the bipolar BG N, after a while, try it in the opposite sense : one sens is clear and dynamic the other sense is fleshier and darker… it helps to find the best equilibrium with the whole system!

  86. Hi Pedja,

    I have please a quesion about the divider chip without the 470 pF cap. Is there a BcK speed to respect in relation to the 14 x 0.1 uF DEM caps when one inject its own Bck speed like with Ernest front end above ?

    What happen if the crystals are 45.xxx or 49.xxx Mhz range ?

    Or does the divider can’t work without the Aya II own front end with its 50 Mhz XO ?

  87. Cheers Ernst, and thanks for posting.


    Ernst’s board is -DS, with divider input connected to the BCK sent to TDA. In that way, in -DS edition the divider itself will work with any source. Since TDA1541A BCK input is claimed to have a limit at 6.4 MHz, it is the TDA as a whole that sets the upper limit here, and not the DEM clocking circuit.

    In 2014 version, the DEM clocking circuit input is “open”, so it can be connected anywhere, including the source MCK, which is normally a higher frequency. In this case you should check if divider chip input can accept given frequency, and you have to choose the adequate output as well.

    According to Philips papers, with synchronous clocking necessity for DEM filtering decreases. I have tried going that route too, and tried removing DEM caps, but did not like the results.


  88. Thank you for the input.

    So if Mclk used, does it mean the external MClk should be 5.xxx/6.xxx Mhz XOs max with the non DS version ?

    Better to keep the clock from TDA pin 2 (Bclk) with a coaxial 50 ohms wire with the gnd shield connected near pin 14 (Dgnd) ?

    On the DS I assume this is the /2 output at the divider, so Bclk has to be max : 11.xxx/12.xxx Mhz. Better to use Bclk with the non DS as well (like the DS) ?

    Sorry if I mix the concepts !


  89. Predja

    Any advice on how to wire the isolation transformer for 230v. Not quite sure and it may be a silly question – sorry for what maybe a silly one.

    The primary of the isolation transformer gets the red and black lead from two coils connected = 230v.
    The secondary of the isolation transformer and primary of the step-down transformer simply connect each wire withs mate – black to black and red to red for each115v coil.

    Do I have it right?

  90. Eldam,

    If you use MCK as an input to DEM clocking circuit, you can also use 11.2896 MHz or 12.288 MHz, with probably any regular HC series binary counter, and maybe even twice higher frequencies, but you will have to check the max. frequency specifications of the given manufacturer.

    For digital ground routing, it is always suggested to use the point as near as possible to TDA pin 14. For shielding, assuming it is really only a shielding and not the ground path, it is not necessary to use this point, and in fact some power supply GND point can work better, or you can simply scrape the top side ground plane (actually ground fill), and solder the shield there.

    In DS version the whole DEM clocking part is moved physically closer to the TDA, so BCK path from TDA pin 2 is shorter. However my own AYA II sample is also 2014 version, and I connected BCK from TDA pin 2 to binary counter input (by the resistor), and it works fine too.


    It is no problem, of course, and this should be probably included into the assembly manual.

    Isolation transformer secondary windings should be connected in series, just like its primaries, when used with 230 VAC – the “outer” poles are then connected to the main voltage (step down) transformer. As opposed to the primary side, which “center tap” should be left floating, the center tap of the isolation transformer secondary side should be connected to the ground. This way the outer poles will have 115 VAC each, with respect to the ground, so they will be the same voltage but the opposite phase, and thus symmetrical i.e. “balanced”, while the voltage transformer will still receive its required 230 VAC.


  91. Antonio Maria Ferragut

    Pedja, could you make a simple schematics on how to connect isolation transformer to mains transformer in the 230v case?

  92. Thank you Pedja for all these inputs,

    Yes right my mistake, if clock wirering and coax the upper layer is indeed the gnd return 🙂 and not shielding !


  93. Antonio,

    Here it is. Colors may differ, but the principle is this. All windings are in series.


  94. Thanks as always Predja

    Hmmm. My isolation transformer hums once the load is connected. Is this normal?

    Could it be the earth grounding point?

  95. No, it is not normal.

    Is it the hum that comes from loudspeakers, or mechanical hum coming from transformer itself?

  96. Hello Aya Dac loving folks,

    There is recent talk of output caps here.. So maybe we could explore the options with Line Output Transformers too (in lieu of output caps.)

    I’ve recently discussed Jensens (JT-11-BMCF) with Pedja through email, and he has been graciously very helpful..

    I’m also looking at the Lundahl LL1684.. These have amorphous cores, and are said to be very intolerant of even a small amount of DC offset (saturates the core easily..) But has anyone tried these transformers with the Aya 2014 or DS?

    Another option is the Bifilar wound Cinemag CMOB-1H (High Nickel) types:


    They seem like direct competitors spec-wise to the Jensens mentioned above. They are slightly less expensive, but based on their heritage (winders for old Altec), looks like good quality too. Anyone tried ’em?

    Thanks for any feedback, or anything you guys may share.

    Best regards,

  97. Hi Frederick

    May I ask why ? My pass experience with Sowter did not convince me of its benefit.
    My opinion is for low voltage swings it adds more drawback then benefits. Yes highs & mid might be clearer but you loose drive, dynamics etc. Besides it becomes picky on the requirement on your preamp. Anyway PEDJA has done a fantastic job on AYA, aside from the tweaks that we made, there really is nothing more that u can ask for


  98. Hi Jaffrie,

    Thanks for chiming in.. Well, I like the sound of quality transformers in Dac output stages. But it all falls upon implementation I guess, and how suitable the output stage circuit is.. I tried it in parafeed once in another dac that was modified. But the nearby power transformer in that modded dac makes ’em pick up stray EMI / some 60Hz hum.. So line output transformers needs distance and most likely some shielding (the power transformer) in a fully DIY implementation.. BTW, I had Sowter MC step up transformers, obviously another app, but they were very undewhelming so I sold them (replaced by infinitely better Hashimotos.)

    Anyway, Pedja himself uses Jensens (as an option) in his current roster of commercial dacs. So I would think transformers sounds good to him too.

    I like caps too, don’t get me wrong.. Maybe like the new Jupiter Coppers suggested above, or Audyn Copper foils.. If anyone has tried ’em already.

  99. Hi Pedja

    How can I attach a music file. Like to share with fellow owners on how good the AYA is .


  100. Hi Predja

    The hum on the isolation transformer seems to have gone. I’m checking the voltages on the board. So far Ive resolved some of the issues which were my fault.

    I’m getting pin 28 +4.22VDC and on pin 15 -15.33VDC.

    Are these good enough? I’ve used Eldam’s mod on Caps 308 & 309 & 303 FWIW. Reason I ask is because all the other voltages so far are spot on.



  101. Hi Predja

    Found the pin 28 issue – BD139 put in incorrectly – its collector voltage is 4.2v so tats sorted. According to TDA data sheet the 15.33VDC is within limits so I’m guessing its fine.


  102. Frederick,

    This Cinemag looks pretty much like JT-11-BMCF copy. It looks fine, but I never tried it though, so I am not sure how successful copy.

    People from Jensen actually do not recommend anything above 0.1 mA running though its windings, so with 40 Ohm winding resistance the maximum offset would be 4 mV. However, as we already talked, in my experience these transformers work fine with ten times higher values. I guess they are careful with these specifications, which is good, but in the real world of such a DAC, with thermal drift of up to a 10, 20 or 30 mV, Jensen transformers do just fine.

    Also, without output coupling caps this DAC can intermittently send up to 3 V DC to its output, be it associated to the lack of proper clock signals at TDA input, or to the synchronous data mode of operation. Anyhow, Jensen can stand such a torture too.

    And, one more thing to consider here, and the one I probably also should stress in the e-mails, is the output buffer. Please note that OPA861 is not internally limited i.e. protected from short / overload, so care is needed in this regard too.

    With 3 V DC at its output, and 120 Ohm output resistor in series with 40 Ohm winding being a DC path to the ground, the output OPA861 might be intermittently due to provide up to 19 mA or so, which is about to test its capabilities.

    And, you might in fact be tempted to remove this series resistor, and thus let the output transformer operate the best way (with lowest possible source impedance), but in this case you might conclude that the output buffer should be able to supply notably more current, 75 mA or so. This is actually not the case, firstly because the AYA II output stage supply is current limited to about 55 mA, and secondly, even if we suppose that all this could be drawn by one single (“shorted”) chip, it must be shared between two sides of OPA861 current mirror (its “emitter” and “collector”), so in this case the (“emitter”) output would be this way limited to some 27-28 mA.

    BTW, TI tests revealed that the most critical OPA861 part in this regard is not any internal transistor but metal trace, which blows first. Now, is 25 mA or 30 mA enough to fry it or not? I would be the most happy if I could tell you from experience, but I never actually used AYA II with output transformers, so be careful. (I did use them with The Model / Model S DACs, but their output buffer is different.)

    BTW, speaking about possible coupling transformers advantages and benefits, do not forget that, instead of the DAC output transformers, you can also use the (pre)amp input transformers. They will work also for possibly other sources, and input transformers are often easier to design (as they do not require low resistance windings).


  103. Jaffrie, now it should be possible to add media files.

    And, one information… There was a problem with replies notification software here. It is (hopefully) fixed a few hours ago, however all the previous subscriptions are lost. So, to keep an eye on this topic, the next time you reply, please check the notification box below submit reply button, and subscribe again. Thanks.

  104. Hello Pedja,

    Thank you for the very detailed reply.. You’ve given me a lot to chew on. I appreciate the caution. I understand now that while it is possible to use Jensens, there are still big risks (plus it has never been actually tested in the Aya II..) All the while I thought that the Model S’ output buffers are “similar enough” to the Aya II that the risks of using line output transformers are almost non-existent..

    Best regards,

  105. Basically, AYA II was not meant to work with output transformers, but there are people using it this way. Still, transformers do like low impedance source, and things may get more complicated once you go this route, and remove the output resistors.

    The main advantage of Model S output buffer is that it is more robust than AYA II output buffer.

    @ Brent: Yes, -15.3 V is fine.

  106. Even if it works core size of the opt is important to good sound reproduction especially in the bass

  107. Hi Pedja,

    Thanks for the further clarification.. It’s interesting that there are those brave enough to use line transformers with the Aya II. Yes, from what I deduced in your explanation above, Robustness is the main issue.. And not an issue at all with the Model S II / USB.

  108. @ Jaffrie: Sure, that is why these Jensens are quite substantial for line level devices, about half kilogram each.

    The things with signal transformers however get somewhat different, once you move them from source output to the (pre)amplifier input. In that case you do not have a requirement for low winding resistance, and thus you can achieve required inductance by the winding, and not that much by the core.

    Further more, due to their higher winding resistance, I would consider such input transformers mostly safe for use with directly coupled AYA II output buffers. In turn, their reactive impedance components may be higher, so even if AYA II output stability is mostly managed by R417/R418, it is not bad to check that part too.

  109. Think its way better to use transformer as interstage instead either line out of preamp or between input n driver stage of power amp. Thks for your thoughts Pedja

  110. Jaffrie,

    Recording 11 was very sound; clear and bright. Recording 13 was a lightyear from the original sound; pretty muffled.
    Btw, Monica/Mojo is a pretty good DAC despite the simplicity. But I expect AYA II being superior after run in.

    Cheers Ernst

  111. Jaffrie,

    Human mind automatically concentrates on the the source i.e. on the direct portion of the sound, while microphone does not distinguish direct from delayed / echoed part, of course within its polar pattern. So I guess that is where the “difference” came from.


  112. Kenneth,

    Yes, several boards still remained, and two EI transformers as well.


  113. Hello Pedja,

    do you “burn in” your AYA Dac’s before shipping and what Sound do you use for it?
    Thank you for request.

  114. They usually worked for an hour or two, just to make sure everything is fine with them, but no longer than that.

    I have no special recommendation regarding burning in, apart from listening to the music, and waiting for a week or two. Burning in does not make miracles, but it is certainly audible.

  115. Brent Petersen

    My compliments to Predja on the design of this dac – my Marantz CDA94 sounds veiled when compared to this implementation of the TD5141A. The sound does make me smile and she’s not even properly broken in yet. At some point I will try some other output mods but for now I am happy.

    The DAC runs a bit hot though – around 50 degC for the Transformers and the dac chip – is this normal?
    Means I’ll have to add some serious ventilation to the box when I place her inside it.

  116. Thanks, Brent.

    A 50°C on the surface itself is still fine, even though it is on the high side.

    Of course, the temperature can increase, once you put the DAC into the box, so ventilation holes that make good air flow path might be welcome.


  117. Thank’s Jaffrie!

    Yes with this one i am. I have one more pcb that i’m going to tweak little different for fun.

  118. Hi Patrik,

    Nicely done! A photo if the innards would be great to see too…


  119. Thank’s Frederick

    Nothing special inside! The sec trafo cables was little short so i made them longer and i had some white sleeving over that i cover them with.

  120. Hi Patrik,

    If your load has DC blocking cap at its input, you can also try without the DC blocking cap. Different sound presentation.

    Worth to try it and keep the prefered conf.

  121. Thanks Patrik! I guess distance is still your friend even with a toroid.. I might just emulate your faceplate lay out, clean, with small toggle switches at each end, but most likely in black.. Thanks for sharing, and happy listening..


  122. Hi Pedja
    Forgive my ignorance, is this going to be a further performance enhancement over the present usb connection even on 44.1 k recordings


  123. Yes, it is the asynchronous USB i.e. master device, with its own master clocks that control the DAC directly (so no PLL), as well as data flow from PC.


  124. Hello Pedja,

    This is cool.. But does this also entail that the SPDIF and USB input sections of the Aya II DS be disabled for the new board to work?? Making the Aya II DS ‘purely’ a USB input dac, via the new USB to Simultaneous Data converter board?? The firmware thing where it could be switchable to I2S or SPDIF output is a bit fuzzy to me for now.. Maybe an illustration in the near future would help for us not so technically adept..

    I guess if we’re gonna have a chassis, having extra space for a new board and another transformer is a good idea..

    Thank you.


  125. Hello Frederick,

    You should disable only the AYA II USB stage, and connect this external USB board to U.FL connectors J301-J304 instead. AYA II S/PDIF input stage should remain available for use with any appropriate S/PDIF source (CD transport etc.).

    Existing USB stage can be disconnected by removing its output series resistors (R118/R119/R120). The stage itself can be also fully disabled by disconnecting its supply (AC1), which is recommended not only to make the chips there fully quiet, but also because that way you will have that transformer secondary winding available to feed this new board.

    I will still check the options of making this new USB board to output both simultaneous data, and I2S & S/PDIF at the same time, but the chances are it will be rather only one at the time, so either only simultaneous data mode, or (alternatively) I2S & S/PDIF mode. This board is actually meant as a PC (USB) interface designed for TDA1541(A), so having the outputs other than simultaneous data is not really the imperative. I2S and S/PDIF outputs is the option that should be understood rather as an added feature that keeps the board more “open”. For use with AYA II, it will be of course recommended to use this new USB board in simultaneous data mode.

    The only practical problem here would be that the TDA1541(A) mode in the AYA II 2014 / DS is not automatically switched between simultaneous data mode required for use with such a board, and I2S required for use with on-board S/PDIF stage – it must be done manually by the on-board switch (S3) instead.

    Regards, Pedja

  126. Hi Pedja

    Just for knowledge sake, Ian Canada is selling boards of similar nature I think . May I ask the difference between the both ? Goes without saying I offcourse will stand on your side cause it made especially for Aya


  127. Hello Pedja,

    Thank you for all the info.. I’ll just have to wait as more details about the board emerge.. Yeah, it’s great that we could save on another transformer by using the unused secondary winding for the Aya II DS’ USB input.. Noted on the (S3) manual switching for Simultaneous Data Mode.. A minor inconvenience, but if that tiny switch can be mounted off the PCB (for front panel chassis mount) without any drawbacks, then that would be cool..

    Any idea on the new board dimensions and on the USB socket placement on the board?

    Many thanks..


  128. Hello Jaffrie,

    I am not familiar with Ian’s board, nor did I ever had it at hands, but as far as I understand what it does is to convert between different PCM protocols. So with TDA1541A it can be used to convert from I2S (more common) to Philips simultaneous data protocol (rare), which is preferable mode for TDA1541A – please see:
    TDA1541A and Model S USB (part 2) – Simultaneous data mode.

    So, to use it with PC (USB), prior to it you also have to decode USB to some PCM protocol, which normally spells “you also need some USB to I2S converter”. In that way, to get Philips simultaneous data protocol to feed the TDA1541A from USB you need two stages, one to decode USB to I2S, and said Ian’s board to convert I2S to simultaneous data.

    And that is what in fact some AYA II 2014 / DS users did, and still do use. For some others, this turned to be too complicated. The “problem” is, apart from the old Philips CD players from 80’s (designs associated to TDA1540), and said Ian’s board, (and Audial Model S USB input stage, of course) there is nothing that can possibly feed Philips TDA1541(A) in this mode. This is also somewhat limiting factor in the Audial Model S MkIII use, in terms of its PCM direct input full utilisation.

    And that is how the idea for USB to simultaneous data converter board came. Of course, its USB part and clocks would be adequately designed too.

    Also, please note that this planned board would be made in a way to output simultaneous data protocol directly from USB decoding chip, so without intermediate conversion to I2S. In fact, I would have to change the plan somewhat to make it able to accept also I2S as input and convert it to simultaneous data protocol (as you can see from my previous answer to Klaus in the other topic). So if you would need to convert I2S to simultaneous data protocol, you would still need Ian’s board.


  129. @ Frederick:

    I would not recommend to wire that switch any further from TDA1541A, since those are TDA supply lines, and by doing this you will be at risk to pick up some interferences. You might notice that in the Model S MkIII the switch that changes TDA1541A mode is at back plate, but it actually only controls the switching relay.

    I am still not sure about possible board dimensions, but it should be relatively small, say something like 10 x 5 cm, or close to it.


  130. Thanks again for the tutorial Pedja.
    Frankly to me all this conversion is still
    beating round the bushes for the sake
    of convinience & creating more issues
    to mess up the sound. I don’t give a damn
    what others would say, me I still believe that
    we have not reached the ultimate in Red Book
    play back yet. Would be nice if your board is
    strickly I2S to simuteneous mode. That way I
    can connect either a CD transport or SD card
    player directly to AYA or can I via AYA DS ?


  131. Hello Pedja,

    I appreciate the detailed response.. That would be a relatively small board, nice. SMD parts helped with the economical size I guess. Thanks again.

    Best regards,

  132. Predja
    Just a clarifying question re the isolation transformer wiring:

    The secondary center tap which is taken to ground in your diagram: is that the power socket ground, the chassis (only) as a ground, or the pcb ground point, or could this be left floating?

    Currently I have it running on the mains earth but would like to avoid it as my mains earth has a 5v voltage sometimes.



  133. Regularly produced Audial DACs have an isolation transformer secondary center tap grounded to the chassis earth / ground point. This point is located at the bottom plate, near the mains socket, and it is also where the earth lead from mains socket, and PCB ground (C2 ground side, or pad next to it) are connected.

    Of course, the insulation has to be removed / scraped from the plate at that point. Ring connector (or spade, alternatively), screw and nut work fine, and you can use one ring for several leads.

    You can use such a setup also without the earth connection from the mains, of course provided everything is safe without it.

    Also, you can leave the secondary center tap to float, but this way you will have conventional 1:1 isolation transformer, and not so called “balanced power”.


  134. Hi Predja

    Thanks for the reply. Just to confirm the option for wiring where the secondary centre tap is connected to only the chassis – is it balanced?


  135. Hello people,

    whichone Isolation Transformer do you use? And is it sense or can i spare the money?


  136. Hi Predja

    The Standard EI transformers you supplied are EI-75 correct? I’m trying to source end bells for mine and just want to be sure as some manufacturers don’t specify the dimensions.

  137. Brent,

    If chassis is connected to the DAC ground – yes, but if chassis is floating or it is connected only to the mains earth – no. What “balanced power” makes balanced is its symmetry around actual device ground, and not around the mains earth.

    As for the supplied isolation transformer, yes, it is E-75 core.


  138. Hi Predja

    I guess the next obvious question is where is the best place then to take a ground connection from the PCB-to-chasis for the balanced operation?

  139. Hi All,

    Anyone had good news about their AYA integration and/or tweaks ?

    Have some tested mine with sucess (or not) ? 🙂

    Any subjectiv improvement with sourcable passive parts found till the beginning of the year ?

    regards to all,


  140. Hello Eldam and other Aya II DS builders,

    I’ve listened to the Aya for the first time with Jupiter Copper Foil 100V coupling caps the other day, it was playing for a couple of days at a friend’s house he installed ’em for me (mounted outboard from the pcb ‘cos of their size..) Bottom Line: These caps are like they were made specifically for the Aya DAC, they go together beautifully sonically.. Very impressive to say the least.. BUT the heart of the lifelike sound / natural tone is Pedja’s excellent design. He’s a real wizard.. I took a calculated gamble on this DIY dac and I’m very happy I did. Plus Pedja is a pleasure to deal with.. I can’t imagine how his more sophisticated finished Dacs sound if this DIY design is already this good..

    BTW, everything else is stock on the board except for the coupling output caps.. For now I’m doing some adjustments on the aluminum chassis that were locally made for me (the screw holes) .. The aluminum top cover flexed a bit after painting and baking in an oven even if fairly thick guage.. And I have to adjust or change the footers too, some loose thread on one of the screws.. I’ll post photos maybe next week or so..

    And oh, it already sounds really good with Jriver playing ripped cd’s to .wav for the USB input..

    One day Eldam, I’ll get to try your Cap tweak provision on the board..


  141. Thanks Frederick,

    Looking forward to see how it looks once finished 🙂

    It’s true it is a long time it has begun : 2014 and a little less for the DS version !

    Does anyone know what is the minimal input impedance the AYA II is able to load whithout the last buffer stage (with just the first OPA861 and the 110 ohms output serie resistor (shortcut protection) please ?

    I’m without the DC blocking caps and the 100k shunt résistors before the RCA plugs.

    Sorry if already asked



  142. Thanks, Frederick.


    There is no exact equation or relation that can tell the minimum loading impedance for such a direct I/V output, but I personally would not go with less than 10 kOhm, simply because that additional load will act as a part of the I/V conversion.

    Also, be careful when connecting this node directly: many years back when I was talking to the OPA861 designer, he told me that they found OPA861 “collector” to be more damage-sensitive than its “emitter”.


  143. Hi Pedja,

    Thank you for the tip. I will remember it when choosing a new Preamp (mine being the weak link of the hifi system now)

    So I assume it is more confortable to use a volume pot nearer than 10K than 100K, to setup the spl volume at home. (not using the pot in its higher attenuation position and have also a better headroom confort zone with the pot nearer to 21H00 or 24h00 position…).

    Best regards


  144. Usually the potentiometer value is chosen as a highest value that still preserves stable conditions at amplifier’s inputs.

    As for the attenuation levels, it is the potentiometer curve that determines this, rather than potentiometer value.

    Anyway, if you are in search for pre-amplifier, I would strongly suggest the low impedance shunt potentiometer, as used in the Model A. This would require the output buffer in the AYA II (it will drive 1 kOhm and lower impedances with no problems), and due to fixed series resistance the atenutation curve can not be fully logarithmic, but it is still the best sounding pre-amp “topology” I am aware of, and certainly the best if you can use cermet pot.

    More details on such a pre-amp / potentiometer will follow in one of the upcoming posts about the Model A.

  145. Thank you very much for all that.

    I have been thinking to putt a pot between the 861s but finally I don’t want to waste the good layout and grounding of the pcb ! And certainly will waste the zero trimming stability made before (I’m with no DC outputt cap conf as my actual preamp (the said weak link now)has DC input blocking caps!

    I had also a thought about putting one pott after the 861 buffer and putt a buffer again after the pot, a 861 inverted again or one of the very dead quiet of Texas Instrument/BB in unity gain… But I gave up as I’m not sure it is more transparent than my 47K ohms input Pre (a Yamaha C-X2).

    Looking forwards to read your next paper about the Model A pot input stage…

    best regards


  146. Hi folks,

    I stole Patrik’s faceplate layout a few pages back. Except mine obviously is in black (aluminum chassis) with a black acrylic fascia. I’m still unsure what type of feet to use. One of the hardwood feet that was made for me didn’t come out right..


  147. Here’s the innards.. I could have ordered and used Tektronix clone ceramic type tag strips instead of plain tag strips. But that’s what I already have locally.. I also ran out of cotton sleeved solid core 23awg copper wire for the caps, so one channel has slightly shorter wires for the other Jupiter coupling cap.. Thanks..


  148. Really nice chassis in black Frederick👍 How does it sound with those 2 extreme Jupiter caps? I would also want 2 of those, but couldn’t afford them right now.



  149. Hi Patrik,

    Thanks! You inspired the faceplate layout, so big thanks to you.. I made a comment on my initial glowing impression on the a few posts back (but I think it has more to do with the dac’s overall design, and the new caps were just icing in the cake in clarity..) There’s still some breaking in to do for the whole dac.. The caps were on sale when I got them, and they’re relatively affordable compared to those other high end boutique non-film caps.. I’ll most likely update my impressions one of these days when I get to listen to it with other speakers/systems.


    BTW, it would be interesting to know what kind of speakers Aya (original or II DS) builders personally use in their system.

  150. Thanks for this inputt, it helps a lot.

    Because I have no clue of all these things and I don’t want to waste the nice sounding result of the AYA II. My last “bad” idea was this time to putt a Muse vdigital volume control chip from Muse after the opa861 buffer. This chip has the advantage to have only a lader resistive attenuation network but no embeded aop which are not always good at this low level of miniaturisation (while being often on the diamond buffer shematic 🙂 ). And also it seems it has on one side the numeric stuffs and the analog on the others side which is “maybe” simplier for the layout !

    Unfornatully, it says notthing about the sound quality when just embeded simply in a dac with just an output buffer ! So I prefer hundred times a solution which I know works already well with the AYA and ears certified 🙂 !


    PS not finished the casing because of that, plus the landing of a Raspberry P3 as Library management device (usb or I2S outputt, both good for the AYA II 2014 & DS edition)

  151. …. while the rasberry Pi is not able on its own to be Simultaneous mode ready 😉 …. but still can see an output device which can be simultaneous mode ready with uf-l outputt for the AYAs…. 🙂

  152. Hi Pedja,

    Thanks for the kudos and footers recommendation.. The hardwood feet (with some soft damping underneath) made for me were unevenly turned, obvious for 1 foot at least. So it was a no go even if it did sound good with them..


  153. Hello,

    There were several special, mostly DIY oriented AYA II DAC (TDA1541A) offers during previous years, and one of them is this you can see in this topic. The AYA II DAC has been however officially discontinued in 2009.

    For regularly available products, including two non-oversampling, TDA1541A based, Model S DACs [1] [2], please visit Audial online store.


  154. Hello Pedja,

    Traffos arrived today, many thanks.
    I have a question please when looking the connection shematic you provided in the previous page of this blog.

    I use 230 V. So the primary and the secondary 2x 115 V are each tapered in serie as the shematic, ok. But I see the tapered SECONDARY is connected to a ground : I believed it should be floating as the tapped primary ! So where must I connect the tappered secondary of the Isolator transformer to the AYA AGND (where?) or to the Earth of the wall grid (in the case I have one) ? Or can we use the two secondaries of the isolator transformer to have a symetric voltage as the main traffo has also a main 2x115V primary. Sorry if stupid questions, total lack of knowledge about that !

    About the beaming : as it’s diy and I can : does it worth to put the isolator transformer outside my AYA wood cabinet, far from it (at one meter for instance in an iron case) to prevent more beaming on the digital front end, or is it of a non interest (non hearable) ?

    Thank you in advance



  155. Hello Eldam,

    You can leave the isolation transformer secondary center tap to float, and then you will have usual mains isolation (1:1) transformer. But, if you connect this secondary center tap to the ground, then you will also have so-called balanced power, with it is own benefits.

    In Audial units, this tap is connected to the chassis earth ground point, which is the point at chassis, near mains socket. The same approach usually works the best even if your home electrical installation does not include (safety) earth (might be the case with older buildings).

    Putting this isolation transformer into the separate enclosure or chamber or simply further from the other electronic, and even further from the mains voltage transformer, is always the good idea.


  156. jaffrie chen

    Hi Guys,
    Was wondering if anyone here has a USN version ll board for sale ?

    Thank you

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