TDA1541A and Model S USB, part 4: TDA1541A grades and series

One of the questions I’ve been receiving from prospective customers has been like this:
“Which TDA1541A grade is used in the Audial DACs?”

And it obviously suggested people’s ultimate wish to have something precious – still, more often than not, it was naive to some extent. I say this not only because Audial DACs are famous for using all quality parts (and not one or two for marketing purposes), but also because those who really know the difference between TDA1541A grades are extremely rare. Err, and I’ll take a trouble to say this, if you can find one at all.

So, is S1 (single crown) really better than plain TDA1541A (or non -A), and is S2 (double crown) then better than S1? So if you have a plain TDA1541A (or non -A), can you improve upon it by installing S1, and can you further improve by using S2?

The only positive answer goes partially to the last part – if you have S2 you can not go further than that – and if S2 were still available I would put them into Audial DACs (indeed, at least to avoid those questions). But at the end of the day, the whole situation with TDA1541A grades is not that simple.

To avoid misunderstandings at this level, let me remind you these specifics: TDA1541 (non -A) was launched in 1985, and it had no grades – funnily enough, this early 1541 was normally specified for exceptional 1/2 LSB linearity.

The grades came with TDA1541A, which superseded TDA1541 in 1988. Both S1 and S2 grades are specified for their THD+N of 0.45% (-47 dB) at -60 dBFS, as opposed to 0.8% (-42 dB) specified for non S TDA1541A. In addition, S2 is specified for THD+N of 0.0014 % (-97 dB) at full level, as opposed to 0.0018% claimed for non S2 grade. It is important to understand that the S versions are guaranteed by Philips for this performance, but the fact they are guaranteed doesn’t mean that non S grades can’t match the same performance level. As a side notice, apart from S grades there is also R1 grade, however Philips documentation is kinda confusing about it – sometimes it is slightly better specified than unmarked TDA1541A, sometimes it is inferior – and my findings are that it is indeed inferior.

Going through a bunch of different TDA1541A (and non -A) series over the time, one thing came to me quite clearly: every series of TDA1541(A), and there were quite many as there were different production runs that spanned more than one decade and different countries, so, every series of TDA1541(A) performs somewhat distinctively. This means that each series shows both somewhat characteristic distortion pattern, and somewhat characteristic sonic properties.

I tried to point out this issue about five years ago by posting these plots for several different TDA1541A series:
http://www.diyhifi.org/forums/viewtopic.php?p=13118#p13118
(Scroll down to the last post at this page, and also see the next page comments, please.)

As you can see at these plots, two out of three non S1 TDA1541A chips in fact fulfill S1 criteria, and it is only the one marked as R1 grade that doesn’t do. And what might surprise you more, both of these non S1 chips perform in fact slightly better than S1 chip, though the difference in this regard can be considered negligible.

In addition to this, my later experience with additional TDA1541A series in some way also confirmed Carlos’ guess. It doesn’t apply entirely, as you can see series HSH8844 performing better than HSH8910 (S1 grade at that), or say HSH9314 (this one I measured later, so it was not shown at these graphs), however newer TDA1541A series, those made in late 90s, often perform better than the older ones. (Please note: two first numbers of the code mark the year, and another two numbers mark the week of production, so 8844 means that it was made in 1988, week 44.)

Apart from S2 versions, I ultimately found the best performing version of TDA1541A, both objectively and subjectively, the one made in Taiwan in 1998. In fact there were S2 series originating from the same process, and samples not marked as S2 achieve actually very similar performance. An effort to improve upon this sample of TDA1541A by installing (genuine) S2 sample was reported also by customers as ineffective – no sonic improvements were noticed.

Taiwan made 1998 series is the one used in the recent Audial DACs. And once the available stock is depleted, Audial will cease TDA1541A based DACs production – it became too tough to ensure the same or similar performing TDA1541A chips on regular basis. And in days when even TDA1541A series that didn’t pass basic quality control are leaking to the market, and as I went through the mess of receiving completely fake TDA1541A samples even from renowned stores, it would be too much still to ask for that.

 

 

 

 

Related topics:

TDA1541A and Model S USB, part 1: 192 kHz?

TDA1541A and Model S USB, part 2: Simultaneous data mode

TDA1541A and Model S USB, part 3: TDA1541A today

 

 

One Reply

  1. 07-11-2011

    And as a follow up for those still wondering about consistency within the given series… So, do the samples originating from the same run also sound and measure the same?

    The answer is: sonic properties are generally consistent within the series, even though the measured performance can vary. And yes, that is opposed to the findings on different production runs: they usually show some sonic differences, even when they measure practically the same. (Here I wouldn’t go deeper into this issue, but I hope that the reasons behind can be also understood intuitively – even if this might appear somewhat puzzling for the moment.)

    As for behavior of series used in the Model S USB (HSH9815, HSH9822)… At -60 dBFS, even order components are usually residing between 52 dB and 55 dB below the carrier, which applies to the lower order harmonics, which then usually decrease for about 2 dB until twentieth harmonic. Odd order components level might vary more – for some samples these are up to 5 dB below even order ones, which puts them on pair with S1/S2, but sometimes these can equal the even order ones, which is why claimed general performance of the Model S USB at -60dBFS is not better than 0.8 %. In practice however the odd order components of this series still never goes above that of the even order ones, as is the case with previously shown HSH8940 (R1), or say with HSH9314, which total distortion figure at -60 dB can exceed 1%.