Introducing the Model A

The first Audial amplifier release is near.

And, as announced earlier this year, it will be stereo amplifier, based on National power opamps. Those who followed my previous work with these opamps will be probably interested to know the way the original design evolved – and many parts of it indeed have changed.

Evolution in the amplifier itself was notably associated to the use of lower impedances. Back in 2002 I followed the (main)stream that dictated the use of high impedance input amplifier, and that was why I settled on and experimented with input buffer. (The one I recommended was very good one though, dare I say.) Since those days I moved however practically entirely to quite capable sources, which can drive sub 1 kOhm impedances with no issues. Apart from putting an input buffer out of equation, this also made possible to design volume control at lower impedances, which appeared to improve potentiometer based volume control to previously unexpected level. Such a volume control clearly overcame any other option, whether it is based on a classic pot, resistive attenuator, TVC, LDR, or even digital potentiometer. Yes, such a low input impedance appears quite radical change that breaks some traditional audio concepts, and relates closer to some other electronics worlds – but its sonic advantages justify that easily.

And that is why the Model A is recommended as (“integrated”) amplifier with low impedance volume control to anyone having a source that can drive 1 kOhm load. All Audial DACs of course count here,  and you might be surprised, many transistor based devices can do it too. And in my opinion, when used this way, Model A is a highest class amplifier, regardless of price.

For those with different requirements, different Model A options will be offered. So it can be shipped with more conventional input impedance (25 – 50 kOhm), with or without volume control. Model A will normally have one input, but it can be also equipped with two inputs, selected by toggle switch at back plate. (So we avoid adding any significant internal wiring, and also make minimal compromises by avoiding rotary switch.) It will be 25 W amplifier, but on request its power can be increased (more than safely, of course) and it can be shipped as 50 W version too.

Model A will have a passive, and not active regulated supply, even though the one I have published decade ago was very good, and became very popular in the meantime. Dynamics and deep and effortless bass I heard later from SMPS made me scratch my head, and move from where I’ve been back then. The problem with SMPS however was that it just got dry and tiresome after some time. So another work was obviously required. And it took some time to think about it and to solve a couple of puzzles, but ultimately I found well tweaked passive supply setup actually able to provide all the good sides of both linear regulated and SMPS options, with no shortcomings.

Regarding the parts, there will be standard and premium Model A versions, and later will include pure copper connectors, uninsulated internal wiring, and cermet potentiometer.

And yes, we made somewhat new chassis design too.

The first pictures and other release information you will find here in about ten days, so before the end of this year.

 

Related topic:

Model A, the first appearance