choices, choices !!!

Hallo all,
Would an amplifier sound different or better when two of them are built precisely the same topology and the same build but the rail voltage of one is +- 50 dc and the other +- 70 dc. Off course with higher voltage components. What I am trying to determine is that does a higher voltage has any advantage over a lower voltage build, all components within their SOA off course. Some people say that higher voltage amps sounds better and more open ?:confused: Plse help before I start my Slewmaster build to try and do it right from the start. I do have 4 ohm AR66bx speakers that I love. :) BTW it is the five pair vertical fet amp that I am building.
Last edited:


2003-02-11 9:02 am
When you increase the voltage, the operating points of every transistors also change (for better or worse). Increasing V by keeping R constant would probably increases I (and for many transistors this may also increase linearity). In most situations this is a good thing. But in general it is a measurable performance change. (So ask the designer, how much improvement or reduction in performance by using different voltage).
I would say it depends on the design. If the amplifier is designed to operate at ranges including those in question, then it should be linear within that range, and thus won't make any difference whatsoever. If they have the same gain, you can use one for left and one for right without hearing any difference at all. The only considerations are output power requirements and device ratings (just about every component).
The VAS in particular distorts. That distortion varies dependant on the proportion of the full swing that is used.

If one compares the open loop distortion of the low supply rail voltage amplifier to the high supply rail voltage amplifier you should be able to see the VAS proportion effect.

Then use NFB to reduce that open loop distortion and they both appear to be somewhat similar.