VSC Amp, Looking for Sonic Improvements

Don S

2006-11-25 7:09 pm
I call this amp the "VSC" for Very Simple Circuit!

After thinking about this for a long time, I have decided to post this. I know it will open up many cans of worms. That is not my intention.

This is not in a pursuit of POOGE solutions. I am looking for valid, explainable improvements to the circuit operation to increase its listening pleasure. I will give a simple example of what I am talking about. The original driver emitter resistor was 100R, after talking to many forum members it was suggested that I change this for a much lower value. The difference was well worth the extra heat on the drivers. I can say for sure that every area of the amp’s performance improved. This was due to the drivers operating in class A most of the time, and also this is where the drivers are at their most linear operating point. These are things that are not thoroughly discussed in electronics theory.

I am looking to improve the sonic performance without changing the basic simplicity of the circuit. I would like assistance tweaking the component values, FB compensation, semi-conductors, and connection layout in the pursuit of increased audible performance. By that I mean warmth, depth, space and air.

As it is now I have an amp that is detailed, dynamic, and very controlled. These are all very good qualities in an amp. However it misses the mark in the areas in the paragraph above that prevent it from being a true music lover’s amp.

I believe that the stages of the amp that would benefit most from circuit changes are the LTP, and the VAS. Everything beyond them is a classic EF, with devices and component values that are close to many outstanding amplifiers.

Below is the circuit. I am running +/-73V rails at idle.

Please help and enlighten me!

P.S. Happy New Years to All

Don S


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