What contributes most to a change in how an amplifier sounds?

@atmasphere 

It all sounds amazing.  It's so complicated.  Very elegant prose.  SAT verbal score was kinda low so forgive me I don't understand this too well. Some scary things related to a D amplifier.  Wish I would've pursued an advanced degree maybe this would've helped.

"What contributes most to a change in how an amplifier sounds?"

amp designer, manufacturer, components incl. tubes, speakers, listening room acoustics, preamp incl. tone control feature etc., listener, music program and source, cables, RFI environment. 

amidst all of these really good comments there were no comments from people who actually build amplifiers that I could see. It would seem to me an amplifier designer is putting together an amplifier he would need to choose between lots of parts to create something that was good. I would love to hear what these parts are contained within an amplifier that impact sound which is really what it’s all about.

What is it about the transformer?? What is it about the wiring? What is it about the chassis? What is it about the chips? What is it about the capacitors? What is it about the power of the amplifier? etc

HI alexberger,

Understand that you have tried various ways for improvement on the cathode RC bias circuit. I experimented using the simple transistor/mosfet shunt regulator to replace the RC. First of all, the bias voltage can easily be adjusted. Secondly, it doesn't not require any bypass capacitor at all. 

I am happy to share the schematics with you.

Johnny

What is it about the transformer?? What is it about the wiring? What is it about the chassis? What is it about the chips? What is it about the capacitors? What is it about the power of the amplifier? etc

@emergingsoul Which transformer- the power transformer or output?

Steel chassis are effective shielding at audio frequencies; not so good at RF frequencies. If there are tubes you don’t want the chassis to be resonant. This is less important with solid state. If the circuit is fully balanced and differential you may not need the chassis to shield anything. But with single-ended this can be important.

The insulation of the wire is probably the thing that affects it the most, since you can interchange the word ’insulation’ with ’dielectric’ which is something found in capacitors to insulate the plates from each other. Put another way, wires cause stray capacitance. They also have an inductive property but that isn’t an issue at audio frequencies.

Chips- that’s a tricky one. Since opamps are chips I’ll just say that opamps from 40 years ago are not nearly as good as opamps are today. So older opamps have a ’sound’ which is why you have to be careful changing them in guitar effects pedals because you can alter the sound of the pedal. Guitar players are very picky about that sort of thing.

Capacitors are affected by dielectric absorption of which Teflon is one of the better insulators, followed by polystyrene (which is a lot harder to find these days), polypropylene and mylar. Paper capacitors are pretty terrible but they have a following because of the distortion they make. Another factor is ESR (equivalent series resistance) which should be kept low; the higher this value the longer the cap takes to charge. Caps can also change value with temperature; this is called temperature coefficient. There are caps nowadays called ’NP0’ whose value do not drift at all.

Really if you want to learn more there are books for this sort of thing. Norman Crowhurst wrote some wonderful stuff 60-70 years ago and his books are worth finding. Many are on http://www.tubebooks.org/technical_books_online.htm