Upgrading a simple Class A amplifier with better components

[Mark Tillotson]

For a class A amp the obvious thing to check is the temperature rating of the caps - 105C or better would be good for good lifetime at elevated temperatures. Its poor design for class A to have the pcb mounted on the heatsink as they run hot all the time.



Adding thermal insulation between heatsink and pcb would help keep it cool.

 

[OldDIY]

Set # 1 is for use in an around PC speaker. Power supply 12 v. The output power is less than 3 watts. Output transistors and driver Chinese TIP41C. The radiator is small with horizontal fins.
If you take only the PCB and replace the parts, you can build JLH 1969.
JLH 10 Watt class A amplifier

 

[JMFahey]

1. Which components here might be worth desoldering and replacing with higher audio grade components?

None.
If you want better sound buy a better DESIGN.

I've heard good things about capacitors from: Nichicon KZ Muse, Nichicon KG gold Tune and Elna Silmic II.
Is it possible that I would hear better audio if I would replace these caps with "better, audio grade" caps?

NO.

2. In persuit of higher quality audio, am I allowed to simply ENLARGE the voltage or the capacitance (or both) without any riscs?

NO
In fact you might actually worsen sound, if higher voltage was achieved by sacrificing other parameters.

I want warm mids, deep base,

We all do, but6 that will NOT change with capacitor brand or price.
Try a better design instead.

and enough headroom for momentary energy going to the voicecoils of the speaker (active system, so no passive filters inside the speaker).

Get a larger amp, period.
Double the power will give you 3 dB more headroom and so on.

3. What are the two blue potentiometers for? I asked the distributor about what these are/do, and he simply replied:
"Please don't touch them: the designers have tested every single model by hand before shipment!"

Excellent answer, do not mess with them.
You have no clue so you are dangerous.

So upon receiving the amplifier, what should I measure where, with my voltmeter sothat I can check (over time) that the potentiometers are indeed set correctly?

You have no clue about what to measure and which should be the proper values so trust the manufacturer who knows better.
By the way, WE can´t suggest anything either.

I have upgraded my speaker crossover and amp capacitor with better ones, and the sound difference was HUGE!!!!

We are talking amplifiers here, not crossovers.
Micro amperes of current involved vs. full Amperes.
Not even comparable duty.
And your single opinion is untrusty, you are a biased witness.
Doubleblind testing was invented to avoid that.

 

[phase]

I'm sorry to disagree...

Do you realize that you are responding to a thread that’s over 2 1/2 years old, and that the poster in your case is certainly not going to read your reply, as he’s moved on from this world?