How about even simpler with good clean sound?

[thaumaturge]

Guys, I know I'm really a noobee here but the simple amps I'm seeing are all WAY more complicated than the first diy solid state I built back in 1978.

I made lots of logistic mistakes on it but it still measured out at -90 s/n and .01% distortion (residual of gen) and was flat to about 200KHz using ho-hum parts. (Would actually still do 30+ watts on AM band)

Outputs were 3055/2955 (since updated to D44VH10/D45VH10's), had TO-5 2N2905/2N2219A drivers, a plain old 4558 op-amp 2 1N4148 bias diodes 15V zeners for the op-amp and a handfull of passives and boom it was done! Add some honking filters, a bridge and a 44VCT transformer it pumped out sweet 50W RMS per channel....

So would there be any interest in a schizmo of it? Maybe update the op-amp to a 5532 or LM4562 ?

Doc

[transistormarkj]

You may want to check out the "Chip Amps" section, those schematics are even more minimal. They reflect the state of today's art about the same way as your 2N3055/2N2955 amp reflected 1978's state of the art.

[thaumaturge]

Hokay.... Were actually MJ(E) flatpaks. Point was that it was all discrettes and even if you smoked it you could replace every semiconductor in the box for under $10... But if being an old design makes it a boat anchor, so be it.
Doc

[godfrey]

Let's have a look at the schematic anyway.

[thaumaturge]

Will do so after I read up about posting pics here.... just tried and failed.
Doc

[godfrey]

You need the "manage attachments" button in the "additional options" section of the reply page.

[ingenieus]

From the details that you give, it sounds very similar to this circuit from Elektor.

Have you seen my thread?

Very simple class B amplifier

We are working out the details of how to make an amp that is even simpler than this.

[thaumaturge]

Best as I remember it at the moment. Drivers were 2N2905A / 2N2219A Sorry if this comes out weird, first pic I've posted here and every Forum is different in how they deal with such. Anyway, obviously missing a few values but the basic gist. Floating caps shown are optionals applied as needed if the amp decides it's an oscillator. Seem to maybe recall some resistors there as well. My schematics are on the other side of the state at the moment. Will fill in the blanks when I get access to them.... assuming there is interest.

Doc

[buzzforb]

This is really not that simple if you consider the op-amp. Do something simple and discrete. N0 simpler that gainclone

[thaumaturge]

Guess it depends on what your goals are as well. An LM4562 op-amp has a noise spec of 2.7nV per sqrt/Hz. GOOD LUCK pulling that out of discretes for your front end. I know this design is quiet. Using just a 4558 it ran about -90db s/n. That's quiet enough that between cut one and two of a new ECM vinyl record I thought my amp had broke... because it was dead silent! Then the second cut started. Whoa! Good enough for me! Doc