"Punch" mini-amp with a 32 Ohm speaker?

[antonis]

I don't know what you have fed your simulator, but I think it is not the schematic I posted.

R6 value was wrong..

[Clint Eastwood]

You can greatly increase the efficiency with a push-pull output stage and still get class A. 

The amp will sound different I imagine. You get less of the lo-fi sound with lots of 2nd and third harmonics.
I wanted to build it, but cannot find a high impedance speaker in my scrapheap....

Below is a version with a Jfet as first transistor, now the input impedance is guitar friendly.

R6 value was wrong..

συμβαίνει στον καλύτερο από εμάς   (I hope my greek language simulator makes sense..)

[Rob Strand]

The amp will sound different I imagine. You get less of the lo-fi sound with lots of 2nd and third harmonics.
I wanted to build it, but cannot find a high impedance speaker in my scrapheap....

Quite possible.    I suppose from that perspective you could have a low current version of what you have then feed that into a buffer stage which doesn't clip and drives the speaker.

[SeneX225]

Hi! Sorry I've missed the updates, was busy at work for the best part of the week.

First of all: thank you very much for your effort on the schematics!

I've been raking my brain how to lay hands on a TDA7052 (which turned out to be very hard and more widely available TDA7052A, for all my research, just wouldn't do), but both of your circuits have a distinct lack of any chips, which sits with me just right.

I will (or, at the very least, attempt to) build both versions, of course. I'm very curious about differences in sound. 

I have, however, a couple of (probably) very rookie questions, regarding this schematic:

It's possible to simplify a few things but I'm not doing it.   The idea is only to show push-pull
you can get class A and more efficiency with push-pull.

What are, exactly, those RCs? And if I just plug in two 560Rs as both R8 and R9, will it be fine?

Sidenote: this made me curious what "push-pull" meant in this case (my guitarist brain jumped directly to the funky split-coil pot, of course) and now I know a bit more about output structures. Thanks!

[Clint Eastwood]

What are, exactly, those RCs? And if I just plug in two 560Rs as both R8 and R9, will it be fine?

Sidenote: this made me curious what "push-pull" meant in this case (my guitarist brain jumped directly to the funky split-coil pot, of course) and now I know a bit more about output structures. Thanks!

The two Rc's added up form the load resistance for Q3. Their summed value determines the current that flows through Q3, and consequently the idle current through Q2 and Q4. You will have to experiment. Higher values for Rc =>lower current.
The Rc resistors with C4 form a bootstrap current source, wich increases gain and linearity. For a good explanation of the bootstrap trick see https://sound-au.com/articles/bootstrap.htm
A nice explanation of push pull can be found here:
https://www.electronics-tutorials.ws/amplifier/amp_6.html
These two sites are great anyway for learning about (audio) electronics.
Good luck, I hope you can get some great sounds from these circuits!

[SeneX225]

The two Rc's added up form the load resistance for Q3. Their summed value determines the current that flows through Q3, and consequently the idle current through Q2 and Q4. You will have to experiment. Higher values for Rc =>lower current.
The Rc resistors with C4 form a bootstrap current source, wich increases gain and linearity. For a good explanation of the bootstrap trick see https://sound-au.com/articles/bootstrap.htm
A nice explanation of push pull can be found here:
https://www.electronics-tutorials.ws/amplifier/amp_6.html
These two sites are great anyway for learning about (audio) electronics.

Thank you very much for the explanation and the links! I'll be sure to check them out.

Good luck, I hope you can get some great sounds from these circuits!

I will report back once I build at least one of the two versions (depends on which set of transistor will get to me first) and later, hopefully, with a comparison between both.

[Rob Strand]

I will report back once I build at least one of the two versions (depends on which set of transistor will get to me first) and later, hopefully, with a comparison between both.

Keep in mind that circuit was just demonstrating the idea of a class A push-pull output.

You might need to add a Zobel network across the output (say 100nF in series with 10 ohm or so).  Also if it oscillated you might need to add a small base-collector cap on second transistor (Q3) - IIRC as mentioned on the schematic.