John Broskie's Class A regulator amplifier

[radumar1]

Hello,

Has anyone here built this very simple, low power single ended class A amplifier based on LM317 and an opamp ?

If so, what THD profile does it have ? H2 predominance or H3 ?

I will try to build it as soon as possible but meanwhile, I wonder if there's anyone happy with this configuration.

Bests,
Radu

 

[lineup]

It will work even has not very high efficiency.
It is a constant class A supply from the lower LM317.

But if you wait I will simulate this circuit. Then I can tell you harmonics.
----
Edit:
It is more H3 than H2.
The distortion is however very low.

 

[radumar1]

Lineup, thank you very much for your quick reply. I was aiming at H2>H3. I built several opamp-class B amps with astonishingly low THD, but had been unhappy with their distortion profile due to higher H3, H4...

 

[6L6]

The Amp Camp Amp will have more output and 2nd harmonic dominant. Very easy to build, even point to point.

 

[lineup]

H3 and H5 is higher than H2 and H4.

Here is my circuit. Only some resistor changed from the original:

 

[radumar1]

Thank you, will look at it.
Bests

 

[radumar1]

H3 and H5 is higher than H2 and H4.

Here is my circuit. Only some resistor changed from the original:

View attachment 1423106

Thanks for your simulation. Indeed, this THD profile ... not desirable, at least for me, I think.

Bests,
Radu

 

[lineup]

Here is the Fourier result in my simulation:

 

[radumar1]

Thanks for your help. Yes, odd ones prevail until the 9th -- this config is not for me, I reckon. Think the real producer of odd harmonics is the opamp and its feedback resistor network.

 

[Elvee]

If irregular chip amps are your thing, here are some more (all physically tested):

Post in thread 'Plan to make LM 317 power amp'

2021-08-04 8:43 am

You can find some answers and ideas in these threads:
SE class A regulator-chip-amp madness
The Voltage-Regulator-Chip Amp family welcomes a new member:
Yet another funny Chip-Amp
And now, the Regulator-Chip JLH Amp.
What happens when you cross a Tringlotron with a Regulator-Chip Amplifier?
Class A Chip Amp: and now, the complementary version
Just for fun: The Regulator-Chip amplifier

• Elvee

 

[radumar1]

I started this journey in search of the 'tube amp' sound in amplifiers without using valves. I'm interested in any amp configuration that is able to output moderate but prevalent H2, over odd ones. I had spotted your stereo, three-regulator design which looks very interesting and I would like to build it sometime.

Thank you Elvee!

 

[Elvee]

Thanks, it will be cheap and surpriseless thus easy to experiment