"Gain Clown" Composite Amp

[Sebastiaan]

Here is the 33watt version.
I am still looking for the 70watt version.
I remember the paralleled lm1875's for outputs but the inputs each may have been in some sorted nested composite configuration.
I believe there were two articles.
The first one showed this circuit and some single ended ones to descirbe the concept of reducing the higher distortion and noise of the power amp to that of the lower noise and distortion of the driving opamp.
The second article was the BPA 70watt amp itself.
This performance was amazing for the early 90's and for what was reasonable cost at the time.
Nowdays it is even better and cheaper in cost, even, with the higher power output chips and even lower noise and distortion opamps than that of day. jer

Dear,

There are errors in this schematics.

The + and - from IC1 should be reversed, this way the circuit don't gonna work. Second, I doubt if this going to work well, without any local feedback around the LM1875's. In my simulations it got wrong. I will try if I can make something from it, but I can already tell you, if you want to go nested/composite, there are better ways to do this. Still this schematic is a inspiration

With kind regards,
Bas

 

[Sebastiaan]

I found my NE5534 design.

I build this amplifier many years ago, and as far as I remember I sticked to the values as in this simulation.

The first NE5534 stage is slowed down with cap C1.

The system is DC coupled with a servo injecting into pin 8 of the NE5534. This configuration gives lower noise, and has less influence into the passband then a conventional DC servo configuration.

No matter what people think about the NE5534. In this design it gives a super holographic performance, with a dead silent black background.

With kind regards,
Bas

 

[geraldfryjr]

I found that print off of the net so I'm not sure if it has been changed.
I will keep looking for the original article,I have it some where still,I hope.
I have almost all of the radio electronics magezines from 80's and 90's until they just disappeared one day.
I know I had that one,as it was one of my favorite ones because of that circuit.
So I,ll keep looking. jer

 

[geraldfryjr]

"There are errors in this schematics."


Oh yes I see, it was probably a typo as it happend quite often in that publication. jer