Op amp to Discrete Conversion - Possible?

[apehead]

Would it be possible to convert a preamp using op amps to transistors?

[Enzo]

ANything is possible, but it would be highly impractical. The circuits would be nothing alike, and a whole new circuit board would be required.

[David Schwab]

There are some plans on the internet showing a discreet op amp made from transistors, but I'm sure it doesn't function like the real thing.

The question is why would you want to do this? There's nothing wrong with the sound of a good op amp.

[apehead]

I just mistrust IC's, that's all. I have an ART tube MP that I wanted to hot rod a bit.

[R.G.]

I just mistrust IC's, that's all. I have an ART tube MP that I wanted to hot rod a bit.

Sigh.

Would it be possible to convert a preamp using op amps to transistors?

Absolutely yes! It will require a redesign from the sheet metal up, though; it will use more power, have higher - and more objectionable - distortion, and be dramatically more prone to drift, aging and parts tolerances.

And why is it you trust transistors more than IC's?

[apehead]

Because I almost always prefer the sound of an older, discrete circuit to any chip based amps I've heard.

[Steve Conner]

That's probably because of the circuit topology, though, not the components. What do you think op-amps are made of inside?

I disagree with R.G. on the objectionable distortion, though. A discrete JFET preamp with no global feedback will have sweet-sounding distortion that an op-amp (either monolithic or discrete) won't.

[David Schwab]

I just mistrust IC's, that's all.

IC op amps are made of transistors... they are pretty much made the exact same way. An op amp is a small multi transistor circuit, all in one package. That's why it's an "integrated circuit."

I have an ART tube MP that I wanted to hot rod a bit.

it's not going to be hotrodding it. Swapping IC's for better ones would be though.

[tedmich]

Sigh.


Absolutely yes! It will require a redesign from the sheet metal up, though; it will use more power, have higher - and more objectionable - distortion, and be dramatically more prone to drift, aging and parts tolerances.

And why is it you trust transistors more than IC's?

a light coat of this is reported to cure op amps (and most everything else) of their non-musical character:
http://www.trt-wonder.com/page10.html

he goes on for pages (the spray can is $100) and includes a description of an "infinitely blind" experiment which makes Clever Hans sound like particle physics...

they sell caps too
http://www.trt-wonder.com/page20.html

things did sound better when I was a kid...before all that loud music took its toll on my ears.

[Don Moose]

For all the work you're looking at investing in this, why not think about tube op-amps?

[Enzo]

Hey! The original Philbrick units. Those are a favorite of Bob Pease at National.

[jrfrond]

The generalization that discrete sounds better than opamps is entirely unfounded. I've seen, heard and repaired crappy-sounding discrete designs, and wonderful-sounding opamp designs e.g Music Man.

Sure, you can do a wholesale rebuild on anything, but all you'll be able to use is the chassis and possibly the power transformer, because the circuit board will have to be designed from the ground up.

[Don Moose]

Irregular, but enthusiastic reader of Pease Porridge.

[Enzo]

His troubleshooting analog circuits book is a personal favorite - I learn something new every time I read it.

[gbono]

wow, I can't believe that Bob was laid off by NSC in March - sign of the times. I bet NSC hired outside "consultants" to make that brilliant decision