Opamp replacement in power amp section

[jdparsons1]

I have a solid state amp with a NE5532P opamp in the power amp section. I have some other opamps laying around and was thinking about experimenting switching it out for something else. Will any dual opamp work for this? I have two specifically i was thinking about changing it to, a Brown Burr OPA2134 and a OPA2604AP.

[Enzo]

As far as I know, all the 8-leg dual op amps have the same pinout, so you can swap away. I don;t know the particular ones you mention.

I would say that the 5532 is an old school low noise op amp and it works pretty darn well. COnsidering that a power amp is a whole circuit, and not just support parts for the op amp, I am not sure what improvements you expect. But try it and report back.

[Steve Conner]

My worry would be that the op-amp might be inside the power amp's feedback loop, and maybe they tweaked it so it was stable with the NE5532. Other op-amps have different GBW, phase shifts and so on.

So I'd say if you want to change op-amps, change any other one but that!

[zero cool]

I have not seen an amp that uses an Op-amp in it that is tweaked so tightly that a drop in type opamp change would be an issue. I would try an LM4562 opamp which seems to be a favorite. We did an experiment on a prototype car stereo product we were developing and we swapped in many different types of op-amps for this buffer type device. while in the lab (read living room) there were subtle changes we could hear. when in a car....pfft, not a chance you could tell a difference between any of the op-amps we tried! So I guess, whatever it is you expect to gain. may be largely dependent on the speakers/system/room/environment etc the amp will be used in.


and honestly. I know of no high end audiophile type, or even mid fi type amps that use op-amps for anything in the actual audio path. so if your considering a power amp that has an op-amp in it for any sort of audiophile or critical listening...well I say go for it for fun, but dont expect any sort of sudden audiophile magic to happen.

No matter how much "bling" you put on a mack truck, it will just never be a ferrari!

[Enzo]

Well, remember, you are in guitar amp land over here, for the most part.

[Steve Conner]

Yeah, I've seen a few musical instrument and PA amps that use a NE5532 or NE5534 as the first stage of the power amp. Most recent one I noticed was the Mackie SWA1501 powered sub.

I also once built a copy of the Alexander current-feedback hi-fi amp. This uses a high-performance op-amp as the first stage. The NFB gets shoved back into its output, and it drives the rest of the amp through its supply pins!

http://scopeboy.com/original.gif

And from my electronics experience I know that circuits like that can be touchy. The SSM2131 op-amp specified for the Alexander circuit is now discontinued, and I don't have the guts to try modifying it for a different one. I'd bet that if you swapped in a NE5534 there would be smoke.

I've never seen a circuit quite so perverse in any MI or PA product, but I'd still be a little worried.

[Enzo]

Well, it wouldn't hurt to know what circuit the OP was talking about, but I have never found the MArshall circuit 8080/8100 to be all that touchy, and the ubiquitous PV 400BH uses one corner of a TL074, but that circuit too, seems pretty stable.