Opamp substitutions

[Jmsteele187]

Has anyone used a TI tle2062cp op amp in place of a 4558?  I pulled one out of a bass preamp that I had laying around.  I looked up the pinout of each op amp, and they match up.  I'm just wondering how it sounds compared to a 4558.  Or should I just throw it in a socket and see for myself.

[R.G.]

I think it sounds like a strong presence of florals and fruit, a good, solid ear feel with a finish of oak and vanilla.

There's a whole lot of blather about subtleties of opamps on the internet. It takes more time to type than it does to resocket and listen.

Bear in mind that the central purpose of opamps is for the feedback to make the underlying amplifier's quirks NOT matter in the output, so the designers try hard to NOT let differences show through, although that's not exactly how they think about it.

Socket it and listen.

[slacker]

Or should I just throw it in a socket and see for myself.

Yeah, try it and see. For 99.99% of pedal circuits opamps are interchangeable so a 4558 which is a dual opamp (two opamps in one packeage) can be replaced with any other dual opamp. Any differences in sound are normally fairly subtle.

EDIT: R.G beat me to it.

[antonis]

I pulled one out of a bass preamp that I had laying around. 

Desoldered..??

[Jmsteele187]

I pulled one out of a bass preamp that I had laying around. 

Desoldered..??

I didn't have to de-solder the chip.  The chip was actually in a socket in the preamp.  So all I did was de-solder the socket, so I could re-use it.

[Mark Hammer]

The most obvious aural aspects of an op-amp would be its noise level, and its capacity to reproduce high end in accordance with its own input impedance and the impedance of the signal source.  The former is readily audible, while the latter would really only matter more if the op-amp was being used to process a wide-bandwidth signal.

The tle2062cp is an ultra low-power chip, but that's not anything you'd necessarily hear.

[Jmsteele187]

Thank you for your thoughts.  I'll try it out and see what happens.

[MaxPower]

So does this mean the AD797 was/is overpriced? I always wanted to try one but I'm too much of a cheapskate.

[12Bass]

IME, the AD797 is not well suited for op amp swapping as it requires careful circuit design for optimal performance.  I've been happier with ADA4637-1 as a replacement for chips like the TL072, or LME49990 as a sub for bipolar op amps like NE5532.  Still, the advantages of these high performance chips would probably be lost in most guitar rigs.  I use some of them in my bass rig, but it aims for much higher fidelity than what electric guitarists tend to use.

[bool]

Well, realistically, you could use something like a LM4562 (...LME49720) as a pre-gain device for something like a LM741 or LM1458 in the clipping section, to keep the overall SNR down a bit. But even there, a 5532/5534 could do that ... and even be re-used in the clipping section for not much money.

A 797 could be better used elsewhere.

[MaxPower]

I should've mentioned the AD797 usage would be for a mic preamp, not a guitar pedal (I pretty much stick with the TL07x for these). I have a mic preamp circuit from a book that is calls for an AD797. I substituted an OPA277 (I think. I can't remember what it was anymore) and it sounds better than the crappy cheap commercial mic preamps I have. I just wondered if the AD797 would be any improvement in tone/etc.

I think I've seen Paul recommend the 5532 for mic preamps in a couple of topics so I'll try those next time I build a mic preamp.

[amptramp]

The 5532 has low voltage noise but being bipolar, rather high current noise.  It is great for mixer boards where impedances are low.

I have a Conneaut Audio Devices Equitek E-200 microphone that has OPA2107 op amp input stages and MC33178 output driver op amps, all powered by 18 VDC / 9 VDC / ground phantom power.  It came with two leaky 9 volt NiCd batteries that I took out to avoid further leakage damage.  Someday I may find a use for it.  It has switchable cardioid / figure 8 / omnidirectional settings with two microphone elements inside.

There are some other interesting things you can do - the LM318 was first seen as a video amp but the input was such that if both inputs were tied to the negative supply, you could parallel the input with FET's connected with their drains to the offset pins (which are connected to the collectors of the internal transistors).  I was the first Canadian customer for the national LH0062 which was their hybrid that was exactly that - an LM318 with FET inputs.  BTW the basic LM318 has an input noise of 11 NV/root Hz.  The 5532 has the same input structure, so you might be able to build a wideband low-noise FET input op amp if you can find matched FET's.

[12Bass]

I should've mentioned the AD797 usage would be for a mic preamp, not a guitar pedal (I pretty much stick with the TL07x for these). I have a mic preamp circuit from a book that is calls for an AD797. I substituted an OPA277 (I think. I can't remember what it was anymore) and it sounds better than the crappy cheap commercial mic preamps I have. I just wondered if the AD797 would be any improvement in tone/etc.

I'd expect the AD797 to perform well if the circuit is designed for it.  Should sound clean and relatively neutral.

[karbomusic]

http://It came with two leaky 9 volt NiCd batteries that I took out to avoid further leakage damage.

I assume you knew but those are to handle sudden peak demands etc. I'm surprised they leaked, mine (E200/E300) are 15 years old.

[amptramp]

http://It came with two leaky 9 volt NiCd batteries that I took out to avoid further leakage damage.

I assume you knew but those are to handle sudden peak demands etc. I'm surprised they leaked, mine (E200/E300) are 15 years old.

I got the mike at a garage sale a few years ago for $10 with its plastic case and foam padding material and all the documentation.  I figured someone may want one of these at some point.  If my daughter continued in music, she might want a really nice studio mike like this but she is more inclined to the open mike nights at local bars and clubs - and they already have the mikes.