Your most used or favourite OpAmp(s) ?

[brett]

TL072 - ultra-high input impedance, reliability
NE5532 - ultra low noise

741 - cheap (for comparators, etc)
386 - for driving little transducers etc
3080 - for signal generators/modulators

[Steben]

I can't really say the 2262 sounded better than the TL052, just that it got notiably louder.  I was experimenting with Mosfet clipper and I didn't want the op amp distorting a lot so I thought the R to R feature would be good.

In a diode to ground distortion, the op amp contributes lots of distortion too and that may be why they sound different, the ratio of op amp to diode clipping.  Thinking along the lines of a Rat with the LM308 having a low slew rate, the 2262 seems to meet the need.  I haven't tried a 2252 yet.

TI is great for that.   

2262 has a 741-slew rate. LM308 a bit lower.
2252 has an even lower slew rate around 0.1V/ms. Actually this means in simple terms that there is even more treble cut at high gain. The lower the gain, less treble cut. Looks like TS-style-circuit-in-a-chip in a way.

At full gain from treblish to smooth dark you have then (duals):
TL072("trebliest") - NE5532 - RC4558 - TLC2262 - LM1458 - LM358 - TLC2252("darkest")
(singles):
TL071("trebliest") - NE5534 - 741 - LM308 ("darkest")

just a selection, you could add a lot more.

[WGTP]

On old post of mine below.  http://www.diystompboxes.com/smfforum/index.php?topic=17942.msg104878#msg104878

Notice â€" Highly Subjective Op Amp Evaluation by lo-tech Guitarist

This saga started out with a modified version of Gus’ Muff Fuzz #1 or Gary’s Mockman.  Both add a 470K/1meg resistor across the diodes, as a mod to stop gating.  Since the Muff Fuzz runs one op amp into the other which has diodes in the feedback loop, it seemed like a good test bed.  If you are going to use dual op amps, you might as well use both of them!  I was going to leave it alone, but I couldn’t.  I was getting too much noise, but really liked the sound.  This is the first distortion with diodes in the loop I have tried, and I like the smooth rich distortion.  The diodes in the circuit such as GE's, SI's and LED's make a much more noticeable difference than the op amps.  I think I can hear a difference when using a Jfets or Mosfets as clipping diodes.

I initially tweaked the diodes and found that using LED’s raised the output, but the noise did not increase, plus the LED’s had a nice chunk to them.  The down side is that the distortion level is lower, so I used an MPF102 Jfet for the other diode which has a slightly higher clipping threshold than a single SI (I tried a Jfet/Mosfet combo, but it was too fuzzy for my taste, the Jfet/SI combo is nice, I’ll probably need some switches). This got more distortion, plus more even ordered harmonics due to the asymmetrical distortion produced by dissimilar clipping thresholds.  The LED is 1.8v and the Jfet .7v.  I hypothesize that having diodes with higher clipping thresholds provides the op amp with more opportunity to clip, whereas using lower threshold diodes results in the diodes clipping more and the op amp less.  I may just be dreaming.

As I sorted thru the op amps I had, thanks to one of the “elders” of the forum, I was also watching to see which op amps others were using.  I started requesting samples from various manufactures and found that Texas Instruments had most of what I wanted and was vary gracious and quick in providing their samples for the test.  I also searched thru their list of op amps and found others to try.  (Thanks TI.com) 

I needed some consistent way of measuring the 15 or so op amps I had.  Each time I thought I heard something different; I would later be unable to duplicate the findings.  Most of my observations have question marks by them. It's difficult to hear differences between 2 seemingly different designs of op amps like a 4558 and TLC2272 cmos.  It's more difficult to hear a difference between 2 op amps of the same basic design.

I came up with 2 tests besides the basic and highly subjective listening test.  I have found that one evening something sounds great and the next day it doesn’t. 

First was the plug it in and see how much “Noise” it made test.  I had members of the family assist and was surprised to find that some noise, even though the same perceived volume was judged as harsher than others.  Smooth and flowing vs. harsh and irritating seemed to be the difference.

The second test was the plug it in and see how quickly and how much “Feedback” it got while the guitar rested on the bed opposite the amp test.  I think this relates to gain.  The 4558 was adjusted to slowly develop feedback and with no changes to the set up different op amps were substituted.  Another unexpected finding was that the CMOS op amps would feedback on a lower harmonic than the others.  Does this mean more gain at certain frequencies?  Were the harmonics odd vs. even???

In all tests the TI RC4558 served as the constant with which the others were grouped.  I had to group them in clusters to make testing reasonable.  I use a standard group that included the 4558, a Jfet input group which includes the TL072, a CMOS group which includes the rail to rail op amps and the high performance group that includes the Burr Browns.  Each time the 4558 was used to compare the others in the group.  The results of the tests are below.

If you don’t stand in exactly the same spot when you test, that has more impact on the sound than different op amps do.

I did find that most of the op amps with high gain were also noisy.  This would seem to be typical, the OP275 being tops in both categories.  I think the Muff Fuzz circuit with 1 meg resistors in the loops seems subject to noisiness.  Lying on top of my SS amp didn’t help either.  I’m sure it will be quieter once I get it into a junction box.  Still obvious differences existed between op amps.

The TI RC4558 is not a bad choice and I can see why it is commonly used.  When maxed it breaks up nicely and it isn’t nosier than some others with the same “gain”.  The noise was judged as being harsher than some others though.  At times it seems to have sort of a swirl to the distortion that is a little different, but at other times it doesn’t.  2 commonly recommended op amps, the LF353 and NE5532 do sound sweet, but have less gain than the 4558 and less bass.  That can be remedied.

Distortion:  For me that is what it is all about.  The 4558 has plenty and maybe the 4559 has more.  The higher gain op amps don’t necessarily break up more or have higher levels of distortion and sustain.  Some seem to stay clearer, perhaps due to there design for hi-fi circuits/slew rate.  Some sound more “robust” or have more balls than others.  Some may emphasis different harmonics, but again the diodes have much more noticeable effects on the nature/character of the distortion.  You don’t have to have your family/friends come in and help you hear the difference.  If you don’t stand in exactly the same spot when you test, that has more impact on the sound than different op amps do.

I have concluded that most of the difference between the op amps was due to more or less gain, distortion, highs and/or lows.  These are all things that can be addressed with different caps or different gain settings.  This seems to account for most of the differences I could hear repeatedly.  The ones I thought had sweeter smoother highs, turned out to have less gain and/or bass, which smoothed out the highs and could be accomplished by using smaller input caps.  I found that I could use a larger input cap with some op amps that would sound too woolly with others or some diode combinations worked better for the same reason.  The cmos op amp’s that go rail to rail seem to be a bit woollier than some others which works better with smaller caps or SI diodes.  The Jfet/Mosfet’s as diodes worked better with less wooly op amp cap combo’s.  This is based on my particular taste and could differ from person to person.

Output:  I haven’t turned the output pot very far at all, so I’m assuming that they all have plenty of drive for a tube front end, although this version doesn’t have a gain control and doesn’t get really clean.

It's fun searching, even if it is subjective and tone is pretty much that way.   My double picking and jazz scales are much better than before I started. 

OP AMP’s

Bi-Polar Op Amps
RC4558   Old standby good gain and distortion, some noise, Mojo???
RC4559   Turbo version of 4558, cool   
NE5532   Very Quiet, sweet highs, less gain???
LM833   Nice w/big bottom??

Jfet Inputs
TL052      Originally sounded superior, but now like the rest
TL072      Another std.  sounds good less mid’s than  4558
LF353      frequently recommended, sounds good, quiet/less gain
LF412      Little stronger than LM353

High-Performance
OP275   Lots of gain and noise.  Probably fine enclosed.  The hi-fi
  -  -  -      Op amps seem to be slightly smoother/creamer sounding???
OPA3140   Quieter than 2604 probably less gain, nice
OPA2604   Almost as much gain as 275 but quieter may not break up as much

Cmos â€" Rail to Rail
CA3260   Mosfet in Cmos out spec.s sound cool
TLC2262   Cmos may sound fatter w/sweeter highs??? I will probably use
TLC2272   one just in case.  Usually lower noise.
TLV2372   Sounds nice

:roll: