OP AMP Evaluation

[WGTP]

I have 15 different op amps that I'm evaluating for distortion qualities in a modded Muff Fuzz.  I'm trying to think of ways to evauluate them without test equipment.  It's hard just listening too them because they all sound cool in the MF and it's very subjective from moment to moment.

The first test I have thought up was a simple noise test.  Plug them in and see how noise they are.  The problem with that is that more gain may mean more noise and in use it may not be turned up as high.

The second is the "set the guitar down and see how much feedback you get" test.  I think this relates to gain.

I guess I will use the TI4558 as the bench mark.  All the others are different.  I'm having trouble with the difference between a 052 and 072, so I'm not sure about hearing the difference between different 4558's.

So far each has a little different "Character" to it.  Some are louder, brighter, cleaner, dirtier, crunchier, chunckier, midier, etc.  ]

The NE5532 is quiet and has a nice treble sound.  The 353 has a nice treble as well.  The 4558 "goes to hell" nicely the 4559 is more robust, the Burr Browns have big balls, the 052 has a nice combination of stuff, the cmos are sort of wooly, etc.  I'll post my final results.  

[Kilby]

Why not post some recordings of each, then w can dhave a poll

[Paul Marossy]

Cool, I'm interested to hear what you find.  

I like the JRC4558 and LF353/351 as well. I mainly use a NE5532/34 when I want the circuit to be very quiet. The OPA134 works pretty well in some circuits, too. a LM1458 and a LM741 can sound decent, too, even with their rather poor specs. It really depend on the circuit that they are in.

It would seem to be a challenge to create a circuit that would objectively test opamps.

[runmikeyrun]

I ended up using the 353 in my muff fuzz.  I ended up having to do some mods to get it to stop gating off as the signal level dropped, and the 353 was the one that worked the best.  Other than that, they mostly all sounded the same with about the same amounts of distortion, etc.  

Yes, a test with sound samples would be in order, if you have time.

[petemoore]

Function variance among types brands etc varies alot more for transistor types and individuals than opamps???
 Do you think OA's vary as much in characteristiecs as transistors do?
 Not quite sure I understand the reason OA's biasing issues seem to occur less frequently than when using transistors.
 I'm guessing that internal parts of the OA partially compensate bias??...sorry I like to put my guess in too...
 It may be obvious I've done far more transistor tryouts than Opamp A/Bing

[Fret Wire]

On the last set of TS-9's I modded to 808 specs, they had TA75558's in them. After the standard mod, (JRC4558 and 10k and 100ohm resistors), the gain on the stock reissue had to be set 4 notches higher than the modded TS-9 to have equal gain. Other than that, not much audible difference. I presently have 6 TS-9's laying around. I think I'm gonna do a shoot-out and see what's what. BTW, They all have the TA7558, this is listed as a low power op amp. Any good projects that use this chip?

[WGTP]

Thanks to Texas Instruments Samples, I'm up to 15 op amps now HHHHHHHEEEEEEEEEELLLLLLLLLLLLPPPPPPPP.

I say 2 more last night with a slew rate of 45u/%&*.  HHHHEEELLPPPPP.

[javacody]

My TS5 came with a TA75558. I swapped it out for a TI RC4558P. After reading about stacking opamps, I gave it a shot and when I stacked the TA75558' on the TI RC4558P, it added quite a bit of clarity to the sound. Very nice. Two TI RC4558P's thickened up nicely and got an "ampy" sort of sound. Anyway, after you've recorded the samples of single opamps, then try stacking them and recording more samples.  

[donald stringer]

I have heard several people talk about getting free samples, how is that done?