AMZ Superbuffer ....IC comparisons

[powerplayj]

Has anyone experimented with IC's other than the TL072's for the AMZ SuperBuffer?  I didn't have 2 TL072's on hand so my Superbuffer has a TL072 and a Burr Brown.  (Many hype the Burr Brown for OD applications but it didn't wow me in my OD/Distortions so, I now have a $5 IC in my buffer!).  I was just curious if anyone has done any type of IC comparison as I basically want the IC that seems to retain the most highs.  I'm not sure if retention of highs equates directly to the IC specifications or if it is an intrinsic audio property such as what is heard when different IC's are tested in a tubescreamer and such.

[Arn C.]

I believe what I have read here at the forum over the years is that TL072 and NE5532 are supposed to be two of the more quiet ones.

Peace!
Arn C.

[Ben N]

Disclaimer: I am no expert. Other people here are.

But, in the absence of any other response I wil tell you what I (think I) know.  That is that the circuit as designed is very tonally neutral, meaning it does not emphasize or deemphasize any frequency. It is flat. Choice of opamps will make very little, if any, noticeable difference. However, where you may hear a difference is in how the circuit interacts with what preceeds or follows it. TL072, with its JFET input, has such a high input impedance that paralleling two of them will still have no appreciable effect in terms of loading. OTOH, a 5532 has rather low input imedance (IIRC-check the datasheet); putting two 5532 inputs in parallel cuts it in half again. Unless your signal source has extremely low output impedance, a double (or quad) 5532 bufferis likely to cause noticeable loading, and degradation of highs (the technical term is "tone-sucking"  ), not something you want out of a buffer. Other bipolar opamps, like the 4559, are better. If I was using a 5532 or its kin, I would not parallel, since they have plenty of current drive capacity as is. But I digress.

The short answer: You aren't likely to do much better than TL072, or other JFET-input opamp (LF353?) for retention of highs. Don't mix & match (this is a buffer, not a Barber overdrive pedal), just use two of them. They couldn't be much cheaper. If you still aren't getting enough highs, try using one. Beyond that, look elswhere--it ain't the chip. Getting an audiophile B-B chip is fine (assuming it is high input impedance), but the only effect may be to reduce noise a tad, and you shouldn't be getting much noise even with the TL072.
hth
Ben

[Mark Hammer]

The central aspect of the super buffer is that it provides greater signal current, by use of multiple parallel op-amps.  The greater signal current assists on overcoming the potential "leakage" through the cable over extended distances.

If half of a 4558 is "good enough" for short distances, then consider that paralleled sections of even something as humble as a 4558 will yield an improvement over a typical 25-ft+ cable.  Of course, if the signal is SO well preserved that everything clean on out to 15khz safely makes its way through, then I suppose you can't rely on the cable to do your dirty work for you and bleed all that 12khz hiss to ground.  In which case, it makes sense to use a low-noise op-amp like a 5532/5534 or an LM833 or TL072, etc.

Of course, I suspect Ben makes a good point about the 5534/32 already being capable fo providing greater signal current.