@AnalogKid Genius! Thank you.

 

It dates back to the 741 (and, really, doesn't everything?). I didn't invent it, but you're welcome.

ak

 

Thread moved. My bad.
Thanks, mods.

 

My bad.

I don't think so. I asked to split the Thread so, "audio" would be in the title. (I would never remember to search for CD4066 if I was looking for low level audio amp chips.)

 

The 5532 was developed as an audio part. The 082/072 tried to replace it in audio applications but the limited output swing precluded that.

 

@ramancini8

Are you aware of any noteworthy differences between the OPA2132 and OPA2134? If not, do you have access to anyone who does? Both seem to be very low noise, very clean and provide a 'beautiful' sound when used as a guitar preamp. I cannot tell the difference but many claim there is a difference. I just don't know if they are perceiving a difference between a 2 or 4 stamp on the part number of if there is a real difference.

 

Are you aware of any noteworthy differences between the OPA2132 and OPA2134?

Post #7, John says there is a difference, but I guess you asked Ra because you want a second opinion.
No objection. Just checking in case you didn't notice post #7.

 

Post #7, John says there is a difference, but I guess you asked Ra because you want a second opinion.
No objection. Just checking in case you didn't notice post #7.

Yes, but I've used both and I believe Ron may have some inside information.

 

Post #7, John says there is a difference, but I guess you asked Ra because you want a second opinion.

Yes, but I've used both and I believe Ron may have some inside information.

I would be very interested in that as well. Mr. Mancini's book is printed, bound and heavily sticky-tagged and on my bench as we speak. That along with an original copy of Operational Amplifiers by Tobey, Graeme and Huelsman (of the original BurrBrown) pretty much cover what I know (who am I kidding??) about the subject. Thanks and kudos to Ron for his superb reference.

Re: the difference between the 2132/4 all I can tell you is that in testing my preamp, I was surprised to find that I liked the 2132 a little better than the 2134, despite the latter's 'Sound-Plus' moniker. In passing, I had my guitar / music teacher / professional musician/ department head over to hear my results so far and did an impromptu A-B test, swapping first the TL072, 2134, then 2132 in and out. The 072 was clearly inferior but I swapped the 32/34 back and forth, sometimes telling him I swapped when I didn't etc. With him playing the same rig with no other settings changes, he also liked the 32 better. Very marginal differences, especially compared with the 072 but we both agreed that the 32 had a bit more something to the sound. My non-musician but otherwise spectacular spouse had the same opinion. So did a couple of band-mates a few nites later. Nobody could quantify why they liked the 32 vs 34 but they always did - usually with comments like 'a little fuller/maybe a bit sweeter and how's about another scotch?' That said, either of them sound terrific compared to the 072.

I'll be the first to admit that other than the obvious noise specs, I don't exactly know why. So far, as I've said, it seems like the amps that show up on favorites lists for tonal quality all seem to have high slew rates and GWP. And its entirely possible that flaws in my circuit prevent the 34 from reaching its tonal potential.

There does seem to be a big difference in 'what's right' between rigs for music creation vs. music reproduction. Ron noted that the 072 didn't make the cut in audio applications vs the 5532. Maybe in the hi-end stereo field that's true but the 072 shows up in every one of the several dozen instrument amplifier schematics I have that are recent enough to use them. Even the Marshall MA50C tube amp I have on the bench uses the 072 in non-critical places (reverb recovery for one). Of course, 5%THD is the typical guitar amp spec that I've seen and the noise mainly comes from the guitarist... Plus the 072 is dirt-cheap compared to the others.

One thing I don't want to do here is give the impression that I am in any way even a passing authority on any of this stuff. The original post, now moved, was to alert that TS to some other possibilities for his op amp choice. I am way out of my comfort zone as it is and a year ago would have (did) laugh at the prospect that ears trump datasheets. But they do when preconceived notions get in the way. I should have known.

Several years ago, my then guitar teacher (another UNT jazzer) remarked how he wanted to get some fancy expensive cable for his guitar. *Snort* To show him how wrong he was I went to Tanner's (local surplus shop) and bought some cheap coax, soldered some plugs onto it and told him to try it. He LIT UP. Called it fantastic. I called him nuts. But no.. he swapped my old RoadHog in and out with my new cheapie and I was amazed at the difference in sound. The cheapie had a crystalline sparkle to it that kept the lows too. With the advent 0f my 'perfect jazz amp' project I thought I'd take a closer look at the cable. Compared to the RoadHog, it had very low capacitance/ft (about 19pf) and really low dielectric absorption. Plus a nice stranded shield with a layer to suppress microphonics. The perfect cable! And of course understandable given the HiZ drive from the guitar and who knows Z of various amps. Alas, no longer available so I made up a few with the leftovers for my jazz friends and a buddy as his beat-the-cancer gift. All love their wonderful cable. And its kind of cool to see a musician you know and respect on stage, tearing it up, playing through that cable.

Its a whole new thing for ol' JohnInTX. Bear with me, please.
Cheers!

 

Like a lot of other people, I can't understand it all...or justify it! Low capacitance coax and low dielectric absorbtion were valuable discoveries I share with John. When it comes to polishing a design, I let my audiophool school me. Gotta respect an excellent musician! The trick is to know when to obey the ear and when to believe the math. One rule that seems to keep me safe is, never design in an op-amp or a transistor that he can tell is there. I sent this guy circuits to ear test and empirically estimated him at 23KHz for a high limit. Yes, I know the math says that's impossible, but he found differences that can only be explained by assuming he can hear that high. So, that's my two rules for designing for musicians. Never install a transistor he can find with his ear and assume a 23KHz upper limit.

 

The trick is to know when to obey the ear and when to believe the math. One rule that seems to keep me safe is, never design in an op-amp or a transistor that he can tell is there. I sent this guy circuits to ear test and empirically estimated him at 23KHz for a high limit. Yes, I know the math says that's impossible, but he found differences that can only be explained by assuming he can hear that high. So, that's my two rules for designing for musicians. Never install a transistor he can find with his ear and assume a 23KHz upper limit.

I can learn more in 15min at AAC than I have in the past in a semester. Thanks.