What's the current state of the art in IC OP Amps?

[Whoops]

I'm wanting to try swapping out op amps in a couple of cheap bits of audio gear. What's a good option for 8 pin socketed OpAmps? A lot of manufacturers and mod shops brag about using Burr Browns. I'm pretty green at modding, so I'm sure I'm leaving out pertinent information in my post.

Not that I think that you asked anything wrong.
But you will not have the replies you want around here, you should post in Diyaudio forum, there's a lof of IC Opamps enthusiasts over there.

I don't buy your description "was like going from a ribbon trash mic to a C414. Huge. The transients were clearer and the low end was tighter", neither will people around here

 

[abbey road d enfer]

In general, if not full agreement with 'Abbey Road' here,

Where would you not be in "full agreement"? Honest, I'm not challenging you, I just want to know and maybe learn a thing or two.

 

[moamps]

About 10 years ago I was changing opamps to a friend in his Soundcraft Ghost mixer. For the test, we changed the opamps for only two channel modules and measured and listened to the difference we got compared to the other unmodified modules. I, with my measuring equipment, could not determine that there were significant changes, except for slightly lower noise and slightly smaller THD distortions in the third decade. Listening, however, we found that there were some small improvements, and a friend later after two weeks of working with the mixer decided to change all 072 and 5532 ICs with some OPA and LME, I don't remember the exact numbers. We later changed all the electrolytic capacitors as well which brought some more improvements.

 

[Newmarket]

LME49720 can be used in place of NE5532.

Also see LM4562 (=LM49720)

 

[abbey road d enfer]

About 10 years ago I was changing opamps to a friend in his Soundcraft Ghost mixer. For the test, we changed the opamps for only two channel modules and measured and listened to the difference we got compared to the other unmodified modules. I, with my measuring equipment, could not determine that there were significant changes, except for slightly lower noise and slightly smaller THD distortions in the third decade. Listening, however, we found that there were some small improvements, and a friend later after two weeks of working with the mixer decided to change all 072 and 5532 ICs with some OPA and LME, I don't remember the exact numbers.

It would be interesting to know what part of the signal path improved by rolling opamps.
I would think a method that obeys the rules of scientific analysis would replace only one opamp at a time. Actually, if it was possible, one ought to replace only one half of a dual.
One place where a significant improvement would be probable is the summing amps, but you say opamps were changed only in the channel.
The "phase" inverter is probably the stage that benefits the less from better opamps. Stages with high noise gain are where it counts.
In the 600, the post-fader amp was spec'd as a 5532, because it was audibly quieter and measured better THD, because of the load it has to drive. However, the swishing noise (due to noise current) when moving the fader was such a nuisance that I initiated an ECO to replace with a TL072. If it was today, I would use an OPA2134 or such.

We later changed all the electrolytic capacitors as well which brought some more improvements.

Do you remember if you replaced them with same value/same voltage, or did you take the opportunity to increase one or both, as new manufacturing techniques allow?
For me, it's one of the good reasons for re-capping.

 

[moamps]

It would be interesting to know what part of the signal path improved by rolling opamps.
........
For me, it's one of the good reasons for re-capping.

We also changed the summing opamps at the end of the operation. The new capacitors were larger both in terms of supply voltage non intentionally (nowadays some capacitor values are no longer sold for low supply voltages) and in terms of values intentionally. We also replaced the original (SMPS type) power supply with the CPS275.
The Ghost console is very inconvenient to service as far as I can remember. In order to remove one module, it was necessary to unscrew all potentiometers from the front plate. So we changed all the opamps on two modules, and we didn’t have time for a lot of experimentation because the mixer remained in operation.

 

[abbey road d enfer]

We also changed the summing opamps at the end of the operation. The new capacitors were larger both in terms of supply voltage non intentionally (nowadays some capacitor values are no longer sold for low supply voltages) and in terms of values intentionally. We also replaced the original (SMPS type) power supply with the CPS275.

So there were many factors changed. Actually too many to pinpoint where the improvement comes from...

The Ghost console is very inconvenient to service as far as I can remember. In order to remove one module, it was necessary to unscrew all potentiometers from the front plate. So we changed all the opamps on two modules, and we didn’t have time for a lot of experimentation because the mixer remained in operation.

Indeed. Experimentation is much easier on a true modular desk.

 

[JohnRoberts]

Caveat I am clearly not a fan of second guessing original design engineers but am getting used to that. Allow me to share some observations.

You won't make an old POS console into a high performer just by upgrading some op amps. You need to understand how negative feedback (NF) works. All (most) audio path transfer functions are completely defined by the NF networks applied to op amps. In a decent design with adequate loop gain margin the result is extremely close to the NF transfer function... If this NF network is using lousy parts or poorly designed, a better op amp will only get you the last percent closer to the lousy NF network transfer function.

In a poor original design where the op amp was being asked to deliver more gain than it has, some slight improvement could result from using a better op amps, but the stronger op amp could also reveal flaws concealed by the old op amps.

As abbey has already shared off the shelf op amps by the late 70s were faster than needed for audio and quiet enough to not corrupt audio when used appropriately.

I am a strong believer in bench testing. A simple frequency response plot of every channel can reveal dried out old capacitors (typically revealed by weak LF response). If you find one bad cap, I would replace all of the same value as they are likely next to fail.

If you can't resist hot rodding channels with modern op amps. Document your experiments with more measurements. If convinced you have found some magic op amp substitution, you can flip the polarity of audio in one channel and then subtract the modded channel from a stock one in a sum bus. The difference you get if they don't null completely can advise you of what has changed.

JR

 

[moamps]

....
You won't make an old POS console into a high performer just by upgrading some op amps.....

If this post of yours was meant for me, then you should read my post 23 again. We made changes to two modules, I made measurements and they showed no significant improvement, a friend used these modules in the studio for a while and as a FOH console and came to the conclusion that he liked the changes so much that he wanted to modify all channels. We then made additional changes described in the post 26. He was pleased with what he got, and as he himself said he got a more reliable and better tool to work with. He never even thought to put a Neve or SSL sticker on it. End of story.

 

[JohnRoberts]

If this post of yours was meant for me, then you should read my post 23 again. We made changes to two modules, I made measurements and they showed no significant improvement, a friend used these modules in the studio for a while and as a FOH console and came to the conclusion that he liked the changes so much that he wanted to modify all channels. We then made additional changes described in the post 26. He was pleased with what he got, and as he himself said he got a more reliable and better tool to work with. He never even thought to put a Neve or SSL sticker on it. End of story.

If my post was meant for you specifically I would have quoted your post, and NO I won't read your post again. I will leave it up to you to determine if the shoe fits.

I am offering general advice for the several people around here who don't understand high level circuit design and how components degrade after decades.

JR

 

[john12ax7]

We made changes to two modules, I made measurements and they showed no significant improvement

I've had similar experiences. In the end the best way to determine if something sounds better is through listening. Things can measure the same and sound different, and vice versa. And it's also not easy to correlate "good sound" with measurable differences.

 

[living sounds]

The most important thing is not the op amp but what surrounds it. So much can go wrong with grounding and decoupling, PCB design, stray capacitance, RF,...

I don't think anything 'better' than an NE5532/5534 is needed in most pro audio circuitry, unless it is for very specific low noise application, offset or high frequency requirements.

Speeds that are good enough for audio and not much more have the benefit of better stability than high speed op amps. One may perceive added "clarity", while in reality it is artifacts of the op amp fighting with high frequency noise and in response produces nonlinearities.

I've wasted way too much time "rolling" op amps, my only advice from experience is to stay away from it and maybe look for other improvements in the circuit, though it is easy to degrade performance this way, too. For example, adding PSU decoupling caps without exact understanding and taking measurements can make the circuit unstable by changing the power lines impedance response.

One upgrade I like is improving problematic grounding in some older gear (though not in consoles, which tend to be far too complex). ) Improper handling of chassis ground vs. audio ground, especially in connection with balanced audio (pin 1) is sometimes the reason for degradation, and can be fixed if you know what you are doing.

 

[living sounds]

I've had similar experiences. In the end the best way to determine if something sounds better is through listening. Things can measure the same and sound different, and vice versa. And it's also not easy to correlate "good sound" with measurable differences.

Been there. Way too often I "heard" an improvement, then went on to change it in the whole unit (sometimes even a console), and when I made an actual mix with the 'improvement' it turned out to be anything but.