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Anybody OP amp rolling?

pma

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There are pretty big differences between opamps concerning their parameters, this being true for audio parameters as well, however this place does not seem to be the one to discuss it in deep. There are also big differences regarding opamps immunity to EMI, escpecially the beloved LM4562/LME49720 line behaves pretty poorly in this regard.
 
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Wombat

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There are pretty big differences between opamps concerning their parameters, this being true for audio parameters as well, however this place does not seem to be the one to discuss it in deep. There are also big differences regarding opamps immunity to EMI, escpecially the beloved LM4562/LME49720 line behaves pretty poorly in this regard.

Start a thread, if you wish. I think it will be more rationally informative.
 

PaulD

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Indeed Womba & LTig! It's been explained on ASR many times:
- Only a properly conducted listening test is worth anything (double blind and level-matched), and they are annoying and difficult to undertake!
- Cognitive biases cause HAVOCK with sighted casual listening tests, for everyone (me included) because we are human and ALL subject to these biases, so they have zero value (ie results cannot be replicated).
- We can measure everything that can be heard, this has been supported here many times, there is no magic, there is nothing that we can hear that cannot be measured, so measurements capture everything that we can hear (even more). Properly conducted listening tests have verified this.

Scott Wurcer designed the 797 opamp (sorry for outing you Scott) and knows more about them than anyone else on this forum, probably more than most people on the planet. Ask him about opamp rolling. Yes pma there are differences between opamps, but a competent designer today will select the optimum opamp for a particular part of a circuit and substituting another will, 99% of the time, offer no value but it will sometimes give worse performance.

A whole lot of the performance of a piece of modern equipment will depend on the circuit layout and the details of the components chosen. Modern engineers are often very very good. Unlike 40 years ago when substituting a high-performance opamp could probably improve the performance, that is no longer true. Bruno Putzey's balanced preamp/volume controller that was in Linear Audio (and online in EDN I think) is a case in point, substituting other opamps will almost certainly degrade the performance.

If you have something 40 years old and swap the opamps you might, might, improve the performance, but a higher performance opamp may also break into oscillation in the MHz region etc etc (which could present in the audio band as noise) and actually degrade the performance.

If we practiced medicine the same way as subjective audio reviews we'd still be selling snake-oil to cure cancer...
 
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Matias

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Wombat

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Indeed Womba & LTig! It's been explained on ASR many times:
- Only a properly conducted listening test is worth anything (double blind and level-matched), and they are annoying and difficult to undertake!
- Cognitive biases cause HAVOCK with sighted casual listening tests, for everyone (me included) because we are human and ALL subject to these biases, so they have zero value (ie results cannot be replicated).
- We can measure everything that can be heard, this has been supported here many times, there is no magic, there is nothing that we can hear that cannot be measured, m so measurements capture everything that we can hear (even more). Properly conducted listening tests have verified this.

Scott Wurcer designed the 797 opamp (sorry for outing you Scott) and knows more about them than anyone else on this forum, probably more than most people on the planet. Ask him about opamp rolling. Yes pma there are differences between opamps, but a competent designer today will select the optimum opamp for a particular part of a circuit and substituting another will, 99% of the time, offer no value but it will sometimes give worse performance.

A whole lot of the performance of a piece of modern equipment will depend on the circuit layout and the details of the components chosen. Modern engineers are often very very good. Unlike 40 years ago when substituting a high-performance opamp could probably improve the performance, that is no longer true. Bruno Putzey's balanced preamp/volume controller that was in Linear Audio (and online in EDN I think) is a case in point, substituting other opamps will almost certainly degrade the performance.

If you have something 40 years old and swap the opamps you might, might, improve the performance, but a higher performance opamp may also break into oscillation in the MHz region etc etc (which could present in the audio band as noise) and actually degrade the performance.

If we practiced medicine the same way as subjective audio reviews we'd still be selling snake-oil to cure cancer...


Plenty of self-diagnosing medicators around. That alternative-health industry makes audio snake-oil merchants look like the under-funded amateurs that they are.
 

Wombat

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JJB70

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I think op-amp rolling is another example of the audiophile urge to tweak with things. I think this urge to tweak goes back to turntables and tube gear, but in most cases I think that it is at best pointless with digital and solid state gear and may well make things worse. My own advice would be that if people want to tweak and be creative, which I do fully understand (my main hobby is making model trains) then get into DIY and do it properly. Build your own amplifiers etc, even if performance is not great I can understand that the pleasure of building your own equipment is its own reward.
 

Phorize

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trl

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That is one hell of a subjective post with many suppositions.

For a brief moment I thought I was on one of those forums that ASR is the antethesis of.
Well...yes and no. I did several measurements with different opamps in my gear of background noise and THD as well, so my above assertions are a mixture between both subjective listening and objective measurements as well. What I tried to write in the above post is that we should always keep in our DIP8 sockets those opamps that are measuring best (usually the default ones) or the ones that are having the lowest DC and still measuring good enough.

BTW, here's a very good posting of our ASR colleague @Earfonia: https://www.head-fi.org/showcase/bu...d-opamp-v5i.21562/reviews?page=3#review-18921. As you can see, some opamps perform better when used in lower gains, some others perform better when used with higher gain.
 

JJB70

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HA! As if the BRZ wasn't underpowered already...

I really don't think it is. Subaru (and Toyota) basically went the same direction as Mazda with the MX5, a simple and light(-ish) car with sweet handling that is a hot to drive at speeds which won't result in losing your driving license. It was never meant to be a supercar, but a good handling affordable coupe, something it does extremely well.
 

direstraitsfan98

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I was thinking of doing this to my amp, the Akitika GT-102 which I've talked about here. How much are opamps? They look like they ought to cost under a dollar.
 

gene_stl

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I independently invented(discovered?) op amp rolling in the 1970s. A friend of mine had a Crown IC 150A preamp driving a DC 150 power amp and Bosee 901 spikkers.

At that time Matti Ottala's article on Tranisient Intermodulation Distortion came out and one of the culprits was "limited slew rate" I also had, and studied, all the wonderful National Semiconductor Analog data books.

We opened his preamp which had iirc LM301 op amps in it. I already had a stick of LM318s which I was going to use in my electronic crossover network. I offered to "upgrade his op amps" since they were in sockets. The LM318 was used in BGW amps which advertised fast slew rate.

We did so one evening. I was very hesitant to turn it back on because I knew even then that I might have created an oscillator. But I figured there were nine voice coils in the Bosees and I would have time to switch it back off if something horrible occured. I took a deep breath and switched it on.

It worked fine. I heard no improvement. It didn't seem to be oscillating at least not at a frequency I could hear. My friend kept the "mod" until he cycled on to other equipment. Never got a chance do any measurements on that preamp. I did not like the sensation of wondering whether I created an oscillator. This was before I had any bench gear.

The LM301 we removed was not as primitive an op amp as the 741 and 701 but back then there might have been an improvement in transparency using a 318. I could not hear it.
 
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gene_stl

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I was thinking of doing this to my amp, the Akitika GT-102 which I've talked about here. How much are opamps? They look like they ought to cost under a dollar.

The Akitika stuff is one of the few decent values in audio these days. I have looked at it closely since I have a left over Dyna Stereo 120 with the proverbial blown channel. The Akitika is circuitry they designed for stereo 120 replacement and your amp is for people that don't happen to have a Dyna carcass to be organ donor for only the power transformer and chasis. It is much more modern in design and performance than the ancient Stereo 120.

I would recommend that you leave things as they came from the factory. The Akitika amps are based on the excellent LM3886 power amp chip from TI. Same as used by Neurochrome which is on the far left of ASR s SINAD listing. Edit:The Akitika circuitry has no rollable op amps. only the LM3886 and three transistors. There is a "rollable" op amp in the power supply but this is not in the signal path and rolling it will do nothing.

If you like the sound of it with 4367s that is a very good recommendation. Amp tweaking is unlikely to improve matters. If you must co ordinate with Akitika and follow his advice perfectly. You are not going to come up with anything he has not thought of.

Your next step should be bi amping those wonderful speakers. Nothing else. JBL has lots of data on how to do that perfectly.
 
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NickK

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People buy different amps because it sounds better to them - op amp rolling is no different.

How much of that is surjective is a different thing - hard cold measurement is the only way, then pick your poison based of ear or graph!
 

trl

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You need to do measurement for each device and after each opamp change, otherwise is useless. Same opamp in device_no1 may measure better or worse than if using it in the device_no2. Also, needs to be absolutely the same stage the opamp is used: input stage, I/V, LPF, Voltage-Gain, low-power buffer, high-power buffer etc.

Randomly doing measurements to opamps used in amplification different stages and on different equipment doesn't tell a full story of those specific opamps. This is why, when "upgrading" opamps, we all need to read datasheet first, then carefully read what manufacturer has to say about possibility of rolling opamps.
 

SIY

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I wrote this in a different context, but it's likely applicable here.

And then a sociological aside: one major reason for the wire craze is that it takes absolutely no knowledge to swap wires, just a credit card. In fact, knowledge here is a detriment to the “fun” of applying exotic “solutions” to problems that only require simple and inexpensive solutions. Capacitors are not far behind- there is the additional barrier of having to solder, but beyond that, it takes no knowledge to read internet reviews, whip out a credit card, and swap in an expensive component with a good story. Follow it up with uncontrolled listening with a pre-existing bias and no actual knowledge to clutter up things, and you have a wonderful story to tell people on the Internet.
 
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