@Thx1326
You are starting to straddle the line here between the half of the population who may not be on the more sensitive side of the Threshold of Audibility bell curve, and other half who notice more about sound. You will get some bad advice from both extremes, because people do imagine things that aren't real sometimes, and sometimes other people believe they know how to measure all there is and all there can be, which is sometimes not exactly right either.
Anyway, if you want to try opamp rolling it depends on the application. With digital audio sometimes the opamps vary in their tolerance to RF, whereas in pure audio frequency circuits they may do much better.
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This should never be foregone.
Nevertheless, one should evaluate other opinions in advance so that the range of types for a shortlist becomes smaller.
The “old hands” now all know that the lowest possible value of the “THD+N” parameter is not the reference of all things for the qualitative perception of the sonic character.
Otherwise, the NE5534 would still be one of the best in comparison tests in terms of the perceived sonic character, as the measurement results in the attachment of post #660 clearly show.
But because that's not the case, I started this thread.
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Well... I thank all of those who have replied and offered help. I've narrowed down the "short list" to those four listed below but still have NOT made a final decision regarding the final replacements ... it shouldn't be this difficult. And as we all know, specs DO NOT tell the whole story. I did install DIP 8 sockets so that op-amp "rolling" could be possible, but I definately don't want to do that due to my past experience with tube rolling. I never can quite settle in on a decision as I always feel I didn't quite "hear" what I was "supposed" to hear so I'm never quite satiated and end up with a bunch of tubes I don't use... guess they will be spares. I really am not interested in opamp "rolling".
So hear I am with this beautiful condition Kenwood Basic C2 preamplifier that looks like it just came out of the factory, recapped, new metal film resistors and transistors, gold plated jacks and some other items. It kind of got out of control as this was a trip down nostalgia lane as this was the model of the first preamp I ever owned and bought when it was new. And will most likely be the last preamp I ever by. It is an enjoyable form of "therapy" if nothing else.
In the original preamp, the 4 opamps were as follows:
The Flat Amp section (main board): NJM2041D - Current model - NJM2068DD
Phono PreAmp (main board): NJM4560D - Current model - NJM4580DD
Tone Control Board: NJM4560D - Current model - NJM4580DD
Filter Board: NJM4560D - Current model - NJM4580DD
So, the obvious thought is that any "high quality" current model should offer benefits over the originals due to newer manufacturing methods, materials and improvements in some specific specs. The candidates have come down to these four choices - with a short explanation (order of listing has no relevance regarding preference).
1. NJM2068DD and NJM4580DD: They were good enough for the original and chosen for their sonic characteristics, the new ones should be some level of improvement.
2. TI/Burr-Brown OPA1642: Specs are very good. Low noise JFET design op-amp known for its low noise and ultra-low distortion. It provides superior sound quality and speed for demanding applications. Users have described its sound as having great detail and "silky smooth highs and upper midrange".
3. TI/Burr-Brown OPA1656: Specs are very good. Low noise CMOS design, highly detailed. Designed for enhanced AC performance with very low distortion and low noise. It’s noted for its high bandwidth and high open-loop-gain design. Some users have reported that it sounds better than any transistor preamp they’ve heard. As a caveat, it seems that the majority of the "audiophile" groups can find nothing good about CMOS opamps???
4. TI/Burr-Brown OPA2604: a low noise JFET design operational amplifier designed for enhanced AC performance. It’s known for its very low distortion, low noise, and wide bandwidth. The overall sound balance is quite neutral, and detail is very good without being extreme. Some users have reported that it has a wider soundstage and higher clarity than some other op-amps.
So there it is. Comments and listening experience are all welcome. I kind of figure any one of the four would be a step forward. I'd be very appreciative of knowing what you think.
Thanks to all... once again!
So hear I am with this beautiful condition Kenwood Basic C2 preamplifier that looks like it just came out of the factory, recapped, new metal film resistors and transistors, gold plated jacks and some other items. It kind of got out of control as this was a trip down nostalgia lane as this was the model of the first preamp I ever owned and bought when it was new. And will most likely be the last preamp I ever by. It is an enjoyable form of "therapy" if nothing else.
In the original preamp, the 4 opamps were as follows:
The Flat Amp section (main board): NJM2041D - Current model - NJM2068DD
Phono PreAmp (main board): NJM4560D - Current model - NJM4580DD
Tone Control Board: NJM4560D - Current model - NJM4580DD
Filter Board: NJM4560D - Current model - NJM4580DD
So, the obvious thought is that any "high quality" current model should offer benefits over the originals due to newer manufacturing methods, materials and improvements in some specific specs. The candidates have come down to these four choices - with a short explanation (order of listing has no relevance regarding preference).
1. NJM2068DD and NJM4580DD: They were good enough for the original and chosen for their sonic characteristics, the new ones should be some level of improvement.
2. TI/Burr-Brown OPA1642: Specs are very good. Low noise JFET design op-amp known for its low noise and ultra-low distortion. It provides superior sound quality and speed for demanding applications. Users have described its sound as having great detail and "silky smooth highs and upper midrange".
3. TI/Burr-Brown OPA1656: Specs are very good. Low noise CMOS design, highly detailed. Designed for enhanced AC performance with very low distortion and low noise. It’s noted for its high bandwidth and high open-loop-gain design. Some users have reported that it sounds better than any transistor preamp they’ve heard. As a caveat, it seems that the majority of the "audiophile" groups can find nothing good about CMOS opamps???
4. TI/Burr-Brown OPA2604: a low noise JFET design operational amplifier designed for enhanced AC performance. It’s known for its very low distortion, low noise, and wide bandwidth. The overall sound balance is quite neutral, and detail is very good without being extreme. Some users have reported that it has a wider soundstage and higher clarity than some other op-amps.
So there it is. Comments and listening experience are all welcome. I kind of figure any one of the four would be a step forward. I'd be very appreciative of knowing what you think.
Thanks to all... once again!
Well I've a list of 10 or so high quality audio opamps and the OPA2604 isn't in them because its significantly noisier than them by 6dB or more ("low noise" is in every opamp datasheet BTW, its meaningless without the numbers!). Add OPA1688, LM4562, OPA1612, ADA4625, OPA1652, OPA1662, NE5534A (phono) to that list at least - there are probably more choices if you search the relevant manufacturers selection guides.
And there are criteria for selection you haven't highlighted, such as not using bipolar on a tone-control circuit, low current-noise for phono, package choice.
And there are criteria for selection you haven't highlighted, such as not using bipolar on a tone-control circuit, low current-noise for phono, package choice.
This has been a very informative thread. It is nice to have a comparison of specs and electrical performance to help "weed out" those that should not make the cut. But in the end, regardless of the technical specs and performance, doesn't it really come down to "how do they sound in the application they are being used in?"
Have any of the technical guru's here tried or listened to the discreet opamps such as the Burson's or Sparkos? Does anyone have comparative specs or real life experience with these being used in an audio chain?
Thanks in advance.
Have any of the technical guru's here tried or listened to the discreet opamps such as the Burson's or Sparkos? Does anyone have comparative specs or real life experience with these being used in an audio chain?
Thanks in advance.
I just found this interesting thread.
To save some reading time, has it been discussed which discrete/OpAmp gives the least of IMDs? Is this performance considered in the short list?
I understood that the IMDs will benefit from low THD, but I also understood that it is not a direct proportionality: circuits with ultra low THD can still give significant (audible) IMDs.
To save some reading time, has it been discussed which discrete/OpAmp gives the least of IMDs? Is this performance considered in the short list?
I understood that the IMDs will benefit from low THD, but I also understood that it is not a direct proportionality: circuits with ultra low THD can still give significant (audible) IMDs.
No... that is, unless the THD raises very steeply at higher frequencies. Then, and only then, you could have a good THD @ 1kHz but only fair IMD/Multitone specs.
if 1:1 IMDs at 0dB are below 90dB, any Opamp is okay for me.
Do you have here any pass/no pass reference value to choose the long list of OpAmps?
For short list I get it, it must be short (the best of the best). Still, info where the others are performing (the delta performance) is also useful.
P.S. I'd add also a reference to Noise somehow; as a IMD difference of 3dB burried in a +20dB noise... is not relevant in my opinion.
Do you have here any pass/no pass reference value to choose the long list of OpAmps?
For short list I get it, it must be short (the best of the best). Still, info where the others are performing (the delta performance) is also useful.
P.S. I'd add also a reference to Noise somehow; as a IMD difference of 3dB burried in a +20dB noise... is not relevant in my opinion.
And: what @KSTR wanted to communicate: the fundamental mechanism behind even order harmonic distortion and IMD is mathematically the same. See here: http://www.acourate.com/freedownload/k2/TheHarmonicDistortionMyth.pdf
And no, I deem my english to be good enough to not need chatgpt to understand anyone
T5: if we have -70dB noise floor and -90dB highest harmonic (or even THD), then the harmonics start being recognizable by a typical ear/brain.
Rephrased: non-musical harmonics or IMDs can be detected as low as 10x smaller than the noise.
It is an approximation. My opinion for a better metric (see title).
Rephrased: non-musical harmonics or IMDs can be detected as low as 10x smaller than the noise.
It is an approximation. My opinion for a better metric (see title).
On pg. 2+3 in the mentioned PDF link I read this:And: what @KSTR wanted to communicate: the fundamental mechanism behind even order harmonic distortion and IMD is mathematically the same. See here: http://www.acourate.com/freedownload/k2/TheHarmonicDistortionMyth.pdf
And no, I deem my english to be good enough to not need chatgpt to understand anyone
The equations shows up the term 4ab. It is equal to the multiplication of two frequencies (or
to the amplitude modulation of a frequency by another frequency).
Such a modulation creates the undesired side frequencies.
The amplitude of these side frequencies is even by 6 dB higher than the intended double frequencies.
So we already suspect it: music isn’t just a single frequency or a sum of two or three.
Music is an arbitrary mixture of frequencies.
Thus adding k2 does not result in pretty nice harmonic frequencies.
Summary: in ideal case we would expect to get the original music pitch shifted by an octave.
But in real case we can hear that the harmonic distortion in a myth.
Even with a simply k2 distortion we get non-linear harmonics.
Of course someone may argue that k2 is more nice to listen to than to k3 or higher.
But this is not an argument against the non-harmonic results with any distortions.
So the best way is to avoid the distortions as much as possible.
Uli Brüggemann, AudioVero
Some of these statements are true, but when looking at all of the statements made here, the question remains as to why in some cases (both in preamplifiers with discrete and integrated op amps as well as in power amplifiers) good sound properties can be recorded on listening tests with a high measured THD+N value and in other cases poor sound properties despite very low measured THD-N values.
Because music isn’t just a single frequency or a sum of two or three, but a highly complex mixture of not only different frequencies but also different wave forms, the best agreement between the measurement results and the results for perceived sonic quality in listening tests can be achieved by choosing the height of the measurement frequencies for IM well outside the audible range (e.g. 199KHz + 200KHz) and then reasonably satisfactorily low values for THD-N and IM receives.
Interestingly, this can only be achieved with certain, mostly simple circuit topologies, which on the one hand have relatively high values for low-order distortions, but which only increase insignificantly in direction to higher frequencies.
The character of the residual distortions (fundamental notched out) is always sinusoidal, both in the simulation and in reality.
check out post #9 under
https://www.diyaudio.com/community/...o-o-os-0s-versus-later-aleph-versions.148640/
Unfortunately most engineers claim, all this observations are absolute nonsense.
you get 75% my support. As a 25% mystery for me remains the psycho-acoustic performances of the valve-based circuits.
But I am not at your level, for example I do not understand your call for 199-200KHz IMD test as relevant for audio range, much less why is your preferred method at all.
Only little thing that I know and I can comment is that, when I designed a special project for 50W in a 3mH inductor load with 300-600KHz BW, happening sometimes back in 2015: at the prototyping phase I checked EVERY SINGLE passive component to be ideal until at least 6MHz, ideally until at least 10-20MHz. So, it happened that most components who passed this criteria were old 80's batches of rare expensive high quality ones.
No wonder, and actually is kind of silly, to expect such kind of passives in the batches today (as you said you did tested them and 'surprisingly' failed in 199-200KHz IMD test).
Immediately after this project, I started to use the old stock much more carefully, only for really special requirements
Prost!
But I am not at your level, for example I do not understand your call for 199-200KHz IMD test as relevant for audio range, much less why is your preferred method at all.
Only little thing that I know and I can comment is that, when I designed a special project for 50W in a 3mH inductor load with 300-600KHz BW, happening sometimes back in 2015: at the prototyping phase I checked EVERY SINGLE passive component to be ideal until at least 6MHz, ideally until at least 10-20MHz. So, it happened that most components who passed this criteria were old 80's batches of rare expensive high quality ones.
No wonder, and actually is kind of silly, to expect such kind of passives in the batches today (as you said you did tested them and 'surprisingly' failed in 199-200KHz IMD test).
Immediately after this project, I started to use the old stock much more carefully, only for really special requirements
Prost!