Starting a thread to evaluate various op-amps in the output of mainly DIY or legacy DACs.
Here are my recent findings, in case they may be of interest. I've just done listening tests on a bunch of op-amps in the output of my V-DAC, which originally comes with a NE5532. It has a replacement DIP8 socket and also has the 47uF output cap removed. Input is SPDIF via a V-Link, and a V-PSU was used. The V-DAC directly feeds a 2 stage SE tube amp into Mission 761 speakers. Test tracks were Bill Evans album "I Will Say Goodbye" and some Keith Jarrett for piano, Dee Dee Bridgewater "Keeping Tradition" for vocals and Solti Meistersinger (most recent) plus some Steely Dan and modern gospel. Tonality of acoustic instruments was in this case the main consideration.
Top group - judged to have all-round good natural tone including the most realistic piano and vocals
OPA1612
OPA1642
AD8022
AD8066
LT1361
LT1364
Eliminated for various issues
LT1469 - rather thin, very clean
AD8599 - too thin, very clean, excellent high treble
LM6172 - wooden piano sound
LT1057 - bit meh overall
Previously eliminated in a AK4490 DAC
LM4562 - clean but thin
OPA2134 - quite good
OPA2132 - quite good
NE5532 - OK but not special
OPA2228 - nothing special
The top group would need to be re-tested for a winner, but maybe there isn't an overall winner since I enjoyed them all in different ways. For DIP8 you'd need LT1361 or LT1364, the rest needed adapters. They all sounded stable in the V-DAC though they weren't tested with a scope.
Subjective results which apply to directly replacing a NE5532 in a V-DAC output stage, so may not be the same in other contexts. Still, I hope this might be of some use.
Here are my recent findings, in case they may be of interest. I've just done listening tests on a bunch of op-amps in the output of my V-DAC, which originally comes with a NE5532. It has a replacement DIP8 socket and also has the 47uF output cap removed. Input is SPDIF via a V-Link, and a V-PSU was used. The V-DAC directly feeds a 2 stage SE tube amp into Mission 761 speakers. Test tracks were Bill Evans album "I Will Say Goodbye" and some Keith Jarrett for piano, Dee Dee Bridgewater "Keeping Tradition" for vocals and Solti Meistersinger (most recent) plus some Steely Dan and modern gospel. Tonality of acoustic instruments was in this case the main consideration.
Top group - judged to have all-round good natural tone including the most realistic piano and vocals
OPA1612
OPA1642
AD8022
AD8066
LT1361
LT1364
Eliminated for various issues
LT1469 - rather thin, very clean
AD8599 - too thin, very clean, excellent high treble
LM6172 - wooden piano sound
LT1057 - bit meh overall
Previously eliminated in a AK4490 DAC
LM4562 - clean but thin
OPA2134 - quite good
OPA2132 - quite good
NE5532 - OK but not special
OPA2228 - nothing special
The top group would need to be re-tested for a winner, but maybe there isn't an overall winner since I enjoyed them all in different ways. For DIP8 you'd need LT1361 or LT1364, the rest needed adapters. They all sounded stable in the V-DAC though they weren't tested with a scope.
Subjective results which apply to directly replacing a NE5532 in a V-DAC output stage, so may not be the same in other contexts. Still, I hope this might be of some use.
Indeed - OPA1656. I regret not buying that since the OPA1642 is so good, and frequently compared to it. Do you mean AD828?
I believe the 49720 is the same as LM4562? That sounded thin to me, lacked a full natural tonality. Don't know if it was stable.
Keep the posts coming!
I believe the 49720 is the same as LM4562? That sounded thin to me, lacked a full natural tonality. Don't know if it was stable.
Keep the posts coming!
Andy, what is the configuration of the op-amp output stage you’re referring to?
Is it inverting or non-inverting?
Does it feature gain, and if so, how much?
Is it driven by an active reconstruction filter, or a passive?
Is it inverting or non-inverting?
Does it feature gain, and if so, how much?
Is it driven by an active reconstruction filter, or a passive?
Good question. Here's the output schematic of the V-DAC. I removed the 47uF cap. I'm a tube guy so not able to answer your questions, but maybe you can answer them with the schematic?
I see three opamps per channel (one quad and one dual for two channels). Did you replace all of them at the same time?
I only took out the NE5532 and fitted a DIP socket in its place. Didn't touch the rest except for removing the 47uF output cap.
Just for fun, here’s the portion of the schematic from the Plinius CD-101 CD-player, showing an LT-1363 op-amp being utilized as an active I/V (transimpedance) amplifier. Which is in the same device family as the LT-1361, and the LT-1364 which you have listed. The CD-101 was well regarded by reviewers back in the late 2000s.
Attachments
I think we should compare apples to apples. That is compare the same DAC with different opamps in the same topology. Perhaps the necessary compensation (if any) can be allowed.
Once I compared the I/V converter NE5534 to THS4031, then OPA134, OPA627, OPA828. Each sounded different, but it is difficult to pick the best. Only THS4031 was ruled out.
Once I compared the I/V converter NE5534 to THS4031, then OPA134, OPA627, OPA828. Each sounded different, but it is difficult to pick the best. Only THS4031 was ruled out.
opa1655, lt1028, lme49710, opa627, ad797, ada4898-1, opa2156, opa1611 and the CFAs (different implementation) ad811, ada4625-1, one life is not enough
Thanks for listing some of the single channel op-amps. I used LT1028 in a phono stage - very nice.
There seems to be a lot of love for the Sparkos SS2590 as a single. Expensive, though.
There seems to be a lot of love for the Sparkos SS2590 as a single. Expensive, though.
Is this constant current source put there in order to force the op-amp to work more in class A?
