It seems that this DAC uses the OPA1602. Quick specs: 2.5nV / 35MHz / 20V/μs / ±2.25V min / BJT - pretty good.
$3.59 - not so expensive.
If you really want to improve on the sound of an op-amp, also have a look at the power supply feeding it. In many cases this is the place where someone from the financial department cut costs. Some additional and/ or better caps as well as other common tactics may improve the supply and give a nicer sound in the end.
Maybe there you will find more room for improvement than changing a good op-amp for another good one.
If the device has a very small case, moving the transformer into an external housing can give a better supply voltage, too. An oscilloscope is very helpful to find spikes and ripple on the PS that in many cases can be eliminated with a few parts.
You don't have to fit an expensice super regulator to clean up the supply.
I had some gear where the changing of op-amps really improved the sound drastically. Like night and day. In those cases changing the supplied op-amp for one with the identical name from a known source was the cause for the huge sound improvement. There are so many Chinese fakes around now, you find them anywhere.
So you may not change the NE5332 for some OPAxxx, but in reality remove a relabeled 0.1Cent op-amp from your gear. So you only fit something close to what the circuit designer wanted to have at this position.
Maybe there you will find more room for improvement than changing a good op-amp for another good one.
If the device has a very small case, moving the transformer into an external housing can give a better supply voltage, too. An oscilloscope is very helpful to find spikes and ripple on the PS that in many cases can be eliminated with a few parts.
You don't have to fit an expensice super regulator to clean up the supply.
I had some gear where the changing of op-amps really improved the sound drastically. Like night and day. In those cases changing the supplied op-amp for one with the identical name from a known source was the cause for the huge sound improvement. There are so many Chinese fakes around now, you find them anywhere.
So you may not change the NE5332 for some OPAxxx, but in reality remove a relabeled 0.1Cent op-amp from your gear. So you only fit something close to what the circuit designer wanted to have at this position.
Come on...don't open that Pandora box!Some op amps have 130... 140db PSRR and CMRR...how's gonna help them them those snakeoil paralleled caps?
Nothing. Am I required to say anything? 🙂 The AD797 is pretty old. But then again some swear by the NE5532 as well.
I have yet to be excited about an ADI opamp. The portfolio they bought from LT is pretty solid, but also quite expensive. It seems TI is the innovator in that space, though in all fairness it's the former Burr-Brown (OPAxxxx) and National (LM/LMH/LMV/LMExxxx) folks who do the innovation.
Tom
Certainly not, but without making some measurements there's no way to tell what's been accomplished. One more caution- very often I've modified a circuit and it sounded different. More often than not, when a circuit sounds different, even if you think its better, it has something wrong with it. Oscillating or whatever, but correctly operating circuits tend to sound the same, not better or different.
I'm starting to understand that you can't change anyway. If my LM4562 works under perfect conditions, it might be hard to beat this in my dac.
If you find someone else who can work under the same conditions, you can switch, right?
If you find someone else who can work under the same conditions, you can switch, right?
That's just one way to frame it. If you enjoy the activity, then it certainly is entertainment. But there are other frames too, equally valid and descriptive.
Not to knock Nelson Pass, but his opinion of what "this" is is simply his opinion. There's plenty of room for the opinions of others. I would argue that selecting an opamp for a DAC is a multivariate optimization engineering problem. In multivariate optimization there may be multiple optima. There could also be a single global optimum. Or no optimum. Not all equation systems have solutions. Presumably the designers of the DAC arrived at one optimum. You could have different preferences which would lead you to select a different optimum. But you're unlikely to find such optimum by "rolling" opamps. You're far more likely to find an optimum by analyzing the system and choosing an opamp from its specs that get you closer to what you consider to be optimum in the circuit. Hence the questions, "what's it do" earlier in this thread.
Tom
Tom
I can only contribute a very humble observation. In the output of my basic Chinese AK4490 Dac I tried:
NE5532 - Warm and close sound but lacks detail, pleasant up to a point
OPA2134 - Neutral but highs are rather shut in and it's a bit flat
LM4562 - Clean and airy treble but voices are rather disembodied and piano is quite percussive. It's nearly very good but I suspect the circuit doesn't bring out its potential. It's all surface mount and I haven't looked at the circuit. May be oscillating so hard to judge. Sounds uncomfortable.
LM6172 - not as airy as the LM4562 but seems comfortable in the circuit. Sound is neutral, detailed, and voices are natural. Not much air or sparkle but the treble is all there plus decent bass. For want of anything better this is my choice in this circuit.
These are all socketed devices. I'd love to try some more recent SOIC duals in adapters so open to recommendations.
NE5532 - Warm and close sound but lacks detail, pleasant up to a point
OPA2134 - Neutral but highs are rather shut in and it's a bit flat
LM4562 - Clean and airy treble but voices are rather disembodied and piano is quite percussive. It's nearly very good but I suspect the circuit doesn't bring out its potential. It's all surface mount and I haven't looked at the circuit. May be oscillating so hard to judge. Sounds uncomfortable.
LM6172 - not as airy as the LM4562 but seems comfortable in the circuit. Sound is neutral, detailed, and voices are natural. Not much air or sparkle but the treble is all there plus decent bass. For want of anything better this is my choice in this circuit.
These are all socketed devices. I'd love to try some more recent SOIC duals in adapters so open to recommendations.
Before rolling opamps, have someone else put tape on them with random numbers, hide the list for later, so you don't know yet which one is being tested. The human body is a complex instrument with all the senses interconnected. So always have the same thing for lunch, and wear the same socks, and meditate before testing so that all the nerves are calm. And have a good night's sleep.
Yup, I am joking but posts about amp rolling seem like someone trolling just to get a response. Otherwise, I don't get it.
Yup, I am joking but posts about amp rolling seem like someone trolling just to get a response. Otherwise, I don't get it.
I would not do an OP amp swap. It probably won't work and you'll just ruin the sound. The NE5532 only has a bandwidth of 10MHz, the LM4562 has 55MHz (nearly FM radio ;-)). The probability that it will start oscillating is almost inevitable. The whole circuit and layout must "be able to" (not) run at 55MHz.
As regards oscillation, is one easy fix to use a SOIC op-amp in an adapter and add whatever small capacitors right on the pins?
May well apply to LM4562. The LM6172 appears stable in my DAC but may benefit from a 0.1uF radial ceramic between pins 4 and 8, so I read. And the same kind of thing for other faster op-amps like LM1612, LM1642, LM1656 etc?
May well apply to LM4562. The LM6172 appears stable in my DAC but may benefit from a 0.1uF radial ceramic between pins 4 and 8, so I read. And the same kind of thing for other faster op-amps like LM1612, LM1642, LM1656 etc?
I've had good success mounting an OPA1611 (GBW = 40 MHz ; SR = 27 V/usec) on an SOIC-to-DIP adapter. No oscillation or excess overshoot observed.
Yes, and the ADA4898-2 as well, with these higher-speed ones.
0.9nV/√Hz / 65MHz / 55V/μs / 5V min / BJT
For not very fast ones, in the case of possible oscillations, there are:
OPA1678 - 4.5nV / 16MHz / 9V/μs / ±2.25V min / CMOS
OPA1642 - 5.1nV / 11MHz / 20V/μs / ±2.5V min / Fet
OPA2189 - 5.2nV / 14MHz / 20V/μs / ±4.5V min / CMOS
OPA2210 - 2.2nV / 18MHz / 6.4V/μs / ±2.5V min / BJT
OPA1662 - 3.3nV / 22MHz / 17V/μs / ±1.5V min / BJT
OPA1622 - 2.8nV / 32MHz / 10V/μs / ±2V min / BJT
OPA1602 - 2.5nV / 35MHz / 20V/μs / ±2.25V min / BJT