Hey all -
I've just taken my first step into the much larger world of audiophilia (not a very attractive name, really) by purchasing a nice sound card for my computer - it's an HT Omega Claro Halo.
The documentation says that it is meant to have the op-amps switched out as the stock ones are low-end, but of course I'm pretty lost in this situation.
It says the current ones are 4580 (JRC) - which ones can I even look at that would replace that one?
And I know it's all subjective, but can anyone recommend a good one that would work in this implementation?
Thanks a lot!
I've just taken my first step into the much larger world of audiophilia (not a very attractive name, really) by purchasing a nice sound card for my computer - it's an HT Omega Claro Halo.
The documentation says that it is meant to have the op-amps switched out as the stock ones are low-end, but of course I'm pretty lost in this situation.
It says the current ones are 4580 (JRC) - which ones can I even look at that would replace that one?
And I know it's all subjective, but can anyone recommend a good one that would work in this implementation?
Thanks a lot!
Hmmm, I'm not sure what the difference between DIP-8 and surface mount is. I know that they're designed specifically to be popped in and out for experimentation, so I won't need to wrestle with getting them in and out. They look like all the schematics, but unfortunately that probably doesn't help you 
Again, I'm not sure about the voltage, but it's a PCI card so I believe it's max voltage would be about 5v - that would jive with the current op-amps and their low voltages.
How would these things affect my choices? What should I be looking for?
The best part about it is the support for the card is really great, so once I get a few op-amps I'm thinking about I can e-mail them to make sure they're compatible.
Again, I'm not sure about the voltage, but it's a PCI card so I believe it's max voltage would be about 5v - that would jive with the current op-amps and their low voltages.
How would these things affect my choices? What should I be looking for?
The best part about it is the support for the card is really great, so once I get a few op-amps I'm thinking about I can e-mail them to make sure they're compatible.
OK, socketed means they're DIP-8.
Well, at +/- 2.5V, or a single ended 5V, depending on how it's set up, I'd be looking at Analogue Devices AD823.
If you're up to soldering surface mount chips to adaptors (if you're unsure, that's a no, but maybe you know some-one who can) also consider AD8066.
You could also try LM4562 (same chip as LME49720 as recommended below). It's only just barely rated for +/- 2.5V operation, but it's a very good chip.
Well, at +/- 2.5V, or a single ended 5V, depending on how it's set up, I'd be looking at Analogue Devices AD823.
If you're up to soldering surface mount chips to adaptors (if you're unsure, that's a no, but maybe you know some-one who can) also consider AD8066.
You could also try LM4562 (same chip as LME49720 as recommended below). It's only just barely rated for +/- 2.5V operation, but it's a very good chip.
Well awesome! Thanks so much for all the replies.
It looks like I've got a good list of options. Now can anyone tell me where I can read about the sonic qualities of the different chips? If it is all subjective, is there any way to know which one I would prefer without purchasing them?
Thanks again!
It looks like I've got a good list of options. Now can anyone tell me where I can read about the sonic qualities of the different chips? If it is all subjective, is there any way to know which one I would prefer without purchasing them?
Thanks again!
http://tangentsoft.net/audio/opamps.html - there's a partial list. It doesn't include the LM4562 - you can find reviews of that chip if you poke around the site a little - in short, it's very good, a transparent chip that never feels like it's adding its own signature.
Can you check if the ICs have 24V across them or 5V (pin 40 to pin 8, you can remove the opamp and insert it into the PCI slot, and then switch on and measure the voltage).
LM4562 does not work very well at 5V. I know, I tried. Replacing a 4558 with a 4562 in a SB Live! card I had required me to hack up the power line (cut trace) and rework it to supply 12V to the chip, with a RC filter so it finally was around 10V).
They work very, very well with +/- 12V supply, some card makers are intelligent enough to run them like that (and stick to PCI, as PCI-express cards have no -12V supply).
According to the Opamp distortion paper, as memory goes, the best load distortion characteristics were for the AD797 (unusable in your card) followed by LM4562. I'm currently using a NE5532 in a headphone amp application and find that it is able to deliver all the current needed for a pair of 32-ohm phones, while sounding very good (need to keep input impedance low, but otherwise no hassle to use).
4562 needs good decoupling. I would suggest OPA series if you aren't planning on any hardcore modding.
LM4562 does not work very well at 5V. I know, I tried. Replacing a 4558 with a 4562 in a SB Live! card I had required me to hack up the power line (cut trace) and rework it to supply 12V to the chip, with a RC filter so it finally was around 10V).
They work very, very well with +/- 12V supply, some card makers are intelligent enough to run them like that (and stick to PCI, as PCI-express cards have no -12V supply).
According to the Opamp distortion paper, as memory goes, the best load distortion characteristics were for the AD797 (unusable in your card) followed by LM4562. I'm currently using a NE5532 in a headphone amp application and find that it is able to deliver all the current needed for a pair of 32-ohm phones, while sounding very good (need to keep input impedance low, but otherwise no hassle to use).
4562 needs good decoupling. I would suggest OPA series if you aren't planning on any hardcore modding.
samsagaz said:
Hello samsagaz-
I am sure that everyone here will agree that the "specs" often given for various IC op-amps might help differentiate between the possible performance of one chip vs. another in "ideal" situations, but often this is of absolutely no use once you actually start installing these devices in place of another one in a particular circuit topology. There are just far too many variables that affect the performance of a operational amplifier "in circuit" for datasheets to be often not much more than a crude guess about the possible performance in the real world. If you are seeking people's advice about what they did with a particular amplifier, I would be sure that you are going to do the EXACT same thing with the exact same device that they did.
I have found the previously suggested NE5532 unit to be of fairly good quality in most situations, this particular chip seems to find use in many of the "professional audio" units that are used in recording studios and other low-noise, high-quality devices in this particular field.
Also, as sangram aptly points out in his post here, be prepared to attack the power supply decoupling caps as a possible performance improvement area. I have found that troubleshooting power supply problems in op-amp circuits can often reveal that the power supply design itself is holding back the op-amps ultimate performance level. The cheap capacitors in common use inside most lower-end units lose their performance characteristics rather quickly, I have found. I have been surprised by the amount of power supply "ripple" I have seen on units barely one year old! While not all chips are super-sensitive to it, the "power supply rejection ratio" (PSRR) number given for the IC will often reveal its propensity to amplify power supply ripple noise. I find that almost every manufacturer of high-end audio op-amps has one (or several) papers available for download on this very subject. A rather simplistic but accurate discussion of it is given here by Mr. Warren Young on his personal DIY website:
Op-Amp Power Supply Considerations
You don't always need the esoteric kind of capacitor to get the very best performance, but there are some circuits that will demand it in certain circumstances. There are far too many discussions about the various caps on this board to bother with a re-post of it. I have gotten many great tidbits of knowledge reading through the very detailed posts that everyone usually makes of this excellent forum!
HTH-
Cliff45 said:
Hello samsagaz-
I am sure that everyone here will agree that the "specs" often given for various IC op-amps might help differentiate between the possible performance of one chip vs. another in "ideal" situations, but often this is of absolutely no use once you actually start installing these devices in place of another one in a particular circuit topology. There are just far too many variables that affect the performance of a operational amplifier "in circuit" for datasheets to be often not much more than a crude guess about the possible performance in the real world. If you are seeking people's advice about what they did with a particular amplifier, I would be sure that you are going to do the EXACT same thing with the exact same device that they did.
I have found the previously suggested NE5532 unit to be of fairly good quality in most situations, this particular chip seems to find use in many of the "professional audio" units that are used in recording studios and other low-noise, high-quality devices in this particular field.
Also, as sangram aptly points out in his post here, be prepared to attack the power supply decoupling caps as a possible performance improvement area. I have found that troubleshooting power supply problems in op-amp circuits can often reveal that the power supply design itself is holding back the op-amps ultimate performance level. The cheap capacitors in common use inside most lower-end units lose their performance characteristics rather quickly, I have found. I have been surprised by the amount of power supply "ripple" I have seen on units barely one year old! While not all chips are super-sensitive to it, the "power supply rejection ratio" (PSRR) number given for the IC will often reveal its propensity to amplify power supply ripple noise. I find that almost every manufacturer of high-end audio op-amps has one (or several) papers available for download on this very subject. A rather simplistic but accurate discussion of it is given here by Mr. Warren Young on his personal DIY website:
Op-Amp Power Supply Considerations
You don't always need the esoteric kind of capacitor to get the very best performance, but there are some circuits that will demand it in certain circumstances. There are far too many discussions about the various caps on this board to bother with a re-post of it. I have gotten many great tidbits of knowledge reading through the very detailed posts that everyone usually makes of this excellent forum!
HTH-
Wow Cliff, i really appreciate your words, im really new on this, and the url that you give me have nice info about the ripple/noise.
Thanks for your support! will read carrefully that doc
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