should work, the dac chip is certainly capable of it, as is the spdif reciever, are you sure your transport is set up for this? I cant give specific advice as I dont own this dac, i'm sure someone else will chime in
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Hi, I alo got this DAC few days ago. It's great and I would also like to switch opamps for AD797, but there are two versions one with 30 MHz bandwidth and one with 110 MHz bandwidth. So which one should I buy?
Thank you for help.
Thank you for help.
the 30mhz, we do not need even that and its the wide bandwidth of this chip that can cause problems in builds that are not designed for it. it often requires bandwidth limiting to remain stable
Replacing bypass caps on W8740s
The data sheet for the W8740 suggests 10uf and .1uf by passes.Would it be advantageous to replace these with a high grade Black Gate in 47uf and a .022uf teflon? Thanks
The data sheet for the W8740 suggests 10uf and .1uf by passes.Would it be advantageous to replace these with a high grade Black Gate in 47uf and a .022uf teflon? Thanks
the teflon yes, the blackgate no, I see people using BG in digital decoupling/bypassing all the time and its really not a good idea IMO, they do not have low impedance at high enough frequency for this purpose. you would be better off with a solid polymer cap bypassed with the teflon, or other fast film. even a high grade ceramic or silver mica.
blackgates are good caps no doubt about it, but they are not the solution to every problem like they seem to be used for, ripping out a ceramic to replace with a electrolytic of any kind in this assignment is disingenuous.
blackgates are good caps no doubt about it, but they are not the solution to every problem like they seem to be used for, ripping out a ceramic to replace with a electrolytic of any kind in this assignment is disingenuous.
Black Gates
The teflons to replace the ceramics is probably a no brainer, but the circuit as implemented seems to use 10uf electrolytics. These do not appear to be of a high quality and probably have a high ESR at high frequencies. Would the BGs be an improvement. They have four times the recommended capacitance at 47uf. If not the BGs, what type and value would you suggest. Thanks
The teflons to replace the ceramics is probably a no brainer, but the circuit as implemented seems to use 10uf electrolytics. These do not appear to be of a high quality and probably have a high ESR at high frequencies. Would the BGs be an improvement. They have four times the recommended capacitance at 47uf. If not the BGs, what type and value would you suggest. Thanks
sanyo SEC or similar organic polymer cap (OSCON) maybe 22uf, 10u seems a bit low, and since this is a local reservoir of sorts you could probably go up to 68-100u if it fits. but I hesitate to increase it that much, so 22-47u is probably better.
Oscons
Thank you so much for the help. The Sanyos are difficult to source on the internet. Do you have a source you could suggest for low quantities? Thanks Dr. John Dozier
Thank you so much for the help. The Sanyos are difficult to source on the internet. Do you have a source you could suggest for low quantities? Thanks Dr. John Dozier
Nichicon organic polymer
I have found some Nichicon organic polymer at Mouser. Would these be a reasonble substitute. Nichicon has a good reputation in other areas. Thanks again for your input. I would still like to find the Sanyos though as they began the whole genre.
I have found some Nichicon organic polymer at Mouser. Would these be a reasonble substitute. Nichicon has a good reputation in other areas. Thanks again for your input. I would still like to find the Sanyos though as they began the whole genre.
nichicon oscon I havent actually tried, if you cant get the sanyos, vishay make a very nice one also. I mainly use SMD so tend towards kemet, panasonic SP and murata for oscons, but the sanyo SEC are still amongst the best
Looks like a nice DAC. Two questions:
- Where did you guys buy the AD797 chips? I have only saw then at digikey.com so far and they are the 100Mhz version. I read that the 30Mhz version is preferable. Will need to know where to get it.
- Is the 75 ohm resistor for the input mod 1/4 watt 1% metal film?
The two biggest mods seem to be the op-amps and the output bypass. But if the input mod makes some difference, then perhaps its worthwhile doing.
Thanks,
Philippe
- Where did you guys buy the AD797 chips? I have only saw then at digikey.com so far and they are the 100Mhz version. I read that the 30Mhz version is preferable. Will need to know where to get it.
- Is the 75 ohm resistor for the input mod 1/4 watt 1% metal film?
The two biggest mods seem to be the op-amps and the output bypass. But if the input mod makes some difference, then perhaps its worthwhile doing.
Thanks,
Philippe
Ok, then that's the same thing except in surface mount rather than through hole. Since the DAC PCB has sockets, then I'd go for AD797ANZ-ND instead.
errm it has nothing to do with the package, arz and brz are model assignments, you can get a soic8 BRZ and ARZ.
Was just going by what I saw in digikey. Only diff between the two:
Digi-Key - AD797ANZ-ND (Manufacturer - AD797ANZ)
Digi-Key - AD797BRZ-ND (Manufacturer - AD797BRZ)
seems to be the package and the input offset voltage. Or am I going batty? 🙂 BTW, which DAC are you using?
Digi-Key - AD797ANZ-ND (Manufacturer - AD797ANZ)
Digi-Key - AD797BRZ-ND (Manufacturer - AD797BRZ)
seems to be the package and the input offset voltage. Or am I going batty? 🙂 BTW, which DAC are you using?
Thanks to QUSP
Many thanks for your advice on the OSCONs. I have decided to go with the Nichicon 22uf 63v. I will also be using AD797s since they seem to be stable in this design. I will not be removing the 10ohm output resistors, but will be replacing all signal path resistors with Vishy nakeds. I will also replace the input transformer with the one you suggested. This will be my desktop DAC. My Muse model 2 continues to be my main DAC and continues to amaze after all these years. Thanks again for your suggestions as I have been out of the modification business for a number of years (having fallen in with bad companions and becoming a university administrator). If you have any other suggestions on modifying this DAC pls share them with us. You have been an inspiration.
Many thanks for your advice on the OSCONs. I have decided to go with the Nichicon 22uf 63v. I will also be using AD797s since they seem to be stable in this design. I will not be removing the 10ohm output resistors, but will be replacing all signal path resistors with Vishy nakeds. I will also replace the input transformer with the one you suggested. This will be my desktop DAC. My Muse model 2 continues to be my main DAC and continues to amaze after all these years. Thanks again for your suggestions as I have been out of the modification business for a number of years (having fallen in with bad companions and becoming a university administrator). If you have any other suggestions on modifying this DAC pls share them with us. You have been an inspiration.
Instability with AD797
Has anyone using these opamps in this circuit, actually looked at the output on a scope to make sure threre is no instability? Just asking because I would like to use the 797s instead of the OPA627. Let's just say I am frugal, not cheap. Thanks
Has anyone using these opamps in this circuit, actually looked at the output on a scope to make sure threre is no instability? Just asking because I would like to use the 797s instead of the OPA627. Let's just say I am frugal, not cheap. Thanks
OPA627
Anyone used this opamp in this design? If so how did it perform? Any indication of instability? Was the sound quality improved? Thanks for any input as I am trying to decide between the 627 and the 797
Anyone used this opamp in this design? If so how did it perform? Any indication of instability? Was the sound quality improved? Thanks for any input as I am trying to decide between the 627 and the 797
Generally speaking I personally would choose the 627 over the 797.
But the 627 is quite expensive. Why not just get a pair of Audio GD discreet op-amps for about $50 delivered. They would kill the op-amps, and cost around the same money.😉
http://www.audio-gd.com/Pro/diy/OPA/OPAEN.htm
But the 627 is quite expensive. Why not just get a pair of Audio GD discreet op-amps for about $50 delivered. They would kill the op-amps, and cost around the same money.😉
http://www.audio-gd.com/Pro/diy/OPA/OPAEN.htm
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