... as I have a player here with a faulty PCM1792A - it looks like an A version as it has a capital A under a map of Texas. Can get a 1792 non-A and repair this thing on Monday.
The player uses double DACs, one per channel, Left channel DAC has got a DC offset and kaput, Right channel works fine. So must replace Left.
Help much appreciated.
Cheers.
Joe R.
The player uses double DACs, one per channel, Left channel DAC has got a DC offset and kaput, Right channel works fine. So must replace Left.
Help much appreciated.
Cheers.
Joe R.
Yeah I know, but will non-A repair this machine or not. Have anybody actually done the substitution? There are 1792 in stock out there, from the local Farnell who has no stock of A.
Cheers.
Joe R.
Cheers.
Joe R.
They look identical in specs. Maybe A-type is lead-free?
Shoot an email to TI... see what they say.
Shoot an email to TI... see what they say.
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Thanks for the suggestions, but I can get my hands on a PCM1792 on Monday and fix the player without delay. It seems that the PCM1792A is a replacement for PCM1792?
Cheers.
Joe R.
Cheers.
Joe R.
I am not so sure it is a direct drop-in replacement I am seeking.
I know of somebody who tried replace PCM1796 with PCM1795 and reportedly it did not work? Not 100% sure, just heard about it.
There are lots of players out there using PCM1796, so anybody would like to try out PCM1795 and report back here, that would be interesting.
Cheers, Joe
I just asked an eBay seller and got the following answer:
"Yes, the PCM1792 can be used to replace PCM1792A, just a little difference in spec: PCM1792 has 132dB SNR, but the PCM1792A is 127dB SNR"
Is that the only difference and why T-I only recommends 1792A in new players, no other reason?
I don't hear much difference between PCM1792(A) and PCM1796 - I think the architecture which is shared is the most important contributor to sound, not the nth degree of SNR.
Any comments?
Joe R.
"Yes, the PCM1792 can be used to replace PCM1792A, just a little difference in spec: PCM1792 has 132dB SNR, but the PCM1792A is 127dB SNR"
Is that the only difference and why T-I only recommends 1792A in new players, no other reason?
I don't hear much difference between PCM1792(A) and PCM1796 - I think the architecture which is shared is the most important contributor to sound, not the nth degree of SNR.
Any comments?
Joe R.
Just replaced 1792A with 1792. No drama, works just fine.
Thanks for your input, guys.
Cheers.
Joe R.
Thanks for your input, guys.
Cheers.
Joe R.
Hi Joe,
Good to hear you got it working. I would have been surprised if it didn't work though, since the PCM1792 and PCM1792A are very similar. The only real differences I have been able to find in the data sheet are on page 26:
In the PCM column it says "yes" regarding the Register 20 DSD and DFTH bits for the PCM1792A whereas there are empty boxes for the PCM1792. This could of course also be a typo, I don't know.
Of course there are a few typo's that have been corrected, but nothing that has any importance. The curves on the figures are clearly copied, so TI has not done new measurements and figures for the A-version data sheet.
It is not true that the PCM1792 has a better dynamic range than the PCM1792A, at least not according to the data sheet. They both have 132dB SNR if used in mono mode.
I assume that the difference between the two is a minor chip revision, perhaps to improve the yield in production or some other production related issue. It could of course also be the two bits regarding the DSD functionality and the DF bypass.
Regarding the PCM1795 and PCM1796, now that is a different story! They seem to have the same performance, but the PCM1795 is HW controlled whereas the PCM1796 is SW controlled. So it is no wonder that they cannot replace each other.
Good to hear you got it working. I would have been surprised if it didn't work though, since the PCM1792 and PCM1792A are very similar. The only real differences I have been able to find in the data sheet are on page 26:
In the PCM column it says "yes" regarding the Register 20 DSD and DFTH bits for the PCM1792A whereas there are empty boxes for the PCM1792. This could of course also be a typo, I don't know.
Of course there are a few typo's that have been corrected, but nothing that has any importance. The curves on the figures are clearly copied, so TI has not done new measurements and figures for the A-version data sheet.
It is not true that the PCM1792 has a better dynamic range than the PCM1792A, at least not according to the data sheet. They both have 132dB SNR if used in mono mode.
I assume that the difference between the two is a minor chip revision, perhaps to improve the yield in production or some other production related issue. It could of course also be the two bits regarding the DSD functionality and the DF bypass.
Regarding the PCM1795 and PCM1796, now that is a different story! They seem to have the same performance, but the PCM1795 is HW controlled whereas the PCM1796 is SW controlled. So it is no wonder that they cannot replace each other.
Hi Jens
Thanks for your thoughts. If 1795 is HW controlled, does that mean that there will be some situations swapping out 1796 (or 1792) may still work, or is the HW versus SW set in cement. Is the 1795 HW controlled easier to use/implement? Or is 1796 always SW controlled. I ask as there are plenty of players and DACs out there with 1796 and would there be some instances where swapping would work?
Just for the record, I am not a digital guy, I am an analogue guy. So appreciate the info and everybody has to have his limitations and recognise it (mange tak Harry Calahan). But many of the problems in getting digital to sound right are analogue problems.
Joe R.
Thanks for your thoughts. If 1795 is HW controlled, does that mean that there will be some situations swapping out 1796 (or 1792) may still work, or is the HW versus SW set in cement. Is the 1795 HW controlled easier to use/implement? Or is 1796 always SW controlled. I ask as there are plenty of players and DACs out there with 1796 and would there be some instances where swapping would work?
Just for the record, I am not a digital guy, I am an analogue guy. So appreciate the info and everybody has to have his limitations and recognise it (mange tak Harry Calahan). But many of the problems in getting digital to sound right are analogue problems.
Joe R.
PCM1795 is SW controlled which is Pin and mode control compatible with PCM1792A and PCM1796.
http://focus.ti.com/lit/ds/sles248/sles248.pdf
http://focus.ti.com/lit/ds/sles248/sles248.pdf
Sorry for the confusion😱
Yes, you are right, the PCM1795 and PCM1796 are both SW controlled. I think it is the PCM1796 and PCM1798 that are the SW versus HW pair.
The PCM1795 is the newer 32 bit converter with specifications similar to the PCM1796. I could imagine that with certain interface formats there could be problems, e.g. with a right-justified input.
Yes, you are right, the PCM1795 and PCM1796 are both SW controlled. I think it is the PCM1796 and PCM1798 that are the SW versus HW pair.
The PCM1795 is the newer 32 bit converter with specifications similar to the PCM1796. I could imagine that with certain interface formats there could be problems, e.g. with a right-justified input.
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