Hello All
I did do some research on the forums about this player. Most threads are a year old if not older. I just bought one to replace my player that broke. I bought a 971 for a few reasons. It did not cost much, easy to mod and seems to be a pretty good player in general plus to get my feet wet in the with mods.
I have never did any mods to my electronics in the past though I do feel like I am able to. So I have a few questions and I am currently away from the 971. Remember I am new to this the reason for this thread and that most were old threads.
opamps I see where some said the ad827 seemed to be a good choice if so is this still true to this date or perhaps something new has came out. The opamps are soldered? If so is there a socket you can add to make it easier to rotate? Also when changing the opamps is there anything elase that needs to be changed or is it just one for the other.
One member Ruach if I am not mistaken wrote in a thread There are some very nice mods that you can do to the 971. Putting in a dedicated clock and a transformer for the analog stage will bring the performance of the 971 to another level. He said he had some pictures and other info circuit diagram.
If anone still has this info can I get it.
cr250r1 at gmail dot com
Or you can just email me through my profile and I will reply
If I think of anything else I will but it in this thread.
Thanks All
I did do some research on the forums about this player. Most threads are a year old if not older. I just bought one to replace my player that broke. I bought a 971 for a few reasons. It did not cost much, easy to mod and seems to be a pretty good player in general plus to get my feet wet in the with mods.
I have never did any mods to my electronics in the past though I do feel like I am able to. So I have a few questions and I am currently away from the 971. Remember I am new to this the reason for this thread and that most were old threads.
opamps I see where some said the ad827 seemed to be a good choice if so is this still true to this date or perhaps something new has came out. The opamps are soldered? If so is there a socket you can add to make it easier to rotate? Also when changing the opamps is there anything elase that needs to be changed or is it just one for the other.
One member Ruach if I am not mistaken wrote in a thread There are some very nice mods that you can do to the 971. Putting in a dedicated clock and a transformer for the analog stage will bring the performance of the 971 to another level. He said he had some pictures and other info circuit diagram.
If anone still has this info can I get it.
cr250r1 at gmail dot com
Or you can just email me through my profile and I will reply
If I think of anything else I will but it in this thread.
Thanks All
I've had a 971 for a couple years, great player for the money.
The sockets you need are 8 pin DIPs. The easiest way to remove the opamps are to clip the leads off and remove them one at a time.
If you want to move the player into a much higher performance category then abandon the opamp circuitry altogether and use a discrete output stage with its own PS. There is a forum member named spencer that offered some complete jfet kits with onboard regulation. The only difficult part is finding room in there, but I did it without too much trouble.
If you need it I can send you the service manual for the player.
Best, Bill
The sockets you need are 8 pin DIPs. The easiest way to remove the opamps are to clip the leads off and remove them one at a time.
If you want to move the player into a much higher performance category then abandon the opamp circuitry altogether and use a discrete output stage with its own PS. There is a forum member named spencer that offered some complete jfet kits with onboard regulation. The only difficult part is finding room in there, but I did it without too much trouble.
If you need it I can send you the service manual for the player.
Best, Bill
I also am thinking of modifying my RCD-971. And I have found that recommendation to use AD827 instead of OPA2604 or OP275. The AD827 is a great operational amplifier. However I am having some doubts about that substitution. The issue is that AD827 input impedance rated just 300 kOms. But the original OPA2604 has it as high as 1,000,000,000 kOhms! Any opinions?
Sorry for the late response. I am currently at work and we have been busy.
Bill I would appreciate the service manual to the email address in the first post. Also the discrete output stage sounds interesting. Are the instructions to do that operation pretty detailed or should a rookie even attempt it?
Iliya Thanks for the question. If you do it let me know how it came out and if you had to do anything else. From what research and reading I have done it seems that it was just a replacement almost in kind with no other modifications needed.
Thanks All
Bill I would appreciate the service manual to the email address in the first post. Also the discrete output stage sounds interesting. Are the instructions to do that operation pretty detailed or should a rookie even attempt it?
Iliya Thanks for the question. If you do it let me know how it came out and if you had to do anything else. From what research and reading I have done it seems that it was just a replacement almost in kind with no other modifications needed.
Thanks All
Pars said:
Hi Chris, I started looking for a 991 a couple years ago but abandoned the search. Give Spencer a shout to see if he has any output boards left, he has a thread in the Market Place forum. I know there are other designs on the forum also. The 991 I think uses twice the dac chips in a differential arrangement so you will need two sets of boards, unless I'm mistaken.
Best, Bill
You should be able to wire in an additional transformer at position K24 (as per service manual) so that the DAC and opamps will have their dedicated power supply.
Change C959 and C560 to bigger values like 10,000uf.
Try Spencer's discrete output stage for a more sophisticated mod.
RCD991 uses only 2 PCM63 (the same with RCD971)
Change C959 and C560 to bigger values like 10,000uf.
Try Spencer's discrete output stage for a more sophisticated mod.
RCD991 uses only 2 PCM63 (the same with RCD971)
Who knows anything about decoupling pins 23 & 24 of PCM63? In RCD-971 they are not connected at all. Should I solder 0.1uF caps between those pins and nearest ground trace? What kind of caps are needed there?
Then another question is about decoupling cap on pin 4. Some people say that connection is very important. So should we use BG-N(NX) cap there instead of original BG-F? If so what voltage rating is sufficient?
Then another question is about decoupling cap on pin 4. Some people say that connection is very important. So should we use BG-N(NX) cap there instead of original BG-F? If so what voltage rating is sufficient?
Hey All
What about the 8 pin ic socket? Would this not make switching op amps much easier or is this a bad idea due to soldering being a superior connection?
I also have a onix xcd88 its based on one of the Music Hall players the CD 25. From what I read people are saying the opa627 works really well with that player. Would they work in the 971 dual configuration?
Thanks
What about the 8 pin ic socket? Would this not make switching op amps much easier or is this a bad idea due to soldering being a superior connection?
I also have a onix xcd88 its based on one of the Music Hall players the CD 25. From what I read people are saying the opa627 works really well with that player. Would they work in the 971 dual configuration?
Thanks
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