Rotel RCD971

warpig · 18th June 2009, 03:51 AM

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

warpig · 18th June 2009, 05:28 AM

Another question about opamps that I forgot to ask.

I see that the ad827 has several different types like the below. When buying one does it matter besides the number of pins?

AD827AQ
AD827JN
AD827JNZ
AD827SQ

Again Thanks

Bill Fuss · 18th June 2009, 11:35 AM

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

Iliya · 19th June 2009, 06:15 PM

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?

warpig · 20th June 2009, 01:33 AM

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 Fuss · 20th June 2009, 11:35 AM

Warpig, YGM. Cheers.

Pars · 22nd June 2009, 03:11 AM

Bill,

I have an RCD991 which is very similar. Any info on the discrete stage would be appreciated as well,

Thanks,

Chris

warpig · 22nd June 2009, 06:30 AM

Bill

Thanks work has been rough. Looking forward to a few days off. Checked email and did get it.

Again Thanks

Bill Fuss · 22nd June 2009, 02:36 PM

Quote:

Originally posted by Pars
Bill,

I have an RCD991 which is very similar. Any info on the discrete stage would be appreciated as well,

Thanks,

Chris

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

Ruach · 24th June 2009, 01:40 PM

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)

18th June 2009, 03:51 AM	#1
warpig diyAudio Member Join Date: Jun 2005 Location: New Orleans	Rotel RCD971 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

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18th June 2009, 05:28 AM	#2
warpig diyAudio Member Join Date: Jun 2005 Location: New Orleans	Another question about opamps that I forgot to ask. I see that the ad827 has several different types like the below. When buying one does it matter besides the number of pins? AD827AQ AD827JN AD827JNZ AD827SQ Again Thanks

18th June 2009, 11:35 AM	#3
Bill Fuss RIP Join Date: Oct 2005 Location: Central Florida	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

19th June 2009, 06:15 PM	#4
Iliya diyAudio Member Join Date: Oct 2005	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?

20th June 2009, 01:33 AM	#5
warpig diyAudio Member Join Date: Jun 2005 Location: New Orleans	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

20th June 2009, 11:35 AM	#6
Bill Fuss RIP Join Date: Oct 2005 Location: Central Florida	Warpig, YGM. Cheers.

22nd June 2009, 03:11 AM	#7
Pars diyAudio Member Join Date: Jan 2004 Location: Chicago	Bill, I have an RCD991 which is very similar. Any info on the discrete stage would be appreciated as well, Thanks, Chris

22nd June 2009, 06:30 AM	#8
warpig diyAudio Member Join Date: Jun 2005 Location: New Orleans	Bill Thanks work has been rough. Looking forward to a few days off. Checked email and did get it. Again Thanks

24th June 2009, 01:40 PM	#10
Ruach diyAudio Member Join Date: May 2003 Location: Singapore	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)