Rotel cd player

b_online

Member
2003-04-09 12:04 am
...
Rotel mods

Hi,

The 971 cd is halfway good.
I would probably try to upgrade to a 2nd hand 991, also from Rotel.
Later on, reclock it, and modify op-amps, and everything you can on the output stage.
I have heard that the Trichord Research Clock 3 together with the "Never Connected" power supply feeding exclusively the clock is an amazing upgrade!



Best of luck!
 
Re: Rotel CD Player

hey there - in my opinion rotel makes a fantastic cd player for the money. the rcd971 was my fav cd player at a local hifi shop but i couldn't afford it. but it could sound sooo much better with a little help (hint). brown bread, brown bread - the case, the chasis, the transport, caps ( if you don't intend on changing them), add an emi filiter, upgrade the power cable. it will amaze you. i have a rcd930ax that i have completely done up. just compared it to a rcd1070. the mod 930 blew it away.
:nod:
 

ChuckT

Member
2002-11-29 5:41 am
HK
The 971 is a very good player for the price. Drew advice is good.
The 971 uses the PCM63 dac, a very good sounding dac used by many top end player. The PMD100 is not that bad either, I believe Linn CD12 (1st version?) uses the PMD100.
I would definitely replace the opamp if it uses opa2134. I had very good result replacing the opa2134 with the LM6172 in my preamp. You might also try the LC Audio ad825 module. Can anybody tell me if the 971 originally uses Blackgate inside, my 971 came modded.
 

bequerel

Member
2003-09-01 8:35 am
Yes, ChuckT, RCD971 has BlackGates from the factory.

I have a sample of this player myself, and I have started to modify it.
I have changed the resistors in the analog output stage to Vishays, and the caps to Infinicaps from my parts bin. Will also install an LCAudio clock and change the opamps to AD825.

Some time ago I bought some Lundahl trannies that would make an excellent output stage for the PCM63 DAC. I have some extra PCM63-K DAC chips, so I intend to use them in a piggy-back config (on top of each other), with the transformers connected directly to the DAC chip (pin 5/6 + gnd) to see what I think.
 

ChuckT

Member
2002-11-29 5:41 am
HK
Hi bequerel, I have exactly what you have, LC clock, AD825 , 2 PCM63-K on hand and LL1636. The LC clock and AD825 is already install when I got it. The output BG was also bypassed with a 0.1uf RTX cap, which made the sound almost bright and unbalance, replace it with some MCap and much better. I also pull out the feedback resistor and directly solder it on the opamp.
I haven't put in the PCM63-K yet, not sure if I should do the piggy back as they are 2 different grade. I'll have to finish my other stuff on the table before I put in the Lundahl .
 

jean-paul

diyAudio Moderator Emeritus
2002-09-20 7:20 am
Germany
Desolder the original PCM63's ( only when they're P or J grade versions ) and solder in 2 pieces of PCM63K. K is the highest grade. They're all 20 bit colinear chips and not 18 bit as I read here. I wouldn't use PCM63K in piggyback configuration, for financial as well as for technical reasons.

Please use desolder braid and give up the thought that the old PCM's will survive the desoldering. They are sensitive I can tell you. Clean the board with alcohol and a cotton cloth afterwards while wearing an antistatic band around the wrist that's connected with ground/earth. Make sure you clean again with a dry cotton cloth.
 
jean-paul said:
Desolder the original PCM63's ( only when they're P or J grade versions ) and solder in 2 pieces of PCM63K. K is the highest grade. They're all 20 bit colinear chips and not 18 bit as I read here. I wouldn't use PCM63K in piggyback configuration, for financial as well as for technical reasons.

Please use desolder braid and give up the thought that the old PCM's will survive the desoldering. They are sensitive I can tell you. Clean the board with alcohol and a cotton cloth afterwards while wearing an antistatic band around the wrist that's connected with ground/earth. Make sure you clean again with a dry cotton cloth.


Hello Jean-Paul, can you piggyback TDA1541A? I have seen articles where they are paralelled to decrease errors, I was wonderigf if they could be piggybacked to do the same thing?

Thanks

Anthony
 

jean-paul

diyAudio Moderator Emeritus
2002-09-20 7:20 am
Germany
I don't piggyback any chips. Period. Sorry.

Ok so I want to know if the newer (and AVAILABLE unlike the other one), PCM1704K DAC will work? Or would it require further modification to work?

PCM63K is available for the ones that SEARCH. Why on earth would I suggest a chips if it is unobtainable ? I can buy them here easily so I guess you'll be able to find them as well.

PCM1704K is not a direct replacement AFAIK. You'll have to design a new board for that.
 
rbroer said:
Few years ago I've modded a 971 for a friend.
Put an LCaudio clock in,
LM6172 opamps,
replaced tre coupling caps with film caps,
We both like the player.

Months later we replaced the PCM63's with K grade, but that was a minor improvement IMHO.


I have the same experience/oppinion.
I had very good results even with cheap and old cd players with a well modded analog stage (I also love the LM6172;) ) and, if possible, a good clock.
I have a very old Telefunken:eek: CDP on my fourth:devily: system.
That CDP was given to me.
Inside it's all Sony.
16bit dac, 4x OS.
Really old, Led dispay.
Some people would cry if they listened to it.:nod:
OPA2132 (well bypassed!) replaced the nasty JRC op-amps.
Some new electolythics (nothing expensive) and that's it.
A new clock would be overkill here.
But it sounds very good to me, even as it is.;)

I have an LC clock on my Yamaha CDP I use as a transport.;)
 

jean-paul

diyAudio Moderator Emeritus
2002-09-20 7:20 am
Germany
My experience with replacing PCM63P or J is slightly different. K version is an improvement ( not too big but remarkable ) but if there are adjustment pots on the PCB it is better to remove them if you haven't the equipment to adjust them for least distortion. Leaving them as they are will degrade performance of K or whatever version more than no pot at all. My experience with these chips was not when used in this particular Rotel cdplayer but in some Pioneer models and separate DAC's.

A better clock and better output stage/opamps are the most interesting and rewarding mods, that's true. Last time I bought K versions they were so cheap that I replaced the old ones for them anyhow.

Most of the time the same discussion applies to TDA1541A and TDA1541A-S1. Some hear a difference while others claim to hear no difference at all. I was surprised by Peter Daniels report on the difference a S2 version makes.

http://www.diyaudio.com/forums/showthread.php?s=&threadid=20260&highlight=tda1541
 
jean-paul said:
They're all 20 bit colinear chips and not 18 bit as I read here.


You're right, Jean-Paul.
I made a confusion with the 951, that has an 18-bit dac (PCM69) and PMD100 digital filter (HDCD).
The 971 is another league.
Anyway, on Rotel gear (including some integrated amps) you can usually see OPA2134 or OPA2604 op-amps.
The 971 has two OPA2604 op-amps.