rotel rcd-971 opamp substitution - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 14th June 2011, 09:48 PM   #1
karloss is offline karloss  Slovakia
diyAudio Member
 
Join Date: Dec 2010
Default rotel rcd-971 opamp substitution

Recently I changed opamps in my rotel rcd-971 player (opa2604 to lm6172) and was quite happy with the sound, but as I bought ap tempo 3i, there is some kind of overbalance of high tones when listening loudly. I put opa2604 back and everything was flat again, but also very boring and spaceless. I did some searching and tried lm4562, at first without bypass and then bypassed with 1.5uF 25V tantalum capacitors similar as on the site Rotel RCD-971 , but accented highs remains. What can cause this problem?
  Reply With Quote
Old 15th June 2011, 05:54 PM   #2
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Without actually hearing the Rotel its hard to say.

With any opamp swaps using highish speed devices a scope check for stability is essential imo.
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote
Old 15th June 2011, 06:03 PM   #3
diyAudio Member
 
Join Date: Jan 2008
Location: Virginia
When I installed my LM4562 I found out that the sound improved, especially in the high-end of audio band. It wasn't a strong change thou... definetevly not something that I would complain.
Now, I don't know what are you hearing and why. Maybe you are loading the LM4562 output more than it can handle - I didn't understand what are you using at line out...
  Reply With Quote
Old 15th June 2011, 08:40 PM   #4
karloss is offline karloss  Slovakia
diyAudio Member
 
Join Date: Dec 2010
the player is connected through rotel rc-995 to pass aleph 3. I think players output is always at its maximum, attenuated or amplified with preamp. maybe some kind of synergy with the rest of audio chain, noone ever complained about it. going to try burson discrete dual opamp, it should be direct replacement to opa 2604.
  Reply With Quote
Old 16th June 2011, 01:35 PM   #5
goody75 is offline goody75  United States
diyAudio Member
 
Join Date: Apr 2010
Location: Motown (area)
I recently modded my Rotel RCD-971 and put in some LME49720's, which I think are the same thing as the LM4562.

Have you given the opamp time to burn in? I will say that the first 12 hrs or so with the new opamps, it did actually hurt my ears to listen to the 971 - because of the high frequency. Just make sure you play it on repeat for a day or two before passing judgement.

After it settled in, I have no problems with high frequencies and I even removed the low pass caps at the RCA jacks.
  Reply With Quote
Old 16th June 2011, 02:30 PM   #6
karloss is offline karloss  Slovakia
diyAudio Member
 
Join Date: Dec 2010
no burn-in, probably that is the problem. But those LM6172 though 100MHz did it even after six months. Did you bypass pin 4 and 8 or it is now good as it is? And low pass caps are those red ones right next to each rca output? Should I just remove them or shortcut that connection? Thank you very much
  Reply With Quote
Old 16th June 2011, 05:01 PM   #7
goody75 is offline goody75  United States
diyAudio Member
 
Join Date: Apr 2010
Location: Motown (area)
Bypass for pins 4 & 8:
I don't have a schematic in front of me right now but from what I remember I think there are already 4 blackgates that decouple/bypass the opamp power supplies @ pins 4 & 8. I left those alone and paralleled each with a 0.22 uF Wima MKP4 on the bottom of the PCB. It's not as close to the pin or as clever as the method in the link from your first post but it's pretty much the same thing.

low pass caps:
Yes they are the small, red, ceramic caps and yes there is one right next to each rca output. They form a low pass filter so they allow "low" frequencies through and filter "high" frequencies to ground. If you are having a problem with accentuated high frequencies then you definitely should NOT remove them.

I removed mine based on a controversial recommendation from Lukas Fikus (tda1541 / tube fanatic). It's supposed to give you a more open & airy sound. It definitely helped with my Nakamichi CDP-2A but I did not notice any difference with the Rotel RCD-971. Once again, if you are already getting accentuated high's, removing these caps will only accentuate them even more and I think it's possible their removal can cause damage to your tweeters. At some point, if you do want to experiment with the low pass caps, it's probably a safer bet for you tweeters to calculate a value that will have a corner frequency of 25-30KHZ rather than the 20KHz that most CDP's have. You can easily find a formula online if you need one - maybe even an online calculator.

Warning: I'm a bit of a newbie so I some of my interpretations may be wrong.
  Reply With Quote
Old 16th June 2011, 06:14 PM   #8
karloss is offline karloss  Slovakia
diyAudio Member
 
Join Date: Dec 2010
surely just remove, shorting will mute signal was just curious, because I already heard about it but didnīt know what it is about. Maybe after installing burson opamps I will find it useful. thank you
  Reply With Quote
Old 16th June 2011, 11:39 PM   #9
diyAudio Member
 
Join Date: Jan 2008
Location: Virginia
Burson OpAmps are a waste of money...
  Reply With Quote
Old 17th June 2011, 06:09 AM   #10
karloss is offline karloss  Slovakia
diyAudio Member
 
Join Date: Dec 2010
Quote:
Originally Posted by SoNic_real_one View Post
Burson OpAmps are a waste of money...
maybe they are, did not try them yet. Are you basing this statement on your own evaluation or some reviews out there?
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Rotel RCD-971 gone haywire Alexdad54 Digital Source 53 1st November 2012 01:06 PM
Rotel RCD-971 Issues CR500 Digital Source 25 14th February 2011 10:47 PM
Rotel RCD-971 tray problem... Skorpio Digital Source 15 31st August 2010 12:39 PM
Rotel RCD-971 mods Telstar Digital Source 0 27th December 2007 07:08 PM
shematics of ROTEL RCD-971. guytou Digital Source 6 29th May 2005 12:03 PM


New To Site? Need Help?

All times are GMT. The time now is 04:01 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2