Modification suggestions for Rotel RCD-975 - Page 2 - 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 18th January 2012, 06:38 AM   #11
focal7C is offline focal7C  Australia
diyAudio Member
 
Join Date: Jan 2008
Phase B of mods:

B1. OpAmps u317, u318 changed to AD797ANZ

B2. Main board p/s c183,188,189 changed to Panasonic FR 470uF 25V (meant to have done as part of Phase A).

A little clearer, more detail and separation between instruments, base string vibrations more naturally prolonged. Also confirmed with Fostex T50RP headphones plugged into amp.
  Reply With Quote
Old 4th February 2012, 02:35 AM   #12
focal7C is offline focal7C  Australia
diyAudio Member
 
Join Date: Jan 2008
Phase C of mods:

C2. Installed the Audio-gd JZ-1 module (with combined Low jitter clock and Class A supply)
- Disconnect pin 4 of U314 (TC74HCU04AP IC). I.e. unsolder and pull/bend up
- Wire 1/3FO (11.28MHz setting on 33.86M Type 1 module) to pin 1 of U314
- Wire GND on same side as 1/3FO between ground and C330
- Wire DC input from U301 (NJM78M15 voltage regulator) pin which provides +15V
- Wire GND next to DC input of JZ-1 to negative side of capacitor C306 (next to regulator)

Sound improvements are very noticeable to say the least. In order of magnitude.

1. More separation between multiple vocals (eg backing vocals) and better instrument placement
2. Vibrations of instruments such as didgeridoos and baritone brass are more realistic/pronounced
3. Singing tones have more sounds coming from back of mouth and throat (for singers/recordings that can produce/capture those dimensions of vocals)
4. Handles percussion with more attack and settles faster
5. Little bit less congestion at HF and complex passages

Xavier Rudd's "Food In the Belly" show off these differences well.
  Reply With Quote
Old 29th March 2013, 09:00 AM   #13
focal7C is offline focal7C  Australia
diyAudio Member
 
Join Date: Jan 2008
Default Phase D of mod:

Replaced C354 and C355 signal path output electrolytic Rubycon BlackGate caps 100uF 16V with Jantzen 10uF 400V Cross-Caps. I believe this should give around -3dB @ 2 Hz output response.

The mids are clearer and the highs appear more pronounced. The bass is a little more subtle (less depth) but still accurate and fast.

The sound signature has changed to some degree. The Blackgates gave it a certain sound that I'm obviously used to. The sound was a bit fuller, however this could possibly be attributed to some reverb/distortion. Will have to get used to it with the other benefits seemingly outweighing this...

Had previously measured the DC after opamps and it was very low. Therefore tried without the output caps altogether (just a cutoff cap leg across holes). There was no bass at all. Can anybody tell me why? Buffer role (and a couple of other 100uF caps/ceramics to ground that have a combined function?)

Then used a pair of Wishay MKP 1841 4.7uF 160V film caps I had lying around. Still limited depth and much reduced db at lower frequencies... Hence the Jantzen 10uF Cross-Caps.

Think its amazing how much this already very good CDP has improved with all the mods. And there are more component that can be upgraded or bypassed.
  Reply With Quote
Old 30th March 2013, 04:18 AM   #14
focal7C is offline focal7C  Australia
diyAudio Member
 
Join Date: Jan 2008
Will add that the output response estimate was provided by another modder with experience with this model.
  Reply With Quote
Old 5th November 2013, 09:25 AM   #15
focal7C is offline focal7C  Australia
diyAudio Member
 
Join Date: Jan 2008
Default Mod photos

Modification photos showing:
1. Audio-gd low jitter clock (TCXO and Class A PSU)
2. Wishay MKP 1837 bypass caps and power feed for clock
3. Jantzen 10uF output coupling caps (Cross-Caps)

Plus lots of blue tack
Attached Images
File Type: jpg Audio-gd JZ-1 low jitter clock (TCXO & Class A PSU).jpg (257.8 KB, 45 views)
File Type: jpg Bypass caps and clock power.jpg (215.3 KB, 45 views)
File Type: jpg Output coupling Cross-Caps.jpg (193.3 KB, 44 views)
  Reply With Quote
Old 5th November 2013, 11:43 AM   #16
marce is online now marce  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Location: Blackburn, Lancs
Its OK adding a fancy clock, but the way you have connected it to the PCB leaves a lot to be desired, not even twisted pair (co-ax would be better) but separate leads, long length, return path miles away, it will negate any benefits of the fancy clock.
  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 975 naladog Digital Source 11 9th June 2012 02:41 PM
muting transistors / Rotel RCD-975 androll Digital Source 15 10th January 2011 04:31 PM
Suggestions where to send my Rotel RCD-975 Skeetdaddy Digital Source 7 4th May 2009 03:07 PM
Looking for Schematic for Rotel RCD-975 CD Player dtm1962 Digital Source 1 19th February 2008 01:14 AM


New To Site? Need Help?

All times are GMT. The time now is 02:34 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2