Modification suggestions for Rotel RCD-975

[focal7C]

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.

[focal7C]

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.