Just wanted to share...over 50 electrolytic caps were replaced, including 18 of the 22 Blackgates F that came stock with the player. Opamps were also upgraded from OPA2604s and NE5532s to OPA627BPs. Replacement caps include Elna Cerafines(4), Elna RJHs(8), Sanyo Oscons(14) and Panasonic FCs(27, I think). There are only 6 stock electrolytic caps left on the player.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Hi guys. There was a small but very noticable improvement in bass,dynamics, speed, transparency and soundstage, but without becoming more harsh or sibilant. Those who prefer a warmer and more laid back presentation may not like the changes brought about by the mods. I'm thinking the blackgates somehow gave a slight veil to the presentation. None of the blackgates removed were directly in the signal path, all were supplying power and we opted to replace them with ultra low-impedance caps, in the case of the caps supplying power to the DAC chips sanyo oscons were used. I forgot to mention that the opa627 opamps were biased into class A as well (the class a modules are not visible because they are mounted underneath the pcb)
All mods done by a friend, in stages, we spent lots of time talking and poring over datasheets.
All mods done by a friend, in stages, we spent lots of time talking and poring over datasheets.
RCD 991 Mods
How did approach biasing the 627's into Class A.
I have a 971 that I replaced the 2604's with 627B as well.
I did add 6-7 OSCONs as well as 8 or so Pany FC as well changing all 9 PS diodes to Schottkys as well as adding .068uF between pin + & - pins of the OPA627's.
Let me know.
Thanks,
Dan
How did approach biasing the 627's into Class A.
I have a 971 that I replaced the 2604's with 627B as well.
I did add 6-7 OSCONs as well as 8 or so Pany FC as well changing all 9 PS diodes to Schottkys as well as adding .068uF between pin + & - pins of the OPA627's.
Let me know.
Thanks,
Dan
I have a friend's 991 and am planning to better the analog sound by opamp rolling. 627 is certainly the most fav opamp as I love the sound off them. Apart from the OPA 2604 that the Rotel 991 uses (1 per ch), there are 2 more NE5534 in there AFTER the I/V. Are they also to go in fav of 627?
Attached a schematic.
Suggestions and recommendations will be most appreciated.
Thanks in advance!
Attached a schematic.
Suggestions and recommendations will be most appreciated.
Thanks in advance!
For anyone blindly swapping
Just in case any one thinks of blindly swapping an NE5532 or OPA2604 for an OPA627 (yes I see you used adapters) then your going to be in for a shock... the OPA is a single device, the other are duals.
It's interesting reading listening impressions on opamps in CD players. Must admit I do like the OPA604/2604 particularly as an IV convertor on a TDA1305 DAC. Far more musical than the NE5534.
Just in case any one thinks of blindly swapping an NE5532 or OPA2604 for an OPA627 (yes I see you used adapters) then your going to be in for a shock... the OPA is a single device, the other are duals.
It's interesting reading listening impressions on opamps in CD players. Must admit I do like the OPA604/2604 particularly as an IV convertor on a TDA1305 DAC. Far more musical than the NE5534.
It's very subjective, and will depend on each implementation too. I'll be honest, I've never tried or used the 627 at all.
I do know I preferred the OPA604 to the NE5534 as a V/I convertor as I mentioned above, and I also use an AD845 as an output buffer/filter. That's in a Micromega Stage 2.
Your just going to have to try it I think.
I do know I preferred the OPA604 to the NE5534 as a V/I convertor as I mentioned above, and I also use an AD845 as an output buffer/filter. That's in a Micromega Stage 2.
Your just going to have to try it I think.
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