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pureh2o 28th April 2008 12:04 AM

Look what I found in my new RCD-971!
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Hi all. I am new to this forum. Good to be here. Anyway, I purchased this RCD-971 yesterday, and when I arrived home, I noticed a brown envelope in the bottom of the box marked "971 Mods". Curious, I took the top cover off and found "stuff inside", much unlike my other stock 971 I own. Looks like the OPs have been changed to AD827JUs. A 9V battery has been installed for the polarity. Hmmm. I discovered that it was modified by NW Audio Labs. Sweet! I paid a whopping $220 for it. The sound is awesome. My wife and I can listen to it all day. The only problem I have with it is it is very unforgiving to shock. It will skip if I even tap the desk where it lays. Any ideas on this? I have enclosed a photo of the inside. Maybe someone can tell me what I have here. Thanks all.

kevinkr 29th April 2008 04:18 PM

I see an outboard clock, polystyrene caps in the LPF, and upgraded electrolytics in various places.. :D Pretty nice set of upgrades for the price.

In terms of the skipping issue take a look around the mechanism and see if there are any badly dressed cables compromising the mechanism to chassis isolation. It is also possible that the bushings in the mechanism mounts have just dried out. (Or have been removed deliberately if the unit was used on a high mass base.)

The best solution might just be to put it somewhere where there is a bit more mechanical isolation between it and you.. :)

pureh2o 29th April 2008 05:57 PM

Look what I found in my new RCD-971!
Thank you Kevin. I will check the mech for any problems. I noticed that AD827JNs were used for the OP amps. This was modded probably before the LM4562, and LM6172 were available. I wonder if those would be an improvement. John.

kevinkr 29th April 2008 07:11 PM

The AD827 is a pretty well regarded op-amp, still it might be interesting to try some of the newer ones as well. LM4562 is worth looking at. LM6172 is prone to oscillation and hard edgy sound if not carefully decoupled right at the pins. (This is a very fast part.)

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