Looking for Rotel RC970bx mkII schematic

[KevinLee]

Hello,

Does anyone have a schematic for this rotel pre?

Thanks

Kevin

 

[hifimaker]

Hi Kevin,

Please take no offense... but the Rotel 970 pre is a real POS. Its really not very upgradeable nor worth fixing. I replaced mine with the BOSOZ in the PASS fourm.

Seriously 600% better. I'm not stretching the truth here. My BOSOZ is mated to a Rotel 990 amp. The amp is pretty darn good though.

I'm happy to share more if you email me.

Good luck,

-David

 

[KevinLee]

How did you measure the 600%?

The Rotel is no worse than any other IC based pre.

 

[Cobra2]

If it is similar to mK1...

The gaincircuit would be like fig 10 here: http://hjem.get2net.dk/bencar/opamp/opamp1.htm
I changed op-amp to AD825x2, and gain-resistors from 10k-1k to 8,2k-2,2k, and replaced DC-blocking caps with good 10uF bi-polars.
Also added a blue motorized Alps pot and remote-kit from a diy-member from Denmark...

No way near a X-BoSoZ & attenuator, but ok...

Arne K

 

[hifimaker]

Hi Kevin,

A person can build a PASS BOSOZ for a very reasonable cost.

I bought a surplus metal case for $10, the boards from Kristian K, trafo from Avel-Lindberg, and the rest of the parts from Digikey as a low cost experiment. I have NEVER plugged the Rotel in again.

I sold the Rotel 980 pre and that covered the costs to build the BOSOZ in a nice case.

Seriously, the sound difference is so dramatic you'll kick youself for not doing it sooner or in trying to upgrade the Rotel.

Good luck,

-David

http://www.passdiy.com/pdf/balzenpre.pdf

 

[jean-paul]

I assume you did not mean RC980BX as mentioned in your post. RC980BX cannot be compared to the much cheaper built RC970 etc.

Coincidentally I have a 980 at home and it is one of the better preamps I heard till now. Not one I would discard to build a DIY preamp anyway.