Rotel RQ-970BX Phono Stage - Andy Grove Mod

[OldiesButGoodies]

Found one of these is good shape  at audioasylumtrader and bought it (this was after somehow killing my Emotiva SPS-1 stage by driving it with D cells - that is back in Tennessee getting repaired).  Sounded pretty good in stock form (well,  at least with my low output moving coil):

IMG_0579.jpg by Jose Sifontes, on Flickr

Then I found this "Andy Grove Upgrade" in the net: 

http://imageevent.com/sidandcoke/rotelrq970bxmod

So of course  started looking for parts and between my parts bin and raiding some of Tom's I found almost all that was needed and did the mod:

Audio by Jose Sifontes, on Flickr

I like the sound and the ability to change op amps.  The op amps I had in hand are not the exact ones called for by teh upgrade but I ordered those from Mouser and hope for further improvement.  The 2.45V voltage regulator is no longer manufactured so I ordered a 2.5V that should get me close enough to what mr. grove was trying to do to lower noise and improve gain characteristics.  For $200 total (including my labor,  billed,  at $5/hr) it is a pretty decent sounding phono stage. Wetted my appettite for the upper-class Rotel RHQ10.   

OBG

 

[Jim Pittsburgh]

cool project ....

[Bhope58122]

Hi,

Does anybody still have a copy of the Andy Grove mod? the link above is now defunct   

Cheers,

[OldiesButGoodies]

Hi,

Does anybody still have a copy of the Andy Grove mod? the link above is now defunct   

Cheers,

I have printouts in my files - unfortunately, the files are loaded in a truck as I am moving.  After I settle down in California I will scan them and post them here.  Shame they took it down, it explained the logic of the mod very nicely (Andy Grove designed the production version for Rotel).

Regards,

OBG

[OldiesButGoodies]

Will send a copy of the article to your email address. 

Regards, 

Pepe

PS - I will also load a copy to my HifiEngine account under this model (Rotel RQ-970BX) so that it is available to the masses since the other link died.