Author Topic: Rotel RQ-970BX Phono Stage - Andy Grove Mod  (Read 1369 times)

Offline OldiesButGoodies

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Rotel RQ-970BX Phono Stage - Andy Grove Mod
« on: January 23, 2017, 08:31:40 PM »
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.   O0

OBG

 

Spkr: Harbeth 30.1 on Sound Anchor 4 post stands
Pre: Rogue 99 Magnum
Phono: VPI Aries 1,  Van de Hul Frog
CD: Oppo 203
Cass: Tascam 122MkII
R2R: Revox B77
Sub:

Offline Jim Pittsburgh

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Re: Rotel RQ-970BX Phono Stage - Andy Grove Mod
« Reply #1 on: January 24, 2017, 08:41:30 AM »
cool project ....
Clearaudio Performance SEP/Talisman V2 gold,PL XP-15, Onkyo Integra DSP 8.3, Marantz SR6005, KEF Reference 5, KEF Reference 4C,KEF Q900, , Q800, HSU VFT-15H,Emptek DSA250,Krell S1500 #2 Marantz SR6007,  McIntosh1501, KEF Q600, Sunfire NHTsuper1s, Technics 1200 MkII/ Shure V15 xMR, dbx DX5 ,Jolida JD

Offline Bhope58122

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Re: Rotel RQ-970BX Phono Stage - Andy Grove Mod
« Reply #2 on: December 11, 2017, 10:24:54 AM »
Hi,

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

Cheers,

Offline OldiesButGoodies

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Re: Rotel RQ-970BX Phono Stage - Andy Grove Mod
« Reply #3 on: April 02, 2018, 04:02:29 PM »
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

Spkr: Harbeth 30.1 on Sound Anchor 4 post stands
Pre: Rogue 99 Magnum
Phono: VPI Aries 1,  Van de Hul Frog
CD: Oppo 203
Cass: Tascam 122MkII
R2R: Revox B77
Sub: