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Old 25th March 2008, 06:38 PM   #1
thejohn is offline thejohn  South Africa
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Default Robert Grodinsky Research Pre & Power Amp info?

I have the opportunity to get my hands on a RGR Model 5 power amp and a pair of preamps (don't know what model yet) for a very good price...
Googling doesn't turn up much info on these at all.
Anyone have any experience with these amps or RGR equipment in general?

John
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Old 21st June 2008, 06:32 PM   #2
SRMcGee is offline SRMcGee  United States
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thejohn:

Sorry for the late response; I only just found your post. The RGR Model 4 preamplifier was the first high end preamp I purchased. It was very highly regarded by The Absolute Sound in the early 1980s, back when TAS was still credible (and only just beginning to accept advertising). The RGR Model 5 amp was also a TAS favorite, but was too expensive for me at the time (I purchased an Amber Series 70 amp instead). The RGR gear were very well designed and exceptional sounding, but quality control was a little spotty. Resoldering every solder pad was a one-time tweak that, at least in my case, worked wonders. I enjoyed my RGR 4 for about 7 years, until replacing it with a Rowland Coherence. The Rowland was the far superior preamplifier, but the RGR was the better bang for the buck.

If you're still in the market, and the Model 5 amp and Model 4 preamp are still available, you might consider making the investment and then trying your hand at some simple upgrades.

Regards,
Scott
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Old 22nd June 2008, 05:06 AM   #3
thejohn is offline thejohn  South Africa
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Hi Scott,

I was beginning to think nobody else ever had these things, there's so little reference to them on the net.

I ended up getting two Model 4 preamps and a Model 5 power amp along with some other bits and pieces (like a Carver CD player and 3 Sugden A51's) practicaly for free!

One preamp is in original condition and working 100%, the other has been seriously butchered by the previous owner - nearly every componet has been changed - badly!
The power amp is working but has also be badly worked on by someone - the power supply caps are outside the amp, hanging on leads!

Interestingly, this lot came with a set of original schematics for the preamp in an envelope from RGR. Unfortunately none for the power amp!

For now I'm using the working preamp as is, the broken one is in my pile of future projects and the power amp I'm just going to neaten up the bad work done previously and put it to good use too.

Do you know anything about the design / topology of the power amp? Anything out of the ordinary / interesting about it?

If anyone happens to know of a schematic for the power amp I would love to get my hands on one!

Thanks again,

John
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Old 22nd June 2008, 07:01 AM   #4
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It will certainly be interesting to see the preamp schematics. And maybe some pics.
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Old 22nd June 2008, 08:16 AM   #5
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by analog_sa
It will certainly be interesting to see the preamp schematics. And maybe some pics.
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Old 22nd June 2008, 02:10 PM   #6
thejohn is offline thejohn  South Africa
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No prob. I'll get them scanned sometime this week and post them. They're large blueprints so not something I can do at home... Stay tuned!
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Old 22nd June 2008, 04:37 PM   #7
SRMcGee is offline SRMcGee  United States
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thejohn:

Unfortunately, I have nothing left from the RGR Model 4; whatever documentation I had was included when the preamp was sold. The Model 5 amp was a mystery to me -- 100 watts into 8 ohms, sounded terrific (remember, this was the early 1980s) but beyond that I know nothing. However, Robert Grodinsky is alive and well, living outside Chicago, Illinois. He's probably in his late 70s, but the word is he remains active. You might try contacting him directly -- he may be willing to provide some advice (schematics, perhaps).

I'd be curious to hear about the results of your efforts. That Model 4 preamp really was a wonderful little beast (with far superior sonics to the competition in its price range, which included the Apt Holman, Amber, Adcom, Supraphon and PS Audio preamps).

Good luck!

Regards,
Scott
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Old 18th August 2008, 06:19 PM   #8
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I have a RGR Model 4, as well. I can also confirm that it's a very nice little preamp. Unforunately, I am missing one of the rectangular buttons on the face of mine. If you should decide to part out the hacked up preamp, I'd surely be interested in one of the buttons.
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Old 11th August 2009, 03:35 PM   #9
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Default Model five

I got a Model Five of RGR and is a really wonderful amp.
It arrive badly tweaked. I beguin to recover in the following steps.
Change RCA and speaker lugs with Cardas.
Changed BIG caps with 22.000 uF computer grade of CDE.
Changed hook up wire with 16 AWG 19 strands copper silver threads
(19).
Bypass BIG caps with 470 uF (Nichicon low impedance)+0.47 uF+0.01 uF (polypropilen in oil)
Result the best amp I have ( Classe 175, ML Nº29,Threshold S250 , Threshold SA3, Nakamichi PA7, Forte 4a) all of they with new caps.

Is incredible the sound, sweet, ultradefined, dynamic, with a defined and extended soundstage. A really refined and realistic sound
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Old 6th October 2011, 01:18 PM   #10
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Default BGR

Would 300. be to much to put out for that amp?
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