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In Reply to: RE: I think one needs to take that quote with a big grain of salt... posted by Steve O on April 19, 2015 at 20:45:21
Don't recall Carver modding Cit II's. His original line of tube amps were the Silver 7's, IIRC, 200 watt monoblocks. The original prototypes used the huge Dyna A-440 (?) outputs with tertiary windings. These were the transformers used in the Mk VI which never really made it to the market.
IIRC, Victor Goldstein, brought a pair to Seacliff and HP simply loved them, and eventually convinced Carver to produce them. Of course, the transformers were no longer in production and definitely not available for production runs, so Carver built his own. The Dynas were rated for only about 120 watts so the originals used a pair per side , paralleled. Production run amps had one huge output....not quite the same.
He did come out with a smaller amp later, though, perhaps that was what you were thinking of?
Follow Ups:
When did Carver do this work? I remember him as an innovator with solid state, but not tube products (back in the day). I did see him selling a small amp loaded with Chinese parts on eBay about a year ago. If I recall correctly, it sold for much more than I would have ever thought it was worth.
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Buy Chinese. Bury freedom.
...the Carver tube stuff of that era while serious efforts always struck me as a marketing gimmick intended to prove his sand products were every bit as worthy of audiophile appreciation as the newly resurgent tube designs from ARC and CJ etc. In interviews, Carver also came off as considering tube design a trivial task compared to good SS design.
Thanks, I was thinking it was probably an era that came after his SS heyday. Carver was practically a genius with solid state and had quite a few innovative patents to his name. I've never associated him with vacuum tube design, though. Funny that he would dismiss the challenges of tube design, but maybe I agree. It's easier to create a high quality amplifier when you start with better basic components. :)
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Buy Chinese. Bury freedom.
the Silver 7 prototypes used paralleled pair of A-451 outputs.
the Mk VI's used a model specific transformer that was never
offered as a catalog item. And it's primary impedance was
nomially 1650 ohms CT. As opposed to the A451's nim pri impedance
of 2200 ohms CT. The A-440 (and A-441) had a nom pri impedance of
4300 ohms CT and it is the 440 series that had the tertiary winding...
There was another Dyna output with a tertiary winding... though it never
went into production... the original tranneys developed for prototyping
the ST-70 amp had an ouput model A-460--- which had a 4300 ohm pri CT with separate screen windings.
MSL
Builder of MagneQuest & Peerless transformers since 1989
but the transformer sizes were similar hence my thinking they were 440's.
However if they indeed were custom and used only for the Mk VI and used a UL design, it would explain why they went ballistic so often . GE 8417's screens can not take more than 400volts continuously: oh they my work for a while but eventually they go up in smoke
I'm getting senile.I have what I thought are 441's with supposedly tertiary windings but IIRC the seller told me the primaries had a lower impedance of about 1650. Nice light blue potting cases, but no other id. Luckily I bought them before the Silver 7's came out.
Thanks for the info and crash course in dyna iron.
Funny that Dyna came out with those tertiary winding iron so late. I thought the whole idea of UL was to cut manufacturing costs by eliminating the fixed screen circuit as in Altec 340's, 350's and Allen organ amps which regulator tubes like OD-3's and such to power the screens.
UL transformers certainly paid off for Keroes and Hafler.
Edits: 04/20/15
That tertiary winding is also quite useful for CFB topology. That, with a fixed screen supply gives the same effective g2 U-L but with the CFB added to the mix. You can bring g2 to the cathode( with the extra winding attached to the g2's, and cathode grounded), or bring the cathode to the screen( using the extra winding tied to the cathodes and its CT grounded).
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
Carver wasn't selling modded Cit IIs, he was promoting his latest tube amp design concepts that included the g1 clamp, true pentode operation and deep AB biasing. He kinda demonstrated these concepts by marking up the Cit II schematic with them and slyly inviting DIYers to have at it. This was around 2011-2013. At the same time he was offering very limited edition, hand built custom amps utilizing these same concepts on eBay of all places. Not much later he began producing a range of tube amps under the Carver brand with names like "Bob Carver Cherry", Bob Carver Black Magic" and so on. These amps appeared in the 2013 Music Direct catalog among other places. No relationship to the much earlier Silver Seven flagship tube amp that became the sonic basis/reference of his "Transfer Function" marketing campaign for a series of sand amps.
The Silver 7's were designed to show he could design a good tube amp and were a product of his assertion that by altering the "transfer" function, he could make his solid state amps sound like any competing amp available. Didn't work apparently....
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