Re: FOR TRADE: Scott 222C/D OPTs Group: rec.audio.t
- From: "Bret Ludwig" <bretldwig@xxxxxxxxx>
- Date: 19 May 2006 17:28:07 -0700
Idita . wrote:
Date: Fri, May 19, 2006, 1:27pm From: bretldwig@xxxxxxxxx
(Bret Ludwig)
- At any rate, there is no piece of antique radio or audio
apparatus that used a transformer suitable to couple one 211 tube in
single ended operation to voice coil impedance. No one ever did that
until modern times...
... Anything usable will have been made in the last 20 years.
Actually, the Japanese were doing SE 211 in the '60s and '70s with OPTs
made by Lux, Tango, etc. Their aesthetics were borne of neccessity
post-WWII, when the only tubes around were G.I. issue transmitter types,
and single-ended was more economical.
I wasn't aware that it ws that early. The Japanese DIY audio field was
almost wholly an occult phenomenon to Westerners until Alan
Douglas-who, if I understand, has approximately a fourth grade reading
level of Japanese (and I don't mean this unkindly: it's an achievement
for a Westerner to get that far)-wrote a piece in the late Glass Audio
on it. Specialty cult publications like Vacuum Tube Valley and Sound
Practices started up around then and there was a big explosion in
this-even Stereopile started reviewing commercially built SET amps with
abysmal measurements but which they alleged sounded more right.
- The HH Scott OPTs under discussion here can be used for a small
hi-fi amp (the 222 did work okay, it just is difficult for
nonprofessionals to work on and uses goofy output tubes) or in a guitar
amp with good success, I would actually (despite my earlier comments)
not part one out for the transformers, today, personally because selling
the beast on ebay would buy you a new pair and then some. But building
wholly new amps around them would make excellent technical sense. I
parted piles of them out but we were pulling them out of Hi-Fi-Fo-Fum's
and CMC's dumpsters.
My own pair came from a dumpstered unit with missing PT. I built them
into a stereo amp with PP Tungsol 6550s, trioded and run 65mA per
plate, no loop feedback, fixed bias at first, then cathode bias. 8 ohm
speakers were hung on the 16-ohm taps to give proper loading.
The sonic impression was "darkish" but with no
apparent loss of detail. The bandwidth likely improved, however, by
using the conventional taps. Very musical and authoritative within it's
power output, which I did not bother to
maximize.
The 6550 has roughly three to four times the plate dissipation of the
little tubes in the 222, making it a fair bet these transformers were
underspecified in that application.
If I remember right the 10K SE opts used in some Ongaku clone home
brews started as cheap as $99 each. You might want a little more
expensive transformer but I would think $200 would get you a choice of
several.
.
- References:
- Re: FOR TRADE: Scott 222C/D OPTs
- From: Bret Ludwig
- Re: FOR TRADE: Scott 222C/D OPTs
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