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24.34.46.96
In Reply to: LOL! Easy Ed... posted by Ivan303 on September 19, 2004 at 21:09:06:
I had the pictures long before they were posted here publicly, btw. ;-)Look for a review of these soon,
Follow Ups:
Those certainly are some beautiful tubes. Now I know I will be able to revive my RCA photophone amps in style. Hopefully the metal plates will be able to handle it, but since the amps are fairly conservatively run, I don't think it will be too much of an issue.
...the *ultimate* in style for a vintage RCA 845 amp would be metal plate *RCA* 845s. They existed,I have one, sadly with an open filament though. Very cool, brass or alum. base (they came both ways), metal (looks like sand-blasted moly plate, ala globe 10s) plate, tipped at the top of the tube, even! Quite the looker. Makes a nice display tube.
Still, these new ones from SuperTNT will be awesome, and a veritable bargain in comparison to trying to find any vintage metal plate 845s. Of the 5 metal plate vintage 845s I have, 2 have open filaments, 2 are ok fils but wacky otherwise (gassy? hard to say but weiiiiiiiird looking plate curves...don't dare to try them in my amps), and only one checks out perfect in all regards. 1 for 5 - not good odds. :-/
Hmm, It doesn't sound like a good bet that I would ever be able to find a pair of those very early RCA tipped beauties, let alone that they would work properly!
I have an old projectionist's manual from the early 1930's which shows a large Photophone rack of the earlier style with upwards of 8 or more tipped-type 845s in the power amplifier section. What a sight that must have been in full glow!
If the new 845's turn out to work and sound as well as they look, then they should be a real treat.
Keep your fingers crossed I dont smoke a 70 year old power or output tranny. Rewinding a 1200-0-1200V power transformer certainly would not come cheap, let alone the 50lb output transformers.
and on top of everything, you *NEED* four. The amps are properly done for Hi-Fi, and are PP. No half-measure SE here. BTW, don't worry so much about the power Iron, compared to the input or output Iron it is easy to replace...live long and prosper,
Douglas
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Beware the man who behaves deceitfully towards others, for there is nothing else to save you from his deceiving you
Hi,
Do you mean I need 4 845 Photophone amps? Arrgh, it took years of searching to actually find a pair. You better believe that I want a PP amp to drive them though! After all PP parallel pentode amps orinally drove them. The thought of PP graphite plate 801A triodes for drivers is quite tempting. All that graphite and white hot thoriated tungsten is really turning me on.
Then again, to be bizarre, I could go with PP F2a11 pentodes, although I have heard it's a tough tube to work with.
Nooooo, you'll be needin' four 845's for stereo, cause the RCA's are PP you knucklehead...anyway, on the driver amps, pentodes driving pentodes, all PP ought to do it.
I do hate to back to back two TX's, but unless you can do PP through the input TX of the RCA's...we're going to have to. 2:1, or 4:1 step-down to the full length of the RCA primary ought to do it. an amp capable of delivering 10 watts or so ought to be enough.
you ought to hear the little 1619 amp I have going now, or perhaps its big brother with **** thoriated filament beam tubes, or wait for the 813 version, or the truly silly GU80, with its single-pair plate rating of 900 watts...
live long and prosper,
Douglas
!
Beware the man who behaves deceitfully towards others, for there is nothing else to save you from his deceiving you
D'oh! How stupid of me. Of course I will need 4 845's. RCA didn't mess around when it came to their premier theater amp.
I know everyone is against the back to back tranny idea, but I will have to do some research to see if the input tranny is capable of serving as more of a driver/interstage transformer.
Can't wait to hear that 1619 amp. A friend in the Netherlands actually recommended the tube a while ago and I sort of forgot about it.
So many tubes, so little time!
Hey Doug,
I have made a few neat discoveries which would be quite useful for the driver amps. When might you be in my neighborhood? and of course, has there been any discussion regarding the mill?
live long and prosper,
Douglas
!
Beware the man who behaves deceitfully towards others, for there is nothing else to save you from his deceiving you
Howdy,Let's see, I will try to make a trip to the State College area in the next couple weeks, probably on a weekend, so we will have to see what works. I would love to come by and get some ideas for the driver amps, as the photophones should be arriving sometime this week. The 801A still is tempting, but I'm open to anything, as long as it sounds good.
As for the mill, it promises to be extra-exciting this year. I will talk with you off the forum once I find out more concrete info.Regards
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