[Arran]

Maybe they are worth experimenting with, though I would have to use some produced by the Fu Man Chu tube Co. in China, unless I won the lottery. I wonder if the plate voltage could be supplied with a microwave oven transformer? The audiophools would freak at that idea but there is an almost unlimited source of the things, and I think they put out enough milliamps. What I can't remember is whether they are center tapped or not.
What I find strange is why these goofs insist that ancient, obsolete, and obscure tubes, are the way to go for a stereo amp when you have 6L6s, 6V6s, 6BQ5s, available new for much more reasonable prices. When I was looking up rectifier tubes the other day, (specifically the maximum current of a 6X5 and a 5Y3/5Y4) the other day I found a site pitching one brand of rectifier tube over another because they supposedly made the amp sound better???? Please, audiophools, pick up an RCA tube manual, an ARRL yearbook, or something and find out how tubes actually function and how to read technical specs for each tube!!!
Regarding the type #50s again I forgot about the type #10s, I was thinking of amplifier tubes in general not specifically RCA ones. I remember reading that it was a common trick to use a type 171A in a battery set to get more output power, not sure if any came with them from the factory that ways as most adds seem to sell their sets without the tubes.
Regards
Arran

[codefox1]

Hello, Doug: just curious- what kind of voltage rating do you have to look for for your filter caps? Sounds like you would have to go with some relatively expensive units to handle the high voltages.

Also, are there more than the usual power resistors there, or maybe more with a higher than usual power rating?

Series capacitors do nicely to deal with high voltages with or without safety bleeders. Still use fuse! So a couple of'em blow and nothing is wrong, to the next value, and you're out just a little.

[Jayce]

I'm curious as to how the Chinese 50's sound and perform. I know one guy who hates the Russian tubes because he claims they sound crappy. I have used a few Chinese tubes in the past and they sound just fine, but have heard they don't last as long.

[Doug Houston]

The power supplies that had to be used with the 10's and the 50's were a real nightmare to design, then build!

In the RCA "Tomcat" amplifiers, as used in the Victor Electrolas of 1925 through 1927, had to have this halacious power supply output voltage. Thy used a couple of 4 Mf. 1000 Volt caps in the main filters. That was no easy feat, either. They used an X99 tube as voltage amplifier to drive the 10. Its filament was supplied by a tapped resistor string, off of the output of the two 81's.

Because of the X99's critical voltage, line voltage had to be regulated by a big ballast resistor tube. AC power mains into homes could have been anything, and usually were. Sooooooo, the 876 (or 886) regulator tube did the job. That's that big hunker with the mogul base, that could heat an airplane hanger in Alaska.

More on power supplies. Mouser Electronics has some 2 Mf. / 1000 volt polypropylene caps that I use for the main filters in the Tomcat amplifiers. I parallel two on each side of the speaker field, and go away happy.

So now one more blow on power supplies. remember the movie: "The Jazz Singer"? It came out in 1927, with disk recorded sound from 16 inch discs, running at 33 1/3 RPM. The turntables ran off of the projector motors, to maintain sound sync. They had a big bank of speakers of some sort; probably the RCA "104" dynamics. There were transmitting tubes to drive the speakers, so that was no problem either. But, how about the B+ for the audio power amps??? They had a big bank of automotive storage batteries outside, or beneath the stage that were hooked in series for the HV B+ when the show was running in the evening, and the batteries paralleled on chargers during the day.

Resourcefulness always pays off big.

[Arran]

I'm curious as to how the Chinese 50's sound and perform. I know one guy who hates the Russian tubes because he claims they sound crappy. I have used a few Chinese tubes in the past and they sound just fine, but have heard they don't last as long.

Well there is more then one maker of Russian tubes, there is Svetlana (Called winged "C"), Sovtek, and perhaps another. Then there is an American outfit that procured the use of the Svetlana name in the U.S through legal sleaze and is rebranding ramdomly sourced tubes with the name. I can't comment on which Russian brand is best, I did repair a guitar amp with Russian tubes in it and it sounded fine, I think they were Sovtek but I'm not sure as they were rebranded as Fender tubes. I did find some Ukrainian made 6V6s at a garage sale once, new in the box, and they sounded just as good as their U.S or Canadian made counterparts.
When it comes to tubes and audio equipment a lot of it is the electronic eqiuivailent of wine snobbery, Geman and British tubes are the best, American tubes second, and everyone else's is junk especially if it's new production. The reason I compare it to wine snobbery is many will believe that a bottle of wine is better because it costs more and because of the lable, but in a blind taste test they can't tell a $15 bottle from a $50 bottle.
Regards
Arran

[Jayce]

Ah. I'd almost be willing to try the Chinese 50's in my Majestic if I could find a source and get my money ahead. The local guitar shops sell the chinese and russian 6L6 tubes and I think 12AX7's for rather affordable prices compared to NOS American tubes. A friend of mine plays guitar and he always seems to have a box laying around from matched 6L6 tubes.

[codefox1]

Ah. I'd almost be willing to try the Chinese 50's in my Majestic if I could find a source and get my money ahead. The local guitar shops sell the chinese and russian 6L6 tubes and I think 12AX7's for rather affordable prices compared to NOS American tubes. A friend of mine plays guitar and he always seems to have a box laying around from matched 6L6 tubes.

The Shuguang tubes are very good, China. Don't know if they are making 50's now.

[Arran]

If push came to shove and you needed a substitute of a pair of type 50s you could use a pair of 6L6 tubes connected as a triode, with an adapter, using a resistor to drop the filament voltage to 6.3 volts from 7 volts, but a pair of China 50s would be better as you wouldn't have to change the bias voltage.
Regards
Arran

[Doug Houston]

There are 2 Mf./1000Volt Polypropylene capacitors that Mouser Electronics sells. I'm using them in sets of two in parallel to get the 4 / 1000V that I need in a Victor Electrola that I'm currently working on.

It's also possible to use seriesed 10 / 450V. Electrolytics with balancing resistors, but that won't do very well if you really need 1000 Volt capacitors.

I don't understand your question about the resistors. Let's kick it around a little more.

Hello, Doug: just curious- what kind of voltage rating do you have to look for for your filter caps? Sounds like you would have to go with some relatively expensive units to handle the high voltages.

Also, are there more than the usual power resistors there, or maybe more with a higher than usual power rating?