No, just because I haven't seen one doesn't mean that it doesn't exist. I have a dozen or so of each 6AC7 and 6AG7, all metal. The only data sheet I have shows only the metal version, but maybe another manufacturer made the glass flavor. Ebay and Google searches only show metal tubes, so if they exist, they are rare. The searches did show a Russian tube numbered 6J4 or 6X4, but they are also metal.
Note that the 6AC7, 6AG7, and 6SJ7 all have different pinouts. I vaguely remember smoking some resistors finding this out. The 6SK7 is a drop in for the 6SJ7, and gives different distortion characteristics in an overdriven guitar amp.
I have plenty of 6SJ7's in both metal and glass. This tube was one of my go to tubes as a kid making guitar amps for two reasons. They were easy to find in the trash, and I had an old Fender Champ 5C1 schematic. Once a ham radio guy I knew showed me how to convert grid leak bias into cathode bias, I could make good amps with a 6SJ7 and a 6BQ6GT......it's funny how I am almost back to the same combination now over 50 years later.
I often have the thought to recreate one of those amps that I made in the early 60's.......old phenolic wafer sockets screwed to a pine board, some terminal strips from and old TV, a power transformer from an old radio and a vertical OPT from a TV set. Then I think, maybe it sounds better in those old memories in the back of my head than it would in real life, and I say, maybe I shouldn't mess that up.
Later on I made a killer guitar amp in high school out of an old Stromberg Carlson PA amp. I sold it in 1970, and pretty much forgot about it ....until I was wandering the swap meet at a hamfest about 2 years ago and spotted the exact sale PA amp. I bought it, and maybe I will recreate that one.
Ok,
I think I’m going to try three 25DN6 per channel. I have a single running Pentode into a 5K load now at 400V B+, 145V screens, and 52mA which is over 20W dissipation. Never cracks a sweat. Anxious to see what kind of output I’m getting, but hopefully 6-8W.
Do you need to follow the Pentode driver with anything to assist with drive capability? An octal Pentode driver, even a metal can, is find witb me. Six 25CD6 will be plenty of glowing for me.
Thanks!
I think I’m going to try three 25DN6 per channel. I have a single running Pentode into a 5K load now at 400V B+, 145V screens, and 52mA which is over 20W dissipation. Never cracks a sweat. Anxious to see what kind of output I’m getting, but hopefully 6-8W.
Do you need to follow the Pentode driver with anything to assist with drive capability? An octal Pentode driver, even a metal can, is find witb me. Six 25CD6 will be plenty of glowing for me.
Thanks!
6AC7 = 6Ж4, miniature version is 6Ж5П, equivalent of 6AH6
6AG7 = 6П9, miniature version (improved) is 6П15П, no equivalents. 12HL7 has higher transconductance, but lower power.
Miniature 6SJ7 is 6AU6, Soviet equivalent is 6Ж4П
I use in my Edelweiss amps 8CB11. Convenient for stereo, 2 pentodes in the single bulb. 8BN11 has a different pinout.
In Gubernator-71 I use 12HL7 to get 45W from a single ГК-71 tube in A2 mode.
Enjoy!
I’ve used the 6336 and I love it but it’s limited to about 8W and the data suggests not parallelling sections. Singles are limited to around 7W output.
The Gm will be trippled. Are you going to use a single grid leak resistor or 3?
OK, so the driver you use will see a pretty low impedance, less than 33K with the plate resistor figured in. The caps will have to be figured in parallel for the rolloff frequency. I don't know what driver to use to push into that. Seems like K follower territory...
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The Sylvania data sheet calls for 470K max in horizontal sweep duty. I have used 470K for some audio testing, but my experiments are using mosfet drive because my driver boards already have the mosfets.
I am testing some old and crusty looking 36LW6's in my new emulated triode mode.....I have seen good results, exploding tubes (really) and everything in between. This is my first venture into the big tube zone, and the power supply that blows tubes in half is staying turned off......that limits the fun to 550 volts.
I am testing some old and crusty looking 36LW6's in my new emulated triode mode.....I have seen good results, exploding tubes (really) and everything in between. This is my first venture into the big tube zone, and the power supply that blows tubes in half is staying turned off......that limits the fun to 550 volts.
I'm using a single 6C33C on each channel, Lundahl LL1627 @ 2.3K - but there should be no problem with a 1.9k load. 6C33C can handle a lot of current, but you need lower B+ (than your current supply) and a firm negative grid.
Also, the heaters need really solid supply... Super nice sound considering its an indirectly heated triode.
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