Tweed twin HP 6v6 Build

[JGK]

Finally finished my Tweed Twin HP 6v6. Lots of experimenting and fine tuning. Did the cascading gain mod with a Marshall channel. Was way too much so a changed it back to a standard bright and regular channel. Did add a 3 way negative feedback switch and a tone stack lift, dual bias controls and a PPIMV. Ran a quad of New EH 6v6s through it had one drift and red plate within 20 mins had the same problem with Tung-sol reissues also an EH product both were biased at about 22mA at 398 volts on the plates. Swapped them out for some old set Hytrons I had laying around and had no problems. I did up the screen resistors to 1k 5 watt. Pretty happy with it and did experiment running a set of old RCA 6l6s in it too and they sounded really sweet, no denying the Bassman roots there. Will have to do some experimenting as far as new 6v6s I guess I'll get some J&Js. I have never had good luck with the EH 6v6s they have red platted in my original Super Champ too. Its is a loud amp with the 15" speaker it almost makes you sound like your playing a size bigger set of strings. Lots of clean but the MV brings it down to manageable levels. I did build it run it with a pedal board and play gigs with and its sounds big! Thanks to those at the form for all the help and advice.

[brewdude]

Very pretty build

[statorvane]

Very cool amp! I am surprised you had trouble with the New Sensor 6V6s. They had been advertised to handle up to 450 volts on the plates, right? Not sure about the screens.

I had a pair of JJ 6V6S in a 1987 clone a few years ago. They handled 425-430 volts no problem. I liked EL34s better so swapped them out and hardly had to touch the bias. More punch than with 6V6s. I gave them to a friend of mine to try in his 1987 clone.

Again, Very cool amp.

[JGK]

I'm think Tung-sols are just rebranded EH 6v6s. They look very similar. I put the Tung-sols in and biased them at around 22 mAs with about 398 on the plates after about 20 mins I could see the screens flashing and 3 of them red plated, one took out a screen resistor. I also had a pair of recent 6v6 EH red plate in my original Super Champ which is in excellent maintenance. I think its just luck of the draw I know they are advertised to take high plate voltage. J&Js would hold up without a problem. The TSs went back to the dealer so I will see what happens

[Guy77]

I'm think Tung-sols are just rebranded EH 6v6s. They look very similar. I put the Tung-sols in and biased them at around 22 mAs with about 398 on the plates after about 20 mins I could see the screens flashing and 3 of them red plated, one took out a screen resistor. I also had a pair of recent 6v6 EH red plate in my original Super Champ which is in excellent maintenance. I think its just luck of the draw I know they are advertised to take high plate voltage. J&Js would hold up without a problem. The TSs went back to the dealer so I will see what happens

Great looking build.
I had the same problem with Tung Sol 6v6 red plating in an ODS build when they get in the 400v area. I switched out to JJ 6v6 and no problem. Only regret was that the Tung Sols did sound a little sweeter than the JJs in that particular circuit. I probably could have gotten the JJs to sound similar if I adjusted the preamp slightly.

Cheers
Guy

[mojotom]

I had the same issue with Tung Sol 6V6, either red plating or failure at 400V.

The JJ will work and last week if you pass a few weeks and are not noisy/microphonic. Good tubes, more like a 6L6 soundwise, or a cross between V and L.

I found the EH 6V6, if available these days, to work quite nicely at those voltages. I did bias them by using temperature (it sits around 65% dissipation) and that way got the best life out of them at that voltage (and still a “hot” bias). Something like 265 degF.