Tweed Super (5F4) rectfier alternatives... [Archive]

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Cobra

10-06-2007, 05:18 PM

Can you safely use a GZ34 or 5V4 tube in place of the stock 5U4G in a Tweed Super(5F4) circuit? I have no 5U4G's, but I have several GZ34's and 5V4's in my tube stash. Any issues or concerns using these tubes, please advise.
Thanks much!

TD_Madden

10-07-2007, 08:21 PM

I've been told GZ34s are fine...just keep the tubes biased at no more than 17 watts each.

Bruce / Mission Amps

10-09-2007, 05:03 PM

I've been told GZ34s are fine...just keep the tubes biased at no more than 17 watts each.It's probably safe to go as high as 20-22 watts if the choke and the power tranny's high voltage secondary are
up to it...
ie. ... rated at around 200ma.

TD_Madden

10-11-2007, 08:09 PM

Bruce, since I have your 5F4 kit, is it safe to assume I can go up more than 17 watts?

Bruce / Mission Amps

10-16-2007, 06:40 AM

Bruce, since I have your 5F4 kit, is it safe to assume I can go up more than 17 watts?Yes, I use that same tranny combo you have in a cathode biased 6L6 harp amp and idle those power tubes at 20-24 watts each.
It's hot but the Heyboer PTs seem to handle it in stride.