Fender Vibro King reverb problem

[wildeman]

My Vibro was eating EL84 tubes for breakfest so I replaced the EL84 with a 6V6. Now all 6V6 tubes I try are microphonic. i replaced the reverbtransformer also with a special 6V6 type transformer. What could be wrong here.

[billyz]

What is the plate voltage? The schematic shows 470vdc on the Z node.

[wildeman]

Plate Voltage = 472V Screen Grid = 470V on the yellow y tab.
Schematic 232V

[wildeman]

I found the '97 schematic. Is converting the Power Supply the only possibility to get the right Screen Grid Voltage for the 6V6 tube? Is this enough to make the 6V6 driver quiet enough?

[billyz]

I just wanted to point out Zinky ran the Poor little el84 freakishly hard and they don't survive. Since you've already converted it to an octal socket and 6v6. you could try the JJ 6v6s which is known to handle those voltages better. But you may still have tube rattle issues and will need to select for the lowest rattle.
or even a 6l6/ 5881.

Adding a lower voltage plate and screen supply is always an option. which is what I prefer to do with the el84, because I am lazy and dont want to drill out the chassis.

[hbamp]

Thanks Billyz,
I' am gonna convert it to the 1997 model for Danny (Wildeman) Hope this works. Next thicking, vibrato chalenge!

[wildeman]

Thank's Billy, Henk, helping me out.

My Virus blocker, blocked me for TAG. Have to turn it off. Hope this stops soon.

Danny

[cbass]

If you can find some 6v6gta they vwill handle that voltage . Ive never tried the jj certainly easier to find .
Just realized your in Europe so gtas probably not an option

[Stevem]

I have run the JJs at 520 volts and they did not even flinch in a Highwat 50, in fact those two guys put out 29 watts RMS !

[Structo]

That's why I wonder if it is actually a 6L6GT in sheep's clothing.

[rooster]

There should be a Fender fix out there for this EL84 issue. I remember reading about it, a factory fix to reduce the voltage on the tube.

Doing a search I can find a Tim C mod for the amp but nothing concerning the Fender fix.. Well, maybe you are happy with things now.

As to Bruce Zinky and Fender, remember to cross reference the Dual Professional reverb with the VibroKing. The Dual was his first amp for Fender and he may have been more committed when he designed it. I thought the Dual was a pretty good sounding amp actually.