BF Vibro Champ mod

[tele-tubby]

has anybody tried to:

1. switch to a 6L6
2. switch 5ygt to a GZ34
3. fixed bias

on a BF Vibro Champ?

[stokes]

Are you talking about a "real" Vibro or a clone?If you are planning to do it to a vintage amp,you are gonna catch hell from some of the "vintage amps shouldnt be altered" crowd.I dont adhere to that train of thought,usually,but I would draw the line with a BF Fender.I have done just those mods to a SF Champ for someone about a year ago.It needed a new PT anyway so we used a somewhat larger one as well as a Hammond OT that was a closer match for the 6L6.You may want to consider a scratch build instead of tearing up a vintage BF.

[tele-tubby]

Nope. I'm planning on a new build I haven't seen much of BFVC mods around here...

Are you talking about a "real" Vibro or a clone?If you are planning to do it to a vintage amp,you are gonna catch hell from some of the "vintage amps shouldnt be altered" crowd.I dont adhere to that train of thought,usually,but I would draw the line with a BF Fender.I have done just those mods to a SF Champ for someone about a year ago.It needed a new PT anyway so we used a somewhat larger one as well as a Hammond OT that was a closer match for the 6L6.You may want to consider a scratch build instead of tearing up a vintage BF.

[Chris - CMW amps]

Do you want to try some other parts/circuit-options or do you wanna change the sound/feel/tweak some shortcomings?

1st part: just try everything you want
2st part: make clear what you like from the amp and what you don't like. After that it's important to figure out if these wishes are possible in such platform, if so: start tweaking parts-values, voltages, changing OT/speaker/etc. to get the changes you need.

In a few words: do want to mod because you did see some "mods" or do you wanna mod 'cause you don't like the sound/feel/power/etc.?

[MWJB]

"1. switch to a 6L6" yes, no problem, typical 125P1B trannies will cope. If sticking to cathode bias you may want a beefier OT to handle increased current, a 10W cathode resistor and 100v cathode bypass cap on the power tube.

"2. switch 5ygt to a GZ34" No problem with 6L6, given the above, you may need to adjust cathode resistor value to keep plate dissipation reasonable if you intend to switch back & forth between 6L6 & 6V6. I run a GZ34 in my "non vibro" SF Champ, 660ohm to 800ohm cathode resistor should do the job, bias the 6V6 to 16W or so and you should have a good compromise?

"3. fixed bias" Not done this on a vibrochamp, just a champ - though if I was building something along those lines I'd probably aim for a Princeton style bias trem (will disable the trem if switching back to cathode bias though). If building from scratch, a fixed/cathode bias switch is a cinch to install & will work with the stock VC circuit. External bias adjust & test point will make subbing power tubes safer, quicker & fun - though don't forget to play the thing once in a while!:-)

[Fretts]

One of the easiest mods you can do is to lift the inverse feedback. It's a wire that goes from the tip of the speaker output RCA jack to a resistor on the tagboard. Just unsolder it and preferably cap the bare wire end with heatshrink.
It's easy to reverse if you don't like it.

[mcinku]

I did it to my Ceriatone BF Champ...

You can find some info about it here
http://ceriatoneforum.com/index.php?topic=79.0


and here
http://music-electronics-forum.com/s...ead.php?t=4812

[tele-tubby]

you mean you didn't have to change your OT to use a 6L6?

I did it to my Ceriatone BF Champ...

You can find some info about it here
http://ceriatoneforum.com/index.php?topic=79.0

[mcinku]

you mean you didn't have to change your OT to use a 6L6?

Yes, but my OT is different compared to what you get in standard Champ. There is a company which makes PT and OTs for Ceriatone. All I did is asked Nik, if my Champ OT can handle extra current and he said yes.