Hi all I just went through my ultra champ redid the cathode bias resistors since I have a switch and a different OP transformer so I can use 6v6s or 6l6s. I using a 500 ohm R and a 22Uf cap for my 6l6s and a  600ohm/33uf cap for the 6v6s I am now getting static type feedback and vibrato type feedback a max volume with both almost like it as feeding back into the vibrato circuit. not sure what the problem is as I used a 400ohm R for the 6L6s prior. I will look at it again tomorrow to see what give just looking for some feedback from anyone who may have encountered this problem. JGK

Just finished building a Ultra Champ type amp sounds pretty good so far and its very quiet. I am curious as to the warm up and stand by switches as when I turn the power on which hits the power tranny and rectifier tube I have enough power to hear a signal when I play my guitar it comes up to full power when I hit the stand-by after a few minutes and everything seems to function well. Has anyone else experienced this?

Also I used some a upgraded power transformer so I can experiment with different tubes 6L6 types mainly and a dual taped OP tranny to facilitated this. Currently running a JJ 6v6 with a plate voltage of around 406v with a 5R4 rectifier and am looking at tweaking the cathode resister to cool this some. Will post some pics when I get time. Really enjoy the forum. JGK

I've added a mid switch to my tone stack does the 15K resistor need to be removed from the bypass switch or does it serve another purpose in the signal chain as Fender normally used a resistor on the bass pot to provide a mid control? JGK

Just wondering if anyone has added a mid control to there Champ as in a regular Fender tone stack?

As far as the market goes Camps and VB are a fair deal I travel allot and you can find them for around 300.00 or so in stores that carry vintage type stuff. The silverface fenders are also a good deal but they still require some maintenance and overhaul work. I'm not a collector I'm just looking for something around 6=8 watts that I can crank also a class A type vib. I looked at some parts and I think I will just build it as I'd like to do a combo with a 12" speaker since I have quite a few laying around. I've built a Allen accomplice and a Trinity SIII both are a little loud to crank and I,ve got a original Super Champ which is nice amp. Plus its getting to be winter here and I need a project to stay busy with the next month or so. JGK

Thanks, all good info I'll have to do some additional research but I am looking for a low watt amp and even SF Vibro Champs are getting priced beyond reason. Thanks again JGK

Hi all I'm new to the forum and have been looking at building a Ultra Champ as it seems everyone has raved about the design.  I am curious of some of the design specifications compared to a BF or SF Vibro Champ and if anyone has had any problems or explain these more in depth.   

1. Initial 33uf filter cap as opposed to recommend 20uf for a 5y3, also has any tried any other rectifier tube such as GZ34 or a 5UB?

2. Vibrato controls 50K C (what's the C stand for) 2M A as opposed to the 25K and 3M RA pots on the original?

3. I also was wondering about the small cap and what appears to be diodes on the rectifier tube what do they do?

Thanks JGK