Vibro Champ Power Section

[MikeNiteRail]

I am trying to maximize the potential of an unmodded SF Vibro Champ (without any major mods). Right now, I run the amp into a 4ohm 2x10 cab with a JJ 6v6, RCA 5y3, and Tung Sol RI 12AX7s.

Is there anything I can do tube wise (different brands, or different types...6L6 different rectifier) that I can do to make sure the amp is at its potential for volume and tone?

I've heard that a 6L6 is safe to run and will change the tone/headroom but not the volume. I have a JJ 6L6 and TAD short bottle I could try it I knew it was safe. I've also heard of guys using different rectifers...even solid state or copper cap.

By tone I mean bottom end and cut/punch. I am 90% happy with the amp live, but thought I might check to see if there is anything I might be overlooking.

Thanks!

[doc]

Put in an Area 51 fixed bias kit. You can put in a SS rectifier, but I don't think you'll see a big difference with that. Make sure your speakers are as efficient as possible - you could put Rajin Cajuns in your cab.

[doc]

You can also change the bias values on the power tube - I think its increasing the cathode resistor to 1K (several watt) and increasing the cathode bypass cap to 50 watt/50 microfarad to get the power tube into the optimum range. Use search - there's a thread on this mod somewhere.

[Axekisser]

Put in an Area 51 fixed bias kit. You can put in a SS rectifier, but I don't think you'll see a big difference with that. Make sure your speakers are as efficient as possible - you could put Rajin Cajuns in your cab.


I put one of these in my Champ and the difference is subtle. I got the best bang for my buck by putting in variable neg feedback and an adjustable mid control. Mines a '79 so I didn't mind drilling holes in it!

[doc]

In mine the difference with the fixed bias was definitely noticable, but YMMV. I felt it was worth the expense. By far the biggest bang for buck with these amps is speakers, but you already are using 2 X 10s, so that's addressed. I agree that you can get a significant difference with decreasing or removing negative feedback, and that's an easy and cheap mod. You might also consider getting one of the beefier Champ output transformers Allen amps sells.
You're not going to turn it into a Deluxe no matter what you do, but you can make a big change in available volume and headroom compared to the stock amp.