Tubes and the mutant champ

[big bob]

Ive been playing with the champ/mutant. I built it with oversized transformers and some other mods (thanks Brian) so I could swap out tubes. I have played mostly with a 5y3 recto, mated with a 6v6, I think it sounds real nice cranked and even on low volume. I did notice a weird thing, the volume jumps at about 2

Then no noticeable volume gain until about 7. The tone gets grittier but the volume stays stable. I also played around for a little bit this morning with a 5u4 recto and a el34. Quite a bit more volume. I never cranked her above 3 as it was early and I did not want to whizz off the family. This was my thinking. The el34 needs more plate voltage than my unit would normally produce, however the 5u4 even though it uses 3 amps to run (5y3 only 2) it produces more plate voltage for the power setting so I figure they are a good match? This morning I did notice more scooped mids and quit a bit more volume. I plan on further tests later this week when I can really crank her up.

Any thoughts?

[Gitfiddler]

Bob~ I'm probably the last guy who should give out amp technical advice, but have you considered changing the Volume pot to an Audio vs. Linear potentiometer?

 

If your Champenstein has a Fender volume pot, it might be their typical Linear part. They like amps to sound loud really fast rather than a more gradual increase.

[big bob]

Bob~ I'm probably the last guy who should give out amp technical advice, but have you considered changing the Volume pot to an Audio vs. Linear potentiometer?

 

If your Champenstein has a Fender volume pot, it might be their typical Linear part. They like amps to sound loud really fast rather than a more gradual increase.

 

I don't mind the pot, just found it a tad strange. And I really don't want to open her up, it really crowded in there!

[bolero]

kind of hard to guess, since we can't hear the amp!! and "tone" is so subjective

 

I like 6V6's a lot..but a single ended EL34 amp would be pretty funky!!

[big bob]

kind of hard to guess, since we can't hear the amp!! and "tone" is so subjective

 

I like 6V6's a lot..but a single ended EL34 amp would be pretty funky!!

 

The only way I can record anymore is with my iPhone posted to YouTube..... Not a very good way to share..

But what the hey I'll give it a try.

[DetroitBlues]

Bob~ I'm probably the last guy who should give out amp technical advice, but have you considered changing the Volume pot to an Audio vs. Linear potentiometer?

 

If your Champenstein has a Fender volume pot, it might be their typical Linear part. They like amps to sound loud really fast rather than a more gradual increase.

 

I've often wondered about that. I've played some amps that the volume was a steady increase and other that have "jump" spots...

[Hfan]

I can recommend a forum with lots of old amp techs that give free advise, they have helped me in the past quite a bit http://music-electronics-forum.com/f22/

[212Mavguy]

The way to get the most b+ voltage to the el34 and any other tube in the output socket without surgery in your amp is is to run 5ar4/gz34 rec tube. Same heater current and pinout as 5y3 and 5v4, another low cost sub for 5ar4, not quite as high b+, but close and very affordable in VOS. 5ar4 has lowest voltage drop of 5 volt rec types... 5y3, 5v4, 5r4, 5u4, for b+ and plate current. That el34 will need a different cathode bypass resistor to get it to it's sweet spot in current draw, though, and that present lack of current draw is causal to what's missing in the tone. EL 34 biased sweet spot is glorious in the Champ, a bit noisy from heater draw, fine in a live mix. Y'oughta hear a big iron Champ circuit into a 2/15 with a 6550, hehe.. Pant flapper.