champ extra gain stage

[bigsmitty]

has any one out there added an extra gain stage to a champ? can pt handle the extra tube? mine is a silverface converted to 5f1 specs also converted to fixed bias.

[bigsmitty]

tough question huh?

[Cygnus X1]

Takes a while sometimes.

Yes, there is a way...
But it carries it out to an extreme.
My favorite build is an AX84 SEL- 2x12AX7, 1 6V6.
But it is much higher gain than a Champ!

Wiser people here will have a simpler solution.

[Structo]

I would respectfully say adding a gain stage would be self defeating on a Champ.
Why not build something else such as a Deluxe if you want more gain?

[Andy Le Blanc]

Franken-champs are fun. Its easy interchange volume, distortion, and gain,
and use them in the wrong way. You can put a superlead pre and master
volume in a champ. But your not gonna make any more watts. The clipped
signal with everything full up will tax the OPT with serious induction issues.
You'll want to beef things up, which is half way to building an amp that will make better gains any way.

[Rick]

I have just built a 6L6 amp based on the Epi Galaxie 10. I added another 12AX7 up front with both triodes in parallel like in a Matchless Lightning. Then I put in two gain pots. It's easy to build and experiment with and you can get incredible amount of gain from 3 or 4 preamp stages. Different bypass caps, resistors, and plate resistors to the pots will give wildly different gain and tone. Experiment with the tone stack slope resistor and caps. You learn how to cascade gain stages. Kevin O'connor's TUT is a great resource when doing this. You capacitance couple and drop voltage and drain the grid so you don't have a grid go negative. You add resistance to keep the gain under control or else you run the next stage into cutoff. You design your own amp by the time you're done and have something new and different.

These are great fun and cheap to build since you don't need 175$ a piece transformers or 8$/ea. filter caps. You can build one for about $100 or less depending on how resourceful you are. A single 6L6 can get surprisingly loud and sounds great through a bigger cab too. Use bigger trannys and run two 6L6, 6V6, etc. in parallel for more power and SE fun. I have learned more doing this than I did building scads of amps just following layouts and schems.

[Cygnus X1]

Absolutely, Rick.
Ditto!

I took that AX84 SEL and tweaked it until I came up with a great tone (IMO). It was the crashes that taught me the most.
It started off thin and buzzy sounding, and ended up with a nice crisp full distortion-like a big box sound out of three simple tubes.

[bigsmitty]

I'm thinking about putting in trainwreck style preamp in, any body tried something similar?

[Jana]

yup, tough question.

With all the mucking about in the amp already, such as converting it to fixed bias, why not just experiment?

[bigsmitty]

Yeah thats what Im going to do just wondering if anybody has done anything similar.

[MBD115]

I added a 12ax7 to a Super Champ XD, although not really an old style real Champ. It had 1 12ax7 which was shared with the PI, so it only actually had 1 gain stage. I added 2 more in my mod.

It worked great. I put a rear panel mounted gain control on my new V1a and could really crank it up and boy what a difference it made in that XD. It worked great and everything and I had fun doing the mod and all the thinking/planning/buying but in the end it wasn't really worth it. The amp is now setting in a closet and I haven't had it out for several months. Its not the amp I really wanted anyway so I just don't play it anymore.

Build a Vibrolux or something you will like. Maybe it won't wind up in the closet. If you're like me and thinking about modding that amp then there is something about that amp you don't like, so you need to build an amp you will like, then everything will be ok. Mod that Champ and you only prolong the suffering.

Good luck man

[bigsmitty]

Yeah, the champ is just a fun project amp it was a basket case when I got it Ialso have 100 watt superlead and a jtm 45 mojo kit amp

[Big Daddy]

There really is no need to add another stage to those amps. You can mess with the values and get plenty of gain. It depends on what you want it to do. More gain in what frequency band.

What you might want to do is use a different driver tube such as a pentode. I'm working on a 6SL7 into a 6SJ7 into a 6L6GC right now.

So far I have had great success with a dual EF86 and a dual 6SJ7 SE amp built into Epiphone Galaxie 10 amps.

I also built an amp with half a 12AY7 into an EF86 and the gain is amazing. Cascading 12AX7's does not really work all that well. Yes you get a lot of gain but sacrifice tone and it gets muddy. You also end up trying to actually control every stage to balance the frequency response, that's why I gravitated toward pentodes for higher gain.

You might want to think about either a cascode or a parallel first stage. If you add an extra gain stage you also run into more second order harmonics which is not as pleasing a distortion as third order harmonics using just both sides of a triode. I always get a little confused about the second and third orders but I'm pretty sure I'm right about it.

[M Fowler]

Here is a SE amp using mixed pre control for gain.

[Big Daddy]

That's the one I have and it does not work well IMO. I am going to remove one channel and use that as a driver between the TS and Power tube.