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Vintage threads from the first ten years

Re: Bought a Champ! Questions...

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10/10/1999 8:54 PM
Michael Tousek	Re: Bought a Champ! Questions... That makes sense to me, Bruce. But can a Champ, with it's small speaker and cabinet, reproduce those frequencies? If not, then it seems like you should just take them out of the equation so that the output section doesn't waste wattage on them. Michael "I-swear-I'm-not-just-being-argumentative" Tousek

10/11/1999 1:36 PM
jeff	thanks Bruce, good points about sub-harmonics! First there is theory - then there are ears

10/7/1999 2:03 PM

quote:
"Then move over to the 6V6s grid load resitor and consider change it to a 180K. Sometimes that helps a little."

Excellent idea Bruce

Trace

10/6/1999 3:54 AM

Thanks, Tim. Have you seen a Champ with the ceramic Weber speaker? I read somewhere on the WeberVST site that Ted wasn't sure whether it would fit in a Champ. People have put the alnico speaker in with no problem, but I'd rather go with the ceramic if possible.

And I like the idea of the different tone stack values. The current values seem to voice the bass control way down to where it effects frequencies that the speaker really doesn't even pass.

Michael Tousek

10/6/1999 5:00 AM

Hi Michael,

I haven't seen the Weber VST 8" ceramic in a Champ but I have a 10" ceramic speaker in my Champ. If I can fit that in I would think that an 8" could be modified to fit in yours somehow.

I had to make some adjustments to accomodate the 10".

I removed the rectifier tube and replaced it with a solid state rectifier using six 1N4007 diodes. That allowed me to use that empty socket for an extra 6V6. I also added a second preamp tube using a cathode follower. I ended up switching from the cathode follower to the standard black face style preamp.

I'm using an old 25 watt output transformer(Stancor brand I believe) from a tube stereo. I had to cut the wood strip on the right side rear of the cabinet that the back panel attached to in order to be able to slide the chassis back in. I mounted the output transformer on the right front corner of the chassis as that was the only place it would fit. I put 6L6's in instead of 6V6's.

I used a .68 cathode bypass cap because I really wanted to cut the bass response. My preamp is fairly high gain. A 2.2mfd cap would sound very good as well. It would allow for a little more bass without being overpowering. I had a Mesa that used 2.2mfd bypass caps. It sounded very good.

Was this project a lot of work? Yes, but it was fun so what else matters?

Best wishes,
Tim C.

10/8/1999 3:29 AM

Yeah, Tim, that sounds like a nifty little amp you've cooked up. When you had the cathode-follower in its preamp, did you have it near the tail end of the preamp (like a Marshall) or toward the front? In another amp of mine, I used the standard BF preamp with a cathode-follower driving the tone controls, and I thought it sounded really nice. I don't think I've run into any other amps with this configuration -- usually if there's a cathode-follower, the tone controls will be the last thing before the PI.

I've changed my Champ's tone caps over to .047uF and .022uF, and I changed the first stage bypass cap to a 4.7uF (as per Bruce's recommendation). I haven't had a chance to crank it up and see what the low end will do, but the clean sound seems to be about same. I'm guessing that the changes will be more noticeable when it's distorted, since it (hopefully) won't be flabbing out on unneeded low frequencies as much. I'll get a chance to play it loud tomorrow (and loud it is -- my ears ring after playing it at max volume!).

Michael Tousek

P.S. I've found a couple places that have the Mexican-made Aero brand multi cap; does anyone know where I could get a Mallory like the original?

10/7/1999 12:17 AM
JR	Actually I think you paid a decent price for a fine amp. Don't forget, a lot of the Layla album was recorded with one. Oh, crap, actually that might have been a tweed champ, but hey i love my 67. youd be suprised at how BIG they sound recorded when mic'ed right.

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