Ghost Notes From Marshall, Bassman, Etc.

[Chuck H]

Provided the buss wire you used is a nice big heavy one, what you have is not dissimilar from the way I do it. But don't pin it on me to be the authority on this. In fact, in this very post a better scheme than the one I suggested was discovered. Sometimes it's individual to the layout. I don't use a buss, I use the chassis. The chassis can be your "buss" if you follow the idea that distance = resistance no matter how you slice it. And since chassis are usually a nice heavy gauge they have lower resistance than buss wire. But when you consider the resistance difference between the chassis and a fat copper buss wire it becomes moot. Only if you were to use a small gauge buss wire would it matter. Then it would be as if you just daisy chained your grounds. With standard 22 or 24 gauge lead wire that's a bad idea.

Chuck

[daz]

thanks. I think i used 18 gauge if i recall.

[Chuck H]

I was actually thinking larger than that. But if your amp is quiet it doesn't matter.

Also, I use aluminum chassis (because they're easier for me to punch and cut) which has no electromagnetic properties. If I built an amp on steel I would probably use a buss because EMF from the transformers is supposed to be able to linger on the chassis. In that case I would think that a buss connected to the chassis ground would be the quietest arrangement.

Daz, how much ghosting do you have in your build? A little, a typical amount or a lot?

Chuck

[daz]

To be honest i never noticed it. If what you said is right, then i guess it's there but i can't hear it. then again i don't usually crank it way up either. Loudest i ever play it is about bar gig volume, which when i played out was about 3-4 on a JCM 800 master for example. Thats fairly loud, but you said a amp thats good in this regard will still have it but only noticeable when cranked. So maybe i'd hear it if it was on 10. I've had it there just a few times early on in the development but i didn't notice it then. Maybe if i had played it like that longer, i dunno. And amazingly mine has small filters ! I had big ones for a couple weeks recently but went back to the 32/32uf can and 22uf preamp nodes because i started realizing i didn't like that stiffness.

As to the chassis, mine is aluminum for the same reason. But i wonder about the sonic difference and whether it's really a determent or not to use steel. I have a 6V6 build that started life as a 18 watt and i re-did the preamp exacly like my EL34 amp, but it soumnds world different. It has a much more traditional marshall high gain preamp tone. My EL34 amp has it's own sound...marshallish, but with it's own unique character. The 6V6 amp has a much more traditional marshall tone, and i really like it and wonder is it could be due to the chassis. I've tried the JJ 6v6 tubes in my EL34 amp before and it still sounds basically like it does with el34. There *could be* something to the aluminum vs steel debate don't you think?

[Daver]

Back To Our Regularly Scheduled Thread......

Chuck,
I reconfigured the Cathode Follower as a paralleled stage using the same plate and cathode R values. The ghosting once again is a tiny bit better. I think I'll "think Angus" and ignore the little bit that's still there. I do like the tone better without the CF, but it's a tad thinner. I'll need to juggle the tone stack or cathode bypass cap and see what I get. Thanks for all the input!
Dave