Glass Audio Fender Champ 12 reconstruction article

[RomanMtz]

Hello! I was checking te Ampage Archives for info on my recently acquired Champ 12 and I noticed in a conversation there a fellow member "Steve M" posted the following:

"BTW, there was an article in Glass Audio that detailed the reconstruction of a BF Champ using the Champ 12 output iron and a modern high gain preamp. If you're interested, I could send you a copy of the article."

Any chance someone here has that artice they could share with me? Thanks!

Román

[RomanMtz]

Anyone?

Is Steve M still on these forums?

[Tom Phillips]

I remember reading that article. It was published 5 to 10 years ago. The "reconstruction" didn't concentrate on making it a better guitar amp. More like an audiophile changing all they could about the circuit to "improve" it from their point of view. If I could find it in my archives I'm not sure that I could legally distribute it but I'll mark this thread just in case. IMO, other than entertainment value and sparking some interesting comments on this forum, there was nothing in the article of value with respect to a guitar player's amp.
Regards,
Tom

[RomanMtz]

Hey Tom, thanks for the reply! Just a little personal background of this amp...

I bought one of these in craig's a couple of weeks back for $100 bucks... it had a busted Input 1, no Input 2 and the third prong on the power supply cord had been knocked off.

So I replaced both inputs with some I had left over from when I repaired a Red knob Twin a couple of years back, I cut off the power cord and installed an IEC jack and while I was at it, cut off the footswitch and installed a jack for that in the back...

Mine came with an EL34 for some reason (it sounds and works fine) and stock Fender 12AX7's.

I like the clean channel... a little gritty, not completely clean, not much headroom but not necessarily a bad thing. Great for cleanish, mildly overdriven blues. OD channel is a little harsh for my taste. I do use it but with the gain way down. The difference in volume from one channel to the other is also apparent. I have to turn the volume on the OD channel way down if I want to switch from one to the other.

Reverb is OK i guess... don't use it much.

I downloaded the schem and have been trying to figure out the circuit to see how to simplify it and tame the OD channel some or revoice it... I just can't figure out the LDR switching scheme. Also, I'd like to maybe use the second half of the second 12AX7 for something other than buffering the line ins (which I want to remove and use as bias test points).

I dunno... a lot can be done besides the torres mods (which I haven't tried) I guess... I'd just like to figue some mods on my own... any opinions?

[JoeM]

The attached schematic (Ray Ivers posted this), I downloaded here some time ago. It's similar to some mods I did to a Champ 12 I owned quite a few years back. I havent tried these, but they might work well for you.

[RomanMtz]

Hey Joe... thanks for the schem! Actually... while I was searching around the web I did run into this modded schem... I'd just like to understand what those changes in values actually do? Also, anyone understand the LDR switching scheme on this thing?

Any insight? Thanks in advance!