Fender Champ 12 w/ mods... my little 'sleeper'

[Tesla_HV]

I had three amplifiers, a Fender Frontman 15g that I do most of my 'quiet' practice on and a '65 reissue Twin Reverb that I actually rarely use due to its size and weight. I also had a Fender Champ 12 which served as an 'in-between' amp. Not satisfied with what I had, I sent the Champ 12 off to Dan Moser of "The Amp Room", Groves Texas to be modified. Dan gutted the electronics and hand-wired it to emulate a Deluxe Reverb final stage, single channel, with a Princeton Reverb style driver circuit and using 6L6GC’s, no reverb, no vibrato. The idea would be to produce a relatively-light toneful 30W amp. The speaker was changed to an Eminence Cannabis Rex Patriot. Here are the amplifier specs:

The amp:
· Single channel Deluxe Reverb circuit without reverb & vibrato. Vintage N.O.S. Stancor Power transformer
· (2) JJ 6L6GC power tubes (matched) cathode biased
· Solid state rectifier
· German F&T filter caps - (2) 100uf @ 350V in parallel on mains (= 50uf), (1) 47uf @ 500V 0n screens, (1) 22uf on driver, (1) 22uf on pre-amp
· Sprauge, Mallory caps elsewhere, silver mica, carbon composition resistors

The vision with this design has been to keep the solid state rectifier to save space, offset that with going cathode bias to brown-out the tone. The combination suits a 30W 6600 ohm primary output transformer with an 8 ohm speaker – perfectly (27:1 turns ratio).

So I got the package today:

 

[Tesla_HV]

I assembled the tubes which were packed separately and weighed the final product: 35.5 pounds. Here are some more pics:

 

[Tesla_HV]

One more set of pics:

 

[Fearnot]

I always loved the Champ 12 form factor - especially in that snakeskin - so this is a very interesting project. I hope you can put up some audio or video of it soon. Congrats!

 

[euro]

Congradulations! That amp was done up right!

 

[Tesla_HV]

Well just messing around with this amp for a day and it is LOUD! For inside of about a 20 x 20 room, having the volume at "1" is loud and would get the attention of the neighbors. I'm letting it break in a bit before turning it up more. I've been leaving the filaments on without the plate voltage on (standby) and then flipping the standby on when I want to play for a bit. Would this be a recommended break in procedure?

One thing about having a loud amp is that it really brings to light sloppy playing and the accidental plucking of unwanted strings and the such.

 

[Tele Ted]

Cool amp

 

[Tesla_HV]

A bit of a side-by-side comparison. I played the same guitar (MIM Telecaster standard) through both the modified Champ 12 and a Fender Frontman 15G. The volume knob setting on the Telecaster was the same for both tests. The sound level was measured using a SPLnFFT Noise Meter iPhone app which may not give an extremely accurate absolute reading in dB, but would make for a good side-by-side comparison. The volume on the modified Champ 12 was left at "1" and the high e-string was plucked at the 12th fret. Here are the results:

Champ 12 set at 1: 112 dB.
Frontman 15G set at 1: 106 dB.
Frontman 15G set at 10: 108 dB.

The difference in sound quality between the Champ set at 1 and the Frontman full volume is much different of course.

 

[knopflerfan]

Great looking amp and sounds like some cool mods - congrats.