6G12-A Concert w/Reverb?

[Duck Dodgers]

Really like the Vibrato (Tremolo? Whatever!) on the brown face Concerts. I'm considering building one for my next project and have already done a little board layout work for the Vibrato section.

Question here is how to add a reverb. I would like to have it on the Vibrato channel only and leave the Normal channel completely clean.

Short of putting a 6G15 circuit in front I'm out of my depth and need some help from the guru's.

(I actually did consider building in a 6G15 and patching it to either channel. Seems a bit flakey though.)

Thanks.....

[pdf64]

'Short of putting a 6G15 circuit in front'
See vibro-king schematic
http://www.fender.com/support/amp_sc..._Schematic.pdf
which is pretty much what's been done.
So give it a go.
Also search for posts from tubeswell, he's managed to put reverb into a couple of tweed circuits. Peter.

[Duck Dodgers]

Peter,

Good call on the Vibro-King. I hadn't found that one.

Reverb looks alot like the 6G15. Uses a EL84 in place of the 6K6GT and only half of a 12AX7 for a preamp. Works out great since there is an unused 12AX7 half in the Vibrato circuit......

Doug

[tubeswell]

FWIW

I keep on fiddling around with my reverb circuits. I have come to the conclusion that the 6G15 circuit is designed to work wonderfully if there is nothing in front of it (but the geetar). This is because the unity gain from the CF bypass stage is working straight off the guitar output signal, and it enables the mix control to blend perfectly with the single recovery stage from the tank - giving good control and range in the mix control.

I have found from experimentation that when you stick that whole circuit after a preamp stage in a geetar amp, that it makes the 'dry' signal overpoweringly strong, and you need some attenuation either before the CF or after it (in the form of a split-load cathode resistor on the CF - for example) to cut down the dry blended signal from the CF.

However the 'downside' is that this decreases overall dry signal going into the following stages in the amp. The further along the signal path you put this type of circuit the more attenuation you need to give the 'dry' signal in the bypass stage. Or as a corollary, the more gain stages you would need to give the recovery signal to balance things out.

Also I don't think anything beats that pentode driver setup in the 6G15. With a 6V6 (or 6K6) driving a 5k RT into a type 4 pan, you get a beautiful sounding reverb, that a BF style reverb just can't compete with. So I recommend persevering with the idea (of adapting the 6G15 reverb).

My experiments are still a work in progress

JM2CW

[Duck Dodgers]

tubeswell,

I'm starting to get pumped here.......what do you think of the vibro-king reverb? I like the EL84 idea. A little neater with the 9 pin tube setup and the leftover 1/2 12AX7 from the vibrato is very convenient.

Would the 6K6 be better sounding? Thoughts?

Having built a 6G15 as my first scratch build I have to say I love the sound.

Doug

[JoeM]

Zinky also designed the Dual Professional with the reverb in front.

http://www.ampwares.com/schematics/d...ofessional.pdf