Selmer Zodiac lite idea

[chopstuck]

There are a lot of triode driven pentode preamp schematics out there.

I was looking to build a simplified Selmer type push pull amp with maybe 30 watts. Probably with a cathode biased el-34 pair.

My question is what is the better channel on a zodiac ?

THey both have a driven pentode but one has the rotary control over the pre that looks complex.
I'm not sure what it contributes to the overall tone.
The other channel with just a tone control looks very do-able.

I see you have to set up the pentode differently when driven with more signal in the complex channel and not so much in the simple channel.

Any idea why.

Good clip
http://www.youtube.com/watch?v=KdW4z2L5 ... re=related

[LeftyStrat]

I'm interested in this too. I really like that clip, I'd love to know which channel was used.

[Reeltarded]

The one with the selector because it sounds like an AC3,000,000.

Cranky as hell!

[Structo]

My Cousin has an old Selmer.

About the size of a AC30, magic eye tube, push buttons.

Not sure what model it is but it sounds pretty cool.

Similar to Vox.

[Reeltarded]

Dear Tom,

When is your cousin at work?

Sincerely,

Miles

[Structo]

Yeah he has some awesome amps and guitars.

For example last time I was over there he had this tweed bassman.

The thing looked brand new.

I asked if it was a reissue or new cab and he said nope.

It was owned by an old man that had bought it new and never took it out of his house...

His address is http://tinyurl.com/besl3t3

[selloutrr]

That's the rotary channel build version 2 of the Selmer zodiac 30.
However, the Vox reverb tank is making the majority of the overdriven chime. Keep in mind the Selmer won't be that bright on its own. The concrete helps too. The tone control channel unless pushed doesn't break up as smoothly.

[Reeltarded]

Yes, the Selmer is NOT a bright amp. It sounds like Brian May wishes when you crank it.

Stunning.

[Darkbluemurder]

My question is what is the better channel on a zodiac ?

THey both have a driven pentode but one has the rotary control over the pre that looks complex.
I'm not sure what it contributes to the overall tone.
The other channel with just a tone control looks very do-able.

I see you have to set up the pentode differently when driven with more signal in the complex channel and not so much in the simple channel.

Any idea why.

Very cool project. I also thought of building something like the Zodiac 30.

The schematic I have is a bit difficult to read but my guess is that the rotary selector is similar to the FAC switch in the Orange amps or the switches found on the pentode channels in Matchless amps - nothing special really.

The tone control on the simple channel looks very similar to what Dr. Z used for the Stangray. This tone control eats a lot of signal. If you go with that channel you may want to add a cathode bypass cap on the first stage to get enough signal level into the tone control.

The pentodes do not seem to be set up much different in the Zodiac channels. Compared to the AC 15 schematic I only noticed that it does not have a cathode bypass cap. You may want to add one there, too.

Please keep us informed.

Thanks, Stephan

[chopstuck]

I looked to find a schematic of the Vox reverb unit. Saw nothing at Schem Heaven. Is that reverb something different from a typical Fender Rev unit to give such shimmer ?

[selloutrr]

It used el84 tubes instead of American made 6V6. And a few resistor cap differences but same basic design.

[chopstuck]

I have found the two page outboard reverb schematic and taped it together.
Looks like two separate inputs with 10M grid leak bias to 2 12au7 stages in series with a single 12ax7 recovery.

I don't know what the working impedance is of the phono cartridge to match it.
No output transformer. Hmm

Does this sound much different from the Fender unit if you use a standard Hammond/Gibbs style tank ?

I'm looking for that great shimmer - would this thing this driving a pentode preamp channel do the trick ?

[selloutrr]

You may need to tube swap until you find the exact tone you want.

[rp]

FYI

http://www.chambonino.com/selmwork.html

I want to build a Zodiac 30 or 50 one day too. Time for someone to found a DIY Selmer forum or sub-forum, no cloning info out there. That button thing looks more of an involved PITA than the cap selector rotary on Matchless or FAC - see image and here:

http://www.chambonino.com/work/selmer/selm29.html

pict with respect to chambonino.com