Building a Reverb Champ

[tyru007]

Building the AA764 Champ with a few tweaks to the standard layout:
Solid State Rectifier (UF4007s)
Individual power supply caps
MID pot to the tone stack

I'd like to consider adding reverb (similar to the princeton reverb AA1164), using the xtra 1/2 12AX7 as an additional stage to the preamp. The amp basically becomes a princeton reverb preamp section plugged into a Champ SE 6V6 power section.

Any things I should consider? Too much gain?

I was going to use a Hammond 270DX 275-0-275 90 mA for PT. Looks like it still has enough power to the 3 preamp tubes and the 6v6, but not a lot extra. Should I move up to the EX for 125 mA?

[Wakculloch]

Put a choke in the power supply if your gonna use it for recording.
These things hum like they were designed in the 50's.
Take it you're not going into mass production and therefore being Mr Tightwad Fender is'nt an issue.

[Tubenit]

Verb O Champ

This was an idea I had quite some time ago but never got around to building.

With respect, Tubenit

[Tubenit]

Verb O Champ layout

Layout for the amp. If you are using ExpressSCH, PM me with an email address if you want an editable version of the schematic and layout. I have not built this so look for errors.

With respect, Tubenit

[Tubenit]

Verb O Champ FTS

Schematic with 12AT7 and Fender Tone Stack

[Tubenit]

Verb O Champ FTS layout

You could use an inexpensive tag board and use this layout. I have built over 10 amps with the reverb on the far end & the amps are VERY quiet that way. I personally would prefer paralleling V1 and using just one 12AX7 for the reverb. I like the tone of that reverb more than the Fender because it emphasizes the mids more. However, it doesn't do the surf reverb extreme as well.

With respect, Tubenit

[tyru007]

Thanks for the schematics.

Will a Hammond 270EX 275-0-275 125ma have enough power for a champ with a SS rectifier and reverb 2-12ax7, 1-12at7, 1-6v6gt?

[tubeswell]

Thanks for the schematics.

Will a Hammond 270EX 275-0-275 125ma have enough power for a champ with a SS rectifier and reverb 2-12ax7, 1-12at7, 1-6v6gt?

I think 125mA should be sufficient for all the tubes. 275-0-275 with diode rectifier will theoretically give you 388VDC B+, which will drop a bit (maybe to around 368?) with a load on, and be good for a 6V6 with 3 preamp tubes. If you don't like that, you can zener down the B+

I think the heater winding should be at least 2A (1.35A with buffer) for a single 6V6 and three 12A_7s. If you want to construct it so you can run two 6V6 in parallel, I'd make the heater at least 3A, and the HT maybe around 150mA

[walkman]

What type /specs for the reverb transformer ?

[Tubenit]

Fender replacement R/T & tank

This reverb works just fine with a Fender reverb trannie and tank.

[walkman]

do you know what the primary impedance is or a part number for specs?

cheers

[tubeswell]

Standard fender twin reverb tranny

3k2 primary

8R secondary

Do a google search

[walkman]

Thanks....

I found 125A20b Fender Reverb Driver, 3.5 watt 14.5k ohm primary / 4 ohm secondary ?

which one did you suggest?

[tubeswell]

Well there's a few different ones you could use

I've got one of these lying around

http://www.tubesandmore.com/scripts/...item=P-TF22921

Here's another one

http://store.triodestore.com/tf160.html

tubes and more also has one spec'd that has a 2500R primary that they also call a P-TF22921 (is that a misprint? who knows?)

Can't remember where I saw the 3k2 primary (maybe I was thinking of 3 1/2 watts?, although I'm sure I've seen them advertised).