Thoughts on converting Webster 88-24 into Ampeg R12R?

[1blueheron]

I am new, this is my first post here. I recently acquired a 1956 Allen organ which contained a amplifier made by Webster electric. The amplifier works and appears to be in excellent condition. Some of the keys on the organ produce no sound while other work fine. It takes up a lot of space which I have too little of and since my son is an aspiring guitar player, I would like to convert this amp into a guitar amp for him. I do not have a schematic for the amp. The tube compliment is as follows:

1- 6J5
1- 6LS7GT
2- 6L6
1- 5U4G Rectifier.

It appears the amp/chassis could be converted to the same tube complement as the Ampeg Heritage R12R amp.

We like the sound of the reverberockets.

I have good soldering skills, can read a basic schematic, use a multimeter, and have excellent woodworking/cabinetry and speaker building experience. I am familiar with working around high voltage power supplies and capacitiors, but I do not have much experience working on tube gear.

Looking for advice. Is this realistic and what problems might I be facing?

[Stevem]

I don't know about the new Ampeg you speak of , but it must have a solid state reverb drive and recovery section because to make a vintage R12R you need 3 more gain stages , so like another 1.5 more tubes.
That organ amp must use the 6J5 as the phase spilter ( one gain stage) which is a cheap way of doing that job and it produced a lot of distortion.
The real deal amp uses both sections of one tube which which is a much better way to drive the output tubes!

[1blueheron]

Correct.

Below is the 6SL6 6SN7 6SN7 6SL6 6V6 6V6 5Y3 version. I can't find an actual schematic of the Heritage R12R but it substitutes 6L6 for the 6V6 and uses the 5AR4 rather than 5Y3. My understanding is the 6L6 config was also used in some of the vintage ampegs to boost output?

I am attaching a photo showing the amp and it's current configuration. The position currently occupied by the 6J5 ould become either a 6SN7 or another 6SL7GT. I don't know exactly what function the silver colored transformer is serving now but I believe it would not be needed for the r-12r. If so, I could also cut holes for addtional tubes there or I could replace the capacitors and put a tube base where the can cap currently is? I have a surplus of 6SN7GTA tubes at my disposal also courtesy of the organ.

[Stevem]

That's a nice clean chassis there!

That silver transformer is power supply choke.

There are some issues to tend to to make this swap/ change!
1) you do not have enough chassis area to get the needed preamp sections stuffed in there so your best bet is to use what you have there now as the power and output section and mount it on the bottom of your amp cabinet and then get something like a bare Fender tweed chassis for the top mounted preamp section.
The added plus to this is that in terms of 60 HZ hum the amp will be near dead silent!

2) adding two more tubes means your power transformer heater winding needs a spare .600 amps to power all the tubes which it likley does not have in reserve so it will burn up!

3) the power transformer also needs more current out of the high voltage winding to power the added D.C. Section of the amp, so once again it may or may not have that to spare!

To solve number two you could add a small filament transformer and get around that issue, then you could do some things to find out how the PT will react to the added D.C. Current needs.
Now one way around both of these issue's( 2 and )3 would be to drop running the 6L6GC tubes and run 6V6 outputs and give up some output wattage .
This would free up heater current and D.C. Current at the same time!

[1blueheron]

Thank you, the chassis is very clean. It was also very quiet. No percievable hiss or hum when it was in the organ. It surprised me.

There are additional transformers from the organ that ran (42)- 6SN7's. I suppose I could use one of those that for the Preamp section if I could identify the right one and it would have plenty of power? Each set of 3- 6Sn7's had there own sub-chassis connected via an octal base and plug. I suspect I could use one of those for the additional preamp section? Here is a picture of one before cleanup. You will notice each has a set of capacitors and a set of what appears to me to be inductors (donut shaped coils).