Need Build Ideas....

[lexluthier72]

I posted in Mods and Tweeks about an amp Im wanting to build....Here's what Ive got...I want to build a single channel, 2 6v6, octal preamp tube. Ive got an old filmosound chassis, and the transformers. See my thread titled "Need ideas for new build/old chassis" for photos of the chassis. I was hoping for something fender-esque....but all the dual 6v6 amps are 2 channel. I only have room for one volume contol. Any thoughts would be great.
-Erin

[J Martin]

Just build one channel. Schematics for other amps are just a guide and don't have to be copied exactly.

[lexluthier72]

Hey,
Yep, I know...I like the idea of 2 channels, but dont have room for another volume pot, and dont want to mod the chassis. I was thinking the 5c3 fender deluxe, and not hook up the second channel. Mostly looking for other ideas. Im not very good at Modding circuits yet...

[mikeboone]

Single Channel Amp

I just built a single channel AB763 with 2 6L6's. It's not a very far stretch at all to use a pair of 6V6's.

I am a big fan of low features! Fender didn't make any low feature amps that were high power, so I had to improvise.

I attached a photo for reference if you'd like a board layout idea. It is 8.5" x 3.125" fiber board I bought from www.turretboards.com.

[lexluthier72]

Cool. Im still leaning toward the deluxe 5c3. Im wondering if I build up the board, can I just leave the second channel input and volume control disconnected. Will it hurt anything? I could do a stacked concentric volume pot, but im trying to do this on the cheep.
-E.

[mikeboone]

That could work for you. Remember if you decide to only use one side of the preamp tube, you may have to adjust your dropping resistor for your plate voltages slightly. It could go up some due to the lower current draw.

[lexluthier72]

Hey Mike,
I think the 2nd channel has its own preamp tube. There are 2 6sc7s. Correct me if im wrong. If there was a way to get rid of the second channel easily, I would do that...but it looks as if they are tied together. This just seems the simplest way to go. I did also find a schematic for a Gibson BR-6F that looked interesting.
-Erin

[mikeboone]

The 2nd 6sc7 is your phase inverter. Each of these tubes has 2 usable preamps. Look at the schematic and you will see they are labeled V1A &V1B and notice the pin assignements, the numbers indicate which pins are used for each side of the tube.

Have fun and be careful!

[lexluthier72]

Mike,
Thanks....Im a little scatterbrained today...I did see the phase inverter part of the circuit...doh. Now, Lets say I wanted to add the 2nd channel volume pot without putting an extra hole in the chassis. The only really good place for one is on the top of the chassis, (if you are looking at the front of the amp), to the right of the OT...There is a socket for an outboard volume control of some sort, that could be removed, and a plate put in place, drilled for said volume control...Thoughts?
-Erin

[J Martin]

Putting a control on top would be a problem if you ever build a cabinet for the amp.

I recently built a 5C3 for a customer of mine. We had a heck of a time finding a reasonably quiet 6SC7 for the first stage. I gave up and rewired the socket for a 6SL7 and everything is good now and the customer loves the amp.

Is that tube on your chassis with the grid cap a 6J7? That would also make a good input tube for a single channel amp. They were used in some top quality gear of yesteryear.

[lexluthier72]

Yep, Thats a 6j7, but unfortunately, It got cooked when the tranny went. This is all great info....I do not think I will put the chassis in a cabinet, it is meant to sit on rubber feet on its own...still dont know that I want to mod the chassis and pull a tube socket for the extra volume control though...
-Erin