What to do with extra tube sockets?

While I'm waiting on parts for my EH-185 project I've decided to tweak my 5C5 PA. I've got three unused tube sockets just sitting there not earning their keep. Along with the sockets I've got three unused pots. So I was thinking of putting something else in there but what? I have some 6SL7's and 6SJ7's that also need to be doing something. Thanks.
Jason

Howdy

Here's just the project. Stephen Delft, now Simcha Delft after the transformation, is a bit of a legend, a luthier and amp guru.

http://www.amptone.com/images/moonligh.gif

http://www.frontiernet.net/~jff/moonlight/images/TopsideRear640x480.jpg

http://www.frontiernet.net/~jff/moonlight/Moonlight_cranked_amp_tone_at_non-lethal_volume.html

Also

http://www.amptone.com/images/moonlightchassis.jpg

http://www.amptone.com/delftmoonlightamp.htm

Now, that's a pretty cool little amp. However, this is an old PA turned into a 5C5 Pro but I've got three tubes in this thing that aren't being used. I was thinking about maybe putting a 6G5 brown Pro tone stack (just since it's already a Pro) in a separate channel, or something like that.
Jason

Woops ... thought you were looking for an additional wee project ... oh well #:o)

How about making a Brown Super 6G4A harmonic tremolo using two and a half 6SL7 or 6SJ7s instead of the 12AX7s ... Blonde Bassman is the same schematic, one of the greatest sounding tremolo designs ever.

http://www.ampwares.com/schematics/super_6g4a_schem.pdf

Depends what you're using the 5C5 for I guess.

Just a thought.

http://www.frontiernet.net/~jff/moonlight/images/TopsideRear640x480.jpg

Oh snap. I *was* going to build a Firefly, but in my heart of hearts, I love octals way more. Instead of a 12AX7 or 6AV6, the Moonlight really needs a 6SQ7 out front, though.

- Scott

P.S. As for the OP's question, I second the thought of building an octal harmonic vibrato section. :cool: Another option might be to build an additional channel with a pentode preamp tube.

Thanks for the suggestions. I thought about adding tremolo but I have an Ampeg Gemini that has it and I never use it. So here's what I think I've decided, I just need help figuring out how to actually do it, I want an input to be voiced like a 50's Gibson GA-75. Here's the schematic. Like I said I've got up to three tubes free so if I need one for recovery or whatever I've got it. Thanks for the help.

http://www.schematicheaven.com/gibsonamps/ga75_old.pdf

Jason

P.S. I guess I've got a thing for old Gibson amps.

If you stick a pickle in there, it should light up. My friend did that once with a car battery. :lol:

This begs the question "What kind of pickle has the best tone?". I think we all want the answer to this one. :lol:
Jason

Thanks for the suggestions. I thought about adding tremolo but I have an Ampeg Gemini that has it and I never use it. So here's what I think I've decided, I just need help figuring out how to actually do it, I want an input to be voiced like a 50's Gibson GA-75. Here's the schematic. Like I said I've got up to three tubes free so if I need one for recovery or whatever I've got it. Thanks for the help.

http://www.schematicheaven.com/gibsonamps/ga75_old.pdf

Jason

P.S. I guess I've got a thing for old Gibson amps.

Should be easy enough. What sort of advice were you after?

Basically giving you a Gibson tone stack along side your Fender tone stack, and a whole heap of inputs #:o) You have a PA once again #:o)

The three octals are used in the GA75 for two differently voiced channels, looks like three but is really two.

One with one input, while the second channel has four which could be jumpered or actually hard wired as a parallel (jumpered) which would be a nice tonal option.

Both these channels past through their own vol pot and although voiced differently share the same tone stack. Seems a simple Treble and Bass configuration.

Then your hooked in to the Grid of the Phase Invertor, which will lead to the Pro-5C5 power section.

Nice project, good luck with it all.

I have three inputs total on the PA and right now all three are identical and I want to turn one into my GA-75 input. On the GA-75 the bottom four inputs are the instrument inputs and I want to build just one of those into the 5C5. I'm having trouble figuring out what goes where to build it into my PA. The 220K plate resistor will go to B+ coming from my last filter cap of the 5C5 right? But I don't understand how to deal with the tone stacks connections to the resistor on the cathode of the PI and to the second to last filter cap of the GA-75. It looks like it eventually goes to ground so do I just ground that in the PA? Does that make any sense?
Jason

Ok here goes ...

Go through the GA75 and mark or colour the earth or ground wires (lines) in the schematic as that'll make it all clearer.

5C5 B+ from the last filter cap goes to 220K plate resistor on the input valves instr-channel of GA75.

From the grid input to PI on the GA75 (470K, 120K, 0.001uF junction of tone stack) this simple goes to the grid on the 5C5 PI (junction of the two 1M Vol pots).

You may get some cross leak from the Bass control of the GA75 channel if this 1M Bass pot is set too low effecting the vol of the 5C5 channels, but again depends how high they are set ... you'll have to suck it and see ... worst comes to worst make the channels switchable.

Don't alter the PI cathode configuration from what you have in the 5C5.

- The PI Cathode on the 5C5 is grounded through a 2.4K in parallel with a 25uF25V cap.
- The PI Cathode on the GA75 is grounded through a 2.2K, no cap.

Worth a go for sure. I hope that helps.

AND ...

Remember if you are just using one Octal for a single GA75 input channel and want the Gibson bias then to use a 680K resistor on the cathode not the 1.5K shown in the schematic, in parallel with the 20uf electroyltic cap to ground.

This will still leave you with two empty valve sockets, so you could still add a tremolo #:o)

Have fun with it.

CORRECTION:I've stuffed up! I meant to say replace the 1.5K ohm cathode resistor pins 3+6 with a 680 ohm (six hundred and eighty ohm) resistor.

Foreign, you're awesome. That does indeed help. Here's the "before" I'll be sure to put up an "after". Many thanks.
http://www.youtube.com/watch?v=X09z3hrs50s

Jason

Re YouTube - Nice tone.

What make, type, is the CC neck pickup?

I love a nice Tele neck tone, makes great jazz gtr.

PS I'll keep an eye on the thread.

Hey Foreign, it's a Vintage Vibe CC Rider (in the clip it's the CC and a Dimarzio Twang King in series). So any way, I got it all wired up and no sound. I forgot to connect the new stuff to the grid of the PI (which turns out to be rather important :wink: ). The Gibson side is really really quiet though. I don't know if this would effect it but I left the jumpers across pins 3 and 6 and the jumpers across pins 2 and 5. I then ran a jumper to pin 1 from 4 (this is a 6SL7GT). In essence I guess I wired up both sides of the tube so it's like having two instruments plugged in at once. I was just being lazy and made one connection instead of unsoldering two. Do you think that's my volume problem?
Jason

Howdy

I like the feel of the first valve in parallel, Rivera wired the DR2 this way, my favourite BF amp if you can call it that. So no problem with the parallel wiring.

I see that I've stuffed up above, I meant to say replace the 1.5K ohm cathode resistor pins 3+6 with a 680 ohm (six hundred and eighty ohm) resistor.

I slipped a "K" in there by mistake, probably typing late at night. So if you've taken me at my word then there's your problem.

In fact you could even try taking the cathodes pins 3+6 straight to earth, jumper the cathode resistor as in the 5C5. But I'd try a 680 ohm first if that's the issue, as that should be a nice bias.

I hope that's it.

The 680 ohm resistor did the trick. It is loud and proud now. I'll probably try removing the 5C5 just to hear what the GA-75 half sounds like by itself. The controls work for both and that kind of interaction is not what I'm after. Thanks again Foreign.
Jason

Howdy

I'd mentioned before the interaction because of the simple parallel configuration of two tone stacks.

I'd suggested making it switchable and have thought just now that you could use a "6.5mm Stereo ENCLOSED SWITCHED DPDT Socket" for the single GA-75 input such that the DPDT switching in the GA-75 and switches out the 5C5 when a jack-plug is inserted.

http://www1.jaycar.co.nz/products_uploaded/productLarge_2264.jpg

You be looking at the fitting in the DPDT between the input to the plate of the PI.

Does that make sense?

So when you plug in to the 5C5 you get a Fender, the GA tone stack not connected and when you plug in to the GA75 socket it selects that side only automatically.

Seems a nice trick to me.

That's a very elegant way to solve the problem. Yeah, I understand where the switch goes and I'll look around for one those jacks. Thanks man.
Jason

This begs the question "What kind of pickle has the best tone?". I think we all want the answer to this one. :lol:
Jason

http://i263.photobucket.com/albums/ii143/drummerdarko/pickle-delivery.jpg