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I was wondering what it would take to make a separate volume control for each channel.

Looking at the lightning schematic I see that the two inputs go together into pins 2 and 7 on the first 12ax7, then they come out of the tube together at the plates (pins 1, 6) and then go to a volume control.

What if input 1 goes to pin 2, gets amplified, goes to volume control #1 while input 2 goes to pin 7, gets amplified, then goes to volume control #2. After they both reach there they meet up and finish the circuit like the original.

It would be something like the ac30 schematic that this link points to.
https://schematicheavencom.secure.powweb.com/voxamps/ac301960.pdf

The difference being brilliant hi & lo inputs being just channel One input and normal hi & lo inputs just being channel Two, and the two volume controls being Matchless volume controls.

I also don't know if the two 220k resistors (that supply voltage to the plates) would be the right values.

Also, would there be less gain since each input is only using one half of the first preamp tube??

Thanks for your input,

Loy

To do this there will definitely be a loss in gain and therefore the sound. If you wanted to keep the sound the same, it would be best to add another tube.
You could use an V1 stage similar to the 18W which has close to the same voltages but a different, 2 channel configuration.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

I'd actually been thinking of asking if anyone had made a Lightning where one of the parallel input triode stages could be shunted, switchable in peformance - essentially, you'd go from Lightning to Top-boost Vox. I could see that being handy as a lead-boost/rhythm sort of option, or to clean things up so it plays nicely with a fuzz box.

Bear

Interesting idea. Now that might be worth a try. I like options!

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Wouldn't it be possible to wire the first parallel gainstage with 18 watt input jack configuration? Input jack #1 = parallel (lightning); input jack #2 = single triode (Vox top boost)

Jef

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"Remember, there's a big difference between kneeling down and bending over" Frank Zappa

V1 is all used up with the parallel triodes (lightning). You'd need another 12ax7 to do add the VOX top boost, but still another good idea

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Couldn't you just switch out one triode of V1? Using the input jacks, just like on the normal channel of a Marshall 18 watter?

Jef

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"Remember, there's a big difference between kneeling down and bending over" Frank Zappa

Yes, you could do that, but then you've got a single channel amp if that's what you want. Do you think it would be good to have this configuration foot-switchable. Maybe that's the way to go.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

There are lots of amps that have more gain on one input than the other, a most notable example being the JCM-800 which has a whole other cascaded gain stage on the high gain input.

Problem with the 800 is that the setup is less functional for performance for most people because you have to repatch for the rhythm sound and up your volume to match the lead volume. But when we're talking about whether there's a parallel triode stage to just up the gain and grind a little, this difference is a bit more marginal.

The dead simple way to implement switching would be to have an A/B/Y box out on the floor and one input for each parallel triode stage. Easy. But maybe needlessly simple, and passive switching down stream from an active pedal might create pops.

I already have it in mind that I want to do a trem amp anyway, so I'd be throwing in a switching scheme for trem, so it probably isn't much further to add in the preamp shunt. I'll have to get out TUT1 to study that stuff.

(BTW, this is probably a great idea on a trem amp because it is also a way to overcome the perceived volume drop when the trem is active.)

Bear