Unused Triode

[Structo]

Hi Trainwreck fans,

I was wondering the other day about the Rocket amp, it has that unused triode sitting there.
Anybody done anything clever with it?

Also, does it do any good to ground the grid or the whole unused triode to keep it quiet?
Or does it not affect things even though it is heated from the filament?

Thanks, Tom

[soma_hero]

i made a rocket with switchable parallel/single V1. Makes a little more versatility with humbucker/single coil.

[Structo]

Not sure what you mean about V1?

V2 is the tube with the unused triode.
Are you saying that you use all triodes then switch the first triode in and out?
For higher gain?

[ChrisM]

He's saying he used the extra triode and put it in parallel with V1A and made it switchable. This would add about 30% more gain to that stage.

I think that's what he's saying.

[Structo]

I don't think that is something I want to do.

I was wondering if anybody grounded the second triode to kill any noise and if so which pins to ground?
Just cathode and or grid?

[paulster]

Just leave it disconnected and it won't be playing any part in the amp.

There is a slight disadvantage to paralleled triodes which is a reduction in second order harmonics. Unfortunately the site that used to host the diagrams showing the effects is down these days, but that was the downside to the otherwise increased gain and lower noise.

[jaysg]

If you're into major surgery, you could add a Vox Normal channel. One jack, 1M pot, some resistors and caps...

[dave g]

Just leave it disconnected and it won't be playing any part in the amp.

There is a slight disadvantage to paralleled triodes which is a reduction in second order harmonics. Unfortunately the site that used to host the diagrams showing the effects is down these days, but that was the downside to the otherwise increased gain and lower noise.

This effect was only evident for large input signals, on the order of several volts if I remember correctly. Regardless of the topology used, because the signal coming from your guitar is ~100 to 200 mV, the harmonic distortion of the input stage of any guitar amp is practically nil.

[Cliff Schecht]

Hmm.. I doubt there wouldn't be any more than the usual amount of distortion associated with using a high-mu triode in that first stage, especially since its job really isn't to do any clipping. I'd imagine the harmonic distortion in the first stage to be low with standard pickups, it's biased well into the linear region. Being that it's only swinging 10-20V P-P with a standard guitar pickup, there isn't really enough signal there to push it into distortion. Now throw a set of EMG's at the amp and you're talking over 200V of potential swing (although it may clip before then), more than enough to push the entire amp into a heavy saturation. I just put a set of EMG's in my girlfriends Squier and actually thought they sounded great with the amp though, so this isn't necessarily a bad thing, but active pickups are the "exception" to the typical guitar pickup that really only puts out a few hundred mV like Dave says.

Edit: I also found the EMG's to be exceptionally low noise, as they usually are by design. They have a different sound than your standard pickup but can be a great way to cut down on noise in your amp. Then again, I played a bar with my stock Tele and cranked Express last noise and noise surely wasn't a problem! YMMV .