Tube effects loop in a Rocket?

[Curbdog]

Has anyone done this? It seems to me the the cathode follower could be used for the effects send buffer, and the other half of the 2nd triode could provide the return gain into the phase inverter.

I know we have been building Rockets out there, I have built 2 myself. So, I thought I would experiment with an effects loop in one of them. I am very interested to know if anyone has done this, and with what results ! Thanks !

[RJ Guitars]

Curbdog, I don't know if anybody has done it but IMHO I think it would work well. These amps seem to take pedals very well and I'd expect good results from a loop. They are not the high gain outfits like an Express and I can't see any reason not to try it.

rj

[dr. who]

hmm...anyone tried 3 tube reverb in a rocket?

[Bear]

For the 3 tube reverb, you can see if there's an available schematic of the Bruno Underground 30, which is his take on a Top-Boost Vox with, at least on some versions, a 2 knob take on the 3 knob Fender reverb. That might give good ideas on how and where to integrate it.

(If it's in front of the preamp, I'd probably just build it outboard and learn to work out potential ground-loop issues. More flexibility to use it with any amp or not. Portability is probably a wash for most people.)

Bear

[funkmeblue]

why not try the metro amps fx loop. It's not tube but there putting them in jt45's with great results and it's by passable. Just an idea

[angelodp]

Hi, just wondering if any have pursued the loop idea in a rocket yet.

[jjman]

I would expect the signal to be pretty hot there. It's after 2 gain stages that are fully bypassed on their cathodes. And there's no tone stack scooping the mids before that point. A line-level rack unit may be happy but a pedal could be driven too hard. You could try a parallel loop by tapping a weaker signal by using 2 series resistors replacing the 56k cathode. Leave the dry path tap on the cathode and put the loop output on the junction of the 2 resistors. DC blocking caps and calibrating the 2 resistors wouldn't be too hard. The hard part is dealing with the phase reversal. If you have 100% delays or reverb in the loop there’s no need to consider the phase. Otherwise it will matter when switched on. The PI can be modded to be like the those tremolo equipped Marshalls then the effect return can go to the "other" side of the PI. I didn't want to do that on my pseudo express so I used a small transformer to re-flip the phase. I tapped off the 3rd stage after dropping the signal down in a similar manner with 2 resistors in series to ground.

[solderstain]

... schematic of the Bruno Underground 30, which is his take on a Top-Boost Vox with, at least on some versions, a 2 knob take on the 3 knob Fender reverb. That might give good ideas on how and where to integrate it.

Not too long ago, I had a customer's Bruno Underground 30 on my bench. The design uses an EL84 as the reverb driver and a 12AX7 as the reverb recovery.

It works, of course, but it's more complicated than it needs to be for a front-end reverb implementation, at least in my experience. If you're going to put it at the front of the signal, why put it in the amp at all? Use a stand-alone unit of some kind. The simplicity of these TW-style amps is part of their beauty, and adding all that content (it's a LOT of parts) to these amps for what amounts to a front-end reverb, it just seems like a lot of work for the limited gain. Just my opinion.

The other thing I'd want to keep an eye on with the reverb implementation from the Underground 30 is the available heater current from the PT. You're adding an extra EL84 and an extra 12AX7 onto the heater string. I'm sure there are people here who know whether the commonly-used PTs have the spare heater current. I don't know for sure if there's enough current available, but it's worth checking into.