Could this EF86 unit work with a Rocket?

[sbolt]

To the moderator, in advance, I hope I am not violating any forum rules by posting this. Please remove the post if I am.

After lurking over at the Plexi palace forum, I discovered a device made by a gentleman in England that "adds" an EF86 preamp unit into an existing Vox AC30. I think his name is Roger Allock. I emailed him and he stated the unit would cost 150GBP plus shipping.

Here is a discussion on how to implement it.

http://vintageamps.com/plexiboard/viewt ... =2&t=83447

Is it possible this could work with a Rocket?

[FYL]

The Rocket is basically an AC-30 TB clone, adding an EF86 preamp is quite easy Vox-style.

Now is it worth the bother?

[Clyde]

you don't need the kit, just add the tube and run it straight into the PI, either through the bottom (unused) input, or use summing resistors to a common input and use a stacked 500K volume pot. Gain should be very close, tweak as necessary. Definitely worth it.

[rooster]

Wow, quite a nice read. Very polite folks over there! The unit looks great actually, and I see where there is value in the package kind of thing to the right amp and person. But, still the direct build of the circuit into an existing AC30 is do-able if you have the patience and the mindset to geterdone, I suppose.

So I say figure out who you are and make a decision. The beauty of the pre-built self contained unit is the fact that you can keep it and install it in the next amp if you like. At any rate, I think the unit has a value that might be worth the asking price - again - given the right guy and the right amp.

As to the sonic value? Hell, DR.Z, Mark Sampson, and AC30/04 owners think this is a worthwhile goal. Why not? Just remember that the EF86 tube can be microphonic and you may have to go through a few to find the one you like.

[sbolt]

Late reply, but thanks to all for the input

[Luthierwnc]

I'm in late too but pull the Matchless DC30 schematic from SchematicHeaven.com. The phasing works out so you can use the '59 Bassman pre on the top side and the pentode into the bottom of the inverter. You can't use a NFBL off the speaker unless you ground out the pentode side with a switch. The high-cut seems to do a good job keeping it stable without a presence circuit, though.

I've had good luck using s 5879 in that type of circuit. Another change I liked was using a dual-ganged master rather than the phase canceller type. It is different and I like it better -- although it uses an extra inch of real estate on the preamp board.

One last note, the switch that rotates the coupling caps shows a pretty wide spread. If I had mine to do over again, I'd probably just use an on-on mini toggle with the #2 and #4 caps. The settings on the far ends of the spectrum aren't that useable. The high-cut (or brilliant wired the other way) is a pretty effective tone control. I used .0022 with a 250ka pot. Skip