Trem-wreck?

[jjman]

I’m planning my 1st non-Champ build and noticed that the Express might be very close to what was in my mind. (Today is the 1st time I looked at any Wreck schemes so please pardon my ignorance.) I plan to use 6V6s with 6L6/EL34 as a possible option. Not sure about cathode vs. fixed bias yet, maybe both with a switch. Long tail PI.

Issue is I definitely want OP tube bias modulated Trem. Would the “extra” single triode from the preamp be adequate to drive the trem? Maybe for 6v6s but not 6L6s? Should I plan on needing an extra tube since I want the LTPI?

My Harmony H415 uses a 6AU6 for the trem going to the grids of the EL84s, and it sounds great. Anyone know how the strength of a 6AU6 would compare in this application to a single triode of a 12ax7(e.g. 6g3 Deluxe) and a cascaded 12ax7(e.g. 6G9A/B Tremolux) ?

Are there Wrecks with Trem?

[d95err]

I remember seeing a trem-wreck design here. Check the Trainwreck Files section, it migh be there somewhere.

EDIT: IIRC, it was a preap bias modulating tremolo, something similar to the VibroChamp.

[Allynmey]

PM Philmanatee

[statorvane]

Issue is I definitely want OP tube bias modulated Trem. Would the “extra” single triode from the preamp be adequate to drive the trem? Maybe for 6v6s but not 6L6s? Should I plan on needing an extra tube since I want the LTPI?

Here's a neat little trem that modulates the power tube grids. Uses 1 triode of a 12AX7. I modified this circuit for a SE amp. Works great - plenty of voltage swing.

http://www.schematicheaven.com/bargainb ... rb_12b.pdf

I modified one of the caps in the oscillator to increase the speed range. This should work fine.

[jjman]

Hey statorvane

Thanx for the link. Although schematic heaven is down again, I found it from a google on the Kalamazoo. It’s shown attached to a cathode biased setup and I’m still open minded on whether to go cathode or fixed (or switched) bias on mine. I’m very new to TW’s and still need to learn the do’s and don’ts.

The Kalamazoo trem is driving el84’s. What OP tube did you use it for on your SE amp?

I also wonder about the cathode vs. fixed bias in relation to the trem’s intensity. I know some creative switching would be needed to keep the trem available in both modes but I don’t know if the same intensity range would work well for both. I’m guessing it could work.

[statorvane]

Sorry 'bout that, I forgot the Kalamazoo is Cathode Biased.

Here's a link to tremolo oscillators that modulate the power tube's bias. There's a 6V6 PP circuit that uses 1/2 of a 12AX7 (one triode) to modulate the grid.

http://www.lynx.bc.ca/~jc/tremoloCircuits.html

FYI, my SE amp can run 6L6GC, EL-34 and 5881s. I haven't tried other tubes, mostly I use the EL-34.

Hope this helps.