That'd probably be me, I'd guess- I've been working with the V-drum
TD-10 module (and also
the Alesis DM5) as part of my e-drum setup for a while now.
You definitely *can* trigger the unit directly with an audio signal for individual drum sounds and cymbal sounds (the high hat is a slightly bigger problem). The trigger inputs on the module are optimized for a very high-impedance source, because most of the basic percussion trigger pads are a simple piezoelectric cell attached to a backing plate: whack it, and it produces a voltage spike, which the module senses to trigger on. This spike can be a pretty rediculuous voltage (+-5-7v on a well-whacked snare pad!), so you have little to worry about in terms of "frying" the unit with regular line-level audio signals. A single-ended +4dBu signal is not excessive for this, but if in doubt, start at -20dB and work up: the unit has significant make-up gaing in the trigger amps (with the "threshold" control). Drive the triggers with single ended signals only, using a TS cable: the ring inputs are used for an optional FSR rim/choke input from Roland's rubber pads, and get more than a tad bit confused if fed the - side of a balanced signal.
The hot setup is to expand the signal as much as you can, and EQ the hell out of it to magnify the initial attack transient. This will sound like dogmeat, of course, but since you aren't listening to it, who cares? The more transient attack and rapid initial decay you can get, the greater the accuracy with which you can track multiple attacks- 32nd-note fills and the like.
You can also use an unhealthy dose of EQ to kill spill from other drums or instruments in the track that you're rescuing. If you've ever wanted to use the full 18dB cut or boost range of your gnarliest EQ, this is the time. If you have a _very_ fast gate, you can also throw it into the trigger chain to kill excessive bleed. If it's a somewhat slower gate, you can still use it, but if you're a DAW guy you might need to unslip the resulting track a few milliseconds to retain the initial feel (compensating for the gate's opening delay). Avoid using a gate unless there's just no other way to save the, to avoid feel headaches.
Once you have a really crunchy, transient thing happening with the signal to be replaced, you can patch it directly into one of the trigger inputs. Go into the TD-10's external trigger setup menu and tweak the trigger type, senstitivity, retrigger mask time, and so on to get consistent triggers. I used type P1 for this on my TD-10/TDW-1 expander setup, if I recall correctly, but 12a or 8a should work as well.
If you are doing multiple channels at once, the crosstalk parameter can be used to help suppress bleed as well: it was intended to prevent vibrations coupled by the rack from causing false triggering, but it can work nearly as well for acoustic track-to-track bleed (rack toms, for example). If you have one single overhead track, you can still pull the rack toms out to separate trigger inputs using a combination of properly-tuned EQs and the crosstalk mask in the trigger setup- it's really pretty amusing.
If you have enough channels of EQ, expansion, and gate, you can replace the whole drum kit in one pass- setting up individual trigger chains for each part of the kit. The nice thing is that the TD-8/TD-10 series modules have a very nice graphical trigger setup interface with individual control over each trigger input. With just a little care, you can rescue the dynamics and feel of the original track-probably with much less work than setting up an electromechanical speaker/pad trigger setup. Once you have a satisfactory retrigger setup, save it as one of the unit's trigger banks, so that you can get back to it easily in the future.
The highhat is the biggest problem. There is no good way to fish the pedal action out of an acoustic signal. You can easily get a trigger edge and preserve the bulk of the dynamics, but you just can't get the pedal closed/loose/open
subtleties out of a recorded track. To really salvage that, you need an understanding drummer to help you snag that stuff after the fact.
And IMNSHO, you should consider taking the time to stripe the resulting triggers to a MIDI track- this will preserve your flexibility just in case you feel like using a different sound as the mix goes on. The MIDI outs are hot when salvaging, after all... This is another of the reasons that I'm setting up a DAW- to be able to stripe the MIDI outs as I play live, and then go back and mung the drum patches later if I get inspired to do so.
Hope that helps...
