So I picked up one of Trent Jacob's Little Jake pickups. After some trouble with the installation (a DIY job, and let me tell you, I didn't try it on one of my good bocals), I'm now playing with it. You're supposed to use it with a preamp, either a custom or something like the LR Baggs Gigpro. I'm putting it straight into the input of my audio interface, an M-Audio FastTrack Pro. It needs a fair bit of gain to get an acceptable signal level, but the FastTrack preamp is kinda noisy at very high gain, so I'm thinking about getting a proper preamp. Here's a short sample, first recorded with the Little Jake, next recorded in parallel with a decent quality (but rather old) dynamic mic, an AT802.
Little Jake Test by TFox17
Little Jake Test Control by TFox17
A couple of things to point out: the Little Jake does a very good job of rejecting outside noise. It won't feedback, if you're using it to drive a loud amplifier in the same room. When I've played against a delay, or self-recordings with a mic, it was always a struggle to get the signal through amp loud enough that I could hear it while playing while also avoiding feedback. Even without feedback, there's still effects, such as some uncontrolled reverb from the signal leakage. So that's the primary purpose of using a pickup, is to avoid stuff like that. You get side benefits too. Key clacks are gone, for instance, and ambient noise in the room is gone too. The only thing you're getting is the sound actually inside the bassoon. Of course, external sounds can propagate to the inside of the bassoon too, but the bassoon sound is so much louder there, that they are swamped out. It's a signal to noise thing, kind of the ultimate version of close miking. It's not perfect: I was recording while playing a metronome through headphones, adjusted rather too loud (don't ask), and I could end up making out a bit of the metronome sound in the Little Jake recording.
The tone color, however, seems quite different from the far field mike recording. Not a big deal, I think, since mostly people use this as a starting point for effects, as opposed to looking for a true bassoon sound. Still, interesting.
Updated: For reference, as a comparison of microphone differences, here's my other microphone, an AT2020 condenser mic, against the 802. They've been normalized, to try and get their volumes equal, but are otherwise unprocessed. Mic location is bell height, about 5 ft in front of the bassoon, a few feet in front of the wall, with the mics both facing forward, and within a few inches of each other. When I did this yesterday I was surprised at how different they sounded, but today I'm surprised at how similar they are. Certainly there's a lot of things the AT2020 hears that seem to be gone in the 802, but I seem to need the nice headphones to hear them (the laptop speakers aren't enough), and they all seem to be things I'd rather not hear anyway (breathy noises, that kind of thing).
AT2020 Test by TFox17
AT802-Test by TFox17