My Q-filter added quite a bit of noise to the L-280 circuit I used it in. It was probably a shielding issue, but I don't think the coil is humbucking in any case. I could be wrong, but I'd be surprised.

Pete - thanks for your patient reply. I very much appreciate the rules of thumb, i.e. low-pass cutoff freq ~ 1/LC and amplitude ~ R. I think I get it now.

I'm sure Helmuth is a swell guy. Unfortunately, I don't know German, so it's not as if I can be critical about the language barrier. ;) I appended a Google translation of my message to the original text.... Hopefully that wasn't insulting.

Since I already use low-inductance pickups, the Q-filter isn't even remotely useful to me. I may have to break down and spend a little more on a Tonestyler. The thing is, I'd rather have 6 distinct variations rather than 14 more subtle ones.

The soundclip at Big D's website is intriguing. His switch does pop during changes, though. He claims this is due to the smaller choke size and the type of capacitor he has chosen. The switch is inexpensive enough that I may try it anyway.

-Ben