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"VARIABLE Hi-CUT and LO-CUT RACKMOUNT FILTER. It is hard to find much info out there about these, but I did see that recording artist John Vanderslice mentioned incorporating a similar, less feature packed Allison Labs filter into his recording setup. This is a passive unit, requiring no power cord, and all connections and controls are positioned around front. This unit IS VERY HEAVY, and VERY STURDY- extremely well made."
does fact that is is completely passive make it very clean and distortionless?
ReplyDeleteIt almost certainly has inductors and/or transformers in it, which can most certainly be saturated, so it could be distorted, but it depends on how much you drive it.
ReplyDeleteI think something like this would be more about having a unique sound than the cleanest possible sound.
I have one (with all the knobs in tact). It weighs a huge bunch.
ReplyDeleteIt sounds very nice I think, you can hook it up to be high/low/band pass.
One neat thing you can do is to not connect the ground, or connect the ground to some opposing signal, which creates many interesting distortions.
I've also had some fun placing zener diodes and circuits between the taps for extra fun.
Sexxy
ReplyDeletewow, it's been years since the original post. do you still have this?
ReplyDeleteHI i know im quid late but exualy looking for one of these Filters any buddy??
ReplyDeleteok let me know iff you have one my mail is info@electricmonkey.nl thanks kasper
This is an inductor capacitor (LC) "filter set" like you might find in a scientific laboratory. If is correctly damped, it is in fact "very clean" and low noise although if driven hard enough, the inductors will distort (low frequencies first). If it is not damped, it will sound nasal because of peaking in the response. To dampen, it must be driven from a source that is 600 ohms and the output must be loaded with 600 ohms. Modern gear source impedance is 100 ohms or less and destination impedance is usually 10K (some older gear like early 1176 compressors can be 600 ohms). So to dampen you need to add a 470 ohm resistor in series with the input and put a 680 ohm resistor across the output (but not between the LC and HC - just jumper those across). Then it it will sound "correct" (note: using transformers will not help because they just reflect the load of the other side). Filters like this were used in many recordings to limit bandwidth in track for any number of reasons (especially things like a reverb returns). What makes this Allison Labs filter unique is that it's 30dB/oct which is very steep.
ReplyDeleteI have one for sale.
ReplyDeleteSold?
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