Filter Knobs on Alembics...

Discussion in 'Basses [BG]' started by relman, Oct 17, 2002.

  1. anyone care to explain what they do?
  2. geshel


    Oct 2, 2001
    Probably a "Pickups" question. . .

    Most preamps have tone controls that increase/decrease frequencies above or below a certain point. For instance, the bass knob boosts or cuts everything below say 100Hz. This varies between preamps, and not all are this simple.

    The Alembic system, instead is a low-pass filter. It filters out the frequencies above a certain point. Instead of changing how much they are attenuated, the Alembic controls let you move the frequency where the filter starts. So, in "wide open" mode it doesn't really filter anything since the cutoff is so high. As you turn the knob it moves the cutoff down, until at the lower extreme all you're getting is very low frequencies.

    They also let you select the shape of the "knee" (also known as Q) where the cutoff begins - so that, say, if the filter is at 1kHz, the response might go up to a "peak" around there before trailing off. Or, with the "Q" control down, it'll be flat up to the cutoff.

    This is very similar to the way Wal electronics work, though Wal only have a 2-way Q switch, whereas Alembics are either 3-way (up to Series I) or continuous (Series II).