Dual Filter Voicing Unit
has two powerful bandpass filters combined with a
preamplifier. These three sources are merged together with a mixer.
If a TL074 or 4136 quadruple OP-amps is used I've experienced that you get a
low-noise circuit not only for guitar, but also for (electret) microphone,
while the preamp boosts the signal several times.
Filter 1 frequency range: +-3dB, 250-2500Hz,
+-1.5dB, 250-1500Hz
Filter 2 frequency range: +-1dB, 1200Hz-12kHz
If you need higher input impedance:
change the resistor signed (*) to 470k or 1M, and the capacitor (*) to 47n.
For the cleanest possible sound, use +-15 to +-18V.
Robin Tomtlund
My e-mail address:
robin2@hem1.passagen.se