Doepfer

Hi Tomek

> does anybody have an idea what a ''high frequency filter'' is (not hpf)?
I assume, that you mean a low pass filter, with a fixed cutoff frequency 
above the audio spectrum. If it is used for frequencies in ranges above 
100kHz usuallly no active filtering (with resistors, capacitors, OpAmps) 
is used but passive filtering with coil/capacitor circuits.

Florian