Hi Jose

> If I
> put for example a system with four oscillators two VCA linear and two VCA
> exponential will be ok

I depends on what you intend to do. If you want think of those four
VCO/VCAs combinations as four voices, then there will be two different
sounding groups of voices.

Basically: linear VCAs are intended for usage with ADSR envelopes (which
have exponential characteristics). Log VCAs are intended to be used with
linear controlvoltages, as LFOs, crossmodulation or velocity control
from the midi interface.

Florian