Manual

G ETTInG STaRtED
The FXDf is a small utility module, designed with the assumption the user already has some of the modules
that will benefit from and/ or support the FXDf.
Both inputs on the FXDf are designed to accept typical 10Vpp modular signal levels; however, it could be
highly useful to have a VCA, Attenuator, or some other form of Level Control in series with the inputs on the
FXDf. Modules such as the Optomix, modDemix or MATHS are handy in providing level control prior to the
inputs of the FXDf. This will allow for greater control over the drive of the filter circuits. Signals that are
larger and more powerful will have the potential to overdrive the filter circuits, which may or may not be
desired.
The 6db INput is milder and less resonant. The resulting sounds at the band outputs will retain more of the
original character of the input signal. The 12db INput is aggressive and more resonant. The resulting
sounds at the band OUTputs will have a character that is more distinct from the original sound at the INput.
Keep in mind that both INputs could be used simultaneously to combine two sounds. The result is not
exactly like typical mixing, as the two signals are combined using the filter circuits. Using both INputs also
makes it easier to overdrive the filter circuits. In some cases, this makes for high harmonic signals at the
band OUTputs, which is especially useful when percussively animating the spectrum.
The outputs of the FXDf have many uses, but almost all will be associated with other modules such as
mixers, VCAs, Low Pass Gates, reverberation, echo, pitch-shifting, etc. A traditional use would be to patch
some combination of the 6 filter band outputs to a mixer, and manually set the level of each band, thus
recombining the bands at varied levels to sculpt the timbre of the sound. When patched this way, the FXDf
combined with mixer will operate in a way similar to the original Moog Fixed Filter bank.
One combination that is certain to please is the FXDf and RxMx. In fact, there are headers on these
modules that allows the user to make normalized connection (a connection that happens between the
circuit boards) so that the 6 filter band outputs from the FXDf are connected to the 6 Channel INputs of the
RxMx-- no patch cables required (See Page 4, Expansion). This combination allows for Voltage-Controlled,
percussive animation of the spectrum.
It is also possible to remove frequency bands from a sound by mixing the original, un-filtered signal with
filter bands generated from the 6db Input, as those bands are inverted and will thus subtract from the
original signal when mixed with it. This will also work with bands generated from the 12db Input as long as
your mixer is capable of inverting the incoming signal, as the MATHS. The FXDf could also be used as a
static filter for a sound where one of the bands is selected based on the desired frequency range for the
sound. This allows for fitting a sound into a mix by limiting the frequency range to a single band. For this,
the 6db INput might be the better choice.
In some cases, you might want to do parallel processing of a patch or sound. The FXDf allows for this by
splitting the sounds into 6 bands: each of which could be processed in a number of ways. For instance,
Amplitude or Ring Modulation using the modDemix, pitch-shifting using the Echophon, Reverberation using
the Erbe-Verb, Low Pass or High Pass filtering using the MMG, Low Pass Gaing using the Optomix, etc.
processing each band independently and then recombining using a mixer, it is possible to create highly
complex sounds. In some cases, you might desire to reverberate only Mid-Range frequencies, while you
might want to Amplitude Modulate and distort Bass-Range frequencies. This usage treats the FXDf like an
audio crossover. Other possible uses would be band-limiting feedback paths in patches, or selecting a
single band for signal source in a MATHS Envelope Follower patch. As a utility, splitting the spectrum into
individual bands has many creative uses that are sure to inspire when combined with a few other modules.