Make Noise RxMx - Manual (Page 9)

GETTING STARTED
The RxMx contains 6 Low Pass Gate circuits. The LPG is a specialized type of synthesizer circuit developed by
Don Buchla, where the amplitude of the signal is not only frequency dependent, but also under Voltage Control.
It is in essence, a Voltage-Controlled Filter and Amplifier, a VCFA. Traditionally, the Lowpass Gate has had a
very mild filter slope of 6db/ Octave. This mild filtering, combined with the use of an optoisolator-based gain cell
that turns off, allows for simultaneous control of both the amplitude and frequency domains.
As the LEVEL parameter becomes more positive, the amplitude of the processed signal increases with the lower
frequencies being more quickly amplified than high frequencies. As the LEVEL parameter become less positive,
the amplitude decreases with the high frequencies being attenuated much sooner than the lower frequencies.
The net effect is fast, transient modulation of the signal LEVEL the low frequencies will be more pronounced--
lurking in the spectrum, as the high frequencies are eagerly diminished.
Manual manipulation of the controls will not well display this phenomenon. A fast/short envelope CV of around
+8V will provide beautiful example of the RxMx’s ability to produce acoustic like attack & decay transients. The
processed signal will seem to ring, not unlike a struck drum, piano string or xylophone bar. The Strike INput
allows for ease in programming percussively-animated sounds, taking advantage of these characteristics of the
Low Pass Gate circuit. A Gate patched to the Strike Input will intiate a fast/short control signal to briefly
open the LPG to 100% for a moment before closing with a very organic decay.
The RxMx is called a macro-lowpass-gate because it has 6 LPG circuits that share a single set of LPG controls.
These shared controls are the LEVEL and Strike parameters discussed in the paragraph above. The LEVEL
and Strike controls may be applied to any of the 6 LPG circuits in CH. 1 through 6. The CHANNEL and
RADIATE parameters are used to determine to which of the 6 channels the LEVEL and Strike parameters are
applied.
With CHANNEL and RADIATE Full CCW and no modulation (nothing patch to CH SEL CV IN 1 or 2, or
RADIATE CV IN), “CH. Zero” or no channel is selected and no radiation is applied to turn on adjacent
channels. Therefore, none of the 6 Channel Drive Indicators will be lit-- even if LEVEL and/ or Strike
parameters are modulated, you will get no signal(s) at any of the 3 outputs unless you have something patched
to Aux A and/ or Aux C (this is because the Aux Ins are not processed by the CHANNEL, RADIATE, LEVEL
and Strike parameters).
Setting CHANNEL to around 8 o’ clock will select CH. 1 and if LEVEL and/ or Strike is modulated (or LEVEL
Panel Control is manually set to greater then 8 o’ Clock), you will see the CH. 1 Drive Indicator LED fade on as
the LEVEL parameter is increased. A signal present at CH. 1 IN will appear at Out A or Out B (depending
upon which Out is patched), at a level based on the CH. 1 Attenuator and the LEVEL and Strike parameters.
If the CHANNEL parameter is increased CH. 2 through 6 will be selected and the associated Drive Indicator
LED will light and signal patched to selected channel will appear at the associated Out based on the setting
of the associated Channel Attenuator and LEVEL and Strike parameters. Notice that with RADIATE Full CCW
and no modulation applied to radiate CV in, only one channel will be active at a time.
CH ANNEL + RaDIATE
LEVEL STRiKE +