EURORACK MODULES
PRM2
The PRM2 is a passive Dual Ring Modulator. At it's core it is a standard ring modulator utilizing audio transformers with balanced Primary and Secondary impedance and a 4 diode "ring". 2 switches per ring modulator (Amputate) are added in
line of 2 of the 4 diodes. These switches remove the diode from the circuit, creating a +/-/half wave rectifier between the carrier and input. This configuration can lend to complex rhythmic and unbalanced modulations, depending on the
frequencies of both the carrier and input.
The PCB was designed to hold either the audio transformer that ships with all kits, or a Hammond 107N. Aside from being a
higher end transformer, the primary and secondary are drastically different (10k Primary, 600 Secondary Impedance). For
standard ring modulation, the input can be attenuated with the trimmer to better match the secondary, or, for the reason
I originally started designing this circuit in the first place, was how awesome it sounded with the input over-saturated by the
transformer. Unfortunately this transformer does not work well with the +/- rectification as it results in either the carrier
or the input dramatically overpowers the other signal and it's not useful at all. I opted to keep this option in the design, so
if someone wanted to take advantage of it, they could build one of the ring modulators with the 107N transformer and skip
the Amputate switches. Also, they are extremely expensive ($18+ a piece!).
6hp
+12V 0mA
-12V 0mA
line of 2 of the 4 diodes. These switches remove the diode from the circuit, creating a +/-/half wave rectifier between the carrier and input. This configuration can lend to complex rhythmic and unbalanced modulations, depending on the
frequencies of both the carrier and input.
The PCB was designed to hold either the audio transformer that ships with all kits, or a Hammond 107N. Aside from being a
higher end transformer, the primary and secondary are drastically different (10k Primary, 600 Secondary Impedance). For
standard ring modulation, the input can be attenuated with the trimmer to better match the secondary, or, for the reason
I originally started designing this circuit in the first place, was how awesome it sounded with the input over-saturated by the
transformer. Unfortunately this transformer does not work well with the +/- rectification as it results in either the carrier
or the input dramatically overpowers the other signal and it's not useful at all. I opted to keep this option in the design, so
if someone wanted to take advantage of it, they could build one of the ring modulators with the 107N transformer and skip
the Amputate switches. Also, they are extremely expensive ($18+ a piece!).
6hp
+12V 0mA
-12V 0mA
VG2
VG2 is a Dual Passive Vactrol Gate. No power needed! Each Vactrol Gate has 1 CV Input (gate, envelope, LFO, etc.), 1 Audio Input and 1 Audio Output. The CV Input hits the Vactrol LED, allowing audio to pass through. In addition, there is a simple Low Pass Filter applied to the Audio Output with an Amount (Cutoff) knob. As this is a passive circuit, it will not give you full cutoff control, but it does allow the taming of harsh waveshapes. The LPF is simply the same concept as a guitar's "tone" control. Also, there is an LED at the CV Input for quick visual reference and LED light action!
One thing to keep in mind with a passive circuit using a vactrol is there may be varying differences between each vactrol. One may be slightly "louder" than the other, or have a longer release time or shorter release. These are variations that are inherent with vactrols and can usually be adjusted with a powered circuit, but not with a passive circuit. But, this adds a bit of variation to each vactrol gate making each output unique. It may be found that one output is better for percussive sounds and one is better for melodic sequences. There may also be no noticeable variations at all, but this is part of the vactrol charm and why we love them so much! Each Vactrol that is supplied with the kits are hand-selected by Laurentide SynthWorks. The descrepincies are bleed when silent & top output level. We try to pick vactrol's that have little or no bleed when no CV is applied and that they all have a similar output level, so you won't have to worry about one being waaay quiter than the other.
As this is a passive circuit, it is advisable to use a Buffered Multiple before the CV Input to maintain voltage/amplitude, especially if you are using the top CV to drive both gates..
4hp
+12V 0mA
-12V 0mA
Build Documentation
One thing to keep in mind with a passive circuit using a vactrol is there may be varying differences between each vactrol. One may be slightly "louder" than the other, or have a longer release time or shorter release. These are variations that are inherent with vactrols and can usually be adjusted with a powered circuit, but not with a passive circuit. But, this adds a bit of variation to each vactrol gate making each output unique. It may be found that one output is better for percussive sounds and one is better for melodic sequences. There may also be no noticeable variations at all, but this is part of the vactrol charm and why we love them so much! Each Vactrol that is supplied with the kits are hand-selected by Laurentide SynthWorks. The descrepincies are bleed when silent & top output level. We try to pick vactrol's that have little or no bleed when no CV is applied and that they all have a similar output level, so you won't have to worry about one being waaay quiter than the other.
As this is a passive circuit, it is advisable to use a Buffered Multiple before the CV Input to maintain voltage/amplitude, especially if you are using the top CV to drive both gates..
4hp
+12V 0mA
-12V 0mA
Build Documentation
