SYNTHESIS TECHNOLOGY
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MOTM-110 ASSEMBLY
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such that we can ‘null out’ the carrier (X IN) only for one amplitude setting. For all other
input amplitudes, some of the signal ‘leaks’ to the output.
The ability to reduce the leakage is called carrier suppression. Every effort has been made
to design the MOTM-110 circuit to suppress as much carrier as possible. However,
depending on the relative input signal levels of X and Y, you may hear the input signal at
the output. The unit is not ‘broken’: all ring mod circuits have this behavior.
In fact, that’s what the UNBALance pot does: it purposely adds a DC offset to the Y
channel to allow the modulating signal (Y IN) to ‘leak’ to the output.
So, experiment! The ring mod can make a vast array of bizarre sounds.
AC versus DC Coupling
The ring mod circuit is a DC voltage multiplier. If the X or Y input has a DC offset (like a
pulse wave), this will alter the sound. The AC/DC coupling switches insert/remove a large
capacitor in series with the signal. This will alter the tone, but the effect is highly
dependent on the input signals.
The ring mod can be used as a basic VCA. Set the Y IN to DC, and the X IN to AC. Apply
the audio signal into X IN, and the control voltage to Y IN.
TROUBLESHOOTING
If your MOTM-110 does not work, please verify ALL of the following before contacting us.
The following reference directions assume that you are looking at the pc board with the
panel to the right and the power connector to the left.
All of the IC are pointing the same way: all notches are downwards.
C1, C5 and C6 stripes are both pointing upwards.
D1 and D2’s banded ends are both pointing to the left.
All the trim pots should be set almost in the center (slot is nearly vertical).
The braided wire on the coax goes to the beveled side of the jacks.
There is nothing on all 6 jacks on the top (switched) lug.
The board has all the right parts in all the right places.
No solder shorts or missing joints.
