Synovatron: CV Tools | 4-Channel Attenuverting mixer, Slew limiter [eurorack]

the cv tools module is a 12hp eurorack all-analogue module and is compatible with the doepfer™ a-100 modular synthesizer bus standard.

the cv tools module is a versatile voltage processor intended for control voltage manipulation such as adding, subtracting, attenuating, amplifying and offsetting. it can also be used with audio signals to great effect.

a review by sr (a vicmod member); bought as a kit: "an excellent simple tool. great for cascading polyrhythms. really easy to use and very surprising differences depending on where you tap the signal."

4-channel polarizing cascade mixer section: essentially this section is a 4-channel mixer but with two main differences: the first and most significant difference is that it has a cascade architecture. this has a summing stage at each of outputs out2, out3 and out4 (denoted by the s symbol); out1 is added to out2, out2 is added to out3 and out3 is added to out4.

consequently out1 is just from channel 1, out2 is the sum of channels 1 and 2, out3 is the sum of channels 1, 2 and 3, and out4 is the sum of all four channels. however, when a patch lead is plugged into any, or all, of outputs out1 to out3 it disconnects that output from the next channel�s output summing stage.

the second main difference is that it is a polarizing mixer which allows an input signal�s level to be adjusted or inverted. each channel has a basic gain of 2 and therefore an input signal can amplified by up to a factor of 2 or inverted and amplified by up to a factor of 2 (i.e. -2). this is useful for adding and subtracting signals in varying degrees.

slew limiter:
this could be used to add portamento to a vco control voltage; blending one pitch into the next. this is also called lag or glide on other synthesizers. in the min position there is no noticeable slewing but in the max position it takes just over a second to ramp up or down to the next voltage step.
cv tools specification:
channel 1
input: 3.5mm jack in1
input impedance: 100ko (�1%)
normalled input: vref - jumper selectable to +5v, 0.5v-2.5v or none
bandwidth: dc-15khz (-3db)
gain: level control variable 0 to �2 (�3%)
output: 3.5mm jack out1 - normalled to channel 2 output mixer
output impedance: 1ko (�1%)
output indication: �leds

channel 2
input: 3.5mm jack in2
input impedance: 100ko (�1%)
normalled input: vref - jumper selectable to +5v, 0.5v-2.5v or none
bandwidth: dc-16khz (-3db)
gain: level control variable 0 to �2 (�3%)
output: 3.5mm jack out2 - normalled to channel 3 output mixer
output impedance: 1ko (�1%)
output indication: �leds

channel 3
input: 3.5mm jack in3
input impedance: 100ko (�1%)
normalled input: vref - jumper selectable to +5v, 0.5v-2.5v or none
bandwidth: dc-15khz (-3db)
gain: level control variable 0 to �2 (�3%)
output: 3.5mm jack out3 - normalled to channel 4 output mixer
output impedance: 1ko (�1%)
output indication: �leds

channel 4
input: 3.5mm jack in4
input impedance: 100ko (�1%)
normalled input: vref - jumper selectable to +5v, a-100 bus cv or none
bandwidth: dc-15khz (-3db)
gain: level control variable - jumper selectable to �2 (�3%) or 1 (set by rv7)
output: 3.5mm jack out4 and slew limiter input
output impedance: 1ko (�1%)
output indication: �leds

slew limiter
input: 3.5mm jack in
input impedance: 1mo (�1%)
normalled input: channel 4 output out4
slew range: 0.2ms-1000ms
gain: 1
output: 3.5mm jack out
output impedance: 100o (�1%)

general:
dimensions: 3u x 12hp (128.5mm x 60.6mm).
power consumption: +12v @ 20ma max, -12v @ 20ma max, +5v is not used.
reference voltage (vref): jumper selectable at each mixer input. channels 1-3: 5.00v (set by rv6), 0.5v-2.5v (set by rv8) channel 4: 5.00v (set by rv6), cv from a-100 bus.
a-100 bus utilisation: �12v, 0v, cv used; +5v and gate are not used.
contents: cv tools module, 200mm 16-way ribbon cable, 4 sets of m3 cap-head socket screws, nylon washers and a 2.5mm hex key.