TLN-132 Dual Voltage Controlled Amplifier


Back to Synth DIY Projects

Last updated: February 1, 2007


The TLN-132 is a two channel VCA based on a Solid State Micro Technology For Music SSM 2022 chip. Both channels are identical and feature: separate linear and exponential control voltage inputs with reversing attenuators, a gain control for adding a constant value to the linear control input, and a bias control for adding a constant value to the exponential control input. Both linear and exponential inputs can be used at the same time. DC coupling is used throughout for passing DC signals. One signal input and one signal output are provided.

Total current draw for TLN-132 is 29 mA @+15V and 21 mA @-15V.


This module was sold out from the moment I got the prototype boards made. I only had a few SSM 2022 chips in my stock and was unable to obtain more of them. Consequently, there were very few PCBs made and they sold out almost immediately. I may get more boards made if I can find an affordable source of SSM 2022 chips. Drat.


The User Guide does not contain detailed explanations on how to install parts or which kinds of solder to use. The intended audience is the experienced kit builder who is quite comfortable building a circuit from a description, a parts list, and a schematic. Calibration routines are included.

View the TLN-132 User Guide rev 1.1 (pdf)

Graze over the TLN-132 Schematics rev 1.0 (pdf)


TLN-132_p1s.jpg TLN-132_p1s.jpg
Prototype Stooge Panel
TLN-132_pcb_fs.jpg TLN-132_pcb_bs.jpg TLN-132_pcb_ps.jpg
PCB Top View PCB Bottom View PCB With Parts

Sound Samples

Although VCAs are extremely useful, they're not the most exciting module to demo. Rather like the viola and Rodney Dangerfield, they just don't get any respect. These demos feature the TLN-132 in some simple patches that were recorded without any added effects.

  • EG Response - This example demonstrates the difference between the linear and exponential control voltage inputs. An MOTM-300 oscillator (sawtooth output) provides the audio signal. The control signal is from an MOTM-800 EG. The first two envelopes are fed to the linear input, the last two envelopes are fed to the exponential input. Notice how the audio fades out much more quickly when using the exponential input.
  • Krautrock Pan - This example uses both channels of a TLN-132 to provide automated panning of a bass riff. An MOTM-320 LFO pulse output provides the panning control signal to the linear inputs of the TLN-132.
  • Linear Piano Pan - Another panning example, this time with a piano sound. An Ernie Ball guitar pedal plugged into an MOTM-850 pedal interface controls the panning speed. The linear control voltage input is used. Notice how the volume stays constant as the piano sound is panned.
  • Exponential Piano Pan - Similar to the previous example but using the exponential control voltage input. Notice how the volume changes as the piano sound is panned, producing a tremolo effect.