Serge Equal Power Panner


Serge Equal Power Panner
for music synthesizers.

 

The Serge Equal Power Panner is a sub-module used in some of Serge's designs, such as stereo mixers and panners. It is essentially a small, purpose made analogue converter that converts and sums control voltages in such a way as when coupled with the exponential response of the cgs102v10 gain cells, you can achieve voltage control of signal level and equal powered panning.

Quoted from the mixer section of the 1982 Serge catalog:

EQUAL-POWER CONTROL OF PANNING AND CROSS-FADING
Linear response assures that panning and percentage cross-fade behave predictably in response to a control voltage, eliminating signal level changes as well as annoying slow and fast areas. Equal Power control assures that the perceived loudness of the VCA's will remain constant at all positions of a signal in stereo or quadraphonic space.

Note that this sub-module processes control voltages only. No audio signal is handled by it directly. It requires CGS108 gain cells to function.

The schematic for Serge Equal Power Panner sub-module.

Construction


The component overlay for the VER1.0 PCB. Click here for an enlarged, printable version. Print at 300dpi.

The circuit has been split over two PCBs, one containing the converter, the other the DC mixers.

Before you start assembly, check the board for etching faults. Look for any shorts between tracks, or open circuits due to over etching. Take this opportunity to sand the edges of the board if needed, removing any splinters or rough edges.

When you are happy with the printed circuit board, construction can proceed as normal, starting with the resistors first, followed by the IC sockets if used, then moving onto the taller components.

Take particular care with the orientation of the polarized components, such as electrolytics, diodes, transistors and ICs.

When inserting the ICs in their sockets, take care not to accidentally bend any of the pins under the chip. Also, make sure the notch on the chip is aligned with the notch marked on the PCB overlay.

To install the header, slide the pins partially out of the plastic carrier strip so that you can solder the pins as close to the PCB as possible. (Some headers will not need the pins moved.) Before soldering, trim the portion of the pins that go through the PCB so they are just long enough to reach the other side. Once the header is soldered to the PCB, the carrier strip can be carefully clipped off as it is no longer required.


Header fitting example. Once soldered, the plastic carrier is carefully clipped away with a pair of side cutters, leaving long pins. The long pins will be trimmed when fitting the module to the carrier PCB.

A number of SMT capacitors are used on the backs of this board set. See the photo above for positioning.

Pad identification

There is no manual wiring on this module. All connections are made when the PCBs are soldered to the host PCB.

Set Up

No set up is required.

Notes:

  • The module will work on +/-12 or +/-15 volts.
  • PCB info: 1.4" x 1".

PartQuantity
Resistors (1% metal film)
6.8k1
10k1
13k4
33k3
47k2
82k1
100k2
110k2
150k3
220k1
330k8
Capacitors
47pF1
47pF 1206 SMT4
10nF 1206 SMT1
100nF 1206 SMT1
Semi's
1N41482
CA3046, LM3046, CA3086 or sim.1
TL0711
TL0741
Misc
5 pin 90° 0.1" header strip2
12 pin 90° 0.1" header strip1
CGS102 VER1.0 PCB set1

Parts list

This is a guide only. Parts needed will vary with individual constructor's needs.

 

Can't find the parts? See the parts FAQ to see if I've already answered the question. Also see the CGS Synth discussion group.


 

Article, art & design copyright by Ken Stone