Schematic

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Phase Shifter

The Synthasystem designs and schematics are all
Copyright
z 1975, 2010, 2011 Nyle Steiner
They may not be used for profit, sale, or reproduced in any way without the express consent of Nyle Steiner

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Function

This module shifts the phase of the input signal and sums it to varying degrees with the input signal to produce an output with altered harmonic content. You can set the amount of shift for a given frequency with a knob and/or a control voltage.

From the Synthasystem manual:

The Phaser is a sound modifier. It consists of several networks in series which will shift the phase of a signal a certain amount for any given frequency. The Phaser is equipped with a knob which can cause the output to be all shifted signal, all straight unaltered signal, or anything in between.

The amount of shift, FOR A GIVEN FREQUENCY, can be varied with the frequency knob and/or with a voltage fed into the V.C. input jack.

The most popular use of the phaser involves equally mixing the input signal with the phase shifted signal (knob in the midway or straight-up position). For a particular setting of the frequency knob, certain frequencies will be in phase with the input signal and will add to the overall output level. Others will be exactly out of phase and will cancel each other, leaving no output at that frequency. Still others will fall in between these two extremes of enhancement and cancellation. These points of enhancement and cancellation can be shifted across the entire audio spectrum (range) by turning the frequency knob and/or by a voltage fed into the V.C. input.

Another use involves running the input signal straight thru the Phaser without combining it with any of the input signal (pot all the way clockwise). during the time that the phase is being shifted, a pitch change is perceived. Therefore a vibrato or warbling effect (in some ways similar to a tape deck with unsteady speed control) can be created on any signal by feeding a low frequency sine wave into the V.C. input.

                         Specifications:

                         4 stages of approximately 180 degrees of shift each for
                         a total shift of approximately 720 degrees. Line level
                         input and output approximately ODB.

Use

Inputs/Outputs

This module has 2 inputs and 1 output:

  1. V.C. in - A control voltage here changes the Frequency
  2. Signal in - The audio signal to be modified
  3. Signal out - A combination of the input and shifted signal controlled by the "SUM" knob
Knobs

This module has 2 knobs:

  1. SUM - This knob controls the wet/dry mix. CCW is dry, CW is wet
  2. Frequency - The frequency of the shift
General Connections

Hooking it up is pretty simple. Connect the input signal and a control voltage if desired and set the controls for the desired sound.

The V.C. input can be from any voltage source, Sample and Hold, Sequencer, E.G., VCO, etc.

Component Selection

Resistors

This module was originally built with carbon core, 5% resistors with one or two 1% metal film resistors. So, you have a wide range of options here. I recommend using 1% tolerance, metal film resistors everywhere.

Capacitors

There are probably a billion different ceramic capacitors at a place like Mouser. Pick a capacitor that can fit the hole easily, typically 0.1 inch on centers.

Pick good quality electrolytics where designated.

Transistors

The original used a 2N5172 NPN transistor. These are still available. In any event, you can use any standard NPN transistor and it should work.

Diodes

Nothing special, 1N4148s are fine.

Pots

Your choice for your panel. If you use the panel I laid out, the holes and spacing will work for the Alpha 12 and 16mm pots. You can probably use nicer BTI, Bourns, etc. 9mm pots with "pot chiclets"

Trimmers

Use good trimmers, please. A good Bourns multi-turn trimmer like Bourns 3296Y series will fit the pad layout and work well.

Jacks

For the panel I laid out, a good 3.5mm or 1/8 inch jack will work. I use the Switchcraft 42A Tini-Jax true 1/8 inch jack. These are switched jacks and they work with 1/8 inch plugs and 3.5 mm plugs.

Switches

I'm using an Electroswitch C5P0112N-A Mouser number is: 690-C5P0112N-A for the rotary switch. It can be set to any number of throws from 1 to 12.

Build Notes

Soldering

I assume you know the basics of soldering. I like to insert the low lying parts first, like resistors, diodes, etc. After these, I install the IC sockets. Next capacitors, transistors, connectors. Use a good solder, either an organic flux, which you should wash regularly, or a no-wash flux.

Take a break every so often, wash off the flux if you are using a flux which required cleaning. Double and triple check orientations, pins, and solder joints.

Power Supply Regulation/Filtering

Some additional comments here. These modules are tested to run on +/-12 VDC. The original power supply in the Synthasystem was +12/-10 VDC due to how Nyle designed the -10 volt section of the power supply, not for any magical requirement to have -10 volts.

The power/regulation section has 2 voltage regulators on it which can be set to +12/-10 (or +/-12 volts) depending on your needs. If you are coming from +/-15 volts, you need both regulators and you may as well set one to -10 volts.

If you are coming from +/-12 volts, technically you don't need the regulators, but if you want, install the negative one and set it to -10 volts. The LEDs are not strictly needed. They are there to establish a base current draw so the regulators will work.

Important... if you don't install the regulators, you have to install a jumper between pins 2 and 3 as shown on the Power/Regulation PCB or you won't get power.

Component Placement

Mounting

This PCB has four holes to allow flexible mounting configurations.

Calibration

The only calibration is for the supply voltages. Trim the positive to +12 and the negative to -10.

Panel Notes

There is nothing too special. I suggest using connectors on the PCB and jacks on the flying wires. The spacing and holes are setup for Alpha 16 mm or 12 mm pots. The jack holes are 0.25 inch in diameter.

Purchase

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