ER-301/How to build a simple synth voice

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In this section we're going to create a classic subtractive synth voice.

It is assumed you know basic operations like how to insert units, navigate around your patch etc... but helpful hints and links are provided where appropriate.

Starting with a sound source using one of the built in oscillator units, the sound will be filtered with the Ladder Filter unit and then shaped using a combination of a Linear VCA unit and an ADSR unit.

External Connections

You will need to make three cable connections to get started, for this tutorial we will use channel 1:

  1. Patch OUT1 to your mixer or sound card.
  2. Patch your incoming pitch V/oct CV to A1
  3. Patch your incoming gate CV to G1
Any inputs A1 to D3 can be used for CV/Gate input, however, the IN sockets are specifically reserved for audio input and should not be used for CV/Gate purposes.

Add Synth Voice Units

Assign Inputs

Assign V/oct Input

Input A1 assigned to Aliasing Saw unit V/oct parameter
  1. Select the Aliasing Saw unit V/oct parameter and press S1 then M2 to access the input menu
  2. Choose A1
  3. Press UP to return to the top of the chain

Assign Gate Input

Input G1 assigned to Envelope Input
  1. Navigate to the ADSR unit's Chain Input and press M2 to access the input menu
  2. Choose G1
  3. Press UP to return to the top of the chain

Configure the Units

Gain parameter of Linear VCA set to 1.0
ADSR values set to create envelope shape
  1. If required, tune the Aliasing Saw unit by adjusting the f0 parameter (see tip below).
  2. Set the Gain parameter of the Linear VCA unit to 1.0
  3. Set the ADSR unit A parameter (attack) to 10ms
  4. Set the ADSR unit S parameter (sustain) to 1.0
  5. Set the ADSR unit R parameter (release) to 120ms
  6. Adjust the filter cutoff frequency f0 and Q parameters on the Ladder Filter unit
Any of these values can be adjusted to taste at any time.

By default the tuning of the built in Osc units is 27.5Hz which is a very low A note. You may like to change this, for example, you could set it to 32.7 Hz for C1, See the FAQ for more details and links to the forum discussion on this subject.


You should now be able to send pitch and gate information from your sequencer or keyboard to the ER-301 and hear notes being played.

If you're not getting any sound it's possible you have missed a step in the instructions.

  • Did you remember to turn up the modulation gain on the Linear VCA's level parameter?
  • Is the Aliasing Saw's fundamental frequency (f0) set below human hearing?
  • Did you turn the filter frequency (f0) too low?
  • Are your physical connections correctly assigned to the correct V/oct input and the gate input?
  • Are you receiving a signal? You may use the LEDs on the ABCD inputs to check this.

Saving the Chain

To save your chain, navigate to the top and beginning of the chain and press Save
Enter your filename and press ENTER to save

Once you have confirmed everything is working correctly you should save your chain. This will allow you to quickly recreate this setup in the future.

  1. Navigate to the head of the chain (e.g. OUT1). The commands Clear, Load and Save will be displayed in the small screen.
  2. Press Save (S3) to start the save procedure
  3. Navigate to the folder where you would like to save your chain
  4. Create a new file by pressing New File (S2)
  5. Enter a file name and press ENTER to complete the save

Please refer to the Save and Backup FAQ for help saving your work.

What to try next?

Here are a few ideas to develop this simple synth voice further.

  1. Try different oscillator types instead of the Aliasing Saw unit e.g. the Sine Osc unit or the Aliasing Triangle unit
  2. Try using a sample player and single cycle waveforms as an oscillator
  3. Map the incoming pitch CV to the Ladder Filter V/oct
  4. Map the incoming gate CV to the sync input of your oscillator
  5. Create a Custom Unit following the How to convert a chain to a custom unit tutorial.
  6. Build a multi-oscillator synth following the How to build a multi-oscillator voice tutorial.