ER-301/Joe's Tutorials and Patches

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Unlocking the ER-301's "Hidden" Comb Filter

In this video, we use a Delay Unit to create a comb filtering effect.

  • Creating a pitched oscillator from white noise (and tracking volt/octave)
  • Using the comb filter as an audio effect

Notes and Errata

From Brian:

Just, a small note on your last example where you modulated the delay with a sine oscillator for a phaser effect. The sweeping sounded discontinuous because you were trying to modulate through 0ms delay to negative delays with your bipolar sine wave. The Variable Delay will just clamp a negative delay to zero. Therefore, you would use either a unipolar modulation (via the Rectifier unit) or bias up the delay so that the sweep never goes below zero.

Oh and if you chain multiple delays being modulated in the same fashion but different frequencies, you can get quite a nice shimmer effect going.

See related forum post for more information.

Quantize to Any Scale with Probability

This technique makes use of the sample player as a lookup table, which is used for quantization of pitch CV. The video covers:

  • Setting the lookup values (by recording from a keyboard)
  • Using the sample player for quantizing to the selected values with a random S&H
  • Increasing the probability that a particular note is selected

Notes and Errata

It is worth mentioning that this technique is not useful only for pitch quantization, but also for modulating any parameter to specific predefined values with probabilistic determination of which values are chosen. See forum post for more information.

From Brian:

Just a hint on the random note selection: the White Noise unit outputs in the range of -1 to 1, so half of your random values are below zero. All those negative values will choose slice 0 making it occur more often than not. The solution is either to rectify or push the bias up to 0.5, with gain of 0.5, so that your WN+SH subchain is outputting values in the range of 0 to 1.

Amplitude and Ring Modulation

This video covers the principles of amplitude modulation (AM) and ring modulation (RM or ring mod), the similarities and differences between them, and how to build them using units on the ER-301.

  • Tremolo
  • Ring Modulation as an Effect
  • Amplitude Modulation

Notes and Errata

For further information, refer to the Sound on Sound article on Amplitude Modulation. Also see the forum post for additional information.

Sine Wave Distortion (Wave Folding)

This video covers using a sine wave oscillator to create a distortion effect.

  • Building the effect
  • Applying a Fixed HPF to remove unwanted artifacts created during the distortion process
  • Applying an offset to affect the symmetry of the distortion
  • Using equalizers to further shape the contour of the distortion

Notes and Errata

In the video, I mention that the f0 frequency of the sine wave oscillator cannot be set to 0 Hz. This has been corrected as of the 0.2.23 stable (Alfalfa) firmware.

See related Forum post for additional information.

Creating a Sequential Switch

NOTE: There are easier ways to create a sequential switch as of version 0.3 firmware. Please reference the bump scanner video below.

These videos cover creating a sequential switch within the ER-301. There are two methods, each with unique advantages. The first method uses a pulse wave with delays to activate the switch channels. This allows for gaps during the time that each channel is enabled. The second method allows for CV addressing which switch channel is active.

Method 1 - Delayed Pulse Wave Control

Method 2 - CV Addressable Switch

A full set of patches is included on the related forum post for this version of the sequential switch. 4 and 8 channel versions are available.

Getting CV Out of the ER-301

This video shows a technique for getting CV generated within the ER-301 out of it for use with external modules. The technique does require an external envelope follower module. In the video, I use the Expert Sleepers Disting mk4.

Essentially, the generated CV is "encoded" onto an audio signal by modulating it's amplitude with the CV signal. This audio signal will pass fine through the ER-301's AC coupled outputs. It is then "decoded" by the external envelope follower to create a real time clone of the CV signal.

Notes and Errata

Note that since the CV signal is "encoded" by modulating the amplitude of an audio signal, the CV signal must be unipolar (positive). If you want to encode a bipolar (positive and negative signal, such as an LFO), you would first need to offset and perhaps attenuate it so that it becomes a unipolar (positive voltages only) signal. After decoding, you may need to offset and amplify it to correct for the conversion.

See forum post for additional information and discussion.

Generating Complex Envelopes

This video explores some techniques for using the ER-301 as a complex envelope generator.

Notes and Errata

Some tips from Brian:

  • All osc units have VCAs builtin (i.e. the level parameter) so you don't need to add one after.
  • It might be easier to mix CV using the Offset Unit (which uses a linear fader) instead of the Mixer Unit (which uses a log fader).
  • In the technique where I'm demonstrating feeding the output of an ADSR back on it's attack parameter to change the curve, it is worth noting that the attack, decay, and release portions of the envelope are not linear by default, they are parabolic. See this forum thread for more information.

See forum discussion for more information.

Creating a Cymbal Choke Group

This video demonstrates how to choke one sound playing in a sample player when another sound (in a different sample player) is triggered. The classic example are open and closed hi-hat cymbals. When a closed hat is hit before an open hat hit stops ringing, we want it to "choke out" the remaining ring from the open hit.

While choke groups are most commonly found in drum synthesizers and samplers, this could also be put to use creatively for some non-conventional sound manipulation.

The Bump Scanner Unit Explained

This video explains the Bump Scanner unit, which can be used for "selection" using voltages. The video demonstrates using it to build a sequential switch, but there are other uses for this powerful unit as well.

Creating Custom Distortion

In this video, we use the Sample Scanner unit as a highly customizable distortion unit. Similar in concept to the sine wave distortion video above, this unit takes it to a new level by allowing the use of any single cycle wave form as the basis for distortion.

Notes and Errata

Tip from Brian:

  • Manipulating the input gain that with an envelope would get some interesting textures that depended on the envelope stage. Same for having an envelope control certain aspects of the EQ3 or any filter.

Custom Unit Build: 4 Voice Round-Robin Polyphonic Sample Player

This video started as a request on the forum, and is ground up walk through of creating a four voice polyphonic sample player. The polyphony is "round-robin" style, so it only requires a single gate and pitch input. It achieves polyphony by letting each note ring out until the maximum polyphony is reached. In this case, the polyphony is 4. Once a 5th note is played, the voice is "stolen" from the first one.

This video covers a pretty wide range of concepts including

  • Creating a "Count" using O|D's custom Count unit
  • Using bump scanners for voice selection
  • Using S&H to maintain pitch for each voice

Morphing Vowel Filter

In this video, we use filters to create vowel sounds (formants) on an input signal. We create a couple of different formants and then morph between them.

This video covers

  • Building a bandpass filter out of low and high pass filters in series
  • Routing the input signal in parallel through the bandpass filters
  • Dialing in the bandpass filters to create a "formant" on the input signal