Updates: November 2017
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More about the GR-300 LFO to Pitch and Filter Modification

Features and Specifications
Introduction
Links
Photos
Videos
24-to-25 pin conversion

DIY Roland GR-300 LFO to Pitch and Filter Modification

Features and Specifications:

  • Use LFO (low frequency oscillator) to modulate both the pitch (normal GR-300 operation) and Filter Cutoff (modification)
  • Enables multiple target modulation (both Pitch and Filter Cutoff) similar to standard Analog Synthesizer
  • The parts required are readily available: resistors, small capacitor and basic operation amplifier (TL072).

Introduction to the "Do It Yourself" Roland GR-300 LFO to Filter and PitchModification :

In August 2013, on the vintage guitar synth forum, Mike, from metalbox dot com, had outlined a method to route the LFO from pitch, to modulate filter cutoff. So I tried this, and went a little bit further, adding top panel switches for more options.

To make the circuit work, I needed to add in some buffer circuits to prevent interaction from the pitch modulation with the filter modulation. With the transformer removed from this GR-300, I had some extra room to do these modifications.

So, with the pitch switch up, the GR-300 works as before. Adding in LFO modulation causes the pitch to warble. Now, with the filter switch up, you can use the LFO to modulate the filter, which sounds pretty cool.

It is a simple mod which gives the GR-300 some of the standard features found in other analog synths. And you can still add in envelope modulation to the filter as well.s. Email me for more details.

Links to more information:

Photos:

DIY Roland GR-300 LFO to Pitch and Filter Modification DIY Roland GR-300 LFO to Pitch and Filter Modification DIY Roland GR-300 LFO to Pitch and Filter Modification
DIY Roland GR-300 LFO to Pitch and Filter Modification DIY Roland GR-300 LFO to Pitch and Filter Modification DIY Roland GR-300 LFO to Pitch and Filter Modification
DIY Roland GR-300 LFO to Pitch and Filter Modification DIY Roland GR-300 LFO to Pitch and Filter Modification DIY Roland GR-300 LFO to Pitch and Filter Modification
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GR-300 Filter Modulation Video