Updates: August 2017
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More about the GR-300 Output Modification

Features and Specifications
Roland GR-300 Synthesizer Output Upgrade

DIY Roland GR-300 Modification: Increasing Output and Sustain, Reducing Noise

Features and Specifications

  • +12 dB more output
  • More dynamic range
  • Less noise
  • More sustain
  • Better guitar-to-synthesizer balance

Introduction to the Roland GR-300 Output Modification:

ALG Upgrade

The above waveform shows a standard GR-300 (top) and a "turbocharged" GR-300 on the bottom. The modified GR-300 is louder, cleaner, with more sustain.

Here is a simple modification to increase the output of the GR-300. This is a simplified version of the ALG output upgrade. Just replace two resistors, found in the negative feedback loops of the final output stages of the GR-300. Changing R173 from 56K to 100K provides a stronger signal to the VCA, and changing R166 from 2.2K to 5.1K adds more level to the final output stage.

After studying the GR-300 schematic, I began experimenting with alternate components in key positions. At the end of the day, the process of development was as much experimentation as calculation. I wanted something increased the level, but did not overly exaggerate the output of the GR-300. When you use the balance control to compare the GR-300 synthesizer output to the standard guitar output, I believe you will hear a much better balance of the two sounds.

This upgrade does not change tonal quality of the GR-300, but it does add +12 dB more output. This elevated output signal hits the noise gate at a higher level than a standard GR-300, so it takes longer for a sustained sound to fall below the trigger threshold of the noise gate. The result is more dynamic range and sustain from the GR-300. Also, since the sound is louder leaving the GR-300, less gain needs to be added at the amplifier/console/pre amp input, resulting a better signal-to-noise ratio, i.e. less noise.

I am a real purist when it comes to the GR-300, and almost all my processors are designed to enhance the features of the GR-300 without requiring any physical changes to the GR-300 or to the guitar synthesizer controller. I make an exception in this case, as this one modification actually makes a GR-300 sound better! Compare an upgraded GR-300 with a standard GR-300, and there is no doubt that Roland should have designed the original GR-300 with these features. More output, more sustain, more dynamic range, and less noise! However, this is a delicate upgrade, and involves completely disassembling the GR-300.

This mod works great, and do not effect the sound quality of the GR-300. Also, they do not increase the level of the normal guitar signal, only the VCO synth signal, and the hex fuzz signal.

"The gain is dramatically increased, to the point that I was able to turn the gain down inside my G-303 on all six strings; they had previously been maxed out. The sustain is noticeably improved, even on high notes, where it was too short in the past. I also noticed that when notes fade out, they do it more gracefully, with less abruptness and without sounds of static at the last moment of fade out, which used to happen on some notes occasionally before the upgrade. But the GR-300 tonality that I love so much is completely preserved.

In short, I'm very happy with the upgrade!

Every GR-300 should have this upgrade; it's really the way they should have done the design in the first place. I wouldn't be surprised if Pat Metheny becomes one of your customers! Thanks for doing this! When it comes to guitar synthesizers, you are THE MAN!"

GR user David "I had a chance today to connect it up and tested it last night and it is a vast improvement! I use a Rane 1RU line mixer and of course the stock version of the GR-300 needed the mixer gain cranked to get usable levels. The higher GR-300 output levels improved the headroom dramatically and that, for example, allows me to use the invertible filter and resonance just on the hex fuzz sound alone to good effect. Once again, thanks very much for your great work on the mod and on supporting the GR-300 in general."

GR User Leigh Smith

Details on the GR-300 Design and the ALG Upgrade

Roland GR-300 Roland GR-300 Roland GR-300
Roland GR-300 Roland GR-300 Roland GR-300
Click on any image for larger view.