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GR300 users?
MUFF WIGGLER Forum Index -> Guitars, Basses, Amps & FX  
Author GR300 users?
Any Roland GR300 users around these parts? These have become my favorite music makers and I've been tweaking my floor unit for better usefulness to myself. Modded the LFO to mod the filter rather than oscillators. So far 2x G-303 and one G-505 in my stable. One of the Bass units are next. Up.
That mod sounds fantastic...would love to know more about how you did it....
Short answer: took the output of the modulation VCA (ba662) and rerouted it to the summing node of the filter CV opamp. Had to tweak a few resistor levels to get a larger range. Still not entirely happy, need to tweak a little more but really cool. No data sheet for the ba662 meant I had to guess max current on the control pin. Definitely didn't want to exceed that.
sounds fantastic....may look into that myself...if i have any data sheets i will be sure to find them and get them to ya...
Pretty sure the BA662 datasheet is unobtanium. I spent some time looking at schematics that incorporated the chip to suss ballpark max current om the control pin. Using the LFO on the filter is cooler than simply disabling the touchpads as the Craig Anderton mods do.
For future reference the LFO to filter mod can be found here and his site also contains modifications for increasing output and a few other things.
did you guys see this 0_o

snufkin wrote:
did you guys see this 0_o


I wrote a email to a company in Estonia called Spicetone, maker of the analog hex 6appeal distortion pedal, and asked them if they were working on any other hex products. The 6appeal is a updated version of the Roland GR 100.

I also asked them if they would take a look at cloning the GR 300 with updated features such as extended waveform selections and digital control over the analog functions.

The response was that they were not working on any new products at the moment and would take a look at the GR300. The question would be is whether or not there is a market for such a pedal.

I also sent the folks at spice tone a link to a thread here at muff where someone had reverse-engineered the Roland voltage controlled filter chip ( I believe the IR 3109).

And sent a link to Mark Smarts website detailing his work work tapping into the GR300 pitch tracking circuit in order to trigger another analog synth which he was constructing.
I guess I missed this thread when originally posted. That's my vid (Expedition Electronics). I've posted another where I modded the filter for multiple filter responses like the Oberheim Xpander.

Only other mod I've made so far is replacing the power supply regulator and transistors with 3 terminal regulators. The original was starting to crap out, one rail would intermittently not come up when powered on. The 3 terminals are working well.

I've always got the GR300 in the back of my head. It's such a great tracking synth and the sound is great, even if limited. There's lots more you *could* do, but there's not much room inside (especially in mine).

The wave mod is probably too complicated to make it viable for me to offer it, but I'm going to try to put together some info on my website for those looking to DIY it.

The filter mod is simpler and I have some extra PCBs if interested.
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