GR-300 and 808 guitar controller would you buy one?

Started by chrish, June 30, 2017, 09:48:34 AM

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chrish

#25
Here's a picture of that Guitar Center guitar I just purchased  $350 plus tax and shipping.

Moe and Curly.

Moe has mo Electronics with the addition of a GK 3 pick up.

And Curly has a beautiful wood grain pattern that the Luther took the time to bookmatch.

Okay you caught me eating Christmas ganja food. :D

Thanks again to Sec6 for posting Curly's for sale ad.

mooncaine

I saw it in the store. I've been following its story ever since. Glad it found a loving home with you!

chrish

#27
Original prices and a GR300 review from that era

http://www.muzines.co.uk/articles/roland-gr-300-guitar-synthes/3609

"...in fact, with a decent drum machine and the GR-300 you could sack your whole band..."

"The GR-300 is £515; the cheapest guitar (the G-202) is £299 whilst the1 G-303, G-505 and G-808 are £399, £425 and £499 respectively. These prices are inclusive of VAT."

chrish

If you're on Vancouver Island, Canada and looking to purchase this vintage setup.

Roland GR-300 Analog Guitar Synthesizer + G-202 Guitar - $1800 (Nanaimo

https://nanaimo.craigslist.ca/msg/d/roland-gr-300-analog-guitar/6438965920.html

chrish

I was reading the owner's manual for the GR 300 and on page 2, the manual states "Totally polyphonic: one VCO for each string"

Every review that I've read, and even posted on Dr. Wayne Joness site, states that the GR 300 has two oscillators per string.

Does anybody know which one is correct?

Elantric

#30
Quote from: chrish on January 16, 2018, 09:21:00 AM
I was reading the owner's manual for the GR 300 and on page 2, the manual states "Totally polyphonic: one VCO for each string"

Every review that I've read, and even posted on Dr. Wayne Joness site, states that the GR 300 has two oscillators per string.

Does anybody know which one is correct?

I know of the VCO 1 per string /  and the internal Hex Fuzz as audio sources on older GR-808/303 with GR-300. -  - no Guitar to MIDI with a CPU
http://www.joness.com/gr300/GR-300.htm




Review GR-300 Block diagram
http://www.joness.com/gr300/service/G-303_G-808_GR-300_SERVICE_NOTES.pdf





chrish

#31
Okay I think I get it now.  The Joness site states two oscillators per voice, not per string as I stated. So a voice would be one vco per string and the other voice would be the hex fuzz voice. And the duet mode adds in the fundamental pitch to the mix.

With the two GR 300s that I own now, I've been running those together using the 24 pin output from the G505 guitar and another 24 pin output from a GK1 mounted on the G 505.(my goal is to also add an internal gk3 to that setup and run three cables)

With the two 24 pin hex pickup circuits, no need to find a US-2, although owning one would be nice.

So that two GR300 combination truly does give two VCO'S per string. With the pitch change and filter envelope modulation capabilities on those units, some interesting sounds can be produced.


chrish


chrish

This looks like a good buy.

Roland GR-300 Guitar Synthesizer (220V), GK-1 Cable, 2 GK-1 Pickups, 24Pin Cable
$500.00
0 bids | Ends in 5d 21h
or
$650.00
Buy it now

https://www.ebay.com/itm/Roland-GR-300-Guitar-Synthesizer-220V-GK-1-Cable-2-GK-1-Pickups-24Pin-Cable/232973929153?hash=item363e540ac1:g:LqgAAOSwBBpby~B4

chrish

#34
Busted. One of the things about search data is they keep using that to Market product to you, and it shows up on the phone.

So I was checking out this G 202 and gr 300 setup on eBay and this morning I was greeted with comment from my wife.

" you're not thinking about buying another synthesizer are you?"

https://www.ebay.com/itm/Natural-Roland-G-202-Guitar-Controller-and-Roland-GR-300-Guitar-Synthesizer/332832075848?hash=item4d7e567048:g:rSUAAOSwilVbuWLH

Already own this guitar and synth combo, however the blue color of the one I purchased wasn't my first choice.

I really like  this guitar in the natural finish.

But now I'm busted, so I hope someone else can enjoy this combo, but you may want to search in incognito mode when looking at gear. ;)

chrish

#35
Just purchased a G303 on reverb.com.

Its non functional at the moment because it doesn't have a hex pickup and back cover.

Just disassembled it and cleaned and placed oil on the fretboard.

Lots of green dust scraped along both sides of each fret and generally the Frets are in good shape except for those near the nut.Around 8 of the High string Frets have little wear indentations

The neck is straight and had been sanded by the previous owner.

I'm wondering if I should oil the neck?

The plan is going to be to take the electronic package out of a spare G505 that I bought for parts (pic in this thread)That guitar actually turned out to be in better shape than the pictures showed as did the one I just purchased.

chrish

#36
Well that didn't work.

The G505 board does not fit into the G 303. The G303 has a little extra wood bump in the cavity that holds a tailpiece bolt thread.

So I'm kind of hoping the board in the G303 is good.

If not I believe the op amp IC's are still available.

The good news is the cavity cover is interchangeable although a different design.

Pots cleaned and hex pup in.



PeakSynthesis

No matter what's wrong with your GR-303 board, it's fixable.

The JRC4558 opamps are about as jellybean as you can get and just about any 4558 type will replace them, or you could also upgrade to a TL072 or NE5532, or you could go audiophile and use OPA2134s.

Post whatever problem you're having and it can be solved.

chrish

Quote from: PeakSynthesis on January 25, 2019, 10:09:05 PM
No matter what's wrong with your GR-303 board, it's fixable.

The JRC4558 opamps are about as jellybean as you can get and just about any 4558 type will replace them, or you could also upgrade to a TL072 or NE5532, or you could go audiophile and use OPA2134s.

Post whatever problem you're having and it can be solved.
that's reassuring.

Plus when you read about all the folks here who go in and hack something, it becomes fun to dive in. This is project is good hacker training.

I found a section on Dr. Joness site where he discusses the various electronic cards for the G505, G303, etc.

The G303 card is also different because  Pot placement on the card has to compensate for the curved top of the G303 so they're mounted on flexible spacers.

PeakSynthesis

Just in case you ever need it, here's the exact replacement opamp:
https://www.digikey.com/product-detail/en/njr-corporation-njrc/NJM4558D/NJM4558D-ND/673768

The only other chip type on the board is a quad NAND gate:
https://www.digikey.com/product-detail/en/texas-instruments/CD4011BE/296-2031-5-ND/67241

I think you're spot on in calling this good training. With an amp, a cord, and a resistor anywhere from 10K to 100K you can throw together a makeshift audio probe and tracing any circuit problems should be straight forward. All the logic and control outputs can be checked with a regular voltmeter and the audio probe takes care of the rest. Just post your progress and questions, and the answers are all at arm's reach.

Since you're jumping in at this level I'll also mention that the 4011 NAND gate is sensitive to static electricity and you should observe standard basic static control procedures when working on the board. Most damage from static won't kill parts outright, but it can easily reduce a part that's rated 100,000 hour MTBF to a compromised part with a lifespan of only dozens of hours. Stay grounded and control static and you'll be fine.

chrish

#40
Thanks for that information. I may need to replace an op amp someday.

I'm aware of the static  protocol when working with integrated circuits, but I don't seem to be able to generate a static charge inside my home. Maybe because I live inside of a faraday cage, metal roof and metal siding to ground. ;)

Plus because of my solar home power system I installed extensive grounding which is even beyond the current electric code that now requires a 20 foot rebar under the foundation to dirt instead of the 10-foot driven rod.

Put the guitar back together and the old electronic card is just fine and guitar working  except for two things.

The string ground wire that connects to the tailpiece through an epoxy connection through the wood, broke from too much bending stress.

No noise but wondering about hazard?

And the rear pickup isn't working either because I wired it wrong or the selector switch is broken.

The rear pickup isn't original.  It's a Seymour Duncan humbucker. It had a red and a white wire that were tied together and shrink-wrapped. It had a green and a bare wire that were also tied together that I connected to ground. And it had a free black wire which I assumed was the pickup  connection to the selector switch.

Edit: checked Seymour Site and humbucker is wired correctly.

PeakSynthesis

The broken ground is a tiny, tiny hazard but I would personally never worry about it unless you were plugging a into an older tube amp. I would be much more worried about buzz that came and went as you touch the strings or don't. A lot of the danger from early tube amps comes from the use of a 2 wire cord and then having a coupling capacitor between chassis ground and the wire "presumed" to be the neutral. The big offenders are the amps with "ground switch" that lets you pick which one of the two wires to connect the cap to and that means sometimes the chassis becomes more or less hot. In any case, I always install a capacitor in guitars between the signal ground and the bridge ground. 0.1uF @ 630V is an ideal value for safety but I never use caps rated under 400V for the bridge ground because it is a safety component. 0.1uf is enough to drain the hum but still affords some protection even if the ground becomes hot. I would try to dig out the end of the wire if that's possible and solder a cap in, then pot the mess in epoxy for stability.

On your Seymour it sounds like you could have a break. The simple test I would try would be to remove the heatshrink from the red & white wires and then try shorting the red-white combo alternately to the green and then the black wires. My guess is one of the two coils is open and without attempting repair, the aforementioned trick should get a single coil operating. If you suspect the switch, jumper the outer two connections and you should get both pickups regardless of switch position.

Just as an aside, I remember a story from Neil Young's amp tech talking about measuring something like 170V between the guitar ground and the microphone ground at a gig where Neil was getting a bad shock every time he touched the mic with his lips. Good grounding matters and on stage it's not uncommon to have rinky-dink power with questionable grounding.

chrish

#42
^Lots of good information there. Placed a jumper on the switch and the rear pickup worked.

I'll try cleaning that bad switch.

That's one sweet sounding guitar. And the sanded neck  has a great feel to it. My new #1.

Was getting some unwanted GR300 triggers due to the open A and E strings sympathetically vibrating and being picked up by the hex pick up.

Lowering that side of the hex pickup seems to help reduce the effect so not the standard height that hex pup pitch to midi systems require.

PeakSynthesis


chrish

#44
 here is a rare White G303 with an excellent condition GR300 for sale in the UK.

https://reverb.com/item/33023301-roland-g-303-with-synthesiser-unit