GR 700 "Modified by TTL, Los Angeles" ???

[single_digit]

I have a GR-700 / G-707 rig that I am getting ready to sell. I've had it since the late 90s. However, while I didn't know it at the time, I later discovered that it has been at some point modified by a company called TTL in  Los Angeles. They are apparently now defunct, and Googling has led me to nothing, but I'd love to know more about this mod and how it works. What I know is that it has the following alterations:
-an extra 1/4" jack below the guitar out jack
-an extra MIDI jack (I *think* this is a MIDI through, NOT a MIDI In, but I haven't tested it
-a knob on the front face with "A, B, C and D" selections. I thought this might be to access additional banks of saved sounds, but couldn't figure out a way to get it to do anything
-internally it has an extra/swapped (not sure which) chip labeled "GR700 iF VS.1 TTL"
There may be others I'm unaware of, but I believe this is all.
Any assistance in helping me learn the history of this modification would be much appreciated.

Also, I never really used the GR 700 that much, but I powered it up and played around on it a bit and everything seems to work. BUT I'd love to hear any recommendations on what to test. For example, if a voice chip was bad, what would be the tell for me to determine it?

[Elantric]

I Recall the following

The GR-700 internal Synth engine is based on the Roland JX-3P keyboard Synth and MKS-30 Rack Synth ( a favorite of Danny Elfman)
Both employ the PG-200 knob programmer via DIN 6 connection. The stock GR-700 internal Synth only responds to the 24 pin input , and  does not react to external MIDI NOTE on/off messages, as there is no 5 pin MIDI INPUT  on a stock GR-700.

TTL was an independant  Synth repair / Roland Service Center operation in LA County (edit : identified as Mark Tsuruta, of Roland Japan)
  and using service manuals and inside knowledge  review of the ROM Memory they developed a GR-700 Mod kit using custom ROM  and custom MIDI INPUT Board for MIDI Program Change input which replicated portion of the stock JX-3P MIDI INPUT circuit. The A/B/C/D Rotary switch accesses 3 additional memory expansion banks for loading more Synth patches.



This was a popular GR-700 modification circa 1986 with LA Session players , and a few big name artists  but with the release of the Roland GR-50 and 1st 13pin GK-2 divided pickup and GR-50 lower latency in 1989,  this essentially killed the GR-700, and the TTL GR-700 modification  business model.

at least thats how I remember it in 2023.

Heres John Ambercrombes TTL modified GR-700
https://www.skinnerinc.com/auctions/3490T/lots/1274

All details about the GR-700 TTL Upgrade are documented by Wayne Joness here
https://www.joness.com/gr300/gr700-memory-expansion.htm

https://www.joness.com/gr300/GR-700.htm



https://www.joness.com/gr300/pdf/GR-700_MIDI_INPUT_Notes.pdf

[single_digit]

TTL was a Synth repair operation in LA, and they developed a GR-700 Mod using custom ROM  and custom MIDI INPUT Board which replicated portion of the stock JX-3P MIDI INPUT circuit. The A/B/C/D Rotary switch accesses 3 additional memory expansion banks for loading more Synth patches.

Good info. Thanks! So, what would be the point of that MIDI input then? Can someone essentially plug a controller in and use it as a clunky JX-3P? I've seen other forums where people are attempting to do essentially that in other ways...

Heres John Ambercrombes TTL modified GR-700
https://www.skinnerinc.com/auctions/3490T/lots/1274


https://www.joness.com/gr300/GR-700.htm

I had seen several auction sites (including this one) referencing that auction of a TTL modified guitar, but no info on the mod itself. But the second link had what I think I need.
https://www.joness.com/gr300/gr700-memory-expansion.htm
This would explain why my guitar came with an M-64C module. I'll try plugging that in and switching the banks on the knob to see if it works. If so that solves this part of the mystery for me.

[Elantric]

https://www.joness.com/gr300/GR-700.htm

Roland GR-700 MIDI Input Documentation
Thanks so much to Ben Miler who sent me the "holy grail" of the Roland GR-700 MIDI input modification: the paper documentation on the exact features of the MIDI input modification!

Download the original MIDI Input Documentation (pdf)

While I reversed engineered many of the features, the part I like best is an explanation of the improved tracking in version 1.5 software: sensing the pitch of the note in one half cycle (waveform).

While this is the modern standard, the early versions of the GR-700 required a full-cycle. And the V1.5 software lets you select which mode to use: with the switch in mode 2 (the middle position), your GR-700 uses the original tracking algorithm, and in the mode 3 position, you get the faster tracking!

https://www.joness.com/gr300/pdf/GR-700_MIDI_INPUT_Notes.pdf

[single_digit]

I checked a bit last night and confirmed that the ABCD selector knob does indeed allow extra banks for sounds if you select cartridge first. Most were blank, but I was able to save to them. And the mode 2 setting on the G-707 did seem to track a bit faster. All of this tracks with what you said. I may drag out some other old gear to try the MIDI in. The article said you need to use a footswitch to engage that MIDI in mode. Would a normal keyboard sustain pedal work?

[Elantric]

Remember TTL MIDI INPUT MOD is just program change

No MIDI Note on/ off messages

[single_digit]

So, for the average person who might consider buying this, I presume the main appeal of the mods are increased patch storage and better tracking?

[Elantric]

So, for the average person who might consider buying this, I presume the main appeal of the mods are increased patch storage and better tracking?

Yes and a show band could have Apple Mainstage change GR-700 Synth patches mid song as part of a show control system using the new MIDI INPUT

I meet lots of average people - none know what a 1984 Roland GR-700 is