FTP - DIY adapter to use GK 13 Pin Guitars with Tripleplay

Started by utensil, April 21, 2013, 01:29:52 PM

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Elantric

QuoteIs it correct to assume that the FTP Controller  - modified by Utensil when used with a Godin LGX-SA or LGXT would permit the program up/down switch on the Godin, as well as the guitar/synth/combined guitar-synth switch to work?

Sadly -no

Rorster

Way too bad. A pretty cool idea. I wonder how program changes are made unless via a midi floor controller.

utensil

Quote from: Rorster on May 06, 2015, 07:16:58 PM
Is it correct to assume that the FTP Controller  - modified by Utensil when used with a Godin LGX-SA or LGXT would permit the program up/down switch on the Godin, as well as the guitar/synth/combined guitar-synth switch to work? Also since these guitars have an onboard acoustic preamp for the piezos acoustic function, would that 9 volt battery preamp affect the FTP playability if/when combined with the acoustic function of the guitar. The Godin that Utensil uses has a 9 volt powered preamp I'm almost certain but I don't believe that this question has been specifically addressed.

Sorry this reply a bit late in the discussion, With the pre-amp activated, i.e if a normal jack is plugged into the Godin, the 9 volt is indeed activated and the signals coming out of the 13 pin into the triple play are then too hot and the trim pots need to be used to attenuate. The usage I've normalised to is to leave the trimpots at a general level that work on all my 13 pin guitars (all mine except the Godin are graph tech preamps). For all the other guitars I supply power to the 13 pin jack via an external 9volt battery. For the Godin , I usually have the normal jack plugged in while using the triple play as well so no external 9 volt is needed (the one in the back of the godin activates the preamp) and the trim pots are already set to attenuate to a suitable level.

the triple play is surprisingly accepting of different input sources, i.e magnetic or piezo and performance seems to work evenly well, getting the signal in the sweet spot in terms of strength is to have the dynamics of velocities so everything isn't either max velocity or at a minimal level.

For patch changes I have the triple play mounted on a guitar strap with velcro so I can use it's buttons to for program change etc.


drbill

Reviving this thread...

I'm expecting to have some free time soon (I'm going to change jobs and my current employer will require that I sit out for a while -- in the financial industry, we call this being on "garden leave," or "on the beach."), so I'm really anxious to do this.

My main guitar is my Brian Moore i2.13 (RMC), while I have a few other GK-equiped guitars. If I understand this thread correctly, what I want to do is build a box with separate inputs for GK/RMC, so I can trim the RMC signal while letting the GK go straight through. I'd like to provide a GK-out, as well, to drive my GP-10.

So I think I'd need 3 of gumbo's 13-pin jacks, 6 trim pots, a perf board and an enclosure. Sound about right?

Oh... and I think I have a pile of old Nokia AC adapters. Never thought I'd find a use for them!
GP-10, KPA
BM i2.13p, '76 Les Paul Deluxe w/GK-3, MiM RRS, Ibanez RG420GK, Charvel strat copy w/GK-2a, FTP

utensil

Quote from: drbill on July 03, 2015, 04:57:12 PM
Reviving this thread...

I'm expecting to have some free time soon (I'm going to change jobs and my current employer will require that I sit out for a while -- in the financial industry, we call this being on "garden leave," or "on the beach."), so I'm really anxious to do this.

My main guitar is my Brian Moore i2.13 (RMC), while I have a few other GK-equiped guitars. If I understand this thread correctly, what I want to do is build a box with separate inputs for GK/RMC, so I can trim the RMC signal while letting the GK go straight through. I'd like to provide a GK-out, as well, to drive my GP-10.

So I think I'd need 3 of gumbo's 13-pin jacks, 6 trim pots, a perf board and an enclosure. Sound about right?

Oh... and I think I have a pile of old Nokia AC adapters. Never thought I'd find a use for them!

Basically the RMC unpowered outputs from pins 1-6 are in the right range and don't need to be trimmed. Any of the systems while powered (RMC, Graphtech with +7 and GK with +/-7 ) require trimming.
I myself am going to be reworking my adapter as Its had so much use that I would have been better off using a 13 pin female jack (which was suggested by Elantric) to the ftp rather than a direct male connecter straight to my guitar. The constant usage has worn out the connectors a bit. I plan to make an external box like you mention.How will you duplicate (or buffer I think is the right term?) the signals to send them also out to the GP-10, I wanted to do this with my GR-55 but don't really know how to go about it. other than that your HW list sounds right.

I used 10K pots and these work but 90 percent of the range has no effect and then right as I turn them to the last 10% of the rotation the output is trimmed. I think I will try other value pots this time.

drbill

I'll be very interested to see how your new version comes out! I appreciate your pioneering this for everyone.

I don't know how I'll buffer the signals... I guess I need to read the DIY GKP-4 thread (or just use the one I have). I do want to be able to use both the FTP & GP-10 at once.

I'd assumed all along that the hex pickups needed to be powered. If the GK & RMC both need trimming, then I guess I'll need only one input to the adapter.

It'll be a few weeks before I can get started on this.
GP-10, KPA
BM i2.13p, '76 Les Paul Deluxe w/GK-3, MiM RRS, Ibanez RG420GK, Charvel strat copy w/GK-2a, FTP

scratch17

drbill and I have 2 things in common.

1. We both own a Brian Moore i2.13 guitar. I just got mine last month. New / old stock in almost mint condition with HSC for $600. ;D

2. We'd both like to connect both an FTP and other GK gear, (in my case a VG-99), to the i2.13's 13 pin output.


From what I've read in this thread so far there are two main issues to overcome to accomplish the split.


  • The RMC preamp built into the i2.13 outputs a signal that is too hot for the FTP controller's input. To remedy this, use trim pots on each pin to correct the levels.
  • You must electrically isolate the FTP from other GK outputs going to other gear. Capacitors are used to accomplish this.

I have an idea to use my existing equipment to accomplish the split, with minimal DIY work required. I think others could do the same.

Here is my plan. I haven't tried it yet as I'm reconfiguring my studio at present. If it works, it will do away with the need for trim pots and caps. Comments as to feasibility will be welcome.

I own an RMC Fanout Box. It has six mono unbalanced outputs that parallel the pins of the Fanout's GK input. In my studio I have these six outputs connected to my UA Apollo. This lets me stream the GK output to six separate tracks in my DAW.

I normally have six outputs from my DAW patched back into the six mono inputs on the Fanout Box, so I can process different strings with different patches on my VG-99.

By passing the i2.13's GK output into the Apollo, I can set up a separate six channel bus that I use to lower the levels so that the FTP gets exactly the right input level. This should also isolate the FTP from anything plugged into the Fanout Box's GK pass through output (which I will connect to the VG-99).

Now comes the minimal DIY work. I cut the FTP pickup from its body as Utensil did, and connect the six wires to a female GK jack. Then I can run a GK cable from the Fanout Box's second GK output (which I believe is connected to the returns from the DAW with the level corrected stream) to the FTP and mount it anywhere I want.

There is a possibility that by returning the signal back into the Fanout Box, the signal to the FTP could be compromised (i.e. leakage between GK outputs might occur). If so, I'd build a box with six unbalanced female jack inputs connected inside to the pins of a female GK output. Then I'd connect the returns from the Apollo to the new box, connecting it to the FTP body. That would bypass and completely isolate the FTP from the other GK equipment connected to the Fanout Box.

You could also use an analog mixer instead of the Apollo to accomplish the same goal. The mixer sets levels and isolates the FTP's input from other GK equipment. I could use my Mackie Onyx 1620 instead of the Apollo. But I can set up the UA Console app with the correct levels and recall them any time. For me it's just more convenient.


Hamer Duotone, Brian Moore i213, Taylor 710 BCE 

VG-99, FC-300, RMC Fanout
RJM Mastermind GT10
Kemper Profiling Amp
Radial JDV Mk3, X-Amp
Mesa Recto Pre + 20/20
68 Fender Bandmaster (AB763)
Marshal AS80R

UA Apollo X6, Twin X, Logic Pro, Luna, Melodyne Studio

drbill

I have all my parts and am ready to give it a go. Thinking out loud here about how this will all work out best. I have an SKB rack where I house my MOTU 828 and a couple of drawers. Right now I have my GP-10 on one and Eventide Space on the other, along with a USB hub. I sit my Kemper toaster on the top of the rack and my MacBook Pro on a Roland PC stand (pretty secure for only about twice the price of a decent music stand). On my pedalboard is my Kemper Remote, 3 expression pedals, a SoftStep2 and a PageFlip Cicada (for turning pages on my iPad). I'm sending PC messages from performance slots on the Kemper to MainStage to control everything. What I like about this setup is I can let my son borrow the Kemper or play with just the GP-10 (like I did last Sunday, when we played together) without tearing the whole rig apart.

I have an insane amount of control (I haven't yet found a use for my GuitarWing, but still keep it because it's just so cool).

I am currently running my 13-pin cable there and only run my Kemper ethernet cable and a USB cable to my pedalboard (I like not having to run any audio!).

What I'll do with the FTP is mount the converter in a small box under the pedalboard (where I'll also have my old GKP-4 splitter). I can then just run the 13-pin cable to the GKP, a short one to the FTP in a box and a longer one back to the rack for the GP-10. I guess I'll attach the FTP transmitter under the pedalboard, too (I don't use the switches & stuff on the controller at all).

A few questions/thoughts:



  • Will the FTP charge off USB while it's in use? The stupid battery was soldered in, but one of the connections was lost during disassembly and I'll have to do something about powering the unit anyway. If it'll power off USB, I'll just do that and leave the battery out. Otherwise, I'll reconnect the battery and charge it up before gigs.
  • How long a total (guitar-GKP-4 + GKP-4 to GP-10) 13-pin cable run will work? Roland used to spec a total cable distance when the GKP-4 came out, but I don't know if that worked out in practice or not.
  • Or, I could just mount the whole FTP+GKP-4 contraption in the rack and not have to worry about cable lengths, I guess. Perhaps that's the best


What do you think, sirs?
GP-10, KPA
BM i2.13p, '76 Les Paul Deluxe w/GK-3, MiM RRS, Ibanez RG420GK, Charvel strat copy w/GK-2a, FTP

utensil

I can answer one of those and say that yes the FTP will run directly while being charged without the battery (at least mind does) , I removed the battery to check this because I'm toying with the idea of placing it in the gr55 housing and powering it from the USB power for the USB stick port, either way the battery is just dead wieght.

I was planning on using a passive y 13 pin splitter type connection ( same way as https://www.vguitarforums.com/smf/index.php?topic=7869.0 and also how the us 20 is wired) . These aren't isolated and the respective pins on both will be directly connected. I'm hoping it'll work but can't be sure of how much one system will interfere with the other.

Can anyone post the wiring or explanation (or links) of how to isolate each of the 6 string signals to each system ( or even split a single audio signal into 2 isolated circuits for that matter). I gave up on searching for this as I only found very complex diagrams that seemed to have different applications from splitting audio).

I actually need this for my variax , 13 pin mod too where I'm using piezos to drive both the vax circuit and the 13 pin preamp but can't use both at the same time cause they aren't isolated and if both are powered then everything goes screwy.


Elantric

#84
QuoteCan anyone post the wiring or explanation (or links) of how to isolate each of the 6 string signals to each system ( or even a single audio signal for that matter)

Since the Gk-3 Mag Hex PU is Hi-Z, typically an active opamp buffer ( like the one already inside the GK-3 )is employed for this

http://www.amazon.com/Guitar-Presents-Do-It-Yourself-Projects-Guitarists/dp/087930359X/ref=pd_sim_14_3?ie=UTF8&refRID=0CKJ6PHTJ9DJV0HH3YTW&dpID=51xdX0uIelL&dpSrc=sims&preST=_AC_UL320_SR248%2C320_


drbill

I could not be more surprised & pleased to report that it works!!! 20 year old me is not impressed with my decrepit soldering skills, but I managed to get it done.

I plugged it into the B channel of my GKP-4 and my GP-10 into the A channel. Then started the Fishman app and it's all good. All I have to do now is adjust the trimpots and put it in a box.

Thank you all for all the valuable information! I am so pleased to have this available for all my guitars now.
GP-10, KPA
BM i2.13p, '76 Les Paul Deluxe w/GK-3, MiM RRS, Ibanez RG420GK, Charvel strat copy w/GK-2a, FTP

Elantric


gumbo

Congrats, drbill!

Great to see it come together for you!

Cheers,
Peter
Read slower!!!   ....I'm typing as fast as I can...

whippinpost91850


drbill

GP-10, KPA
BM i2.13p, '76 Les Paul Deluxe w/GK-3, MiM RRS, Ibanez RG420GK, Charvel strat copy w/GK-2a, FTP

GuitarBuilder

Now that the FTP "wart" is no longer on the guitar, it would be interesting to explore a hardwired version (without the wireless dongle).  Could there be a way to connect the dongle directly to the wart, bypassing the radio circuits?  Or better yet, how about connecting the wart directly to a RPI with MIDI?
"There's no-one left alive, it must be a draw"  Peter Gabriel 1973

Piplodocus

I've read this thread a good few times now, but I keep losing the plot as its 4 pages long, peppered with questions, and people are tying to split to use the Roland simultaneously with it, and some of the levels discussed are from other pickups (RMC etc?) other than the standard 13 pin out. Could someone please humour me and summarise the following:

I have a Parker with Graphtech hexaphonic 13 pin out + the acoustiphonic preamp (or I will imminently at least). I wanna run this into a FTP mounted on the guitar strap. I don't really care about switching, I'll use my feet for this. Would be nice if it'll work out any other 13 pin too for future compatibility. So...

1) this will work just as well as the original pickup yes? That seems to be the case from the later posts?
2) all I need is 6x 10k trim pots as attenuators?
3) what about the in-line 10k resistors too someone mentioned?
4) one of the pics above shows some caps too. Are this for noise suppression, not really necessary, or do this form a LPF to improve note recognition or something?
5) will the 9V for the Acoustiphonic and Hexaphonic power the thing entirely (except the FTP)? I thought the standard Roland/axon whatever thing partly phantom powered the Hexaphonic preamp? I could well be wrong though.
6) what's this traktion switch on the Graphtech output do? I believe it changes level on the outputs AFAIK. No idea if this is irrelevant or useful. I assume in either position I still need the trim pots?
7) Then I just wire up the 6 strings, and the ground. Is there a signal ground and a separate shield ground. I can't remember but I thought the FTP has a signal ground and an RF shield. I haven't got any easy access to an FTP for a while though.

Thanks very much for clearing this up and clarifying them all.

P.S. I already have the molex header for the FTP and there's a 13 pin plug in the post!

Elantric

#92
This adapter begs for a short run PCB spin

CodeSmart

Quote from: Elantric on September 28, 2015, 11:12:25 AM
This adapter begs for a short run PCB spin
Or at least a proper drawing to start with. It's not very clear. Not at all.
I think you could make a very tiny PCB for this thing 8)
But I got more gear than I need...and I like it!

Elantric

#94
KastorVGF wrote>
QuoteHello utensil, I must say you did a very great job and I'm going to follow you! However, 2 black wires (the ground and the ground shield) in the 8 pin header which connected to the FTP directly make me confused. I draw a circuit diagram which I am planning to do with. Please tell me if there are any mistake(s). Thank you!!!!!


Utensil wrote>
QuoteHey KastorVGF

your drawing is pretty much exactly how I wired it. The pins on the 13 pin correspond correctly assuming you're looking into the cable (male) part not into the socket, but I'm assuming you've already looked it up since you're planning seems on track. If I remember , the the 2 black cables coming from the magnetic pickup are a common ground (can be confirm that they are connected if you have a multimeter handy). Either way your drawing is exactly how I've wired it. FYI I used 10k pots which seem to work fine.

What type of 13 pin system are you using it with? , I'm assuming  it's not intended for a Roland GK (internal or external) as your leaving out the 13 pin -7v as I did. It works fine with the Graphtech system and the RMC. also if you managed to get the 8 pin connector then I'd suggest keeping your original magnetic pickup intact as it would be trivial to restore your FTP back to original state should you ever want.

I'm interested you hear your results so please share. As I mentioned I've been using this on and off  as well as an unmodified FTP and I can't really notice any difference in performance.

KastorVGF wrote>
QuoteEventually, I have finished it this afternoon. It is not too difficult but you do need tools to do this (I do this in the Lab. of my university xD).
But I must say, as utensil, this adapter give a extremely good result!! I use this with the Graph Tech Ghost Hexpander system which is much better than the origin magnetic hex-pickup!!
Thank you for this post as searching from Google, here is the only place that teach people to make the adapter.
It is very easy to make it on your own, so check this out if you are not satisfied with the magnetic PU!!








---

My 2 cents - the final design should provide

+7VDC  @ 250mA  on Pin #12,

and

-7VDC  @ 250mA on pin #13

to power a GK-2A / GK-3

whippinpost91850


Elantric

#96
QuoteWhat are the 6 chips in the schematic

Bourns 3296 10K Potentiometers
https://www.bourns.com/pdfs/3296.pdf


all info is back on Page 2
https://www.vguitarforums.com/smf/index.php?topic=8413.25

CodeSmart

Anybody knows the attenuation level set with the pots? I mean, does it really need to be pots in there? Wouldn't fixed resistor dividers giving same attenuation on all strings do well?
But I got more gear than I need...and I like it!

Elantric

#98
The Pots are required because the output gain sensitivity is different for the popular 13 pin GK Preamps:

* GK-2A

* GK-3

*  RMC Piezo

* Ghost Piezo

each have different output gain

CodeSmart

Quote from: Elantric on September 28, 2015, 04:36:22 PM
The Pots are required because the output gain sensitivity is different if you have GK-2A vs GK-3 vs RMC Piezo vs Ghost Piezo - each have different output gain
Aha...So a six channel pot would be great  ;D or a six channel volume chip controlled by one DC level (one knob), or a six-channel chip controlled by a tiny PIC. Stop! Now we're getting into work mode again :P.

Maybe the six pots, two connectors and two linear chips making +/-7V out of a 12V supply is just what the doctor ordered.
But I got more gear than I need...and I like it!