Variax in a pedal with 13pin input?

Started by code103s, January 25, 2012, 05:53:38 AM

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code103s

Hi,

I have a graph tech hexpander loaded telecaster which has a 13 pin out. I also have a midi Roland GI20. I have been checking the rackvax to add into my setup but it costs a lot than it is worth ed since I am living in Europe (shipping and customs costs).

Recently I bought a variax 300 and gathering the information to make my own variax in a pedal. My problem for now is to find a way a cost efficient solution for the 13 input for the variax board with a 13 pin through option. I have been surfing the web, there are alot of old brainstorming topics about running the 13pin out into the variax dsp board subject but I couldn't find a one with suggesting a working solution. All topics about the rmc var-001 board also seems to be gone. The only option is the rackvaxs 13pin to variax adaptor, which is again too expensive due to customs and shipping costs. Therefore I would to go for a completely diy project.

I am thinking if it is possible to use Roland us-20 as splitter for the same purpose. My plan is guitars 13pin out --> Roland us-20 Gk in --> us-20 Gk out 1 to variax (pins 1-6 soldered directly to variance hex input) --> us-20 Gk2 out to GI10.

In order to so I need to be sure if it is OK to solder pins 1-6 of the 13 pin cable from us-20 out1 directly to the variax board. There will be hexpander board and us-20 between  the piezos and variax board.

Any up to date, fresh information about the diy solution for variax 13pin integration would be really great.


Elantric

Its actually easier than that

http://www.rackvax.com/store#ecwid:category=1173774&mode=product&product=3958715

GK 13-pin to Variax Adapter Module


Now you can play the Variax sounds using any GK-equipped guitar without breaking your budget.

Use your guitar equipped with a GK-compatible 13-pin pickup to play the sounds available within Variax 300, 600, 500, 700 or James Tyler Variax using our GK-compatible Variax adapter interface.

Installation is as easy as disconnecting your Variax guitar's bridge connector cable and installing in its place the appropriate jumper cable (included) between the Variax main board and the GK 13-pin to Variax Adapter Module board.

Note: This board interfaces the audio signals from your GK pickup to the Variax hardware. Phantom power (±7V) must be supplied to the GK pickup by connecting another GK-compatible device to the adapter module's GK THRU.

Features:

GK IN - plug in your 13-pin GK-equipped guitar here.
GK THRU - This is the phantom power insert point. Connecting another GK-compatible device here will supply power to the pickup connected to GK IN. Can also be used to drive another GK-compatible device such as a Roland VG-99 simultaneously.
Included:

GK 13-pin to Variax Adapter Module
Adapter-bridge link cable for use with Variax 300/600/JTV, Variax 500 or Variax 700*
*Your choice of adapter module version affects which cable is included.

Variax 300/600/JTV version:

8-pin jumper cable for use with Variax 300, 600 and James Tyler Variax
Variax 500 version:

10-pin flex cable for use with Variax 500
Variax 700 version:

8-pin flex cable for use with Variax 700
Variax Bass 700 & 705 version:

8-pin jumper cable for use with Variax Bass 700 & 705
Specifications

Dimensions: 2.9" x 1.5" x 0.83" (73.7 x 38.1 x 21mm)
Weight: 2 oz.

code103s

Thanks for the answers.

I have already checked the rackvax GK 13-pin to Variax Adapter Module. But as I already stated it costs too much.  (200$+50$variax300 addon+shipping+over 100$ customs) Total cost to me is minumum 400$ for this adapter, and this is my last option. I can find a roland us-20 for the half price and use it if it is possible to connect the us-20 13 out directly to the variax dsp board.

datsunrobbie

I think part of the reason for the adapter board recommended by Elantric is that you cannot simply go straight from the GK to the input of the Variax DSP board, something about different voltages from the piezo bridge on the variax guitar vs the GK output. The board has the parts that change the voltage so the DSP board does not smoke when you plug everything in. I spent just enough time in electronics classes in the 80s to know that I don't have the skills required to design such a circuit myself, and I don't think the RackVax folks are giving it away. I'd still love to figure out how to drive the Variax DSP from a GK magnetic pickup without having the pair of 13 pin connectors on the adapter board (ribbon cable in from the GK pickup, ribbon cable out to DSP) so the Variax DSP could be mounted inside a GK equipped guitar. The folks at RackVax said it sounded like a cool idea, but no plans at the time of my inquiry to work out making such an adapter. Parker Guitars seems to have worked out the same sort of thing, but using piezo pickups to drive the Variax and 13 pin out on the Adrian Belew Signature Fly, but it is missing  s1/s2 switches. Their Vernon Reid model has a GK with the usual controls, but no Variax.

code103s

datsunrobbie thanks for the information. It looks like buying the adaptor from rackvax will be expensive but a wise decision. I cannot do the circuit unless someone shows me the way. I checked a few other topics about this issue and they all finalized with we may need a step down circuit, non have working solution yet. Using the us-20 would be really great since it is also a A/B AB box and I have not installed a selector switch on my tele.

I will keep this topic updated when I complete the variax stompbox conversion.


Magiamusical

If I understand correctly I can take the guts out of a Variax 300 connect it to a GK 13-pin to Variax Adapter Module, place it in a DIY box and play the Variax sounds using a Guitar with a GK-3????
Godin LGXT, Les Paul Studio w/GK3, JTV89F w/GK3, GR-55

Elantric

QuoteIf I understand correctly I can take the guts out of a Variax 300 connect it to a GK 13-pin to Variax Adapter Module, place it in a DIY box and play the Variax sounds using a Guitar with a GK-3????


Correct !

PD FX

Well: I've made a 13-pin input on a variax processorboard I salvaged from a variax 300. I've bypassed the 2 TL084's, simply wired smal cables direct to de ADC chips in there, and hooked up a 13-pin input.. The Tl084's are used only to keep the impedance very low, to get low noise out of the piezo's, the ADC reads normal signal levels at high impedance.
works fine fro me. sounds great with LR Baggs hexpiezobridge on my Godin. Sounds from GK2/3 is funny but not as good: ofcourse the variax is build for piezosound source.
If anyone is interested i'll make some pictures, that show how it is done. Remember that this is a rather severe hack, for the experienced hacker only. this also means: no guarantee.
Good practice would involve adding own bufferopamps to it, but I am too lazy for such...


Elantric


PD FX

Now here are the wirings to get a high input impedance, bypassing the TL084's..



PD FX

Now this is my bleuboxed Variax!!
Note 1): I use a Y-cable, so GK power comes from my Roland GR-30
Note 2): the virtual pickup switch is build into the guitar, it uses a simple jackcable.


PD FX

#12
Here I play the bleubox:


code103s

@Guitarpolson great work..i have bought rackvaxs' gk2variax interface to build my variax in a rack, but still have alot of issues with power and grounding setup... The gk2variax interface doesnot provide gk power for the hexpander board, so I need to connect an other gk unit into gk thru port for phantom power...

Would you mind sharing more information about the custom wiring in your bluebox? I am seriously thinking about changing my unit into something like your design.

PD FX

@code103s: thanks!
But I didnt add a +7V/-7V powersupply either, I just use a GK "Y" cable, power comes from my GR55,GR30 or Axon50, whatever I want to combine.. So my solution may not be as good for you as you might suspect, I also need to connect a GK unit.
But: If you've got hum problems with your rackvax adapter, you should try to make a groundlift, it can make a huge difference!
The problem is called "groundloop", if my english is correct.
test it like this: cut the groundshield from a  jackcable, use this cable to connect the output  from your variax module to the rest of your setup, wichich already is connected to the guitar ground via the normal guitar cable or a Gk unit.
Your variax is grounded by the GK connection, you dont need a second ground connection on the output signal, it is the main cause of hum in complexer setups. Since I always use kind of complex setups, i'm used to avoiding groundloops..


TommyJay

Quote from: Elantric on January 25, 2012, 05:09:01 PM
Its actually easier than that

http://www.rackvax.com/store#ecwid:category=1173774&mode=product&product=3958715

GK 13-pin to Variax Adapter Module


Now you can play the Variax sounds using any GK-equipped guitar without breaking your budget.

Use your guitar equipped with a GK-compatible 13-pin pickup to play the sounds available within Variax 300, 600, 500, 700 or James Tyler Variax using our GK-compatible Variax adapter interface.

Installation is as easy as disconnecting your Variax guitar's bridge connector cable and installing in its place the appropriate jumper cable (included) between the Variax main board and the GK 13-pin to Variax Adapter Module board.

Note: This board interfaces the audio signals from your GK pickup to the Variax hardware. Phantom power (±7V) must be supplied to the GK pickup by connecting another GK-compatible device to the adapter module's GK THRU.

Features:

GK IN - plug in your 13-pin GK-equipped guitar here.
GK THRU - This is the phantom power insert point. Connecting another GK-compatible device here will supply power to the pickup connected to GK IN. Can also be used to drive another GK-compatible device such as a Roland VG-99 simultaneously.
Included:

GK 13-pin to Variax Adapter Module
Adapter-bridge link cable for use with Variax 300/600/JTV, Variax 500 or Variax 700*
*Your choice of adapter module version affects which cable is included.

Variax 300/600/JTV version:

8-pin jumper cable for use with Variax 300, 600 and James Tyler Variax
Variax 500 version:

10-pin flex cable for use with Variax 500
Variax 700 version:

8-pin flex cable for use with Variax 700
Variax Bass 700 & 705 version:

8-pin jumper cable for use with Variax Bass 700 & 705
Specifications

Dimensions: 2.9" x 1.5" x 0.83" (73.7 x 38.1 x 21mm)
Weight: 2 oz.



Hey Elantric, I believe from seeing you on the Line 6 Forum that you like myself have the James Tyler JTV-69.  I also have the same setup as in your picture of you JTV-69.  My question or questions, can the six pick ups on the JTV-69 not be hooked up to replace the GK-3 pick ups and just add a 13 pin connector for the GR-55 hookup?   Or this connector replacement will that not do it?

Thanks,
Tommy



Elantric

#16
The prior posts in this thread are targeted to those who own already a guitar with 13 pin output, but want to drive the Variax Electronics.

Sounds like you want to accomplish the opposite.

The big hurdle for implementing a 13 pin jack into a Variax is the potential for crosstalk between the two systems, and I recommend using the RMC "Polydrive I
as the path to Roland 13 pin, since this is a very small footprint, and (unlike the Roland GK Internal preamp) already designed for use with Piezo saddles.

I do not recommend the Graphtech Ghost "MIDI Expander" piezo pre-amp, due to excess hiss and noise on that model. 
http://www.rmcpickup.com/polydrivei.html

But using a common set of piezo saddles to feed two separate piezo preamps can be problematic

some reference reading
http://personalpages.tds.net/~fdeck/bass/quickand.pdf

TommyJay

Thanks Elantric, this sure does give some food for thought.  The Polydrive I looks very interesting indeed and the nice thing is there is a store in my area, Toronto, the 12th Fret Guitar Shop that is on the list of dealers.  So thank you again for the info, I will definitely give them a call to see about cost and installation costs.  I noticed on the Line 6 forum you were also interested in useing another method other than the GK-3, so is this the approach that you are doing?   I'm my right in assuming that Polydrive I utilizes the Tayler Variax built in bridge pick ups?  At any rate my waranty on my Variax is finished in another couple of months so I guess I have time to research.  Thanks again for the great info.

Tommy

Elantric

#18
My JTV-69 currently has an external GK-3 mounted on it.
https://www.vguitarforums.com/smf/index.php?topic=359.msg34534#msg34534



I tend to have too little time to pursue all the side electronics projects i want to tackle. Always busy with 9-10 hour days at day gig, and 16 hrs month average with side paying PCB design work, and band practice, oh yea a minor social life outside the forums too ;) 

QuoteI'm my right in assuming that Polydrive I utilizes the Tayler Variax built in bridge pick ups?

I'm not suggesting that the RMC Polydrive 1 will be plug and play with the Variax. I do anticipate there will be problems using a common set of L.R Baggs Variax piezo saddles to feed two separate destinations :

Destination #1 - the Variax A/D to DSP Board inside the JTV Variax.

Destination #2 - RMC Polydrive 1

This thread may provide more incite
http://line6.com/supportarchive/thread/23857

QuoteRe: Hex pickup midi system
by smashmashup on 2009-01-29 02:28:38 From the Horses mouth . . . .

Ghost FAQ: Line 6 Variax


Can I run both the Variax and the Hexpander off the same set of saddles?

Some Graph Tech customers have tried this with a simple Y-connection and found that the two electronic circuits interfere with each other if they're both powered on. If either is shut off, the other one works fine, so yes, you can run one or the other, but not both at the same time.

The difficulty with running two systems from two manufacturers off the same set of piezo pickups is that there may be loading, impedance mismatch, or other unpredictable interactions between the two electronic systems, when they share a common node at the connection to the piezo. There may be another way to do this, perhaps with some kind of buffer between the pickups and the circuits, but the solution remains undiscovered at this time.



Quotebut the solution remains undiscovered at this time.

Or "borrow" a Parker Adrian Belew Model and determine its electrical schematic

http://images.thomann.de/pics/prod/parker_belew_anleitung_.pdf




TommyJay

I know that feeling...lol  I am still doing my day gig too at 68 but not playing pro any more just for enjoyment ...haha.  So I take it you are still using the the GK-3 mounted as in the picture?  How do you find the tracking and ghost noises?  I am having problems sometimes with a couple of patches like the Lead 02-1 Nice tenor as an example.  Been playing with adjustmenst and it is getting better.  BTW I noticed the way you have your pickups setup with the mount.  Does that give you any problems because of the distance...over the 20ml?

Anyhow took enough of your time and much, much appreciated again for the info.

Thanks,
Tommy

Elantric

My GR-55 tracking was bad, until I implemented the advice from Jim Williams

Read all GR-55 setup docs here:
https://www.vguitarforums.com/smf/index.php?action=downloads;cat=18

TommyJay

Thanks I will check that out when I get a bit more time.  Gotta run out now so thanks again for the info from Jim,  actually downloaded a couple of his patches.  He does a nice with his patches.

Thanks again,
Tommy

TommyJay

Hey there hope you don't mind but I think your name is Steve, at least that is what appears to be on the Line 6 forum.  Anyhow hope you don't mind me using your real name.  I just wanted to say thanks for your last post to me.  Wow between you, Jim and Shawn, how can anyone go wrong setting up their GR-55 with the GK-3.  I am actually at my office and am able to at times jump in and read.  Too bad I couldn't bring my system in...lol  Oh well at least I am able to log into VGuitarForums as it is not blocked by the Company Firewall.

So at least I can read and prep for doing the real thing.

Thanks again, oh and I hope where you live it is warmer than this freezing weather in Toronto....ahhhhh. Hate the cold.
Tommy


Quote from: TommyJay on March 04, 2013, 04:53:12 PM
Thanks I will check that out when I get a bit more time.  Gotta run out now so thanks again for the info from Jim,  actually downloaded a couple of his patches.  He does a nice with his patches.

Thanks again,
Tommy

Elantric

QuoteI just wanted to say thanks for your last post to me

You are welcome


QuoteWow between you, Jim and Shawn, how can anyone go wrong setting up their GR-55 with the GK-3.

Id say bulk of GR-55 owners have tracking problems, and (present company excluded) short attention span, need for instant gratification.
True, we have a lot of information here tucked in various posts with stickies
https://www.vguitarforums.com/smf/index.php?board=61.0

and separate download area with additional documentation,
https://www.vguitarforums.com/smf/index.php?action=downloads

and often conflicting recommendations as each GR-55 / VG-99 owner has unique needs and discovered and wrote about the means to achieve those goals.

greekjgg

A year in now with my Gr55 I'm starting to have issues all of a sudden. I know that the unit can freeze when plugged in usb to a mac, OK, I can deal. I also used the cable connecion cleaner, we will see if that helps. Now last night during a gig, my patches were acting funny like using the exp pedal to toggle between sounds, one side there was no sound? So is there a benefit to backing up the unit and doing a factory restore after so long?

In the meantime, I'm looking at adding to the arsenal as well as redundancy. I used to have a variax years ago. I'm looking at these rackvax transplants. Are they still a "relevant" option since they've been out a while? I see the luthier kits for the antares autotune guitars are on the brink as well as the fisherman pu systems. Ultimately I love the GR55 for the synth sounds. I'm pretty ok with the guitar sounds, however I think my sound needs a little thickining as well but i hear great things about the POD HD500 along with a variax. I do play in multiple tunings so that is a requirement in my redundancy and I would like some extra features like pitch shift doubling like scorpions or some bon jovi tunes. I have a dtuner pedal as a backup as well and I'm also looking at the TC Helicon voicelive GTX as well for backing vocals so I'm trying to get a guage on what works, what has worked well but it seems right now there are some interesting alternatives that are starting to hit the market.
Setup:
Homemade EVH Frankenstrat with built in GK3
GR55
Rocktron Talkbox
TC Helicon Voicetone C1
Tech 21 Power Engine 60