More than 6 string Multi-string MIDI Pickup?

Started by TreeFidy, December 18, 2009, 11:53:47 AM

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TreeFidy

Hey all,

Maybe I'm not searching the site correctly, but I can't seem to find the topic discussed anywhere.  I'm wondering if the possibility for a hexaphonic pickup would exist beyond 6 strings.

Now hold on, I know what you're thinking.  "Current MIDI technology only exists for six strings, so anymore than that is impossible."  But I've been reading in other forums and on Graphtech's website that it's possible for two piezo pickups to share one channel (http://www.graphtech.com/kbase.html?ArticleID=15).  I've also seen that on Frameworks Guitars website concerning their 7 string MIDI model (http://www.frameworks-guitars.com/nylon.html).  In those articles, they do state that it is possible, but in a MIDI context, only six of the MIDI'd strings will sound at one time, which means only one of the shared piezo pickups will trigger the MIDI module.

My question to you good people is this:  Since there is no MIDI tracking happening on the VG99, does this "shared piezo" phenomenon not affect the VG99?  Because of the absence of actual MIDI tracking in the VG99 processor (with the exception of the MIDI-out function), will the two shared strings sound when played simultaneously?  If so, is it then possible to have more than one set of shared strings?

Brent Flash

Huh?   :o

I am not sure what you are wanting to do, but if you put two GK-3 pickups on a guitar and run that into two VG-99s you can trigger 12 MIDI channels. But two MIDI channels would trigger at the same time because they would be on the same string. But if you had a 12 string guitar (not a traditional 12 string but a guitar with 12 independent strings on a great big wide neck) you could have 12 independent MIDI channels with two GK-3 pickups going to two VG-99s.

Is that what you are talking about? ???

TreeFidy

Actually, I was referring to using a seven string with only one hexaphonic pickup.  Perhaps, here is a better explanation:

- using piezo pickups would allow all 7 strings to have their own signal.

- we know that only six strings can trigger at a time, but the explanation given at those websites I mentioned earlier claims that all seven can be MIDI'd with only one Hexaphonic circuit.  To do so, you must split the strings into 5 individual channels + 2 strings on one shared channel.  This means that 5 strings will function normally, but of the remaining two strings on the shared channel, only one will sound at a time.  This doesn't mean that the signal for one of the strings will be forever useless.  Judging by their explanation, they are implying that the string that was most recently strummed or plucked will sound.  I am assuming this means that MIDI will work on the 2 strings sharing the channel, just as long as both strings are not played simultaneously (this is implied when they claim guitar players can play bass lines with shared channel with no problem).

- Their explanations were meant for MIDI modules, which are limited to 6 strings because of current technology.  The VG99 does not use MIDI to trigger it's internal sounds.  If no MIDI tracking is used, would ALL 7 strings sound simultaneously?

If I understand it correctly, MIDI is limited to 6 strings only.  Because only 6 signals can be processed at a time to trigger the MIDI sound module, there is an inherent limit to 6 channels for MIDI tracking.  But because our VG99 works like a stomp box and not a MIDI module, there would be no need to process the signal for MIDI triggering, hence (theoretically) removing the limit to process only 6 signals at a time.

Where my confusion is lies with the information of where and how the signals are processed.  Assuming you had 2 strings on a shared channel, do both signals even reach the VG99 unit, or are they "filtered" out at the hexaphonic preamp?  Even if it reaches the VG99, are both sounds on the shared channel "filtered" then, or would both signals sound as a result of the lack of MIDI translation?


I'm really sorry, guys, if I'm confusing anyone, but I hope this helps to explain it better.

Brent Flash

#3
You have to think of the VG-99 as a unit that has 6 audio inputs. (NOT INCLUDING THE REGULAR GUITAR INPUT) Those 6 audio inputs are fed by the six humbucker pickups in the GK-3. The 13 pin connector has the six audio feeds (plus regular guitar signal) in it. It does not carry MIDI.

Brent Flash

#4
With piezos... I guess you could combine two or more together somehow and feed one of the six audio feeds in the VG-99.  ???

admin

#5
At preset, all Guitar processors with GK 13 pin Inputs have 6 channels max.

A Luthier could make an instrument with more than 6 Piezo pickups, and a multichannel preamp could be fabricated to interface to a third party multichannel PC interface ( MOTU 828, Firepod, etc)  - then run a VST Plug in  - one per string, as Dark Fire does running multiple VST instances of Guitar RIg , under Ableton Live.

Shoot me a PM if you are interested.

vanceg

I have seen Graphtech based pickup systems which have up to 14 Piezo elements in them.  This is not all that hard to build. But the point still remains that any MIDI gear that uses the 13 pin standard is going to be limited to processing 6 channels at a time. But, there is no reason your instrument couldn't use two 13 pin connectors!  That makes it quite easy to set an instrument with up to 12 strings up to have separate pitch-to-midi conversion on each string.  I have surely seen this done on WARR guitars and sticks. 
If you wanted to get really elaborate, I could most surely have someone build you a custom preamp which would support 7 channels of piezo signal...but again, what would you use to do your pitch to MIDI conversion?  All of the devices on the market are based on using 6 strings. 

I like the idea of simply combining two strings....that's likely the simple method here:  Run two Piezo signals into one channel of the Piezo preamp....that way, you are still using standard off-the-shelf pitch to MIDI conversion devices and the standard 13 pin interface.

TreeFidy

Hey Fellas,

Thanks for all the info.  Being quite honest, I just couldn't let go of my 7 string.  I've got big hands, so the wider neck has been a comfort for me to play.  I run a GK-3 on it right now, but since I got the VG-99, I haven't played my standard setup since (and I don't think I'll be going back to it either...).  It certainly feels awkward to have a string on a guitar that I can't use, but then again having the VG-99 may not require the use of that 7th string.  If anything, I may just order a set of 7 piezos from graphtech and try the setup they recommended.  Not sure how its going to turn out, but I'll let everyone know how it goes!  Thanks again for all the help!

vanceg

If I can get to it, I'll hit the Graphtech folks up for advice at the NAMM show. Their engineers are normally pretty responsive.  I bet if you just hook two Piezos into the low E string input on their Hexpander system, this would work quite well. Of course, you will suddenly have two strings on one 'channel" of the VG-99 and that could get a little weird.

Vance

TreeFidy

vanceg,

that would be great and I appreciate the help.  I'm not too concerned about playing the low b and e strings at the same time.  In fact, I don't think I've ever used a seven string to riff like most heavy metal guys.  Besides the neck fitting my hands so well, I've learned to incorporate that low B for basslines and extended couterpoint while playing solo fingerstyle.  Since I won't be playing both strings at the same, I don't think I'll have a problem with channel sharing.

Thanks again for the help!

vanceg

I did speak briefly to one of the techs/support folks at Graphtech about this while at NAMM.  He hadn't heard of anyone doing this (running both the 6th and 7th string piezo elements into the 6th string input on one of their Hexpander devices.  He said he could imagine it causing some overload due to their just being additional signal on that one channel, and that Pitch to MIDI converters may get very confused if they were presented with two pitches at once, but that conceptually - it might be worth a try. 

It sounded to me like 'we sure wouldn't guarantee that it would work, and I could see where there might be problems, but it could work - try it out'

I'd think you'd need to do some more detailed investigation, perhaps have someone with a Graphtech system try routing two of their strings together (on a six string) and see what happens. 

ALL THAT SAID: proceed at your own risk!  (but ain't that always the case?)


Quote from: TreeFidy on December 29, 2009, 12:20:31 PM
vanceg,

that would be great and I appreciate the help.  I'm not too concerned about playing the low b and e strings at the same time.  In fact, I don't think I've ever used a seven string to riff like most heavy metal guys.  Besides the neck fitting my hands so well, I've learned to incorporate that low B for basslines and extended couterpoint while playing solo fingerstyle.  Since I won't be playing both strings at the same, I don't think I'll have a problem with channel sharing.

Thanks again for the help!

nix808

sup Tree Fiddy
My pickup supplier, Ubertar can make you a pickup for 7 string.
No need to mix 2 strings into one channel.
I am happy to make my guitar to MIDI software track another string for you.
Here is Ubertar's website->
http://www.ubertar.com/hexaphonic/
... and the page where my converter is here at VG->
https://www.vguitarforums.com/smf/index.php?topic=10492.0
If you are interested, let me know.
Cheers
Rock and Rock my boat, as long as you don't rock and rock my boat!hehe