Cycfi Six Pack Project - Hexaphonic Pickup Project

Started by Elantric, May 24, 2013, 04:33:28 PM

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Elantric


http://www.cycfi.com/projects/six-pack/

Hexaphonic Pickup Project


04-02-2013 09:54 PM

Hi!

I designed and built the carbon-fiber-bamboo guitar. Currently, I use DiMarzio Injector pickups. On my next iteration of the prototype, I would like to experiment on hexaphonic pickups for hex processing.

The Cycfi Six Pack Project is an ongoing Open Source Hardware project for the development of an active hexaphonic pickup system designed for hex processing. The pickup has six low impedance coils. The hex pickup is active with six differential low-noise, low-power pre-amplifiers —one for each coil. It has the same footprint as the ubiquitous Strat single coil, with a very low profile: 8mm (0.3 inch).

As an Open Source Hardware project, all the designs (schematics, PCB layout, software, bill of materials, CAD drawings and source code) will be freely shared, 100% free.

I would very much love to hear your thoughts and gather ideas while the project evolves!


https://plus.google.com/103979734696864240228/posts

http://www.cycfi.com/projects/six-pack/




rolandvg99

THAT looks interesting. Looks like a pickup that could be flush mounted considering its active specs.
To V or not to V: That is the question.

My little Soundcloud corner

shawnb

My big question is what is the target application & enhancement over what I have.   Is it intended to feed Variax?  Roland?  FTP?  A general MIDI port?  If it is intended to provide additional flexibility to feed these technologies, that would be very helpful to know. 

It would also be very interesting to know whether it should 'sound' and 'feel' better in amp modelers such as Variax & Roland. 

What is the ultimate value add?   
Address the process rather than the outcome.  Then, the outcome becomes more likely.   - Fripp

Elantric

#3
My fear is many folks stumble upon the idea of hexaphonic guitar processing then neglect to search for prior examples and proceed to work in a bubble of mis belief assuming they are the first.

Roland mis marketing the GK13 cable as a MIDI cable does nothing to help in this matter and actually does great harm to their brand,fueling global misconception.

There remains a significant population of young generation guitar techies ill informed and not understanding hex guitar processing goes back  a Long long time.

https://www.vguitarforums.com/smf/index.php?topic=4213.msg29018#msg29018





I had the same conversation with Steve Ripley in 1980, since his custom guitar with stereo panning for each string was lifted straight from a 1978 Bartolini hex pickup wiring example note. Didn't stop him from selling the idea to Eddie Van Halen and Kramer , and move to Nashville with the money he made

shawnb

It could be a wonder product for guitar tech, if it:
  - had as-good-as or better mag pu performance than gk, and
  - had an approach/adapters for feeding Variax/Roland/Axon/FTP/5-pin midi
Address the process rather than the outcome.  Then, the outcome becomes more likely.   - Fripp

Elantric

#5
Upon first glance , using an array of 6 large single coils with a wide mag flux pattern will lead to severe adjacent string crosstalk and mis triggers during guitar to MIDI use.


djowel

Hi, I am the designer of the Cycfi Six Pack Project. I got this link from some traffic I am getting. Wonderful forum you have here!

Quote from: Elantric on May 25, 2013, 07:15:55 AM
Upon first glance , using an array of 6 large single coils with a wide mag flux pattern will lead to severe adjacent string crosstalk and mis triggers during guitar to MIDI use.

Well, first of all, the pickup is not designed for MIDI use. It's intended for hexaphonic DSP processing with one effect stream per string. Second my plan is to do intelligent phase cancellation, again using DSP processing. For the reasons above, I set my goal to have the utmost sonic performance for the coils without worrying about crosstalk at the pickup stage.

Virtual Madness

#7
Hi Joel, and WELCOME to VGuitar Forums!  :)

My name is Royce, and I'm happy to hear of your project. Congratulations on a great idea!

The sound samples at your site were interesting. The Hex pickup sounded so sweet and clear compared to the Strat and Les Paul samples. I liked the improvement that the "Hex on Stratocaster take two with 1000 turns and better electronics" sound sample showed. The 2000/3000 turns experiment will be interesting.

For what it's worth, I hope you'll keep the "Roland" community in the back of your mind somewhere, for different experiments somewhere down the road.

We really need a better Hex pickup to come along. I don't know sound wise if it can or should be different at all from the Roland GK pickups (GK-2a, GK-3) since the VG units were programed using these pickups, (perhaps Steve will chime in on this) but god knows we could use a better physical product.

What we need is a Hex pickup that comes in at least 2 models:

Model 1 - Fender string spacing

Model 2 - Gibson string spacing.

What would be even better, is if somehow the string spacing could be adjustable.

The other thing we could use, is a better design regarding the radius factor. What I would like to see, is a flat top pickup (no radius) that has "Individually Adjustable" magnetic polepeices.

I'd also like to see the pickup shortened (Strat single coil size or even smaller) by having the wires come down through the middle of the pickup rather than from one end.

You may have to maintain the thin width established by Roland to be able to meet the distance requirement from the bridge (The magnet should not be any further than 20mm away from where the string leaves the bridge saddles)

Here are some Roland GK Pickup Specs:

1. Each individual pickup on the Roland GK-2A measures 540 ohms

2. The optimum distance between the pickup magnet and each string is 1mm when each string
    is pressed down at the highest/last fret on the neck.

3. The maximum distance allowed from the bridge saddle to the pickup is 20mm

4. The minimum distance allowed from the bridge saddle to the pickup is 10mm

5. The pickup should be 15mm from the bridge if your using an acoustic guitar strung with
    Copper, Brass, or Bronze wound strings.

None of this will be of any use to you now, but maybe some day it will!

Cheers, and best of luck to you on your project. (I know i'll be watching/listening!)

Royce (Virtual Madness)
The greatest power in the universe is imagination!

djowel

Quote from: shawnb on May 25, 2013, 12:07:52 AM
My big question is what is the target application & enhancement over what I have.   Is it intended to feed Variax?  Roland?  FTP?  A general MIDI port?  If it is intended to provide additional flexibility to feed these technologies, that would be very helpful to know. 

It would also be very interesting to know whether it should 'sound' and 'feel' better in amp modelers such as Variax & Roland. 

What is the ultimate value add?

Hi shawnb,

The goal is neither MIDI nor amp modeling. There's already a lot of that in the market. The goal is primarily to experiment on new sounds instead of emulating existing ones. The ultimate goal is Acoustic Synthesis with feedback into the strings using magnetic drivers (e.g. like what's done in the Moog guitar --which is in general a polyphonic sustain system). Unlike the Moog guitar though (or the sustainiac), I'd like to go beyond infinite sustain.

djowel

#9
Quote from: Virtual Madness on May 25, 2013, 08:22:54 PM
Hi Joel, and WELCOME to VGuitar Forums!  :)

My name is Royce, and I'm happy to hear of your project. Congratulations on a great idea!

The sound samples at your site were interesting. The Hex pickup sounded so sweet and clear compared to the Strat and Les Paul samples. I liked the improvement that the "Hex on Stratocaster take two with 1000 turns and better electronics" sound sample showed. The 2000/3000 turns experiment will be interesting.

For what it's worth, I hope you'll keep the "Roland" community in the back of your mind somewhere, for different experiments somewhere down the road.

We really need a better Hex pickup to come along. I don't know sound wise if it can or should be different at all from the Roland GK pickups (GK-2a, GK-3) since the VG units were programed using these pickups, (perhaps Steve will chime in on this) but god knows we could use a better physical product.

What we need is a Hex pickup that comes in at least 2 models:

Model 1 - Fender string spacing

Model 2 - Gibson string spacing.

The other thing we could use, is a better design regarding the radius factor. What I would like to see, is a flat top pickup (no radius) that has "Individually Adjustable" magnetic polepeices.

I'd also like to see the pickup shortened (Strat single coil size or even smaller) by having the wires come down through the middle of the pickup rather than from one end.

You may have to maintain the thin width established by Roland to be able to meet the distance requirement from the bridge (The magnet should not be any further than 20mm away from where the string leaves the bridge saddles)

Here are some Roland GK Pickup Specs:

1. Each individual pickup on the Roland GK-2A measures 540 ohms

2. The optimum distance between the pickup magnet and each string is 1mm when each string
    is pressed down at the highest/last fret on the neck.

3. The maximum distance allowed from the bridge saddle to the pickup is 20mm

4. The minimum distance allowed from the bridge saddle to the pickup is 10mm

5. The pickup should be 15mm from the bridge if your using an acoustic guitar strung with
    Copper, Brass, or Bronze wound strings.

None of this will be of any use to you now, but maybe some day it will!

Cheers, and best of luck to you on your project. (I know i'll be watching/listening!)

Royce (Virtual Madness)

Hi Royce,

I'll surely keep that in mind. Thanks for the suggestion! What you say might be possible if there's sufficient interest. The constraints and requirements of such a pickup is not that difficult to satisfy.

Thanks for your interest in the project. I'll keep this forum posted on the developments.

aliensporebomb

This looks fantastic and very professional.  I've got guitars with radiuses from 10" to 20" so something that would be as easy as slapping a regular pickup form factor in there is attractive.

That being said, the Ripley Hex Guitar - that was going to be my next instrument around 1988 and I had already put money down on a really nice seafoam example when I was laid off.  Ouch.  I stayed with my Roland GR system another year and decided then that I needed a shred machine because surely that whammy was more interesting than foreward thinking guitar.  Hmmmm.  A weird episode.
My music projects online at http://www.aliensporebomb.com/

GK Devices:  Roland VG-99, Boss GP-10, Boss SY-1000.

djowel

#11
Hi!

After countless hours experimenting and iterating over the basic design, I think I've reached a point where I have something that I am actually finally satisfied with. Here now, let me present version 1.0 of the Six Pack Hexaphonic Pickup. The design is modular. Visible in the xray view below, the Hexaphonic Pickup actually contains three smaller dual active pickups sitting on a main board which contains no more than biasing electronics and a micro-miniature header connector.

http://www.cycfi.com/projects/six-pack/final-design/



Features:
  • Six low impedance coils (2000 turns, 450Ohms D.C. Impedance, flat frequency response, 20Hz-20kHz).
  • High performance, ultra low noise OPA209 (OPA2209, dual) differential Op Amps.
  • Single supply (4.5V to 36V).
  • Stainless steel height adjustment screws and springs.
  • Gold plated, 1 mm pitch micro-miniature positive lock connector (Hirose).
  • Premium 0.1% thin film low noise matched resistors.
  • Fender Stratocaster Profile (11.8 mm height excluding connector).

Elantric

#12

Address these points and you may have a LOT more interest here.

* Provide Six Discreet signal output paths  - one per string Seems you already have that covered.

* Implement a method for adjusting the string to string spacing once prior to installation.

QuoteGuitar String Spacing at Bridge (Narrow  to Wide)
(Observe there can be nearly a 1/4 inch difference in the string spacing at the bridge from guitar to guitar.)

Rickenbacker = 1.98 inches (50.29mm)

Gibson Tuno-O-Matic = 2.0625 inches (52.45mm)

Fender Import Strat  = 2.0625 inches (52.45mm)

Floyd Rose  =  2.070 inches (52.58mm)

Fender Jaguar / Jazzmaster / Mustang = 2.1875 inches (55.56mm)

Fender USA Strat  = 2.21875 inches (56.35625mm)
https://www.vguitarforums.com/smf/index.php?topic=8612.msg61762#msg61762


* Implement a method to adjust the height of each pickup pole piece,  to achieve consistent distance gap between top of each individual Pole piece and bottom of string for various different radius Fretboards (Vintage Fender  = 7.5" Radius, Gibson  = 12" Radius, etc.

* Verify the design implements minimal adjacent string crosstalk. Perhaps model the existing magnetic flux

http://www.integratedsoft.com/papers/techdocs/tech_5mx.pdf


djowel

Quote from: Elantric on June 05, 2013, 05:10:51 PM
Address these points and you may have a LOT more interest here.

[snips]

Makes perfect sense. I'll keep that in mind.

djowel

Hi,

Does anyone here know the cross-talk specs of the GK pickups in terms of db? Right now, I am getting -38db based on recent tests.

Thanks in advance!

Elantric

#15
Its rather crucial to measure adjacent string crosstalk with a properly setup GK-3 hex pickup

The GK-3 Hex Pickup MUST be located no more than 20mm away from the bridge saddles.
The GK-3 Hex Pickup Height MUST be located no more than 1mm away from the strings.

If the above physical GK-3 positioning during installation is not achieved, the measured Crosstalk performance WILL suffer. 

I recall greater than -45dB adjacent string crosstalk rejection is obtainable, ONLY if the above physical constraints are met during the GK-3 Hex PU installation. 

Details here:
http://www.roland.com/V-Guitar/howto.html

Of course its extremely necessary to achieve good adjacent string crosstalk rejection, as this directly impacts DSP Alt Tuning and Guitar to MIDI performance (fewer bad notes) 

mapperboy

elantric,
Re your reponse to djowel regarding the criticality of the proximity to bridge and string to GK-3 gaps...do you think it may be possible to attach some kind of pole piece extensions to the individual poles?
I ask this because I've been forever seeking a way to match/modify the built-in curvature (and it's limited 'adjustment') of a GK-3 to any of my guitars. With judicious cutting and fitting of many types of spacers as well as crafting a custom spring-loaded height adjustment system I always end up with either good #1 string gap, acceptable #3,4 gaps and too much gap on #6 or the reverse.
The Roland pickup shell curve has just too much radius!
If the #1, #2 and #5 and #6 poles themselves could be slightly extended by a couple of mm then I think the rather flat curve of my guitars (Ibanez ARZ and Rickenbacker 360) could be made to match the GK-3 and brought up to optimum install specs.
I'm thinking last ditch at this point...have you ever rehoused the entire little pcb with the pole pieces in a new custom shell?
Cheers in advance...
-mike     
"No such thing as spare time.
No such thing as free time.
No such thing as down time.
All you got is life time. Go!"
- Henry Rollins

Elantric

Measurement study comparing popular mag hex pickups



And Must Download this doc with pics comparing many Mag Hex Pickups by Roland, Yamaha, Fishman Tripleplay
https://www.vguitarforums.com/smf/index.php?action=downloads;sa=downfile&id=41

djowel

Quote from: Elantric on June 26, 2013, 03:48:14 PM
Its rather crucial to measure adjacent string crosstalk with a properly setup GK-3 hex pickup

The GK-3 Hex Pickup MUST be located no more than 20mm away from the bridge saddles.
The GK-3 Hex Pickup Height MUST be located no more than 1mm away from the strings.

If the above physical GK-3 positioning during installation is not achieved, the measured Crosstalk performance WILL suffer. 

I recall greater than -45dB adjacent string crosstalk rejection is obtainable, ONLY if the above physical constraints are met during the GK-3 Hex PU installation. 

Details here:
http://www.roland.com/V-Guitar/howto.html

Of course its extremely necessary to achieve good adjacent string crosstalk rejection, as this directly impacts DSP Alt Tuning and Guitar to MIDI performance (fewer bad notes)

Thank you, Elantric. FWIW, in my tests, I am getting -38 db without any extra effort (I have my hex-pickup at around 3mm from the strings). I will be attempting another experiment with smaller diameter magnets and coils plus mu-metal shielding around the coil (to minimize flux leakage).

Virtual Madness

Hi Joel,
Do you have a GK pickup to work with?

If not, I have an extra Roland GK-2A that I would be willing to loan you, if that would help.

Let me know.

Royce  :)
The greatest power in the universe is imagination!

djowel

Quote from: Virtual Madness on June 27, 2013, 05:30:54 PM
Hi Joel,
Do you have a GK pickup to work with?

If not, I have an extra Roland GK-2A that I would be willing to loan you, if that would help.

Let me know.

Royce  :)


Gee, thanks for the offer. I'll keep that in mind. I have a very old GK-1 somewhere in the closets in my studio, but I guess that technology is already quite old and wouldn't be up to par.

Virtual Madness

OK, just let me know if you change your mind.

Have a great weekend, Royce  :)
The greatest power in the universe is imagination!

musicman65

#22
I may be reading this wrong, but I think djowel is more interested in reinvention of hex analog synthesis....not creating a better hex pickup for COSM modeling/pitch to midi use.

His pickup due to its traditional location will be rich in harmonics which is the opposite goal of GK pickups. Relocation may yield good results, who knows.

The currently available hex breakout boxes can provide a similar experience with a GK minus the harmonic tone content.

I, for one, believe there is a small but viable market for aftermarket GK pickups with options for surface mounting, adjustable poles for height and radius, and under pickguard wiring. Available in Gibson and Fender spacing. Of course a replaceable cover in white, black, and cream would be perfect. I'd buy 3 for $100 - $120 each immediately.

For the emerging FTP market, an onboard signal splitter that provides the correct output for the FTP device would allow Roland and FTP co-existance.

I would think somebody could do well with this.

bd

djowel

Quote from: musicman65 on June 29, 2013, 12:03:24 PM
I may be reading this wrong, but I think djowel is more interested in reinvention of hex analog synthesis....not creating a better hex pickup for COSM modeling/pitch to midi use.

Almost right. Perhaps this article by Craig Anderton will make it clear: Put a Hex on Your Guitar - Pickup, that Is

It will not be analog synthesis. I will be doing DSP processing: one for each string. Of course, the pickup can very well be used for analog processing and synthesis as well.


abhijitnath

Quote from: musicman65 on June 29, 2013, 12:03:24 PM
I may be reading this wrong, but I think djowel is more interested in reinvention of hex analog synthesis....not creating a better hex pickup for COSM modeling/pitch to midi use.

His pickup due to its traditional location will be rich in harmonics which is the opposite goal of GK pickups. Relocation may yield good results, who knows.

The currently available hex breakout boxes can provide a similar experience with a GK minus the harmonic tone content.

I, for one, believe there is a small but viable market for aftermarket GK pickups with options for surface mounting, adjustable poles for height and radius, and under pickguard wiring. Available in Gibson and Fender spacing. Of course a replaceable cover in white, black, and cream would be perfect. I'd buy 3 for $100 - $120 each immediately.

For the emerging FTP market, an onboard signal splitter that provides the correct output for the FTP device would allow Roland and FTP co-existance.

I would think somebody could do well with this.

bd

I'd buy this in a heartbeat. On a (possibly) related note, has anyone tried rehousing a GK-3 in a symmetrical shape in line with the radius of their own guitars, or would this not work?