Looking for a Thesis subject

[ACS]

Thank you guys for all your input.

I've made an overview, to show to my thesis-partner tomorrow to discuss the possibilities.

Dude, that looks great!!  Best of luck - the possibilities are endless...  I'd buy one

Found this - thought it might be just what the Doctor ordered...  All the hard work's done for you! :lol:

http://www.stewmac.com/shop/Electronics,_pickups/Pickups:_Guitar,_electric/1/Graph_Tech_Ghost_Pickup_System_for_Guitar.html

[carrejans]

Artificial? Oh heck yeah, definitely not as pretty as using hex PU. It would certainly have at least some glitches and "jumps", especially when pulling off double stops and such. My idea behind this is not to make it control digital patches of different guitar models or any sorts of realistic instruments, but rather use it as an input for an (perhaps virtual-)analogue synth where excellent tracking and guitar-y feel aren't that important. It would certainly need a bit different approach to playing also, just like EHX's monophonic synth pedals and octavers, where you'll just mess up the tracking if you don't take it gentle and back off the tone knob.

The problem with frequency analyzing is that it needs a pretty long sample of the signal, so that sets the "refresh rate" of this device quite low (not influencing oscillator fidelity, as I mentioned before). The sixth string is 83Hz, so one would need to aim lower than that. Then again, I might be way off here, I'm not familiar with the exact algorithms.

---------
Jimbo

- Actually I'm not so interested in making it control an analogue synth. I prefer to use it like ACS suggested (using all kinds of effects on user-selected strings)
- I am not that familiar with frequency analyzing in practice with audio. So, I have no idea if Gausmarkov's and yours idea of it, is really possible; and will be fast enough to not have a delay.

[ACS]

Thank you guys for all your input.

I've made an overview, to show to my thesis-partner tomorrow to discuss the possibilities.

Dude, that looks great!!  Best of luck - the possibilities are endless...  I'd certinaly buy one

Found this - thought it might be just what the Doctor ordered - six discrete outputs...  All the hard work's been done for you! :lol:

http://www.stewmac.com/shop/Electronics,_pickups/Pickups:_Guitar,_electric/1/Graph_Tech_Ghost_Pickup_System_for_Guitar.html

[carrejans]

Thank you guys for all your input.

I've made an overview, to show to my thesis-partner tomorrow to discuss the possibilities.

Dude, that looks great!!  Best of luck - the possibilities are endless...  I'd certinaly buy one

Found this - thought it might be just what the Doctor ordered - six discrete outputs...  All the hard work's been done for you! :lol:

http://www.stewmac.com/shop/Electronics,_pickups/Pickups:_Guitar,_electric/1/Graph_Tech_Ghost_Pickup_System_for_Guitar.html

Haha, yeah thank you.

[carrejans]

I never heard or played with a piezo pickup.
Is it always acoustic-sounding? If it is so, that would be a pitty.
The normal piezo pickups, is it just one piezo sticking on the wood of your guitar?

ACS, the ones you posted have indeed 6 outputs; and can be usefull. But too bad you have to replace your bridge saddles.

I have to investigate more on this piezo system.

[JimRayden]

I never heard or played with a piezo pickup.
Is it always acoustic-sounding? If it is so, that would be a pitty.
The normal piezo pickups, is it just one piezo sticking on the wood of your guitar?

ACS, the ones you posted have indeed 6 outputs; and can be usefull. But too bad you have to replace your bridge saddles.

I have to investigate more on this piezo system.

Yes, piezo sounds more acoustic because it preserves the high and low frequencies magnetic ones don't. But that's a good thing. If you've got all of your frequencies intact, it'll be easy to simulate different pickups and guitars with filters and such. Yes, the piezo pickup for acoustic guitar is just one piezo stuck to the inside of the body, for electric guitar it's built into bridge saddles, I have yet to see a different implementation.

Let me warn you that the hex-pickup thing is very similar to the Gibson digital guitar concept.

---------
Jimbo

[carrejans]

Let me warn you that the hex-pickup thing is very similar to the Gibson digital guitar concept.

Oh, man, it was too good to be true.     
But the Gibson has a breakout box, with 6 jack outputs. Nice for in the studio; but not for the avarege player at home or on stage.
So, it is still different than the Gibson concept. I want to have a box, with a LCD, so the user can chose to put effects on the strings he likes.
Any idea what kind of pickup system Gibson uses? Magnetic or piezo?

[JimRayden]

Both, apparently. I'm sure the hex output is from a piezo bridge.

---------
Jimbo

[carrejans]

We handed in our proposal to a professor. Now, we have to wait... Let's hope...
Thank you everyone for helping out.
I will keep you updated if we are allowed to do this.

[carrejans]

Ok, so the professor of DSP thinks our idea is great for a thesis. So, we are probably allowed to do this.
One of the teachers of analog electronics, who is a guitar player, doesn't think it is a good idea. He thinks if we do it with filtering, the signal will sound really bad; and if we use the other option (piezo or opto pickup) there is no advantage to the Roland GK system.
Do you think there are advantages? (I have never used the Roland GK system)
Plus, he thinks that if we use the piezo, the sound will not sound as great as if you would use your humbucker. (I never used a piezo either)

[SeanCostello]

Plus, he thinks that if we use the piezo, the sound will not sound as great as if you would use your humbucker. (I never used a piezo either)

The sound will be horrible with piezo. This is where the research part of your thesis comes in. What sort of filter can you apply to make the signal sound good? My guess is that it would be some sort of lowpass filtering, combined with a delay-based comb filter, where the delay is based on the distance between the bridge and the humbucker. The humbucker will not be a "point source" pickup; it has a wider magnetic field, so the comb-filtering will not be as sharp as with a single-coil pickup with a tight magnetic field.

Theoretically, the piezo pickups will have all of the harmonics present from the string, so you can modify them to your heart's content. If this doesn't hold true, a paper that discusses this would be useful as well.

Ideally, you could come up with a variety of filters, to emulate various pickups and pickup combinations. Perhaps you could figure out some sort of analysis method, to capture the impulse responses of different pickups in different locations. I don't know if anyone has come up with an analysis technique for this yet, since it wouldn't work with the standard microphone/speaker combo used in capturing impulse responses for convolution.

Sean Costello

[rotylee]

http://www.gibson.com/RobotGuitar/guitar.html
look at the tail piece.....
isolating each string has been done.

manual
http://www.gibson.com/robotguitar/robot-guitar-manual.pdf
pg24


i think low latency networking of music signals is a good thesis.
like yamahas mlan. digital transport...

And it is likely we will see Yamaha expanding on mLAN with work on Open Generic Transport. Read up on it here:
http://linuxaudio.org/en/press/lud53-Audio_Libre.pdf

4 Feb 2003 The Institute of Electrical and Electronics Engineers Standards Association (IEEE-SA) has begun work on a standard to extend the reach of musical instrument digital interfaces (MIDI) by allowing for MIDI transmission over Ethernet and IEEE 802.11 (TM) networks. This promises to give those in the music field significant new creative possibilities for composition and performance.

The new standard, IEEE P1639 (TM), "Standard for Transmission of Musical Instrument Digital Interface (MIDI) Data within Local Area Networks: Distributed MIDI - DMIDI," should be finalized by the end of 2003. It will retain backwards compatibility with existing hardware and software under the original MIDI specification, which is now 20 years old.

http://standards.ieee.org/announcements/p1639app.html
http://www.midi.org/about-midi/ethernet.shtml
http://openmuse.org/transport/mip_intro.html


cat5 to microphone connector
with a specially designed switch/hub

the dice 2 chip is good place to look
http://www.tctechnologies.tc/
https://dev.tctechnologies.tc/tcat/tags/release/public/latest/docs/firmware/DICE_Firmware_DevEnv_User_Guide.pdf
https://dev.tctechnologies.tc/tcat/tags/release/public/latest/

[carrejans]

Here is an update.

A while ago, it was ok for the school to do this project. Then when we handed our proposition in, they said "no", because we didn't have a supporting company. After discussing a while, we are allowed to do this project, if we find a professional musician, who will cooperate. So the search can begin. 

Here is an updated version of our proposal:

PROCESSING ELECTRIC GUITAR OUTPUT FOR EACH STRING SEPARATELY

The ultimate goal with this product:

The user will be able to choose an audio effect for each string of his guitar separately. On the black box he can choose the effects on each string separately with the help of an interface (LCD + buttons).
He is able to:
- pitch shift each string separately (no need for tuning your guitar for alternate tunings)
- put delay (echo) on only those strings, chosen by the user

Possible extensions:

- more possible effects can be chosen (phaser, chorus, reverb, distortion, ...)
- an implemented effects loop (some effects sound better after the preamp of the guitar amplifier)
- six output jacks for each string separately (can be interesting in studios, to put every string on a separate track of the mixer)
- ...

Two possible ways of dividing the guitar signal into 6 separate outputs

Possibility 1:   
- keeping original pickups
- connection between guitar and the processing box with normal instrument cable
- dividing the audio signal into the 6 different signals inside the box
- processing the separate signals inside the processing box (pitch shifting, delay, ... with the help of DSP)

Possibility 2:   
- using/making pickups with outputs for each string
- using/making a cable for the 6 separate signals
- or putting ADC's inside the guitar/pickups and sending the signals via Ethernet or USB cable
- processing the separate signals inside the processing box (pitch shifting, delay, ... with the help of DSP)

Solutions for the problems of splitting the signal

Possibility 1:   
- problem: same note on different strings have the same frequency
- possible solution: each string has its own sonic personality. The fundamental frequency will be the same, but each string has different amounts of each of the overtones that accompany a fundamental. So we pick out a fundamental from the signal and pick out its overtones; then we have to look at the relative amplitudes.
- another problem: this sonic personality will be different on each guitar and probably each string brand
- possible solution: before using the box, the user has to "train" the software to calibrate the system (cfr. voice recognition software)

Possibility 2:    
- problem: when using a normal magnetic pickup, each polepiece will not only pick up the vibrations of its corresponding string
- possible solution 1: isolating each string and its accompanying polepiece from the others
- possible solution 2: using piezoelectric pickups (these are built into the saddles of the strings)
- possible solution 3: using optical pickups (fairly recent development (1969) that works by sensing the interruption of a light beam by the string)

Advantages & disadvantages

Possibility 1:   
+ no extra pickup has to be placed, originals can be used
+ no special cable is necessary, normal instrument cable can be used
- theoretical possible; but is it possible in practice? Difficulty?
- user needs to train the software
- will the sound loses its character? Will it sound a bit artificial?

Possibility 2:   
- extra pickup needs to be placed
- requires a special cable
+ easier to implement in software
+ no need to train the software
+ no excessive filtering; sound will be less artificial

I am now making an email for some musicians. I also want to explain the advantages to the existing Roland system. The problem is, I never used such a system. So, I want to ask you, is it correct what I state here?

The Roland system always uses MIDI. They don't use piezo-pickups, but MIDI-pickups. It generates MIDI-signals, that will trigger samples in the synth. So, you don't hear your guitar, but samples.


Thank you for all your help. I will keep you updated. And let's hope that possibility 1 is really possible and won't sound artificial. It would be nice to have this system, without having to make adjustments to your guitar.

[ACS]

Hi there, as far as I'm aware the Roland hex system controls a synth via midi - but the pickup system is not piezo based.  There are however other systems that use a piezo pickup, but again to control a midi synth.  So both what you've come up with here, and what I suggested earlier in the thread are original ideas as far as I know!

Again, good luck with it - it's great idea either way, with some outstanding possibilities.

Aidan

[levon]

Hey man great project ild definatly be keeping an eye on this.


go laser/optical sensors...!!! that would be wicked

[carrejans]

This week I will give an update on this. Subject has changed a bit.

Now, I am looking for hex pickups (non MIDI ones). Do you know any?
Thank you...

[widdly]

The only midi pickup I can think of is the RMC ones and the ones factory fitted the parker midi fly guitars.  All the rest are hex pickups that are converted to midi by an external unit. 

The standard for hex pickups is the 13 pin output.  This is used by Rolands gk-2a, gk-3a, the graph-tech piezo ones, the yamaha ones, and the godin guitars factory fitter ones.  Some of these use piezos elements in the bridge and some use little humbuckers.

The 13 pin output contains 6 separate audio feeds, a mixed feed and some control signals.  There is a pinout here...

http://johnp.net/projects/guitar-synth/roland-pinouts.html#13pin

The 13 pin sockets are hard to find.  The easiest option is to buy a 13pin cable and cut it in half to bust out the 6 seperate feeds.  You will need to supply the hex pickup with power though as they usually contain preamp circuits.

[hoopshot]

I had a thought this morning, and I know I won't have the bandwidth to follow up on it. I don't know of any system that works this way currently.

You could add a piezo pickup for each string to an electric guitar and then used the outputs to tell you the fundamental frequency and attack point for each string. This may give you enough information to intelligently filter the analog output so that each string could be treated separately in an analog effects system (or digital if you prefer). The upside is that you could use the real pickups to create the sound, as opposed to filtering the piezo output to model an electric pickup sound. You could create really cool envelope follower effects with this (where each note was tracked well). You could also do separate distortion on each output of the filter to get a sound like a hex pickup running into 6 different distortion boxes. If you are interested in this, try to find the Craig Anderton QuadraFuzz article (I can't remember if it was in Guitar Player or his book). It makes a cool sound because the modulations between strings aren't amplified by the distortion.

I think with onboard circuitry you could send the string information via a serial channel, and you might be able to just use a stereo 1/4" jack to connect the guitar to the offboard system. What do you think? 

--Will

[widdly]

The bit where you "intelligently filter the analog output so that each string could be treated separate" sounds difficult (impossible?)....especially in the analog domain.

If you want "real" hexaphonic pickups, check out this...

http://musicthing.blogspot.com/2008/08/six-output-pickups-for-stereo-guitars.html

[hoopshot]

The bit where you "intelligently filter the analog output so that each string could be treated separate" sounds difficult (impossible?)....especially in the analog domain.

Yes, I was thinking of using a DSP for this. You could have adaptive filters controlled by the frequency info from the piezo pickups. It wouldn't be easy, but he was looking for a thesis subject. People above were talking about analyzing and filtering the analog output, which would be much harder without knowing the frequency beforehand. It would still not work if you played the same note on two different strings -- that case really needs a hex pickup with independent outputs.