Guitar Of The Xxi :d

[Yannovitch]

Hello, ( French so excuse me for the mistakes )

My mind is not in peace actually ... I've a lot of idea of customization and sound experimentation.

In the electronics area, I would do a lot of things.

I would like to submit you my idea, so the good electronic geeks can say me what's possible to do, and what's not.

The guitar on which I would like to do all this work is a PRS Soapbar SE.

The PRS have in factory configuration 2 P90 from PRS.

I would like to have a lot of mic, to have a lot of possibility to choice the sound.

I would like to have in this order the pickups :

Hexaphonic Piezo on a Floyd (it's possible, I'm sure) => P90=> Benedetti Rock or ToneZone=> EMG89 => a sustainer driver

Do you think it's really too much ? I have a lot of place

after that,

pickups => knob to activate or not each pickup => pots for the volume of each pickup

Do you think it is a bad idea to do that (alteration of the signal...?) ?? It would be amazing to dozen the level of each pickup independently!

Or is it possible to have a switch which can "choice" the volume of the micro I want to control, and to send the signal of the pickup I've choice on the pot, but with the other mic continuing to fonctionning ( with a endless pot for example, I've no idea if it s possible or not ...)

If that's possible, why not do the same for the tone ...

so we have pickups => independent control of the activation of each pickup => independent control of the volume of each pickup => independent control of the tone of each pickup => general volume => jack.

In parallel, I would like to implement the sustainer system.

How can I do that ? Is it possible ?? Do I must remove the EMG because it's not the same output signal level and because it's an active pickup ??

And, I'm enough crazy to think I could do more

I'm thinking for a long time of the ability to control from the guitar the level of the different adjustment of an effect, or of the possibility to control a VSTi to use the computer like a filter for the sound of my guitar.

I would like so to implement a midi controller in my guitar like this http://www.ucapps.de/midibox16e.html

So I would implement 7 or 8 knob with 7 or 8 luminescent pot ... Is it just a bad idea ?? If not, how could I do that ??

Yep, have a good day and let's

[Yannovitch]

Just a little up :D

[curtisa]

I would like to have in this order the pickups :

Hexaphonic Piezo on a Floyd (it's possible, I'm sure) => P90=> Benedetti Rock or ToneZone=> EMG89 => a sustainer driver

Do you think it's really too much ? I have a lot of place

So you're going to retrofit a floyd to a PRS? Guess you could do it, but it wouldn't be cheap. I certainly wouldn't want to attempt it myself, make sure you locate a good, reputable luthier to do the work!

And that's 3 pickups, a hex piezo AND a sustainer - I reckon you'd struggle to fit so many pickups on the guitar.

pickups => knob to activate or not each pickup => pots for the volume of each pickup

Do you think it is a bad idea to do that (alteration of the signal...?) ?? It would be amazing to dozen the level of each pickup independently!

One volume pot per pickup, 3x pickups plus the piezo makes 4 volume pots all up. Do you have room on the guitar for all of them?

It could be done, but with so many volume controls for each pickup you'd need to do it actively, ie with a battery-powered on-board mixing system, which may not be such a stretch as you'll need the battery for the piezo anyway.

Or is it possible to have a switch which can "choice" the volume of the micro I want to control, and to send the signal of the pickup I've choice on the pot, but with the other mic continuing to fonctionning ( with a endless pot for example, I've no idea if it s possible or not ...)

If that's possible, why not do the same for the tone ...

Now this is getting really complicated! Yes, this could be done too, but again you're looking at active control of the pickup selectors and volume controls. And an "endless pot" is raising the bar even further because now you're talking on-board digital control. That's a lot of work in there!

I'm thinking for a long time of the ability to control from the guitar the level of the different adjustment of an effect, or of the possibility to control a VSTi to use the computer like a filter for the sound of my guitar.

I would like so to implement a midi controller in my guitar like this http://www.ucapps.de/midibox16e.html

Nah, too much. You'll never fit it all in the guitar. You'll never get enough batteries in the guitar to power everything for any reasonable amount of time, let alone all the control systems you want aswell.

In my experience, having a super complicated control system in a guitar is more of a hinderance than a help. When I did a similar thing with one of my old Yamahas I found myself spending more time fiddling with the controls than actually using the instrument. I'd start with the separate volume controls idea myself and see how far you can take it before moving on to something more adventurous.

[Geo]

In my experience, having a super complicated control system in a guitar is more of a hinderance than a help.

I agree. Sometimes Strat controls are too much for me!

Edited February 15, 2007 by Geo

[Yannovitch]

Yes, I agree too, however, I want precisely know which of this control is useful, and which not ...

We can imagine a box to give a phantom power by a trs jack to all of the chips, and there, the problem of the battery is resolved, or just place a lot of battery in the guitar, and find chips with ULV.

I agree that for example, this guitar : Guitar with on board digital control has too much control on board.

When you say

Nah, too much. You'll never fit it all in the guitar. You'll never get enough batteries in the guitar to power everything for any reasonable amount of time, let alone all the control systems you want aswell.

In my experience, having a super complicated control system in a guitar is more of a hinderance than a help. When I did a similar thing with one of my old Yamahas I found myself spending more time fiddling with the controls than actually using the instrument. I'd start with the separate volume controls idea myself and see how far you can take it before moving on to something more adventurous.

I think too that I can't have a clear control of the parameter of my effects and preamp and guitar if I have too much disponible control pot.

But I know that "customized" control pot, sort of multi push pull, exist, and with this type of pot, I can have only 2 or 3 pots, where I needed 6 or 8 before ... Do you see what I mean ??

And which pickup do you think I can remove ? My goal is to have a total versatily of sound, and I think so that a piezo or an optomic system http://www.optomik.com/ is useful because I can say that I want only distorsion on one or two cords, a flanger on another, ... just like the new Gibson digital ! http://www.gibson.com/DigitalGuitarNew/gibsonDigital.html

And the EMG 89 can give me "aggressive" sounds, the Benedetti a smooth sound of Tele/Stratocaster, and the Dimarzio Tonezone, a more warm and medium sound, like the old Gibson LP ... Moreover, this Mic, particulary the EMG, have a strenght output signal, so I can do easily tapping on my guitar

And the sustainer is here to give me the opportunity to modify the parameter with pot, without playing, or to have more harmonics ...

Which pickup is preferable to remove ??

Edited February 15, 2007 by Yannovitch

[Yannovitch]

I've found this

http://www.precisionmusictech.com/gmax.htm

What do you think about ??

I think, that I can realize myself with a uC and 2 pot+LCD&knob a system to control all the configuration of mic like this, but what about the sound ?

Edited February 15, 2007 by Yannovitch

[curtisa]

Yes, I agree too, however, I want precisely know which of this control is useful, and which not ...

We can imagine a box to give a phantom power by a trs jack to all of the chips, and there, the problem of the battery is resolved, or just place a lot of battery in the guitar, and find chips with ULV.

True, but then the guitar becomes limited by the power supply box you have to plug it in to. If you wanted to use this guitar in a performance via a wireless system it's out of the question. If you're quite happy to use the instrument in private or onstage with a lead all the time, then that's less of an issue, but you will have to make sure you have the power supply box with you all the time. Personally I would never use a TRS jack for phantom powering as there is the risk that you'll plug the lead in with the power supply switched on, and short out the power supply as the lead is inserted into the socket. I'd be using something like an XLR connector where you cannot accidentally short two or more pins together as you plug the lead in.

I think too that I can't have a clear control of the parameter of my effects and preamp and guitar if I have too much disponible control pot.

But I know that "customized" control pot, sort of multi push pull, exist, and with this type of pot, I can have only 2 or 3 pots, where I needed 6 or 8 before ... Do you see what I mean ??

Yes, you can get dual concentric pots (never seen triple concentric pots before), but they are mondo expensive, and typically only a custom production item. Other alternatives are pot on top/rotary switch on bottom, but again they're expensive and hard to come by.

That said, you may be able to scavenge some parts from dead car radios or television sets.

And which pickup do you think I can remove ? My goal is to have a total versatily of sound, and I think so that a piezo or an optomic system http://www.optomik.com/ is useful because I can say that I want only distorsion on one or two cords, a flanger on another, ... just like the new Gibson digital ! http://www.gibson.com/DigitalGuitarNew/gibsonDigital.html

And the EMG 89 can give me "aggressive" sounds, the Benedetti a smooth sound of Tele/Stratocaster, and the Dimarzio Tonezone, a more warm and medium sound, like the old Gibson LP ... Moreover, this Mic, particulary the EMG, have a strenght output signal, so I can do easily tapping on my guitar

And the sustainer is here to give me the opportunity to modify the parameter with pot, without playing, or to have more harmonics ...

Which pickup is preferable to remove ??

Which pickup you leave out is entirely up to you, and also dictated by exactly how much room on the guitar there is for all your pickups. Personally I think you're being too adventurous in trying to extract so many different sounds out of one instrument, however I'm more than happy to be proved wrong! I've got no idea how much room there is between the bridge and neck of your PRS for the pickups, but from what I remember of that model line there's only room to fit 1 bridge humbucker, a single coil middle pickup, and a neck humbucker. That leaves pretty much no room for a sustainer (which has to go in the neck position). The piezo floyd system will look after itself, but you've still got to retrofit the bridge into the PRS which wouldn't be an easy or cheap task.

I've found this

http://www.precisionmusictech.com/gmax.htm

What do you think about ??

I think, that I can realize myself with a uC and 2 pot+LCD&knob a system to control all the configuration of mic like this, but what about the sound ?

I've got no idea what you can expect in the way of sounds that can be extracted from such a switching system, but it certainly looks like what you're after. It certainly gives you just about any permutation of humbucker/split/phase/series/parallel combination you could ever want, although I notice that it still relies on the existing selector switch to select the pickup combinations - I'm guessing you need to program all your sounds into "banks", each bank containing 5 pickup combinations (if you have a 5-way switch), and if you need further permutations you change to the next bank of 5 combinations.

If you can program your own code and CPU you've got the scope to include or omit anything you want

Cheers,

Curtis.

Edited February 16, 2007 by curtisa

[Yannovitch]

Which pickup you leave out is entirely up to you, and also dictated by exactly how much room on the guitar there is for all your pickups. Personally I think you're being too adventurous in trying to extract so many different sounds out of one instrument, however I'm more than happy to be proved wrong! smile.gif I've got no idea how much room there is between the bridge and neck of your PRS for the pickups, but from what I remember of that model line there's only room to fit 1 bridge humbucker, a single coil middle pickup, and a neck humbucker. That leaves pretty much no room for a sustainer (which has to go in the neck position). The piezo floyd system will look after itself, but you've still got to retrofit the bridge into the PRS which wouldn't be an easy or cheap task.

You're right, I've only room for 2 humbucks & 1 single coil normally.

But I said in my first message that I want to implement a vibrato system, and I've enough space to win 5 cm or more if I do that.

If you can program your own code and CPU you've got the scope to include or omit anything you want

You're right, but I'm asking myself what's the most ergonomic way to do that, because I want to have more space and less pot & knobs ... I've not enough money and knowledge to implement a tactil LCD for example, but if I do all with knob, it's less expensive to buil without uC.

So if you have any suggestions ...

Yes, you can get dual concentric pots (never seen triple concentric pots before), but they are mondo expensive, and typically only a custom production item. Other alternatives are pot on top/rotary switch on bottom, but again they're expensive and hard to come by.

Can you give me some websites where I can find what you say ?

True, but then the guitar becomes limited by the power supply box you have to plug it in to. If you wanted to use this guitar in a performance via a wireless system it's out of the question. If you're quite happy to use the instrument in private or onstage with a lead all the time, then that's less of an issue, but you will have to make sure you have the power supply box with you all the time. Personally I would never use a TRS jack for phantom powering as there is the risk that you'll plug the lead in with the power supply switched on, and short out the power supply as the lead is inserted into the socket. I'd be using something like an XLR connector where you cannot accidentally short two or more pins together as you plug the lead in.

You're not alright, because the power-wire-less is in experimentation actually

You're right about the danger which the TRS jack represents but my goal is to have not too much "not standardized" things in my guitar. It's more easy to buy 10 jack of 5 m, even if it's TRS jack, than to build 10 XLR to Jackx2 ... You see what I mean ?

But the problem is bigger than a TRS or XLR : if I want to implement the MIDI system who has been describe in my first message, I must have midi in and midi out in my guitar ... So or I build proprietary connector, or I have a multicore cable and I plug an XLR for the phantom power, 1 jack for the sound (and if I want to have separate sound, I must have 7 jack or more ), a midi in and a midi out.

Or the best I plug only the XLR for the phantom power during pauses, and this alimentation reload Lithium Ion battery, and the audio and midi is wireless.

Concerning the midi wireless system, I know it exist. The Audio too ...

[curtisa]

You're right, I've only room for 2 humbucks & 1 single coil normally.

But I said in my first message that I want to implement a vibrato system, and I've enough space to win 5 cm or more if I do that.

No, you won't gain anything by changing the vibrato system - the scale length of your instrument has to stay the same. If anything, you may find you'll lose some space due to the positions of the pivot points on the floyd being reasonably far forward compared to a stop tail or Strat-type bridge

You're right, but I'm asking myself what's the most ergonomic way to do that, because I want to have more space and less pot & knobs ... I've not enough money and knowledge to implement a tactil LCD for example, but if I do all with knob, it's less expensive to buil without uC.

So if you have any suggestions ...

Maybe a rotary encoder (or multiple rotary encoders) with an integrated push-switch in the shaft? You'll need to implement it with uC though, say a PIC micro or an ATMEL micro. Doing anything like this with descrete logic chips is not practical.

I think whichever way you look at it, the only way to do everything you're hoping to achieve with the instrument, you'll have to do it with a uC - there's no way you'll be able to fit it all inside the guitar and power it otherwise.

Can you give me some websites where I can find what you say ?

Omeg offer dual concentric pots and dual concentric switch-pots, although I think they will only manufacture such parts if you place a minimum order of 100 units.

http://www.omeg.com.

Google searching reveals a number of places where you can get dual concentric pots if you only want certain pot values.

You're not alright, because the power-wire-less is in experimentation actually

OK, but wireless power isn't available yet

You're right about the danger which the TRS jack represents but my goal is to have not too much "not standardized" things in my guitar. It's more easy to buy 10 jack of 5 m, even if it's TRS jack, than to build 10 XLR to Jackx2 ... You see what I mean ?

I would have done the phantom powering with an XLR at both ends of the lead - you still have to plug the lead in to the power supply, and that carries the same risks as plugging into the instrument with the TRS plug. If you were to go for XLR's at both ends, you can just use a regular microphone cable which shouldn't be any harder to find than a regular guitar lead.

But the problem is bigger than a TRS or XLR : if I want to implement the MIDI system who has been describe in my first message, I must have midi in and midi out in my guitar ... So or I build proprietary connector, or I have a multicore cable and I plug an XLR for the phantom power, 1 jack for the sound (and if I want to have separate sound, I must have 7 jack or more ), a midi in and a midi out.

OK, so you want a regular guitar signal, MIDI, and possibly phantom power. You'll need 2 poles for the guitar signal, 1 pole for the phantom power, and a minimum of 3 poles for the MIDI (MIDI does use a 5 pin plug as standard, but only 3 of the pins are actually wired up). You can get 6-pin XLR plugs, which would cover all your signal and power supply requirements in a single connector.

Or the best I plug only the XLR for the phantom power during pauses, and this alimentation reload Lithium Ion battery, and the audio and midi is wireless.

Concerning the midi wireless system, I know it exist. The Audio too ...

Even if you want to transmit all the signal wirelessly, you'll still need on-board power for the MIDI, piezo pickups, and the MIDI/audio radio transmitters - lots of batteries!

I wouldn't let the problem of implementing "non standard" components into the guitar bother you - based on the amount of customisation you're talking about, the fitting of an XLR plug in the guitar is the least of your worries!

[aidlook]

I read the first post..but couldn't bother to read the whole thread..

But I'd start of with DPDT miniswitches for activating each individual pickup.

Then concentric tone/volume knobs for all of them.

alternatively I'd get push/pull pots for pickup on/off as well as volume or tone control.

[Yannovitch]

Okay,

Thank you for taking time for my crazy idea

I read the first post..but couldn't bother to read the whole thread..

But I'd start of with DPDT miniswitches for activating each individual pickup.

Then concentric tone/volume knobs for all of them.

alternatively I'd get push/pull pots for pickup on/off as well as volume or tone control.

I thought of push/pull pots for the volume and tone control, and a switch for each pickup, but I don't want to have 10 knobs & pots on my guitar, like here http://web.mac.com/doug.theriault/iWeb/Site/Instruments.html

After discussion with friends, I think more and more to use a DsPIC ( mix of DSP & PIC) to have 10 inputs in the CAN of my DSPIC, and to make a real digital wireless transmission, and to have the capabilities to control all of the combination of pickups and tone and volume for each pickup with only two ledring pot.

But I'm asking myself about the respect of the signal.

The ADC (Analog to Digital Converter) is in 12 bit resolution, whereas the resolution of the signal in the rest of my audio parc is 24bit ...

And the DsPIC Development board is expensive ...

The wireless option is the only option I consider now, because the utility of this complicated electronic customisation is to have separate output.

If I have 3 or 4 pickups + hexaphonic (so 6 output) piezo, it makes 10 output. I can't use an XLR connector, and I don't want to have 10 jack plugged in my guitar

So if I must have a not standard output, it's preferable to consider the wireless option.

But it's hard to transmit 1 mbits min by wireless with fiability... Maybe the Ethernet ?? But encapsulation over Ethernet is too hard for the room available :S

So, with wireless capabilities, the problem is the battery ... But my idea was to use the phantom power to reload the battery ... It's not a good idea? Too hard ??

My project begin to enter in the reality, it's cool !

[curtisa]

I thought of push/pull pots for the volume and tone control, and a switch for each pickup, but I don't want to have 10 knobs & pots on my guitar, like here http://web.mac.com/doug.theriault/iWeb/Site/Instruments.html

Why 10? Even assuming a separate output for 3 pickups and a piezo that's only four volume controls. If you were to implement hexaphonic output in the piezo aswell, you'd go nuts trying to alter 6 more volume controls for each string output, irrespective whether you had 6 separate volume knobs or one multi-function volume encoder controlled by a uC.

After discussion with friends, I think more and more to use a DsPIC ( mix of DSP & PIC) to have 10 inputs in the CAN of my DSPIC, and to make a real digital wireless transmission, and to have the capabilities to control all of the combination of pickups and tone and volume for each pickup with only two ledring pot.

But I'm asking myself about the respect of the signal.

The ADC (Analog to Digital Converter) is in 12 bit resolution, whereas the resolution of the signal in the rest of my audio parc is 24bit ...

And the DsPIC Development board is expensive ...

You're doubling up the amount of research and development if you incorporate AD/DA into the audio signal - by doing so you'll have to develop some kind of DAC at the receiving end of the guitar output.

The AD in those PIC's won't be the highest quality in the world, but it may be usable. I haven't heard of anyone doing audio DSP with a PIC - I think you'll find a dedicated DSP chip is preferred for that sort of thing.

Using only two encoders will make controlling all your pickups and outputs quite tricky, esepcially if you're planning on using the guitar in a performance. Imagine playing the instrument and at the same time scrolling through a bunch of menus to find one volume parameter for the 3rd string piezo output, and you accidentally scroll past it, and lose your place in the performance because of it

If it were me I'd still prefer to have 1 knob per pickup (4), rather than 1 knob per output (10), or two multi-function knobs.

The wireless option is the only option I consider now, because the utility of this complicated electronic customisation is to have separate output.

If I have 3 or 4 pickups + hexaphonic (so 6 output) piezo, it makes 10 output. I can't use an XLR connector, and I don't want to have 10 jack plugged in my guitar

So if I must have a not standard output, it's preferable to consider the wireless option.

But it's hard to transmit 1 mbits min by wireless with fiability... Maybe the Ethernet ?? But encapsulation over Ethernet is too hard for the room available :S

So, with wireless capabilities, the problem is the battery ... But my idea was to use the phantom power to reload the battery ... It's not a good idea? Too hard ??

Sounds to me like you're starting to talk yourself out of the idea now!

I've got no idea how you'd implement multichannel audio over wireless ethernet, but I know that it's a lot of work to start from scratch - it's not the sort of thing I'd want to DIY, waaaaay too complicated

Honestly, I admire your passion and tenacity for wanting to do such an adventurous project, but I'd take a couple of steps back from the ideal and focus more on what is practical. I've done similar things to you aswell in the past - I very nearly completed a DIY version of the Mesa Boogie Triaxis preamp many years ago, even to the point of having all the CPU code developed. But it eventually got to a point where I was aiming way too high and achieving very little in return, so I stripped it all down and made a simple valve preamp with a bunch of knobs and no CPU control whatsoever.

What about thinking a little laterally here? What about having a guitar with 3 pickups (1 volume knob for each one) and a hexaphonic piezo (with one volume knob for all 6 outputs), and then doing all the fancy blending and combining away from the guitar, with a foot controller or something, like what Roland do with their VG systems? If you're not wanting to use such a customised guitar in a performance, what about running all the multiple outputs into a small mixer and doing all your processing that way?

[Yannovitch]

Hello curtisa

Yhank you for your quick answer, it's really constructive to come write and read in this forum

Why 10? Even assuming a separate output for 3 pickups and a piezo that's only four volume controls. If you were to implement hexaphonic output in the piezo aswell, you'd go nuts trying to alter 6 more volume controls for each string output, irrespective whether you had 6 separate volume knobs or one multi-function volume encoder controlled by a uC.

Using only two encoders will make controlling all your pickups and outputs quite tricky, esepcially if you're planning on using the guitar in a performance. Imagine playing the instrument and at the same time scrolling through a bunch of menus to find one volume parameter for the 3rd string piezo output, and you accidentally scroll past it, and lose your place in the performance because of it

Yeah sure, but after a long discussion yesterday, my friend thought that the best thing to do is maybe to have a memory of all the possible combinaison, with 5 knob to recall the most used combinaison, but with all the controls fully adjustable if I want.

Do you not agree ??

The AD in those PIC's won't be the highest quality in the world, but it may be usable.

Yeah, it's my problem, with the 12 bit resolution ... But having a 24bit resolution is really very expensive to implement and develop.

I haven't heard of anyone doing audio DSP with a PIC - I think you'll find a dedicated DSP chip is preferred for that sort of thing.

The DSPic have a dedicated DSP with audio codec built inside, and it's more powerful that all the PIC or AVR.

You're doubling up the amount of research and development if you incorporate AD/DA into the audio signal - by doing so you'll have to develop some kind of DAC at the receiving end of the guitar output.

I've got no idea how you'd implement multichannel audio over wireless ethernet, but I know that it's a lot of work to start from scratch - it's not the sort of thing I'd want to DIY, waaaaay too complicated

No, it's honestly fully realisable, I don't want to implement over wireless ethernet, but over wireless OR over ethernet ... I don't want my guitar to become a wifi access point I will use the same principe that the UHF transmission which is implemented in the UHF Sennheiser or Shure, and if it's too complicated, the principe of a Radio transmission ... The DSPic for example have a multiplexer, so I make the ADconversion, and I send all the 5ms a different input to the wireless module for example, or I use the same principe that for the telecommunication, with a modulation which allow me to send 10 canal at the same time.

If I find a really secured way, I have just to do the inverse processus at the reception, and if I want, I can have a full digital system, with no more conversion D/A, for example with implementation of an ADAT link in the receptor (but it begin to be very, very, very complicated =o)).

and then doing all the fancy blending and combining away from the guitar, with a foot controller or something, like what Roland do with their VG systems? If you're not wanting to use such a customised guitar in a performance, what about running all the multiple outputs into a small mixer and doing all your processing that way?

I want to have the minimum of work to do with my feet, it's really more complicated for me to switch and control from my feet that from my hands, and when I want to control FX with my foot, switching within the menu with the knob to have the chorus and not the delay under my feet, is the bes thing to have a poor performance for me:D

I want to use the guitar in the studio and in live performance ... I want my guitar to allow me all the experimentation I want to do ... I want to create a new type of instrument (mode megalomaniac )

Honestly, I admire your passion and tenacity for wanting to do such an adventurous project, but I'd take a couple of steps back from the ideal and focus more on what is practical. I've done similar things to you aswell in the past - I very nearly completed a DIY version of the Mesa Boogie Triaxis preamp many years ago, even to the point of having all the CPU code developed. But it eventually got to a point where I was aiming way too high and achieving very little in return, so I stripped it all down and made a simple valve preamp with a bunch of knobs and no CPU control whatsoever.

I admit I'm a little bold, and I agree that all this stuff begin to be more complicated than I expected.

If I could do without uC & cie, I will be the first to do it, but I want to have a really simple way to control all this ****

But I'm fed up to cancel all my project, because it's too difficult ... Heeeelllppp me please, and if it's good at end, before making copyright I will give you the full cpu code and the electronic PCB

Edited February 19, 2007 by Yannovitch

[curtisa]

Yeah sure, but after a long discussion yesterday, my friend thought that the best thing to do is maybe to have a memory of all the possible combinaison, with 5 knob to recall the most used combinaison, but with all the controls fully adjustable if I want.

Do you not agree ??

OK, this is starting to make a little more sense to me now. So you could conceivebly have the "look" of a 5-way switch/volume/tone, but the actual function of those controls is a lot deeper than that. You'll probably find you'll need some kind of display built into the guitar so that you can see exactly what parameters you're adjusting with the encoders at any given time. 2x16 backlit LCD would be my preference.

The DSPic have a dedicated DSP with audio codec built inside, and it's more powerful that all the PIC or AVR.

Hmmmm...dunno. Do you have a specific DSPic part in mind? Datasheet?

No, it's honestly fully realisable, I don't want to implement over wireless ethernet, but over wireless OR over ethernet ... I don't want my guitar to become a wifi access point I will use the same principe that the UHF transmission which is implemented in the UHF Sennheiser or Shure, and if it's too complicated, the principe of a Radio transmission ... The DSPic for example have a multiplexer, so I make the ADconversion, and I send all the 5ms a different input to the wireless module for example, or I use the same principe that for the telecommunication, with a modulation which allow me to send 10 canal at the same time.

If I find a really secured way, I have just to do the inverse processus at the reception, and if I want, I can have a full digital system, with no more conversion D/A, for example with implementation of an ADAT link in the receptor (but it begin to be very, very, very complicated

Oh, I'm sure it's fully realisable, but I'm just questioning if it's cost-effective, and worth your time as a DIY project, especially the wireless side of things

Wired ethernet sounds like an interesting idea, but the cables invovled are a little on the "light duty" side of things for my tastes - I wouldn't want to take an ethernet cable with me on stage! Maybe ethernet with a different cable, something more rugged?

Another thing to consider - are you sure you want to do all this customisation to your PRS? With all the extra control circuitry you're wanting to install, there's no way you're going to fit it all inside the guitar without routing more cavities into the body. Have you got a cheap, crappy guitar that you could experiment on first without worrying too much about ruining the body and/or finish while you develop all these systems?

[Yannovitch]

loooool

Do you have a specific DSPic part in mind? Datasheet?

Yep, the best of the 30 MIPS dsC, the 6014A http://www.microchip.com/stellent/idcplg?I...ocName=en024766 , but the idea of having a 12 bit ADC do not enjoy me. I'm considering the "true" DSP now, because they have true 24 bit ADC ... But it's more complicated and with less possibilities. Because, I still want to have the midi controller implemented in my guitar (I'm bold, I know ) and normally, the DIY controller I want to use (uCapps http://www.ucapps.de/ ) is based on PIC 18Fxxx, and the DSPIC is very similar to the PIC so I can use the DSPIC to do my pickup controller+ADC to wireless AND the MIDI controller, the DSPIC can do multitask and the DSP oftently not ...

But I can too use specialized ADC, like the ADC of Analog Device like this http://www.analog.com/en/prod/0,,760_789_AD1871%2C00.html, and then attack a DSPIC or a good AVR like ATMEGA 128.

WHAT do you think about this idea ? A DSPic or specialized ADC/DAC and uC+DSP ??

but I'm just questioning if it's cost-effective, and worth your time as a DIY project

The only things which are very expensive is the pickups, and the developpment board but the developpment board of a DSPIC for example can serve for developpment of many others applications on DSPIC and PIC , and the other things is rarely expensive ( a ADC cost max 5 $, a uC max 7$, and I can have several DSPIC for free)

The time ... You know I have in my life, the time for my study, around 35 hours, and the rest (especially the nights ) is for my passion and my friends

Another thing to consider - are you sure you want to do all this customisation to your PRS? Have you got a cheap, crappy guitar that you could experiment on first without worrying too much about ruining the body and/or finish while you develop all these systems?

Yeah, it was the first thing that I have considered but the PRS is a SE model that was not specially expensive, and I've not a lot of money to buy many experimental guitars ... If I find in flea market a 1$ guitar, why not ..

With all the extra control circuitry you're wanting to install, there's no way you're going to fit it all inside the guitar without routing more cavities into the body.

I must have more cavities in the body for all the electronics, even if I want to have just one more pickup, so it's not a problem

[Yannovitch]

Hello,

Some more idea.

I thought of the DSP and ADC, because of the 12 bit resolution of the DSPIC and the 100ksps with 16 inputs, where as I have 200ksps with 8 inputs.

But if I use only 8 inputs, maybe 10, the shannon theorem is OK and so it's only the 12bit resolution which is a problem.

I'm afraid of the 12 bit resolution with the dithering problem & cie, but I think it will be good if I don't want to do too much.

So I think I will stay with the DSPIC solution, because if I buy a developpment board, I can do a lot of other things, and the developpment board for the DSP from T.I or Analog Devices is really expensive, and 8 ADC in 24bit/96khz too, with the power problem too

I don't find how resolve the problem of the battery and the power source for all this things.

Someone can say me how to extract properly the 48 V from a phantom power to reload all the battery ???

[curtisa]

Hello,

Some more idea.

I thought of the DSP and ADC, because of the 12 bit resolution of the DSPIC and the 100ksps with 16 inputs, where as I have 200ksps with 8 inputs. But if I use only 8 inputs, maybe 10, the shannon theorem is OK and so it's only the 12bit resolution which is a problem

Well, here's another thing to consider - because you're running multiple audio outputs at once, and doing an A/D conversion on each one simultaneously, you're going to have to multiplex the A/D conversion process, which means that your net sample rate will drop by a factor of the number of signals being converted. The dsPIC may have 16 analog channels, but it only has one A/D on board, and it can only do one conversion at a time.

For example if you were doing 8 channels at 200ksps, each channel's sample rate would then be 200/8 = 25ksps. Nyquist's theorem then dictates that the highest reproducible frequency would be half the sample rate, or 12.5Khz. Obviously performance gets worse as you add more inputs, especially as the PIC cannot run at 200ksps with more than 8 channels. I think a 25kHz 12 bit digital system is going to sound pretty bad - I reckon you need to reconsider your options with this one.

The PIC also has to handle all the MIDI and controls aswell, and it really has to do it without causing glitches in the digital audio side of things. If you have the PIC handling the digital audio and you're also adjusting MIDI paramaters with a control knob, the last thing you want is for clicks and pops appearing in the audio output as the PIC code starts branching off to service routines to handle the MIDI and peripheral interfaces. The digital audio has to take priority above anything else, and I doubt the PIC has the horsepower to handle 8-10 channels AND digital interfacing aswell.

Is there any reason why you can't consider using a PIC purely as a controller? Does it have to be digital audio? You can still do all your switching and volume control in the analog domain, eg CMOS4066 analog switches and digital potentiometer chips, leaving the PIC to handle the MIDI and interfacing quite easily.

[Yannovitch]

Hello,

Thank you for your very constructive answer !!

If we see the ADC diagram of the DSPIC we see effectively that we have 16 physically inpu multiplexed into one ADC, and not 16 simultaneous ADC, I've not seen that :S.

And you're right when you say

I think a 25kHz 12 bit digital system is going to sound pretty bad

, I'm worrying too about the quality of the sound.

But I don't know a lot of chip not very expensive which can have the horsepower for 10 serial inputs from 10 simultaneous 24bit 96khz ADC ...

Considering that, I think it will be maybe better to take an AVR32 which is a powerful uC and DSP, more powerful that a DSPIC (the most powerful DSPIC is at 40MIPS, the AVR32 is 210 MIPS at 150 Mhz), but without ADC integrated. I don't want to consider the TI or Analog Devices DSP, too difficult and expensive, and unuseful for the work I want to do. This will be a good option if I would have my effect board in my guitar, but I'm not crazy

The advantage of the DSPIC for me is to have all what I need integrated in one chip, to be not very difficult to program, like the 18Fxxx and to have a developpment board not very expensive, around 130 $ ( http://www.mikroe.com/en/tools/bigdspic/).

The advantage of the AVR32 is to be a very powerful system, with what I can do everything I want, and to have the compiler & cie free, but the developpment board is really expensive ( around 500 $), and it's really more difficult to program.

but as you say

I doubt the PIC has the horsepower to handle 8-10 channels AND digital interfacing aswell

, with the Atmel I will not have this problem.

An other thing to consider is that if I buy a big developpment board, I want to do a lot of other things with.

I know that for normal uC, universal board exist like this http://www.mikroe.com/en/tools/unids3/, what about the compatibility of the STK1000 developpment board with other chip than the AVR32 ? Is it retro compatible with the 8 bit AVR ? If I buy a 500 $ board, and that I can't use the 8bit AVR, grrrrr

Is there any reason why you can't consider using a PIC purely as a controller? Does it have to be digital audio? You can still do all your switching and volume control in the analog domain, eg CMOS4066 analog switches and digital potentiometer chips, leaving the PIC to handle the MIDI and interfacing quite easily.

But why not have one chip by function, yep ... I'm asking myself of having just the PIC for the MIDI controller, and having an other chip which can took all the audio treatment. But I don't know how powerful must be the chip if I want to treat 10 24bit/96khz inputs simultaneously, and simultaneously have the output ...

I don't want to have a super big board, and having a guitar with more electronics than wood .

I want to have a minimum of Analog to Digital and Digital to Analog conversion,I think for that, less is better =o) And so if I can have a digital wireless transmission, and at the reception, a digital treatment by the effect, it's perfect

It's for that I don't want to have many CMOS & cie ...

An advantage of the PIC too, is that the midi controller that I want to have is based on PIC, if I must rewrite all the code for the ATMEL, I will have so much work to do

The last point is the battery !! Many chip need more battery, and I think it will not be a good idea to have several laptop battery in my guitar

Edited February 22, 2007 by Yannovitch

[curtisa]

Considering that, I think it will be maybe better to take an AVR32 which is a powerful uC and DSP, more powerful that a DSPIC (the most powerful DSPIC is at 40MIPS, the AVR32 is 210 MIPS at 150 Mhz), but without ADC integrated. I don't want to consider the TI or Analog Devices DSP, too difficult and expensive, and unuseful for the work I want to do. This will be a good option if I would have my effect board in my guitar, but I'm not crazy

Nah, forget it. If you want multichannel audio at the sample rates and bit depths you're talking about, you're going to have to consider dedicated multiple ADC's and a DSP, with a CPU controlling the whole lot. The all-in-one solutions offered by Microchip and AVR simply can't do it, the processing power required to do it all seamlessly is too much for 1 chip. If that AVR you've highlighted doesn't have intergrated A/D, you'll have to use an external A/D chip to do it. You could do "pseudo A/D" in software with the AVR, but the processing overhead would be too great for it to work properly over 10 channels.

Effectively you're talking about installing a 10-channel soundcard (with a digital transmitter) into a guitar, and even the cheapest ones on the market only do it using dedicated chips.

Wavefront Semiconductor seem to have low cost A/D's and 8-channel DSP's, check out their range:

http://www.wavefrontsemi.com/index.php?products

But why not have one chip by function, yep ... I'm asking myself of having just the PIC for the MIDI controller, and having an other chip which can took all the audio treatment

My feeling is that this is the ONLY way to do it - one chip per function.

But I don't know how powerful must be the chip if I want to treat 10 24bit/96khz inputs simultaneously, and simultaneously have the output ...

Well if you consider using a DSP, the processing overhead in the uC drops dramatically. Potentially you could use a 40mHz PIC to "run the show", and leave the DSP to look after the really difficult stuff, ie the audio.

The last point is the battery !! Many chip need more battery, and I think it will not be a good idea to have several laptop battery in my guitar

This will be difficult too, yes. I suspect that you won't be able to use regular 9V batteries, they simply wont have the capacity to run it all for very long. You really may have to consider something like a laptop battery pack, though I don't really see that as being such a drawback - when you consider the size, weight and capacity of modern laptop battery packs they're pretty good in comparison to a bank of "C" cells or 9V batteries.

[Yannovitch]

Hello

I'm concentrating now on the battery problem.

I search DIY project with a good system to reload the laptop battery, or other battery ...

If you have some schematics, it will be great

Since this morning I've looked around me, search for the price of the developpment board of each chips, and I think the best for me, with my knowledge, is to go with dsPIC, it's the more easy to program, and with the cheaper developpment board.

But an other dsPIC , the best of the dsPIC33 (the other was one of the best of the dsPIC30) http://ww1.microchip.com/downloads/en/DeviceDoc/70165E.pdf because the main problem is the speed of conversion, and this chip can do up to 500 ksps, so with 10 inputs, I have 50ksps at 12 bit, normally (quoted from datasheet) :

Analog-to-Digital Converters (ADCs):

• Up to two ADC modules in a device

• 10-bit, 1.1 Msps or 12-bit, 500 Ksps conversion:

- 2, 4 or 8 simultaneous samples

- Up to 32 input channels with auto-scanning

- Conversion start can be manual or

synchronized with 1 of 4 trigger sources

- Conversion possible in Sleep mode

and

22.1 Key Features

The 10-bit ADC configuration has the following key

features:

• Successive Approximation (SAR) conversion

• Conversion speeds of up to 1.1 Msps

• Up to 32 analog input pins

• External voltage reference input pins

• Simultaneous sampling of up to four analog input

pins

• Automatic Channel Scan mode

• Selectable conversion trigger source

• Selectable Buffer Fill modes

• Four result alignment options (signed/unsigned,

fractional/integer)

• Operation during CPU Sleep and Idle modes

The 12-bit ADC configuration supports all the above

features, except:

• In the 12-bit configuration, conversion speeds of

up to 500 ksps are supported

• There is only 1 sample/hold amplifier in the 12-bit

configuration, so simultaneous sampling of

multiple channels is not supported.

In 12 bit, without a multiplex of inputs, I can't so have my 10 inputs, in 10 bit yes, but I will not try to play with 10 bit conversion. With 40 MIPS, maybe I can try with multiplex and one ADC at 24 bit/96 khz like the chip from wavefront, or TI, or analog device, no ?? But if I must do a multiplex in input, I prefer use the inside built 12 bit ADC. Our CD is in 16 bit, and it was less at the beginning, it's not horripiling !! And I've less chip in my guitar, it's better ...

Effectively you're talking about installing a 10-channel soundcard (with a digital transmitter) into a guitar, and even the cheapest ones on the market only do it using dedicated chips.

Yep, I had not thinked of that, but it's true, I'm building a soundcard

Aaaah, it makes me nervous, I don't want to have a treatment of sound, I just want to take and send the signal !!

[curtisa]

I'm concentrating now on the battery problem.

I search DIY project with a good system to reload the laptop battery, or other battery ...

If you have some schematics, it will be great

Sorry, I don't have any schematics for battery charger systems. Just do a Google search and see what you can uncover

The 12-bit ADC configuration supports all the above

features, except:

• In the 12-bit configuration, conversion speeds of

up to 500 ksps are supported

• There is only 1 sample/hold amplifier in the 12-bit

configuration, so simultaneous sampling of

multiple channels is not supported.

This is still your weakest link - you still have to multiplex to obtain the highest bit depths for the number of channels you're talking about. In between each conversion of each channel, you have to ensure you have sufficient processing time to send the previous sample serially to the transmitter, service any calls to the encoders, apply any digital volume control the the A/D data, service push buttons and switches, drive the LCD display, and run the MIDI. All without introducing any glitches in the audio. Even at such high processing rates, I still think you're trying to squeeze too much into the PIC.

Microchip expressly state on the website and datasheet that the dsPIC is primarily intended as a "signal controller" ideally suited to motor control. They make very little or no mention of high quality audio performance, I think that's still the domain of specialised A/D's and DSP's, and for very good reason. They may share the requirement of an A/D, but there is world of difference between the output of an analog speed sensor and an audio signal.

Aaaah, it makes me nervous, I don't want to have a treatment of sound, I just want to take and send the signal !!

Another reason why I'd prefer to see it done with the proper A/D's and DSP's, or indeed without any digital transmission at all!

[Yannovitch]

Ok ... If you're really sure it's not a good idea, even if it's just for the beginning, have you some DSP in idea which can be good for what I want to do, at the lowest price and with the max speed ???

The DSP from TI is expensive and complicated to program, and that's the same for the DSP from Analog Device. Maybe it's a good idea to use the ATMEL AVR32 instead of the dsPIC ?? It's a really powerful chip !

DO you think it's a really bad idea to want to begin on dsPIC ? It's a DSP and uC with 80 instructions ( in RISC ! ) , that's not too big, but I'm not a uC NERD , I'm at my beginning, and I'm afraid to spend a lot of money, and can't do what I want to do , on a linux kernel on AVR32 for example.

And you can do more than you think on a DSPIC

The digital transmission will take me less resources than a reconversion with DAC. And concerning the midi controller, it's only the core which is based on the pic, (normally a PIC18F452 but it's adaptable to a dsPIC) not all the stuff is done by the PIC. The digital volume and digital tone control can be done by the DSP of dsPIC entirely in one cycle, and it treat not an adjustment of the ADC but a numeric data .

I'm not asking for playing a video on a touchscreen lcd (even if it will be really coooool ) but just to use a 2x16 LCD ... If I write a really good library for that, in assembler and not in C, it will be enough little code to not overflow ...

On the schematics of ADC

we can see we have a buffer so all not the data is not continuously sended .

It's clear that the dsPIC will not allow me all my crazy idea, but I prefer to try with less is more than too big... At my beginning ! In one or two years, when I will know how to write a good code for DSP, and that I will have more money, I will try to have fun on big DSP , but now , I'm a poor student

[curtisa]

Ok ... If you're really sure it's not a good idea, even if it's just for the beginning, have you some DSP in idea which can be good for what I want to do, at the lowest price and with the max speed ???

The DSP on offer at Wavefront Semiconductor looks like pretty good value. Check that link I posted a lttle further up.

DO you think it's a really bad idea to want to begin on dsPIC ? It's a DSP and uC with 80 instructions ( in RISC ! ) , that's not too big, but I'm not a uC NERD , I'm at my beginning, and I'm afraid to spend a lot of money, and can't do what I want to do , on a linux kernel on AVR32 for example.

Not at all, although if it were me just starting out on PIC coding I'd probably start with the 16F or 18F range - there are plenty of kits and free software available to burn the chips. If you consult the datasheet for the Wavefront DSP you should be able to work out exactly how fast you need to provide it with instructions, and from there you can work out your required processor speed. You may find that the dsPIC is overkill and you can do it with something much lower-specced.

[badsnap]

Well, let me throw in my two cents. I once modified a guitar, in a very simple way compared to what you are suggesting, and these were my results. I rewired the electronics (two HB's) in the following fashion.

A 3 way switch for each PU wired front single/HB/rear single

A 3 way switch for neck/both/bridge

A phase swapping switch for the neck/bridge PU's.

I found that I realistically could produce about 4 distinctive sounds. The other combination were hard differentially perceptable to MY ears. So I hard wired the combinations to a 2 way switch front(or rear) single and HB and a 3 way for neck/both/bridge. I kept the phase switch but it really only does any good in conjuction with 1 other setting.

It was a good idea and experiment but all the coolness was taken away by the reality.

Are you sure you want to try this on a PRS. You run a high risk of ruining the instrument. I would suggest that if you are going to perform this experiment in engineering, and I suggest that you do just for fun and knowledge, that you buy an unrouted body and a neck to go with it and build this guitar from ground up! You may be onto something here but is it worth potentiall destroying the PRS in the process?

Personally, it sounds like a lot of work to dial in the sounds you want, and there are plenty of good effects untis that wil do the same thing at very reasonable prices.

I truely hope you do end up developing a unique and wonderful instrument.

Being predominently a studio player (actuall demo's, I know too many great players and I let them perform the actual final tracks) I have several guitars, each one different. Each guitar has it's purpose. Simple to operate and they give me the sounds I need. When we play live, I am far more accomplshed and comfortable behind the drum kit, so I have no need for a "super guitar".

Peace...Rog

[Yannovitch]

Hi every body,

I was skiing this last week, excuse me to be late

Thanks for your answers.

I will see in details the DSP so, and I will try to not build a supratechno guitar but a supersounding guitar

I will return here, when my project will be more advanced in conception and realisation.