Modifying FTP for internal + piezos

Started by Piplodocus, June 01, 2014, 08:32:14 AM

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Piplodocus

Hello Folks,

I'm new here and wondered if you guys could help. I've got a Parker MIDIFly, the old one from about 2000 with the MIDI-Axe innards, not the new ones with 13-pin graph tech ghost/hexaphonic. It's not the fastest and best at tracking as obviously it's 15 year old computer tech in it, so I was looking at the FTP and fitting one inside. I have 3 questions about it...

1) Can I use my piezos? All Parkers have piezo saddles. In most cases these are commoned together, but in the case of the midi fly they are buffered (via a TL062 and a TL064C) on the underside of the bridge and sent separately down 6 wires to the current VirtualDSP board. I can therefore give the FTP 6 separate inputs at whatever level I like (I can make a mini board with trim pots if required). This is therefore a bit like splicing a Roland/Axon 13-pin to the FTP. I've seen these helpful posts here: https://www.vguitarforums.com/smf/index.php?topic=10103.0 and here https://www.vguitarforums.com/smf/index.php?topic=8413.0 but someone suggested in the second one it wasn't quite right and was lacking the 10% that made it seem seamless which makes all the difference. What's the latest on this? Has anyone got hexaphonic piezos working 100% instead of the Fishman hexaphonic? If I can avoid the extra pickup I'd be a lot happier. Especially as I've looked at where my hand sits and moves when playing, and my palm seems to constantly brush the area the FTP pick-ups "lump" sits.

2) How big is the board? Anyone got any dimensions of it?

3) Has anyone tried locating the D-pad controller elsewhere? can I de-solder it and mount it somewhere else? Are these just 4 (or 5) simple push momentary switches? So I could use any momentary switches and solder flying leads to the board? Or do I need this button?

4) Similar to 3) but for volume knob: Are the PCB pads big enough to solder to? Any idea what the volume knob is? Is it just a pot so I could replace it with a same value external pot? Or is it some kind of encoder thing?

5) Do I need the guitar/synth/both switch? I can't seem to see this on the Godin/Fender installs. If I have MIDI volume knob I can go between guitar and synth without it.

6) As a general FTP question how low does it go? I usually play down tuned a semitone or tone, and if I then put it in Drop-D the current MIDIFly detection only goes as low as D, so I can't get a bottom Db, or C out of it! I assume the FTP will recognise this still?

7) Any other useful info or things I should know?

Ok, I lied. It was 7 questions in the end! Thanks! :)

utensil

#1
Hi Piplodocus

Twas I that posted the comment about my feeling of 10% being off. I continued after that and updated the thread with a working triple play driven by 13 pin but also in the process I tried connecting the piezo's pickups directly to the FTP few points I found may help (mentioned in the thread u refer to https://www.vguitarforums.com/smf/index.php?topic=8413.0):

- Whether you have the piezo's connected directly to the ftp, or after a pre-amp once the signal is in the right range and a bit of time spent on this I would have to reconsider my statement of it performing worse. Without a more scientific test, I would say I can't notice a practical difference between the piezo driven ftp and the original. I've been using my Nylon string Godin with FTP from the Piezo's very happily.

- I've tried with RMC piezo's and Graphtech, Results mentioned in the thread, both are usable, can't speak for others but I'd imagine other piezo's should work similarly with varying output levels requiring one time adjustment.

- IMO , the FTP seems fairly good at taking any input for the expected string range and performing an accurate audio to midi conversion, I think the best way to proceed is to check the signal right after the piezo's into the FTP and if not too weak then you are good to go, otherwise will need to use a pre-amp which I'm assuming is probably in there for the midi conversion but not familiar with that system.I read somewhere that the Midifly uses fish man piezo's and I don't know which pre-amp etc.

- Didn't measure but the board pretty much occupies the entire plastic housing without the thickness. It includes a 3.7 lithium batter similar to whats used in cell phone which can be placed separately from the board for spacing consideration in the body.

- The guitar/synth switch is a slider switch internally which could be replaced or just left unused.

I'm planning on doing an internal conversion too with Piezo's as well but haven't gotten round to it. I would probably keep the original D-pad and lose the  guitar/mix switch as I don't use them at all, another issue is the charging, I plan on having a female usb port flush with the body for charging.

anyway hope it's of some help


Piplodocus

Quote from: utensil on June 01, 2014, 10:01:38 AM
- Whether you have the piezo's connected directly to the ftp, or after a pre-amp once the signal is in the right range and a bit of time spent on this I would have to reconsider my statement of it performing worse. Without a more scientific test, I would say I can't notice a practical difference between the piezo driven ftp and the original. I've been using my Nylon string Godin with FTP from the Piezo's very happily.

- I've tried with RMC piezo's and Graphtech, Results mentioned in the thread, both are usable, can't speak for others but I'd imagine other piezo's should work similarly with varying output levels requiring one time adjustment.

- IMO , the FTP seems fairly good at taking any input for the expected string range and performing an accurate audio to midi conversion, I think the best way to proceed is to check the signal right after the piezo's into the FTP and if not too weak then you are good to go, otherwise will need to use a pre-amp which I'm assuming is probably in there for the midi conversion but not familiar with that system.I read somewhere that the Midifly uses fish man piezo's and I don't know which pre-amp etc.

Great! If it seems 100% with the correct piezo levels in then I'm game to give it a try. I seem to be having another one of my mad plans, so didn't want to spend hours going to great lengths and butchering a brand new FTP to create something that wouldn't work as well as the original for a load of effort. Using the piezo bridge seems far more preferable though, and since I'd have a hole from the old MIDI electronics I may as well go the whole hog while I'm at it!

It appears the 9v voltage for the piezo comes from a separate wire. It's only a unity gain buffer though so I might still need some more gain. I can make a 9v powered additional op-amp board if I need to though assuming it all fits! :)

Piplodocus

#3
BTW, here's the underside of the MIDIFly bridge with it's buffers. Pins are (in no particular order) the 6 individual strings, the summed strings (for acoustic sound), +9V and Ground. As far as I can deduce it's piezo to inverting input with 4.7 M? in parallel with a cap to ground, and output commoned to the non-inverting in, which creates a unity gain buffer to the individual outputs. All these then go via another resistor to a common point, then out via another cap to the acoustic preamp...