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Midi Jazz Bass Build


Matt Golgotha
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I have taken the best part of 2 years to get the parts I need to put this project together and thought I'd document it (was initially going to be a Warwick thumb with midi).

The idea for the project was for the bass to be a mix of very modern electrics and very classic looks, but most important for it to be a straight out work horse that I wouldn't mind taking to any gig and it getting a few knocks and bumps.

I started with a brand new Fender CIJ 2008 62RI sourced from Stratosphere (ebay)

Edited by Matt Golgotha
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[quote name='Matt Golgotha' post='497604' date='May 25 2009, 10:02 PM']I then commissioned a neck from Warmoth (wenge Jazz neck, with zircote finger board, maple fret markers and a flamed walnut headstock veneer) which turned out better than I could have imagined.[/quote]

the plot thickens!

I'll be following this :)

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Following this I selected the John East J-retro (thanks to John for answering all my questions and a great product), which I mated with a pair of black Q-tuner BS Jazz pickups (thanks Erno) which combined are incredible, very open and versatile).

To complete the first (standard) build i bought a genuine fender 1966 f-neck plate (and screws), some hipshot oval reissue tuners, a graphtech nut, a hipshot string retainer and a nice set of thomastic flats. I managed to build the bass this far and it got me though the 6 months of saving for the additional parts (with a cheap 1980's Jap fender bridge).

During this time I had already picked the Graphtech Ghost Hexpander/acousti-phonic electrics and had picked up a Graph Tech/Hipshot GHOST Bass Bridge as I liked the look and also the extra mass of it, also it had the option of body thru stringing).

I then got Simon Farmer at Gus Guitars to put together a 12-pin midi socket that would hook up internally to the Graphtech electrics (he also modified a planet waves 13-pin cable for me too with a connector that screws in to the socket on the bass end).


Cosmetically there were some changes I wanted to make. Firstly I added a Fender Roadworn tortoise shell pickguard (again from stratosphere) and then I decided that the J-retro plate was a bit to thick and shiny so I picked up an original 1963 Jazz control plate (it had already had additional holes cut into it by a previous owner so I didn't feel too bad about modifying it further), and the knobs on the J-retro looked a bit to tall and too modern so I purchased some Allparts concentric knobs (these are to be modded by my Luthier to enlarge as the J-retro knobs are not a standard fit.

Edited by Matt Golgotha
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The bass is currently with my luthier guy, and he is fitting the electrics, routing for the controls, string ferrules & battery box, putting a finish on the peg head veneer (but leaving the wenge unfinished) and installing the bridge.

I still haven't decided at this point what decal to put on (if any) and also whether to get the bass relic'd.

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[quote name='DanOwens' post='501315' date='May 29 2009, 11:31 PM']Wow man! Fretless & Midi!

I likey.

Where did you get the ghost?

Dan[/quote]


I picked up both the bridge and the electrics from Ray's custom shop in New Jersey - he trades under the name rodrira on ebay. The shipping wasn't bad to the UK, plus he ordered much of the stuff direct from Graphtech for me.

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  • 2 months later...

[quote name='EdwardHimself' post='585425' date='Aug 30 2009, 09:57 PM']hang on- how does the midi work if it's fretless? Or am i just missing something.[/quote]


The 13-pin hexaphonic transducer systems (Axon/Yamaha/Roland/Graphtech) convert the bass guitars pitch into midi, via whichever guitar synth module you use, so the electrics will work (as badly) on a fretless as it does on a fretted instrument.

That said, the Roland midi conversion relies on a pitch being sent to it, which it then approximates to the nearest note, but this effectively is limited to notes (intervals) within the 12 tone Equal Temperament/12tet fretted range, which are ratios of 440Hz, not specific notes within the octave, whereas, with a fretless, you have the potential to trigger a note that is closer to the actual true note that the system requires , but this is dependent on your own intonation - an inaccurate player may well trigger a microtone (rather than the desired tone) which may confuse the Roland's tracking system, and cause "ghost notes" or false triggers.

Edited by Matt Golgotha
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[quote name='Matt Golgotha' post='585622' date='Aug 31 2009, 09:51 AM']The 13-pin hexaphonic transducer systems (Axon/Yamaha/Roland/Graphtech) convert the bass guitars pitch into midi, via whichever guitar synth module you use, so the electrics will work (as badly) on a fretless as it does on a fretted instrument.

That said, the Roland midi conversion relies on a pitch being sent to it, which it then approximates to the nearest note, but this effectively is limited to notes (intervals) within the 12 tone Equal Temperament/12tet fretted range, which are ratios of 440Hz, not specific notes within the octave, whereas, with a fretless, you have the potential to trigger a note that is closer to the actual true note that the system requires , but this is dependent on your own intonation - an inaccurate player may well trigger a microtone (rather than the desired tone) which may confuse the Roland's tracking system, and cause "ghost notes" or false triggers.[/quote]

okay. It's just i remember reading about a midi guitar ages ago where the notes were triggered using the frets but i suppose it would be different nowdays as it was like an 80s guitar lol.

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[quote name='EdwardHimself' post='585651' date='Aug 31 2009, 10:56 AM']okay. It's just i remember reading about a midi guitar ages ago where the notes were triggered using the frets but i suppose it would be different nowdays as it was like an 80s guitar lol.[/quote]

The Peavey Midi bass used frets to track the midi note information. Wal also used the same system (both designed by Steve Chick) and he has now released the technology in his own bass [url="http://www.industrialradio.com.au/"]http://www.industrialradio.com.au/[/url]

The Roland style 13-pin divided pickups only use the pitch from the string, either by magnetic pickups (Roland/Axon/Yamaha/Soundgarage/Limex), piezos (RMC/Graphtech) or Optically (Lightwave HEXFX).

The fret sensing technology i would imagine is far more accurate, and appears to have much lower latency times.

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Hi all

The bass is back with me for a week or two whilst i figure out how high the action needs to be before the bassmute is installed and the additional wiring is sorted (currently everything is functioning except the mix mode (mags/piezo) hence the empty hole on the control plate.

Additionally the allparts knobs are installed (and an old 1960's precision knob for the time being) but the shafts need to be shortened slightly, but visually look far better than the j-retro knobs that were originally on there.

My VB-99 turned up today and I have to admit this thing sounds way better than my v-bass. I'm really looking forward to putting this through it's paces tomorrow at rehearsal!

Edited by Matt Golgotha
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how does this work then? i guess you would use this as a MIDI controller, like you would use say a MIDI keyboard? i've only recently started messing with MIDI so don't really understand it well, but i'm guessing this converts the notes you play into a MIDI signal somehow (i realise you explained this earlier, but i didn't have a clue what you were saying :) so we'll say it converts it somehow) then you put the MIDI signal into a synth or whatever? can you use it as a normal jazz as well then? are the pickups normal pickups, and its a piezo bridge or something, or is it how you do the electronics, or are the pickups special MIDI pickups?

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[quote name='Tait' post='591126' date='Sep 6 2009, 12:28 AM']how does this work then? i guess you would use this as a MIDI controller, like you would use say a MIDI keyboard? i've only recently started messing with MIDI so don't really understand it well, but i'm guessing this converts the notes you play into a MIDI signal somehow (i realise you explained this earlier, but i didn't have a clue what you were saying :) so we'll say it converts it somehow) then you put the MIDI signal into a synth or whatever? can you use it as a normal jazz as well then? are the pickups normal pickups, and its a piezo bridge or something, or is it how you do the electronics, or are the pickups special MIDI pickups?[/quote]


Ok, I'll try my best to explain this - let me know if anything doesn't make sense. Additionally if I have any of this wrong feel free to chime in :rolleyes:

The piezoelectric elements in the bridge (the black saddles visible in the above pictures) pick up the sound of the string (the roland pickups do this slightly differently, as they use a mini humbucker for each string, and require steel core strings to drive the transducer but both are referred to as divided pickups, hexaphonic pickups or polyphonic transducers). Each piezo element has it's own connector to enable the signal from each saddle to be processed/sent separately to the preamp.

The preamp is used to amplify the signal to the midi convertor/Cosm device as the signal taken from the pickups is quite weak. (Roland uses phantom power provided through the cable by whichever converter it is hooked up to, whereas Graphtech require a battery for this purpose as they have 2 preamps, the acousti-phonic preamp for the standard acoustic sound, and the hexpander which outputs the piezo signal to the 13-pin output).

For the divided pickup to out put into the midi convertor/cosm device it requires a 13-pin connector. the 13 separate pins are illustrated in the picture attached, but basically are

[list]
[*]one for each of the six individual string outputs (just 4 used in my case),
[*]a master output (either a mix of the six strings available/normal piezo out or a dry signal from the guitars magnetic pickups) which is available by a 3-way switch enabling synth/mix/magnetic sound,
[*]a MIDI volume signal - via a volume control (this can be assigned to a variety of functions on the VB-99)
[*]Two control switches (S1 & S2) used for patch up/down.
[*]Pin -9 is unused.
[/list]
The information read from the strings is taken into the converter, which determines the pitch coming from each of the strings along with note start & stop and transmits this information into a synthesizer, which generates the intended note (this is similar to when you press a key on a keyboard, you generate a "note on" signal, and when you release the key and you generate a "note off" signal

In short what the MIDI generator does is detect which note is being played, convert the pitch of the note so this information can be sent as a "note on" signal, then once the note has decays there is a point where the MIDI generator has to decide to send a "note off" signal. Additionally, if you bend a note, the appropriate MIDI pitch bend signal has to be sent. In essence this requires quite a bit of patience to ensure you have quite a clean attack and decay to avoid creating additional note information.

Each string can only deliver one midi note at a time. Having 6 indivdual strings processed individually enables you to have up to 6 notes (polyphony).

Just to expand on the above, the Roland V-bass is not a midi device, it is a signal processor, but uses the individual information sent via the divided pickup to enable modeled sounds to be used, as well as enabling pitch bend (whammy) individually (per string) or for different tunings to be adopted (up an octave, down an octave, open g etc) but does not out put midi information (apart from sysex/patch control info)

The Rolands GR20, GR30, GR33 & GI20, as well as Axons AX100 & AX50 are midi convertors which allow the guitar to use either their built in sounds or can be hooked up samplers, hardware synths and software synths etc via midi just like you would with a midi equipped keyboard.

Roland's VB-99 is both a cosm modeller (as is the V-bass) and also outputs midi (as per GI20/GR20)


On my install you can either use the normal sounds of the Magnetic picks (q-tuner neo's in this case through a j-retro preamp) via the normal 1/4 jack out put, or through the 13-pin connector (which you then can process separatly through the vb-99/v-bass)

Edited by Matt Golgotha
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[quote name='purpleblob' post='593351' date='Sep 8 2009, 10:06 PM']What's the tracking like with the ghost on a bass ?

The demo on the Graphtec site is very impressive but ofcourse this is a guitar not a bass, but wondering if this matters with the design of this being in he saddles, it sounds like it should be more accurate than a Roland pickup.[/quote]


It seems pretty good so far. There is a bit of delay below the 5th fret on the low E string, and a slight bit of cross talk between the strings which is causing a bit of glitching, but hopefully I'll be able to iron that out a bit over the next few days by playing about with the string sensitivity and the setup (I only got the VB-99 on Friday so I'm still getting used to it). It does seem to track a bit better than the Roland though.

Edited by Matt Golgotha
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  • 10 months later...

I've been gigging this bass for about a year now and thought i'd update a few pictures as I have made a few changes.

The allparts knobs I swapped out on the J-retro were a great upgrade both aesthetically and in use, despite adding a lot to the overall weight of the bass.

I swapped out the Fender "Roadworn" pickguard for a transparent one.

It is now strung with Nexus strings which seem to give a good sound on the fretless neck, and last well.

The S-1 switching system has worked superbly with the J-retro and Q-tuners, and is one of my preferred sounds on this bass.

Also installed is the bassmute, which I highly recommend!

Edited by Matt Golgotha
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  • 3 weeks later...

Nice build.

I noticed that when you bought the body it was front routed. What did you do with this route when you had the bass rear routed? Was it left open so there is effectively a big hole in the bass...? Or did you have the front route filled and redrilled? I can't quite make out from the pics?

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  • 2 weeks later...

[quote name='EBS_freak' post='937197' date='Aug 26 2010, 02:47 PM']Nice build.

I noticed that when you bought the body it was front routed. What did you do with this route when you had the bass rear routed? Was it left open so there is effectively a big hole in the bass...? Or did you have the front route filled and redrilled? I can't quite make out from the pics?[/quote]

I left it open, and in fact had to cut some notches in it to widen it a bit to get the mini switches to sit correctly as you can see in this picture (the shielding you can see is the rear cavity plate). It gives me some options should I want to swap out the preamp at some point.

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  • 1 month later...

[quote name='Matt Golgotha' post='994803' date='Oct 20 2010, 01:51 PM']I've sent off the Bass neck to H G Thor Labs this morning to get the epoxy finish done (classic thick coat) on the finger board[/quote]

yum. I've looked at those necks for a couple of years now... they certainly look the business!

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  • 4 weeks later...

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