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EUB build diary

#21
Videojunkie said:
I am assuming that you are planning to use EB strings on this? Have you decided on a scale length yet?
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34", as that's the scale I know. I have a 32" scale fretless ABG I find fairly mchallenging to play in tune due to the scale length difference. It is unmarked so visual reference isn't possible. If I thought an alternative scale length was viable for me, I'd have bought an electric upright off the shelf several years ago.

I have the ABG to test bowing. It's not loud acoustically, but amplified with the pickup and preamp, the sound seems acceptable when bowed, which is my primary requirement. This is with TI jazz flats, but I expect to go up in gauge on the final product. I'm open to suggestions on strings. The most available alternative to TIs in the UK are Rotosounds. TIs are the most available for me as I have several sets in a drawer, but they are rather too flexible and low in tension. Due to arthritis, I may need to compromise on tension.
 
#22
On checking parts, I can do the bridge in three ways:

1. Under saddle piezo. Correct placement and angle would be key. Adjustment to action would be limited. It would look the best and would stop me fiddling. Carving and slotting the saddle would be tiresome.

2. Electric bass bridge with piezo elements. I already have one which I have yet to put on the jazz bass I was intending to. Saddle height adjustment will just permit matching the fingerboard radius. It won't look great, but would be simplest. This would result in narrow spacing at the bridge which would be functionally marginal.

3. Individual saddles (I have these) with piezo somehow rigged under each one. A compromise on looks, and will require a stepped bridge. I have some small piezos I can possibly use. It will require much fiddling.

4. As 3, but I obtain a DB magnetic pickup.

5. As 3 but four cigar box pickups.

6. As 3, but build four single pole pickups. I think in theory I've inherited a coil winder from my mother when she moved, but goodness knows where that might be. Again, this is in the realms of extreme experimentation. I will be cutting the fingerboard short due to scale length so could potentially build it into that.

4, 5 or 6 could be combined with any of 1 to 3
 
#26
I did a test of an individual string bridge screwed onto a plank, a tuner on the other end. Bit I hollowed a dip under the bridge and put one of the tiny piezo discs I have under it. Seems to do the job. I'll try it though am ultra high impedance preamp tomorrow to double check sound quality.

The tricky bit is going to be hollowing out four consistent hollows and getting even string to string sound. I will look for some tiny trim pots and build a little board to do the following:

* Tie all the grounds together.
* Solder in the mini trim pots.
* Allow for four individual outs I can potentially connect to 13 core Roland cable and my pitch to MIDI unit. That will need a preamp for each string so that won't be right away but I may as well build it in now. MIDI would be a nice option. Since 13 core cables are expensive and not very flexible and in my experience prone to damage I might use four 3.5mm or 2.5mm connections, although I do have 13 core connectors from another unbuilt project.
* A mixed output. I could save space and put that on 3.5mm too, but for compatibility and to avoid plugging in just one string by accident, 6.35mm.

Somewhere there are some rounded maple tiles for crafting my wife has, which might make a nice control plate at the back to connect the little circuit board to and cover it, but I'll side mount the jacks.
 
#28
4 signals - kinda wonder if an RJ45 jack (perhaps the shielded flavor) and a standard networking patch cord (also perhaps the shielded flavor - but that is a bit less flexible) would do the job on 4 twisted pairs in a very common, & easily replaced if it wears, cable.
 
#29
I have never had a great deal of success with multiple piezos . Something always seems to get lost either wired in series or parallel . My latest upright build (2 string ) has an undersaddle piezo rod for an electro acoustic guitar under the bridge , a 40in scale lengths and strung with SBW synthetic gut weedwackers . Fed through a 10M impedance buffer pedal that I built , into a cheap behringer EQ pedal , it sounds pretty good , and will improve when I get a bit more time to play with the EQ . I also bought a cheap behringer ADI21 acoustic DI pedal to play with that has an input impedance of 4.7M and sweepable mid range EQ . This shows a lot of promise . Also fed straight into my PJB briefcase on passive setting sounds very good . The PJB EQ is spot on and also I believe the input is 4.7M when switched to passive .
The secret of any piezo is a high impedance buffer (min 4.7M) and EQ . You will probably want to roll off a lot of treble and hi mids .
 
#30
T_Bone_TL said:
4 signals - kinda wonder if an RJ45 jack (perhaps the shielded flavor) and a standard networking patch cord (also perhaps the shielded flavor - but that is a bit less flexible) would do the job on 4 twisted pairs in a very common, & easily replaced if it wears, cable.
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True, that would work.

I have both 13 core sockets and cables, I've just been underwhelmed by their flexibility, so since it's just for signals to go to an external preamp before it's suitable for the midi interface (which will need 13 core) I thought I might not use it. It's also based on the fact I might never use it or build the preamp. Not building it into the bass avoids extra build effort and bulk for this optional extra.
 
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#31
johnh89 said:
I have never had a great deal of success with multiple piezos .
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I've never tried it, to be honest, other than I have a Les Paul guitar I added a pre- built piezo bridge to. That's six piezo elements in parallel. I have a bass bridge too for an EB. I looked at it a month ago but tidied up my parts drawers and now can't find it...

johnh89 said:
Something always seems to get lost either wired in series or parallel .
Click to expand...

This would be parallel.
johnh89 said:
My latest upright build (2 string ) has an undersaddle piezo rod for an electro acoustic guitar under the bridge
Click to expand...
I considered that option, but I doubt my ability to carve and correctly place a bridge, hence going for the individual EB bridge elements I have, but adding piezo as I don't really want to try and build my own pickups and cheaper DB magnetics are hard to find.


johnh89 said:
I also bought a cheap behringer ADI21 acoustic DI pedal to play with that has an input impedance of 4.7M and sweepable mid range EQ .
Click to expand...
I have two and have used them with passive piezos successfully along with my Award Session pedals which may have an input impedance even higher than that. So I'm fine for external preamps. I also have a spare from an acoustic guitar I could put into an enclosure which even has an XLR out.
johnh89 said:
You will probably want to roll off a lot of treble and hi mids .
Click to expand...
I can tweak as required. The advantage of the acoustic guitar preamp is more EQ bands, but the ADI-21 is fine with my ABG, preamp bypassed or the guitar I have with the triple K&M set up (passive).

If all else fails, I have an acoustic guitar amp, although that would lack low end.
 
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#36
Videojunkie said:
I tried to build a circuit for multiple pizeo connections, but wound up buying a preamp form Richter that works perfectly.
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For the main feed it'll just be all the piezos in parallel into one of the five potential preamps.

The individual amplification option is just for the potential pitch to MIDI connection, which would be four preamps. The only likely commercial option for that is probably from GraphTech. But it's sufficiently low down the priority list I'm not desperate to spend money on it and realistically I'll never build the four preamp box. I'm future proofing it for whoever I gift it to in twenty years time, assuming they don't just use it for firewood :)
 
#37
Slight error when over enthusiastically carving the headstock as I forgot to put in a stop cut and I had a splinter. It's fixable in post. In fact I might cut off the end of the headstock and cap it differently as I can then add some screws and glue for extra adherence. I'll countersink and dowel them in.
 
#38
Videojunkie said:
I tried to build a circuit for multiple pizeo connections, but wound up buying a preamp form Richter that works perfectly.
Click to expand...
Four in, four out I can obtain via GraphTech I believe, as I built in, but since I'll probably never use it, it's not a priority, and I don't want to have to build in space for it as I want to keep the body as simple as possible and within my limited woodworking skills. But building in the connections to future proof I can do.

I may get more carving done over the weekend, but I also have to carve a bit for some windowsills and my arthritic hands are limited on carving capacity.

So, part of my weekend will be testing the pickup option. I tested it into a high Z input that's more medium Z, but I'll break out the actual acoustic preamp and tune the test string on a plank to some sort of pitch and record it and soberly assess sound quality.
 
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#39
As promised , some pics of latest build . Was going to have onboard buffer and EQ but didn't quite work as expected so went for passive piezo and pre amplifier processing . Any questions ask away .
Still got to finish it . fret markers on edge of fingerboard to do and a final sand , wax and polish .

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#40
johnh89 said:
As promised , some pics of latest build . Was going to have onboard buffer and EQ but didn't quite work as expected so went for passive piezo and pre amplifier processing . Any questions ask away .
Still got to finish it . fret markers on edge of fingerboard to do and a final sand , wax and polish .

View attachment 7406150View attachment 7406151View attachment 7406152View attachment 7406153View attachment 7406154View attachment 7406155View attachment 7406156
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That's a very interesting design. The CF elements, 2 strings (that look like they are rubber?) Very cool!
 

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