- Apr 18, 2008
- 16,013
- 1
- 31,725
- Disclosures
- I'm highly opinionated and extremely self-assured
In my experience, piezos work best when pre-loaded with some pressure, such as being wedged between a saddle and bridge, or bridge and soundboard.
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Winter Build Off 2020 - Kuun Space
- Thread starter Jisch
- Start date
Could you could make an internal brace that squeezes them between the back & the top, under the bridge? Kind of like a sound post. It would press the transducers against the top and support the bridge.
Here's the transducer system I'm installing. In looking at them, clearly they aren't designed to be in between anything, they get glued in underneath the bridge just like the K&K system. I'm off to the JJB website to see what they recommend, this is something better done before I glue the top on. Each disc is about .75/20mm in diameter.
From the JJB website: These special surface transducers are under less pressure than under saddle pickups thus decreasing the likelihood of them transmitting a percussive or harsh sound.
From the JJB website: These special surface transducers are under less pressure than under saddle pickups thus decreasing the likelihood of them transmitting a percussive or harsh sound.
I was checking out the JJB website. They recommend gel super glue and have link to a tutorial for acoustic guitar where they position them under the bridge between and slightly behind the string pairs.
- Apr 18, 2008
- 16,013
- 1
- 31,725
- Disclosures
- I'm highly opinionated and extremely self-assured
I'm just reading that now. I think I am going to position them just ahead of the scale length though. The distance between the scale length and where the top gets glued to the back is not very far, I think there will be more resonance out in front of the bridge rather than behind it. I wish I could do this two or three times to find the right spot!
Let's see how this sounds (in a couple weeks).
yes, I will be gluing the cables down. I bought the JJB system with a volume control, that will need to be accessible inside the control cavity, and obviously I need to desolder the output jack. This will feed into an Audere preamp. I also want this to be invisible from the sound hole.
How expensive are the disks? You could always glue in another set (or two) in alternate locations, and then just plug/unplug each element to get the mix you want. I've thought about doing this with those cheapo piezo disks available on eBay since they're usually under a dollar each.
If you believe what JJB or K&K say on their respective websites, these use the basic transducer technology but employ specific matching and dampening to create a better sound. The K&K system is around $100, JJB is around $50. I am fairly certain I'll get usable sound out of this.
The good thing is with the preamp I'll be able to mix in as much as sounds good (it could be zero!). It would be cool to build a test body and figure out the impact of placement is on sound - of course there are a lot of variables here - wood density, thickness, depth of the body and shape that will also have an impact (I think). Unlike the regular discussion on wood tone, it's clearly an important variable when you are using a transducer to pick up vibrations in the wood.
The good thing is with the preamp I'll be able to mix in as much as sounds good (it could be zero!). It would be cool to build a test body and figure out the impact of placement is on sound - of course there are a lot of variables here - wood density, thickness, depth of the body and shape that will also have an impact (I think). Unlike the regular discussion on wood tone, it's clearly an important variable when you are using a transducer to pick up vibrations in the wood.
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A productive lunch. I got the neck carved to some degree - it will need some final sanding for sure. I used a farrier's rasp to do the facets the cleaned it up with the Isawaki and other files before scraping it. As expected scrapers do not work well with birds eye, there's no correct direction to scrape, well there is for a little stretch then you hit an eye and the wood pulls out. It will be all sandpaper from here on. It looks incredible though, pics don't do it justice.
Nothing changed here, but I took a picture anyway. Any thoughts of an inlay are rapidly disappearing in the rear view. I might try doing it one more time, if it's not perfect then I won't do it on the fingerboard. You can't see any of the figuring in the wood with the sanding planer marks in it, but based on what the back of the neck looks like, this is going to look pretty dang cool when it's polished up and coated in CA.
the a few minutes with the bandsaw, oscillating drum sander and dremel and I got this done. More to do here for sure, but it's roughed in.
All this was procrastination so I don't have to glue the top on. I'm sure I'm missing something! I'm going to run into some idle time waiting for glue to dry this weekend, apparently.
the a few minutes with the bandsaw, oscillating drum sander and dremel and I got this done. More to do here for sure, but it's roughed in.
This is how my Ergo EUB is set up. Definitely sounds Fuller and more natural than any of my other piezo bridges, which tend to sound thinner and a bit too bright. It's sort of like the David Gage Realist.
It's raining here today, so no morning bike ride 
but I did get 4 hours in the shop 
I guess I'm at the stage of this build where there are a lot of smaller things rather than big things. Smaller things take longer to do.
I drilled for the output jack, including making a recess inside the body, maybe this will be the first bass where I'm not doing the ship in the bottle thing with my dremel. I didn't take any pics of that, apparently.
I shortened the wires on the transducers, there was a long lead on the volume that made it cumbersome. The red wire there is the output from the pot, the white wire is ground.
I installed the control cover magnets including the holders that go on the body. This is so much easier to do before the body is glued up. I messed up polarity on two magnets somehow. I had to dig them out and flip them over. I am so careful when I install them I think I know how I flipped them, whatever, they're straight now.
I worked on the inside of the tub and front to make it look a little less like it was chewed out by rats. I didn't make everything as neat as I probably should have, but sanding on the inside is not fun at all. It looks great where you will be able to see from the sound hole. Then I put a couple of coats of Tru Oil on it. Boy this is going to look great considering how these pieces look.
Then I glued it up. I put a piece of scrap as a clamp through the pickup hole. I lined things up very carefully and made sure there was enough pressure to keep everything in place and into the bag it went.
The last thing I started working on was the tailpiece. I'm not 100% sure on this yet. I intend to inlay some birds eye and ebony to kind of tie the whole thing together. Before I get too far I'll need to see how it looks up against the body. I'm trying to straddle the line between strong enough and too bulky. I'm probably a bit too far on the bulky side right now, we'll see. I also need to figure out the string height, which is based upon the depth of the neck pocket which has to be deeper than it is right now. My intent is to have the strings load from the bottom. The tailpiece will be glued and/or screwed in place, it won't be held in place by tension alone.
I'll get in the shop for a few hours this afternoon, but I'm not sure what I'll be working on, maybe knobs.
but I did get 4 hours in the shop I guess I'm at the stage of this build where there are a lot of smaller things rather than big things. Smaller things take longer to do.
I drilled for the output jack, including making a recess inside the body, maybe this will be the first bass where I'm not doing the ship in the bottle thing with my dremel. I didn't take any pics of that, apparently.
I shortened the wires on the transducers, there was a long lead on the volume that made it cumbersome. The red wire there is the output from the pot, the white wire is ground.
I installed the control cover magnets including the holders that go on the body. This is so much easier to do before the body is glued up. I messed up polarity on two magnets somehow. I had to dig them out and flip them over. I am so careful when I install them I think I know how I flipped them, whatever, they're straight now.
I worked on the inside of the tub and front to make it look a little less like it was chewed out by rats. I didn't make everything as neat as I probably should have, but sanding on the inside is not fun at all. It looks great where you will be able to see from the sound hole. Then I put a couple of coats of Tru Oil on it. Boy this is going to look great considering how these pieces look.
Then I glued it up. I put a piece of scrap as a clamp through the pickup hole. I lined things up very carefully and made sure there was enough pressure to keep everything in place and into the bag it went.
The last thing I started working on was the tailpiece. I'm not 100% sure on this yet. I intend to inlay some birds eye and ebony to kind of tie the whole thing together. Before I get too far I'll need to see how it looks up against the body. I'm trying to straddle the line between strong enough and too bulky. I'm probably a bit too far on the bulky side right now, we'll see. I also need to figure out the string height, which is based upon the depth of the neck pocket which has to be deeper than it is right now. My intent is to have the strings load from the bottom. The tailpiece will be glued and/or screwed in place, it won't be held in place by tension alone.
I'll get in the shop for a few hours this afternoon, but I'm not sure what I'll be working on, maybe knobs.
Yes, it's a vacuum bag, for oddly shaped objects it works great to clamp them together. It's actually made for making skateboards.
More fun this afternoon.
I finished the truss rod access slot. I tried to make this one neat, I'm usually doing this last minute, so I took my time. I also made the nut and laid out the headstock and tuner placement. I really need to digitize this process, it takes way too long manually. I normally put a laminate over the headstock, but I don't think I'm going to do that on this one, the maple just looks too good.
I continued to work with on the tailpiece. I inlayed this diamond as a sort of reference to the rune I was considering for the fingerboard. I used a router inlay bushing. I made a diamond hole in MDF, run the router with a bushing on the inside to make a hole, then take the bushing off and it makes the part you inlay. I figure the maple and ebony will tie the instrument, like the carpet in The Big Lebowsky.
I sanded down the fingerboard, of course after I got it all the way done I found few scratches so I'll have to go back to 220 or so and go back up before doing the CA coating. But man it looks awesome.
I checked on the bag a few times and it was holding air (or not holding air), but when I checked it just before coming upstairs the vacuum was gone, so I pulled the body out, at this point putting pressure back on won't help anyway. I couldn't help but put all the pieces together. The tailpiece will be moved up quite a bit from where it is in this pic.
I finished the truss rod access slot. I tried to make this one neat, I'm usually doing this last minute, so I took my time. I also made the nut and laid out the headstock and tuner placement. I really need to digitize this process, it takes way too long manually. I normally put a laminate over the headstock, but I don't think I'm going to do that on this one, the maple just looks too good.
I continued to work with on the tailpiece. I inlayed this diamond as a sort of reference to the rune I was considering for the fingerboard. I used a router inlay bushing. I made a diamond hole in MDF, run the router with a bushing on the inside to make a hole, then take the bushing off and it makes the part you inlay. I figure the maple and ebony will tie the instrument, like the carpet in The Big Lebowsky.
I sanded down the fingerboard, of course after I got it all the way done I found few scratches so I'll have to go back to 220 or so and go back up before doing the CA coating. But man it looks awesome.
I checked on the bag a few times and it was holding air (or not holding air), but when I checked it just before coming upstairs the vacuum was gone, so I pulled the body out, at this point putting pressure back on won't help anyway. I couldn't help but put all the pieces together. The tailpiece will be moved up quite a bit from where it is in this pic.
I only got a few minutes before a bike ride this morning. The glue up looks perfect. I got the sides normalized on thr oscillating drum sander and started working on the arm bevel. I need to form the edges a bit as the edge of the top is not consistent after getting all sides straight.
I love doing this part.
I love doing this part.
I expected to get an hour or so yesterday, but a longer than planned bike ride and an earlier than planned daughter visit encroached on my shop time. No harm. I still have 2 months right?
I did get a little quality time with the pieces last night on the couch. For me it's always good to get a chance to look at things like this from here forward - there's a lot to consider and without the pieces in hand I don't always remember all the intricacies.
Observations:
- the lower horn cut isn't wide enough for easy upper fret access
- I considered three or four different possibilities for the tailpiece, I'm still debating that to some degree, I have to test out some theories before I can move forward
- the thickness of the edge needs to be normalized
- The neck pocket needs to be just a hair deeper - since I'm making the bridge I can really have this depth wherever I want it. I want enough room to slap/pop, but it will be closer than a "normal" bass.
- not an observation, but I looked at how the top of the body will look and drew in a rough outline
This morning I was in the shop early before my wife was awake, I started with the edges since I could do that without power tools. I marked 3mm all the way around and filed the sides down to the mark. I need to rework that again in some small spots after the other work this morning.
Next I routed the neck pocket a bit deeper. This body is thicker than my normal bodies so my regular body thinning router jig wouldn't work. I could use the current neck pocket for the template bit to follow, but I needed a bigger platform for the router base. I just screwed a piece of MDF with a hole cut in it to the top (the middle of the top isn't contoured) and routed away. I only took about 3/32" off, but I'm much happier with the depth and the pocket is much smoother now. I forgot to take a pic during the operation, so I just put this back in place afterward (you can see I squared off the corners of the pocket).
With that done I could turn my attention to the top edge of the instrument. I want to make sure there is good access to all fret positions and there is enough room for 5 mounting screws. Normally when I do a bolt on I have about 3.5" of neck pocket, this one will be angled, it's about 4" on the bass side and just under 3" on the treble side. After I got it rough cut on the bandsaw I smoothed it out with the oscillating drum sander. I'll get the treble side flush with the neck after I get the bolts in place.
Here you can see the reworked lower horn, kinda. It still needs a bit more work, but it's getting there.
At lunch I'll get the neck mounted with ferrules and threaded inserts in the neck. It's early to project finishing, but I think I'll be done in a couple weeks or so. I've got no business travel this week so I should be able to get some decent hours in.
I did get a little quality time with the pieces last night on the couch. For me it's always good to get a chance to look at things like this from here forward - there's a lot to consider and without the pieces in hand I don't always remember all the intricacies.
Observations:
- the lower horn cut isn't wide enough for easy upper fret access
- I considered three or four different possibilities for the tailpiece, I'm still debating that to some degree, I have to test out some theories before I can move forward
- the thickness of the edge needs to be normalized
- The neck pocket needs to be just a hair deeper - since I'm making the bridge I can really have this depth wherever I want it. I want enough room to slap/pop, but it will be closer than a "normal" bass.
- not an observation, but I looked at how the top of the body will look and drew in a rough outline
This morning I was in the shop early before my wife was awake, I started with the edges since I could do that without power tools. I marked 3mm all the way around and filed the sides down to the mark. I need to rework that again in some small spots after the other work this morning.
Next I routed the neck pocket a bit deeper. This body is thicker than my normal bodies so my regular body thinning router jig wouldn't work. I could use the current neck pocket for the template bit to follow, but I needed a bigger platform for the router base. I just screwed a piece of MDF with a hole cut in it to the top (the middle of the top isn't contoured) and routed away. I only took about 3/32" off, but I'm much happier with the depth and the pocket is much smoother now. I forgot to take a pic during the operation, so I just put this back in place afterward (you can see I squared off the corners of the pocket).
With that done I could turn my attention to the top edge of the instrument. I want to make sure there is good access to all fret positions and there is enough room for 5 mounting screws. Normally when I do a bolt on I have about 3.5" of neck pocket, this one will be angled, it's about 4" on the bass side and just under 3" on the treble side. After I got it rough cut on the bandsaw I smoothed it out with the oscillating drum sander. I'll get the treble side flush with the neck after I get the bolts in place.
Here you can see the reworked lower horn, kinda. It still needs a bit more work, but it's getting there.
At lunch I'll get the neck mounted with ferrules and threaded inserts in the neck. It's early to project finishing, but I think I'll be done in a couple weeks or so. I've got no business travel this week so I should be able to get some decent hours in.
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