Baltic birch semi-hollow Jaguar

[T_Bone_TL]

I would still ground the strings (at the ball ends) for one thing. Else I think you are just facing down improving the over-all shielding, unless you want to take the radical step (I've suggested it and been laughed off) of attaching a wrist strap (ala electronics repair) to the bass ground. Before "that will electrocute you" is rehashed, a reminder that those have a 1 meg resistor in them specifically to prevent that problem.

But I'm a mere wooddorker (OK, I do work on electronics and have for multiple decades, but not specifically guitar/bass electronics, much. So I'm an electrondorker too...)

 

[mnats]

Too funny - not long after I wrote the previous post I had visions of wearing a wrist strap. With current electrical standards I don't see any increased hazard.

Wish I had noticed the hum earlier as the string through ferrules are now epoxied in place. I think I will punch holes in some copper tape and run that behind the cavity cover. Thanks for your suggestion.

 

[ctmullins]

I’ve had pretty good results with generous shielding, completely eschewing string grounding, on my tapewound-wearing semi-hollow.

 

[mnats]

I’ve had pretty good results with generous shielding, completely eschewing string grounding, on my tapewound-wearing semi-hollow.

Thanks - you reminded me to order some Super Shield. I believe what you’ve written but in the interest of others who might try using a DTAR system I’m going to experiment a bit...

 

[Panada]

I'd go with a clip to my waistband before wearing a wrist-strap.

 

[mnats]

I ran a few experiments with regards to the hum from the ungrounded DTAR system. Making the string ball ends electrically attached to signal ground made no difference. But touching any exposed metal of the string(s) when so connected did as you would expect. Since they are nylon wound that won't help much.

Also, the DTAR preamp itself is encased in a metal box and the cable going to the piezo element is shielded. So additional shielding won't change the level of hum. The preamp case is very effective as the high impedance input is far noisier without the cover attached. But I have an idea that I'll implement later that doesn't require strapping anything to my body and should work for anyone who picks up the bass regardless of playing technique.

Now that the router table is functional, if not complete, I turned my attention back to the neck. The majority of the blue pole truss rod is 6mm wide so I set the router up with a close imperial equivalent bit.

There's a lot going on at the mounting end of a neck. I marked and lightly drilled pilot holes for the mounting screws. The 9.1mm hole drilled earlier from the end for the truss rod adjuster meets the line near the middle of the image. There's a slightly wider part where the adjustment mechanism meets the rest of the truss rod. It's marked 7mm but since I have to get the 9.1mm adjuster into the slot to pass through the hole it hardly matters what the precise size is.

I ran marks for each end of the initial route up each side of the neck blank, then added a temporary mark on the temporary fence at the back to reference the center of the bit. Checking the first shallow route everything seemed to be going OK.

I changed the bit to get the 9.1mm route for the business end of the truss rod. Failed to notice that the carefully drilled hole was slightly off center. Even though this will be a 32" conversion neck and it might matter little I thought I'd try molding in reinforcement as Bruce does on his necks. So from around the 5th fret to the middle of the mounting area is a slighly deeper channel that you can just make out in the foreground. Thankfully the truss rod fit into the slightly misaligned routed channel.

Mixed up some West System and dropped a single length of 12k Toray carbon fiber tow that I found on Ebay. Since I didn't use one of my squeeze bottles some epoxy found its way to the sides of the channel. Carbon tow is like the finest, silkiest black hair you could ever imagine so it readily sticks to whatever it can. I just used an X-Acto knife to push the fibers down into the channel.

Couldn't say how many times this swirled around in my head, but I thought I would write this here for anyone who might be trying the conversion neck thing too. The idea is that you can bolt this onto a regular 34" scale Fender bass, string it up and play it. I'll mention again that this will be a 32.088" *edit* 32.092" scale (as pointed out on other threads) - made by removing the first fret of a 34" fingerboard and moving the nut to that position. The remainder of the frets are exactly in the same place as a normal 34" neck.

Where the 20th fret of a 34" neck would be is where the 19th fret of this 32.092" neck will land. If you need the 20th or beyond it will hang over the neck pocket. I might try this on my second, fretted neck but I will make the fingerboard of this fretless one flush with the end of the neck. All this is probably obvious to others, but since I found it so hard to wrap my head around I thought I'd make a note of it.

Bought a 1 x 1/2" brass bar but decided that I did not want to drill a row of holes twice so I drilled them the long way then cut the bar in half. The outside holes have already been threaded while the inner holes will probably be enlarged for greater weight savings, so I guess I didn't really save myself any time. In any case I had used a hand saw to cut the bar in two, so I made a jig to which I could run the rough side on the router table to flatten it. Brass machines very easily with carbide bits.

It struck my why lutherie is so much fun (not that I consider myself a luthier just yet). I get to incorporate all of my hobbies into one project. *edit* I also get to buy more tools!

 

[mnats]

When I started ordering parts and supplies before deciding on what pickup I'd use on this build I found Stew Mac was discounting some Mighty Mite piezo pickups for bass. When it came it ended up looking almost exactly like the under-saddle elements you can find all day on Ebay for a few bucks though it cost much more than that even discounted with the branded packaging.

Even though it says USA RETRO-FIT PARTS on the front it says "Non USA components included" on the back.

Later, after reading some of Rick Turner's posts on this forum and liking what I read made me seek out one of his piezo systems he made in partnership with Seymour Duncan. I remember feeling a little smug about my decision.

Tonight I decided to try an experiment - remove the Turner Kynar piezo element from the system and solder on the Mighty Mite. I was surprised when I got a sound that would be hard to distinguish between the original element.

No regrets though because having the preamp close to the piezo is definitely a good idea for a number of reasons Turner has detailed. But I'm beginning to think that a lot of what makes it work so well is all the minutiae in the saddle/bridge assembly.

 

[franksidebottom]

Would be great to be able to isolate the installation method into a specified material to create a benchmark for testing these kits as they are creating a lot of interest in builds over the last few years

 

[mnats]

Looking back on some of Rick Turner's posts he mentions geometry with regards to piezo pickups a number of times. After the experiment using a cheap piezo it reinforced the notion that the mechanical part is extremely important. But unless you buy a preassembled bridge/saddle/piezo you are on your own to work out the mechanical/geometrical aspects. So it is with the DTAR, athough the advanced installation instructions are detailed and extensive.

The following is just IMO FWIW based on my observations so far:

At the most basic level, the object is to induce the most stress in the piezo element that you can. That means in a round cable-type under-saddle piezo that the lower half must be fixed while the top half has to couple to the string's vibrations efficiently. Coving the bottom of the bridge slot and the bottom of the saddle promotes this by providing a firm base at the bridge slot while the coved saddle gives the largest contact area to the vibrating saddle. Sorry for my crappy illustration and illegible handwriting.

The DTAR instructions state that the saddle must not be too loose so that it rocks back and forward but must also move freely up and down in the slot. It also suggests a 7 degree tilt toward the ball end of the string which I'd guess would depend on the break angle of the string. That way the forces on the saddle are even front to back and the pressure from the string isn't forcing it in one direction or another. So the saddle is inclined to push evenly onto the piezo pickup element in the slot.

It would be great - if not nearly as much fun - if you could buy a bridge assembly off the shelf that would allow you to adjust all aspects including saddle tilt, intonation compensation, saddle height etc. That way one could simply try each under-saddle piezo system and have that benchmark to evaluate with. But then all those old problems are still unresolved like how do you actually test frequency response without a way to excite the string in a uniform way? It seems to me that the Mighty Mite pickup has a hotter signal than the one that came with the DTAR but how do you go about proving that?

Sticking with the premise that the mechanical system is maybe more important that the choice of piezo element I've ordered a couple of cheap, under $5 piezos. Will report back.

 

[BassHappy]

Looking back on some of Rick Turner's posts he mentions geometry with regards to piezo pickups a number of times. After the experiment using a cheap piezo it reinforced the notion that the mechanical part is extremely important. But unless you buy a preassembled bridge/saddle/piezo you are on your own to work out the mechanical/geometrical aspects. So it is with the DTAR, athough the advanced installation instructions are detailed and extensive.

The following is just IMO FWIW based on my observations so far:

View attachment 3008331

At the most basic level, the object is to induce the most stress in the piezo element that you can. That means in a round cable-type under-saddle piezo that the lower half must be fixed while the top half has to couple to the string's vibrations efficiently. Coving the bottom of the bridge slot and the bottom of the saddle promotes this by providing a firm base at the bridge slot while the coved saddle gives the largest contact area to the vibrating saddle. Sorry for my crappy illustration and illegible handwriting.

The DTAR instructions state that the saddle must not be too loose so that it rocks back and forward but must also move freely up and down in the slot. It also suggests a 7 degree tilt toward the ball end of the string which I'd guess would depend on the break angle of the string. That way the forces on the saddle are even front to back and the pressure from the string isn't forcing it in one direction or another. So the saddle is inclined to push evenly onto the piezo pickup element in the slot.

It would be great - if not nearly as much fun - if you could buy a bridge assembly off the shelf that would allow you to adjust all aspects including saddle tilt, intonation compensation, saddle height etc. That way one could simply try each under-saddle piezo system and have that benchmark to evaluate with. But then all those old problems are still unresolved like how do you actually test frequency response without a way to excite the string in a uniform way? It seems to me that the Mighty Mite pickup has a hotter signal than the one that came with the DTAR but how do you go about proving that?

Sticking with the premise that the mechanical system is maybe more important that the choice of piezo element I've ordered a couple of cheap, under $5 piezos. Will report back.

Hello mnats

Just wanted to let you know how much I am enjoying your posts and this build. I too am a dedicated tape wound/piezo freak at this point in my musical life. I am also a huge Rick Turner and Rob Allen fan. It looks like your bridge design is well thought out and will function quite well. I have five prototype basses that I am doing five different piezo installs in soon. While I don't know if what I have learned so far would be helpful to you, I thought I would share. I am still feeling my way through this piezo thing too, and it's great to find others doing the same.

I wanted to point out something that may or may not be helpful to you. I was slightly shocked when I looked closely at my Rob Allen bridge. I have been playing my "mouse" for 13 years and I never realized that the saddle coffin was not anchored to the bridge. Rob uses corian for the bridge saddle and mounts the piezo in the bottom of the saddle coffin. It's a superb design in my opinion and I thought it might help for you to know about it. Keeping the saddle coffin as a floating object allows first of all - for the bridge to be permanently attached, no need for adjustment screws. Secondly, the coffin itself can be adjusted for intonation purposes at any point. The pickup wire is on the G String side and when you snug the wire down it says put and is in perfect position for the 30" scale on the G string side. Then as you string it up (initially) you can move the angle of the coffin around. The string through design holds the coffin very tightly in place. All these years, I never had an intonation problem (original strings are still on it) and never had an issue with the saddle moving. You can see in the second photo that the aging of the instrument has created a ghost image on the bridge which shows you the exact position of the saddle. Changing strings should be no problem, but certainly you would want to replace just one string at the time so the coffin stays put.

So, on my first go-round, i have used rosewood bridges that I found commercially. I then designed and built my own saddle coffins and then routed a "shelf" in the bridge for the saddle coffin to rest on. In this way the entire coffin can be angled as necessary to provide perfect intonation:

Even on the basses that the strings are going through the bridge, they still clamp the coffin down surprisingly tightly. There are no slots in the saddle either.

I play pretty hard with a pick and I never had any problems so far with the bridge saddle creeping - although I do recognize it is still a possibility.

My friend and electronics installer has been on tour, and will return right around mother's day - so we will be starting the installs soon. I am working with many pickup companies and their piezo products, although I don't have anything from Turner-Duncan so far. I love Rick Turner's work though, and it's something I will be checking out moving forward. I have plans and the wood for 10 more instruments, hopefully, the next batch will be starting this summer. I have designed my own bridges this time, I have several on the drawing board to prototype out. It's all a grand experiment - and many fine companies have donated pickups, some have custom made to my specs and spacing for me, and others have done the favor of giving me stuff at cost. If you are interested in what I am installing and trying out - it is detailed in post 165 here:

Five Prototypes - the minor miracle

Good luck with everything, you have a very nice build going here, and I am very interested in the result.

 

[mnats]

Yours, along with rudy4444's, JLW's et al. have been among the threads that I pore over while working on this 1st scratch build. As mentioned earlier, I was also strongly influenced by Bart Soeters' video to make something piezo and fretless. I'm not entirely convinced a fretless is my thing so I do plan to make a fretted medium scale neck as well.

I take your point about the floating bridge or coffin. The primary reason I've secured mine is so that I don't have to keep readjusting the intonation by dragging the bridge across the still-unfinished top. Pressure is pressure whether it comes from screws or string tension; I think the important things are that the saddle moves with the string vibration to transfer that energy to the top half of the piezo element and the bottom of the element is anchored to something fixed with higher mass. Earlier I was thinking that a low friction thermoplastic might make a nice material for sides of the slot and maybe a formed metal block for the bottom.

That is an impressive number of piezo systems that you're trying. But I wonder - of the various supplies which of them are manufacturing the piezo element from raw materials themselves? At least one looks remarkably similar to the Mighty Mite.

After the piezo it comes down the the buffer/preamp (which, as Turner has pointed out, must appear regardless of which side of the cable it is attached to). The advantage of Turner's is that the supply is boosted to 18 volts which gives greater headroom for the output of the piezo. Piezoelectricity is used with those trigger BBQ lighters so the voltages are not insignificant (remembering the distortion that JLW experienced). But the impedances are high so keeping the buffer close to the element reduces high frequency loss through cable capacitance and reduces induced noise.

I look forward to hearing the results of your experiments. Back in the day, a friend introduced me to your band and the bass playing really stood out for me as the exceptional element of that music. Listening again it still does.

 

[mnats]

Back to the neck, I decided to make a template for the outline using a MIM Fender. First I clamped it to a piece of Malaysian marine hardwood ply and drew the outline. With a jigsaw I roughly cut a distance from the line. I used some stubby screws and a peg at the headstock to hold things in place. Got a nice footswitch for cheap from Ebay that had to be wired up but such a bargain! Well made and looks like it should last. Then I used the flush trim bit on the router table to follow the contour of the neck.

Through this all I managed to forget that I'm not making a 34" scale neck. So the template will have to lose a fret's length. I did remember before routing the outline though so several layers of masking tape near the volute helped maintain a slightly wider transition there.

After trying the router table and a hand held file I hit on the idea of putting the Bruce Bars onto the drill press with a rotary file fitted. Then I just pivoted it on the screw at the end to form the rounded sides.

Judging from other's builds I think the idea is to get these looking as good as possible before burying them inside the neck where they will never see the light of day again.

 

[ctmullins]

Judging from other's builds I think the idea is to get these looking as good as possible before burying them inside the neck where they will never see the light of day again.

Looking great; I’m enjoying watching this!

 

[BassHappy]

Yours, along with rudy4444's, JLW's et al. have been among the threads that I pore over while working on this 1st scratch build. As mentioned earlier, I was also strongly influenced by Bart Soeters' video to make something piezo and fretless. I'm not entirely convinced a fretless is my thing so I do plan to make a fretted medium scale neck as well.

I take your point about the floating bridge or coffin. The primary reason I've secured mine is so that I don't have to keep readjusting the intonation by dragging the bridge across the still-unfinished top. Pressure is pressure whether it comes from screws or string tension; I think the important things are that the saddle moves with the string vibration to transfer that energy to the top half of the piezo element and the bottom of the element is anchored to something fixed with higher mass. Earlier I was thinking that a low friction thermoplastic might make a nice material for sides of the slot and maybe a formed metal block for the bottom.

That is an impressive number of piezo systems that you're trying. But I wonder - of the various supplies which of them are manufacturing the piezo element from raw materials themselves? At least one looks remarkably similar to the Mighty Mite.

After the piezo it comes down the the buffer/preamp (which, as Turner has pointed out, must appear regardless of which side of the cable it is attached to). The advantage of Turner's is that the supply is boosted to 18 volts which gives greater headroom for the output of the piezo. Piezoelectricity is used with those trigger BBQ lighters so the voltages are not insignificant (remembering the distortion that JLW experienced). But the impedances are high so keeping the buffer close to the element reduces high frequency loss through cable capacitance and reduces induced noise.

I look forward to hearing the results of your experiments. Back in the day, a friend introduced me to your band and the bass playing really stood out for me as the exceptional element of that music. Listening again it still does.

Hey mnats

Yes, looking good on the neck! Following this build with much interest.

As far as the piezos go - unfortunately it is really a crap shoot. Not one of the piezo manufacturers I dealt with actually had experience using them in bass guitars. It's funny too, because they would start out in "sales" mode telling me how the piezos work great in guitars or basses. Without exception, I would get passed around to the tech guys and eventually ask if they are the stock guitar piezos - or if they were optimized for bass guitar. Invariably, they would eventually admit that they had never even tried them in bass guitars. So as far as under saddle piezos go, it's uncharted territory. Of course, Rick Turner has done a lot of his own R&D and I wonder about his stuff, if he uses the exact same piezos in his guitars and his basses.

As far as Rob goes, he got lucky in the early days with one of the Fishman systems he experimented with. It is a Fishman guitar system and it was never optimized for bass, but this guitar system happened to work well for Rob's needs, kind of a happy accident. Although all the manufacturers claimed to have piezos made by them to their own specs, it's a good question. Some of them could very well be the same as the Mighty Mite pickup. I am guessing a good piezo is a good piezo, but I always wondered if they could be optimized for bass guitar - but nobody I know of - except maybe Rick Turner - seems to be interested in that.

So good luck with it all. Keep up the good work and thanks for all the kind words about the band and the playing. It means a lot!

 

[T_Bone_TL]

IIRC, the scuttlebutt I've read is that the piezo pickup cable is mass-manufactured for vehicle traffic counting/detection applications. Preamps, etc. may vary but the odds of anyone having enough volume to justify a custom run of cable (for the cable-type systems) are kinda small on any sort of remotely sane economic basis. The preamp package will likely be different from each maker, depending how much is independent and how much is industrial espionage "research." I suspect in most cases disc type elements are also selected from what is mass-pruduced for other purposes that happens to work well, rather than custom-made, but custom manufacture is less unreasonable in that line.

Presumably most makers would prefer to keep their actual source details close to the vest.

 

[mnats]

Rick Turner has been remarkably open about his sources in BassHappy's thread. His post seems to agree with what you've written.

 

[mnats]

Even though I'd done a 3D rendering beforehand when it came to actually making the Bruce Bars much was left to chance. Part of it might have been the primary concern of getting the distance between the business ends right so that it would retrofit onto any Fender body and making sure those threads were straight above all else.

When they were finished they ended up being 8mm in width even though most of the original measurements were Imperial. Oh well, what's another expensive router bit?

I did a test cut on some scrap MDF before marking off the neck and making the first shallow cut. Since the inserts were handmade I expected that there might be tolerance issues so I decided to make the slots slightly long. In the end I did have to do a little more work to the inserts to massage them into shape.

Before gluing the fingerboard in place I cut some stainless steel screws to a length of a sixteenth short of the tops of the inserts, then melted some wax into the threads to keep the adhesive out. That way the bars would be in place to accept the final neck screws and any excess epoxy would hold the inserts into the correct position without fouling the threads.

The Koch book suggest drilling holes for brads through the 1st and 15th fret slots but I only had nails that were much too thick so I used the nut slot and 20th fret (which will end up getting cut). There wasn’t enough material to prevent the ebony from chipping during one operation.

I cleaned up both the fingerboard and the maple with some lacquer thinner before mixing up some West System epoxy. I had not noticed until then that a small amount of resin had dripped out of the pump nozzle onto the display of my 0.01g resolution scale, affecting the LCD to the point where it was ruined. I used a normal gram scale instead, carefully dribbling resin until it just ticked over to the next reading. Went onto Ebay and found a new fine-resolution scale at 1/10th the price of the locally bought one.

Then I masked off the truss rod and laid down some epoxy and spread it with my notched spreader before removing the tape and laying down the fingerboard. After clamping I noticed that the heel end wasn’t lining up with the centerline. Fortunately I’d used to slow cure hardener so it wasn’t much of an effort to remove the clamps and ease it back into place.

In the morning all looked good. I plan to rough the contour of the fingerboard using rudy4444’s method but using the neck blank itself as part of the jig. Thanks for watching!

 

[JLW]

Hey guys, I noticed that my first build is being mentioned in here. In regards to the piezo I used, it was a graphtech ghost acoustiphonic model I believe. There was a thing with one of the pots where you pulled the knob out and it created a MUCH more balanced (to my ears) tone. I did not ever get around to recording it, but it sounded a lot more woody and full. I'm pretty sure that in that recording, it was set to the "bass boost/mid cut" setting or something, because it sounds really scooped and sizzly and trebly to my ears. That also helped with the distortion considerably.

 

[mnats]

Hey guys, I noticed that my first build is being mentioned in here. In regards to the piezo I used, it was a graphtech ghost acoustiphonic model I believe. There was a thing with one of the pots where you pulled the knob out and it created a MUCH more balanced (to my ears) tone. I did not ever get around to recording it, but it sounded a lot more woody and full. I'm pretty sure that in that recording, it was set to the "bass boost/mid cut" setting or something, because it sounds really scooped and sizzly and trebly to my ears. That also helped with the distortion considerably.

It took a long time to find it but I think that you must have used the Acoustic Volume with Mid/Dark Switch option described on page 58 of the Ghost User Guide. The description is a little vague but says that even the normal sound from the Graph Tech Acousti-Phonic pre is EQed in some way. Wonder how the raw output of the piezo sounds if it were simply buffered rather than EQed?

Along those lines I've started to work on a simple buffer with HPF to test the incoming cheap piezos. It might be nice to make a simple DIY platform to share.

 

[mnats]

I'd forgotten that the torrefied maple blank I bought from StewMac was 15/16" thick and had to be planed to the normal 3/4" for a Fender style neck. But with the fingerboard already glued on it would be dumb to try to plane it using that surface as a base.

As you'd all know by now I can be pretty dumb. The thickness ended up being all over the shop due to the lack of support at the headstock end and the fact that the fingerboard itself probably isn't perfectly flat.

Using some boards bought from the seconds section of Ikea I made a base the width of my router planing jig, then used a dado blade to cut a channel slightly wider than the fingerboard. I know that dado blades look vicious but I never understood the fear they seem to inspire in countries like the UK and to some extent in Australia. Maybe that is changing.

Maple is pretty stiff but it's also costly so I decided to run double stick carpet tape along the length rather than in smaller pieces as before. I don't have any measured proof but I'm forming an opinion that it's false economy to try to skimp on tape. It's thick enough to create gaps between the areas where it isn't and scalloping is so Yngwie.

Using some old decking material that I believe is merbau (same stuff I used to make rails for my crosscut jig) I ran it through the table saw to make strips 0.03" thick then sanded them by hand to fit the fingerboard slots. Using West System I glued them, cut them with an X-acto then reused the leftover pieces further down the neck. The technique is the same as what rudy4444 showed in his thread except that I have not radiused the fingerboard so the cut off pieces are nice and flat on both edges.

Progress is slower than it would be due to the fact that the piezo equipped body with the fretted Fender neck is SO satisfying to play. The limitations of magnetic pickups were never as clear to me as they are now. I like definition to my bass tone and took it to the limits of conventional instruments with single coils and roundwounds. But with this bass - equipped with nylon covered flats - there is plenty of definition such that I often end up dialing some high mids out! Always better to have something on tap that you can roll back then trying to EQ something in that isn't there to begin with.