Question for luthiers

[Karl Kaminski]

...now I wonder if the top will resist at such of big pressure and will not entirely collapsing...?

yes, you are affectively muting the top and clamping the pressure down on the top at the saddle (instead of the ribs). Your top with 'sink'/break to that anchor point unless you re-design a new bracing system (ie reinvent the wheel). Not impossible, but to what end? you'll need to build it to test empirically like Matt said.

I would imagine an anchor like that would mute the top from freely vibrating as compared to a traditional bridge plate or a floating tailpiece.

 

[Jeff Scott]

I may have misses it, what bass model are we discussing?

 

[catalin gramada]

Is a Takamine G series, China made with a deformed top.

 

[catalin gramada]

yes, you are affectively muting the top and clamping the pressure down on the top at the saddle (instead of the ribs). Your top with 'sink'/break to that anchor point unless you re-design a new bracing system (ie reinvent the wheel). Not impossible, but to what end? you'll need to build it to test empirically like Matt said.

Yes, I see. The top of a guitar is not designed to work that way, and the rotation of the bridge is part of the structure and not a consequence.

 

[J Wilson]

As was pointed out in a previous post about this, acoustic guitar-style instruments run a 'balancing act' whereby the builder makes a calculation as far as the bracing and top is fabricated, between being light enough to aid top vibration, yet heavy enough to keep the top flat.

Anyone who's spent time around less expensive 12-string acoustic guitars, and that style adapted to a 'bass' instrument often does the same thing: The string tension can swell the top, pulling the bridge up or forward towards the neck with the string tension.

You have two choices:

Either sell it and look for another acoustic bass guitar that will stand up to this, or have it evaluated by a professional guitar tech who's experienced with acoustic instruments. Believe me, guys who regularly work on acoustics will have seen this sort of thing as it can be common, even on six strings, and probably has a strategy to mitigate this.

 

[catalin gramada]

Is a cheap instrument it sound nothing like a bass, I bougth it new for very little money. Still a good platform for experiment. I get rid the pickup and 3 shims under and installed a solid saddle, in order tusq, cow bone and a mapple one build from a upper bass bridge piece. Any shows acoustical advantages over the original pickup sandwithch. The mapple was the winner as is filtered more from the mids content and gives more bass character, still not as articulate like the other two.
Second: it seems it like high action. With low action it gets more sustain and overtones content but not in direction you want to see a bass. More, with low action the body resonance is extremely present somewhere 100 cps around (actually ringing in 2nd A) make it very undesirable. guitarish sound. I try to instal a JLD now, but hell, the post goes directly in the hole for the jack in tailblock...I have to plug it....Will continue. Thanks.
I tried couple af nylon taped and flats I have Labella 760fl works the best .

 

[Matt Liebenau]

For whatever it’s worth I have a JLD Bridge Doctor in a cheap Washburn 12 string and it worked as advertised. The bridge was lowered and most of the belly came out behind the bridge. No sound comparison however as it was essentially unplayable when I got it so the Bridge Doctor went in immediately.

 

[catalin gramada]

Thank you. Well, I did finished put it mine.i just easy tightened ...As sound remarks the sound get tight or bit dry maybe ? The diference in tone is subtle and didn't notice it comes quiet or louder than it was. But I didn't tried ti put a lot of pressure for begining

 

[catalin gramada]

Unfortunately my jld cannot be used to put pressure on the top at a point to see it do something. The plastic rod serving as pivot just did not want to stay in position because the wood they used is not able to keep the screw in position. Even I filled with epoxy this poplar they used is simple not strong enough along the fibers and the pin is smashed out more easy than creating a useful pivotal tension. Is a low quality product I cannot use it...I.m sorry guys



I will try to make it usable with a wood dowel inserted directly and glued in the block. But also a wood threaded insertion seems necessary to add as the crater end pin cuted threads in a very narrow 5 mm wood shoulder. It can be made an bit rigid with a spoil of glue....but a proper wood metallic insertion is the way to do. Unfortunately I can get metric stuff here, meant I have to rebuild it almost from scratch...

 

[catalin gramada]

Hey. I found this pieces of furniture hardware on Amazon. Think better instaled directly on the central hole of tailblock, because it fit perfectly and also don't add mass to the jld device. More can be screwed the strap button on it after the bridge tension is set...Then the jld can be a simple block of wood with a wide groove for the end balls of strings, I already ordered a proper hard maple to do...

 

[catalin gramada]

I installed the device in the guitar and it work. Not complete but takes some belly off. The problem it takes out the bass and is more evident as it get more tension under bridge. So maybe for guitar it work but for bass frequency is a big NO, period.

 

[catalin gramada]

This is a screen capture how it looks inside

 

[rockinrayduke]

My brain hurts now.

 

[catalin gramada]

As my setting is very accessible from the back it was very easy to compare for different tension.. in this case I don't think the weight or the shape will do a substantial diference. The tension in the bridge did. You make it more structural rigid- it loose more bass, is as simple as that. Still, my maple block weight almost twice than original JLD and the print to the bridge is almost double. I may carving it to get same weight and bridge print, but I don't expect miracle happen from that...the top is to rigid and I think the difference will be subtle at most

 

[Matt Liebenau]

That’s part of the balancing act with acoustic instruments, the closer it is to exploding the better it sounds. There’s some hyperbole there but… yeah…

 

[catalin gramada]

My version vs original: The mass is comparable almost same but is more solid structure than original

 

[catalin gramada]

.

 

[catalin gramada]

One more question please : My saddle is pretty high, 5/8 around. The original was 1/2 with couple of shims under. I did not have many options for that because any saddle offert comes in max 1/2 height size, no mater bone, tusq or micarta...But found similar synthetic bone as ivory substitute, like ultrex micarta or g10 elforyn 0.125 thick, used as knife scales and solded in large sheets. Are this any goods to be used as material to cut saddles from, please ?

 

[catalin gramada]

I tried a piece of Elforyn- super tusk made by Elforyn Germany. Is dead plastic s..t and sound like s..t. I wonder if Micarta ultrex USA made is different ? Is still on the way... Till now Graph-teck Tusq shows is best material I had on hand....but unfortunately the widest pice I found is 1/2"...far away from minimum 5/8" I need....

 

[catalin gramada]

Tested also original Ultrex Micarta sheet. Kind of plastic like, dead, no resonant material nothing compared with something may be usefull for a saddle.It seems there are not phenolic comercial boards who may be used. I.ll order some epoxy sheets like FR4, G10 / 11 to see if are more usable. For sure epoxy boards may be more hard composite materials than this phenolic ivory like boards are .And don't talking about tone but all phenolic board I tested damped the sound making the guitar effectively dead.