Killing Two Birds with One Stone: JLD Bridge Doctor #3695 with Brass Pins

[BothHands]

I've been struggling with a lack of bridge pins, as discussed in my prior thread.

I recently discovered a much larger belly/crown in my guitar's lower bout (not my lower bout, ha) which opens up new opportunites (maybe) for improving string height / playability.

In brief, I bought the guitar used. It had a crack in the top that ran right along the edge of the fretboard, next to the high(pitched) E string. I also discovered that the G-string tuning peg was damaged. Ergo, it appears the guitar was dropped while playing, and landed hard on that G-string peg; the shock was transferred to the guitar's top/face resulting in the crack as described.

The string height was too high when I bought it, but the (dual) saddles were already low. See pic below showing the current configuration.



A respected acoustic instrument repair tech/luthier where I used to live cleated the crack from below which seemed to stabilize matters, so I lowered the saddles to just about the limit...and the string height is playable, but not comfortable.

The jerk who traded this guitar in (at Guitar Center) hid the damage, and to make matters worse, replaced his oversized custom bridge pins with standard-sized pins, which FELL OUT the moment I released string tension. So I've been using the aluminum-washers-against-the bridge-plate system marketed by AGF member murrmac123 for about four years. It works well and improved the tone of the guitar instantly (brighter!), but changing strings is a bit of a chore. Don't ask me how old my current strings are.



I just found a local tech who demonstrated (with a straightedge) how the crown in my lower bout (at the bridge) is more pronounced than I had realized, and that may turn out to be A GOOD THING. I would like to lower my string height a bit more, but as you see in my first image, there's little opportunity for that. And for the record, I long ago checked the fret board height relative to the saddle height. A straightedge resting atop the frets contacts the front edge of the saddle, about 1/16" down. That hasn't changed in several years.

The tech confirmed that too, and talked with me about using a JLD Bridge Doctor to flatten out the crown/belly, and thereby lower my bridge and saddles relative to the plane of my fretboard. Too good, right?

My concern: As you see in the first picture, my strings exhibit very little break angle behind the saddles. The strings are almost level from the rims of the bridge pin holes to where they contact the saddles. Correct me if I'm wrong: my understanding is that a lack of string break angle is detrimental to the guitar's tone and/or projection.

See the diagram below. It appears that the JLD brass-pin through-holes will establish a break-point that is even higher than the top surface of the saddle, thereby reducing the break angle of the strings further and negatively impacting the guitar's tone/projection.

TELL ME I'M WRONG (please)

[SRL]

Okay, I will repost my reply here:

Nah, I think you've got it right, unfortunately.

It all depends on how far you want to go. If you're concerned about tone, I wouldn't use a JLD, as they add mass to the top/bridge, making it less responsive. Or maybe you're a heavy strummer and it doesn't matter? Nearly all guitars develop bellying over time; it just depends on how bad it is.

If you want more break angle, and you don't mind modifying the bridge a bit, why not shave some off of the edge where the strings touch the ebony (between the saddle and the holes). Or, cut grooves for each string to pass without touching the wood You could also combine that with cutting some small slots at the holes with a thin file (nut slot files work well). These two bridge modifications would get you a better break angle.

Did your tech mention anything about a neck reset? If your neck angle is off, that can cause the situation where your action is too high, but you can't lower your saddle anymore. Most guitars need a neck reset every decade or three, depending. You can easily check your neck angle yourself with a good straightedge tool. Lay the edge on the frets and move it toward the bridge. The top of the frets should line up with the top of the ebony part of the bridge, ideally just skimming over the top so that the top of the fretwire and the top of the ebony bridge wood are on the same plane. If that's not the case, and the frets "point" to a spot lower on the bridge, closer to the spruce top, you're probably due for a neck reset.

Additional thoughts:

If you need a neck reset, you need a neck reset. Your saddle is already far lower than the designers of the guitar intended, because otherwise your strings wouldn't be touching the edge of the bridge (in between the string holes and the saddle).

So, sure, a JLD will fix the belly, if it's bad enough to warrant a fix, and doing so may improve your intonation a bit, but adding mass to the bridge will suck some volume out of the guitar, it's just physics. Modifying the bridge as I suggested above would also improve the break angle and help compensate for some of the volume loss from adding the truss.

A good "test" to see if your belly is bad enough is to put a straight edge across the guitar's lower bout, at the bottom of the bridge, basically the widest point on the lower bout. Then measure the gap at the edges of the guitar, between the edges of each side of the straight edge and the edge of the guitar. If the total distance you measure is over 1/2", then you might consider doing something about the belly. If you measure, say 3/16" on each side for a total of 3/8", for example, it's probably not worth fixing because you're unlikely to get much of a difference in action.

Another way to test that's a bit harder is to measure the angle of the bridge tilt. It should be ideally be less than 5 degrees. These are all approximations of course.

[BothHands]

The guitar in question is an Alvarez MD350, and Alvarez is notorious for using EPOXY when gluing the neck in place. Injecting steam isn't likely to have much effect and the cost of a neck reset doesn't make sense on this particular guitar, though it's my favorite and pretty much irreplaceable due to its wide string spacing.

Most online reviewers of the JLD system report noticeable improvements in tone, so I'm fairly confident in that respect. I think it would be a good idea to install the JLD system in order to 1) reduce the belly, and 2) keep it from getting worse. And doing so would also resolve my lack of bridge pins.

So a neck reset is out, and I'm not looking to slot the saddle or otherwise modify it IF I can solve both problems with a $50 investment in the JLD Bridge Doctor #3695 with brass pins.

Do you think doing so will negatively affect tone or projection?

[BothHands]

Originally Posted by SRL

So, sure, a JLD will fix the belly, if it's bad enough to warrant a fix, and doing so may improve your intonation a bit, but adding mass to the bridge will suck some volume out of the guitar, it's just physics.

Thanks for your post and repost. FWIW, most online reviews contradict your point. Many claim a noticeable improvement in tone and volume. So I anticipate an improvement rather than a loss of volume, but the x-factor for me is the string break angle.

Originally Posted by SRL

A good "test" to see if your belly is bad enough is to put a straight edge across the guitar's lower bout...If the total distance you measure is over 1/2", then you might consider doing something about the belly.

Neither of us applied a ruler to the gap, but it was right about 1/4" at both edges.

Originally Posted by SRL

Another way to test that's a bit harder is to measure the angle of the bridge tilt. It should be ideally be less than 5 degrees. These are all approximations of course.

Another good point. Thank you. The tech did place a short straight edge on the bridge and showed me how it (the straight edge) does tip downward slightly, toward the sound hole. EDIT: This turned out not to be the case. I tried it myself later, and the top of the bridge is radiused slightly. No way to rest a straightedge on it accurately.

I only need to lower my string height 1/16" or less, and might find that to be too low for my playing habits... So if I'm reading you correctly, the JLD Bridge Doctor does sound like a possible solution, especially if I go with the #3694 version that screws through the bridge, rather than using the brass bridge pins.

But there's always a rub. See picture 2 in my original post. There's not enough room for the JLD screw behind my bridge pin holes. And the tech warned me that these Alvarez bridges can crack where the lower rear section meets the taller front section. I think applying the JLD leverage would likely increase that risk.

So I need expert guidance on what to expect in terms of tone and projection/volume when using the JLD #3695 with brass pins in my particular circumstances. Will the slight reduction in string break angle (from pin to saddle) have a negative effect?

[SRL]

edit: never mind; I read your post above

[SRL]

Originally Posted by BothHands

But there's always a rub. See picture 2 in my original post. There's not enough room for the JLD screw behind my bridge pin holes. So I need expert guidance on what to expect in terms of tone and projection/volume when using the JLD #3695 with brass pins in my particular circumstances. Will the slight reduction in string break angle (from pin to saddle) have a negative effect?

Hmm. Yeah, you've got a very thin bridge where the screw would go through, and while it would fit (it's a very small screw) there's a high chance that the bridge would crack because it's (a) right by the 3rd and 4th string, and (b) much thinner piece of wood.

Many older Breedlove guitars (pre-2017) came with a JLD from the factory, and they used a very thick bridge with ample spacing away from the strings. So, taking their "advice" as it were, I wouldn't "screw" your bridge (haha).

Another option is to pay a luthier to make you a new bridge that can accomodate a screw. It wouldn't have to be a fancy shape either.

If you don't want to do that though, the brass bridge truss version will work. However, due to the lower break angle and the mass, I would expect volume loss—not necessarily TONE issues. In fact, bridge trusses can improve tone because they fix the bridge tilt, which can correct intonation problems. But, they will reduce volume.

For example, think of a guitar top like a speaker cone. Just like with speakers, you want the stiffest, lightest top you can get, because you get the most efficient transfer of energy from the strings to actually moving air (creating sound waves). This is why people pay big money for carbon fiber speaker cones—stiff and lightweight.

You can test this yourself by getting a bunch of lead weights and taping them to your bridge. Or just read about people complaining about the huge rosewood bridge plates on vintage Martins that "kill tone", or the metal screw apparatus on the old Gibson bridges. A lot of money has been spent paying luthiers to swap out bridge plates and bridges on those guitars to have less mass on the guitar top.

[Piercast]

Having installed a few BDs of both types, I mostly agree with the above, with the following caveats.

First, don't use the version with the brass pins unless break angle is already plenty sufficient, because as you remarked you will lose some of this angle through the brass pins. The BD might not apply enough of a correction to compensate so you'll likely end up worse still with MORE strings having insufficient break angle. Get some correct bridge pins first.

Second, I'm not so sure about the OP's assertion that there's not enough material behind the pins to use the standard BD version. I'd check this with the manufacturer first.

Third, and this is from experience with a quite a few installations, I agree that if it needs a reset, it needs a reset, and the BD will not compensate enough. It can help some with bellying, and considering the modest cash outlay I'd certainly try and use one if a reset isn't in the cards for this guitar, but be realistic about expectations, and once more, get real bridge pins first. ;-)

Cheers, and good luck.

[BothHands]

Originally Posted by SRL

Another option is to pay a luthier to make you a new bridge that can accommodate a screw. It wouldn't have to be a fancy shape either. [...] A lot of money has been spent paying luthiers to swap out bridge plates and bridges on those guitars to have less mass on the guitar top.

Yeah, no budget for that right now.

Originally Posted by SRL

If you don't want to do that though, the brass bridge truss version will work. However, due to the lower break angle and the mass, I would expect volume loss—not necessarily TONE issues. In fact, bridge trusses can improve tone because they fix the bridge tilt, which can correct intonation problems. But, they will reduce volume.

I'm not sure what a bridge truss is, but I take your point. Thanks. EDIT: See the LINK in SRL's Post #6 above. I'm hoping I can avoid sapping the volume/projection. The JLD design suggests minimal contact with the bridge plate, and that may account for the good reviews. And while those brass pins with nuts and washers weigh something, they can't weigh much... I don't like the looks of them, so if mass really does prove to be a factor, I might grind the pin tops down (just shy of the through-hole). And maybe shorten each pin's threaded member if they're longer than necessary.

I play finger-style (nails, no picks) with some relatively aggressive strumming/slapping. I also use light-gauge phosphor bronze 80/20 strings tuned a whole step down (to D, not Standard E). That's a combination of "quieting" factors, but this is a big ol' dreadnaught with rosewood back-and-sides and Engleman spruce top. She got some volume.

[SRL]

Originally Posted by BothHands

I'm not sure what a bridge truss is, but I take your point.

Just another name for the bridge doctor, and what Breedlove calls them.

[BothHands]

Originally Posted by Piercast

Having installed a few BDs of both types, I mostly agree with the above, with the following caveats.

First, don't use the version with the brass pins unless break angle is already plenty sufficient [...] you will lose some of this angle through the brass pins.

[...] if it needs a reset, it needs a reset, and the BD will not compensate enough

Thanks for your advice, Piercast.

The lower-bout dome/belly is about 1/4" high. Assuming the guitar top was flat when manufactured, I assume it can be returned to half-as-flat by the JLD Bridge Doctor. So I assume the JLD can flatten the belly by 1/8" and thereby lower the bridge (relative to the fretboard) by 1/8".

If I can lower string height at the saddle by 1/16" that should be fine. A 1/16" improvement would enable a straightedge atop my frets to rest atop my bridge. Acceptable alignment and good string height. But if a full 1/8" improvement is possible, I could increase the height of my saddles 1/16" and recover the lost break angle caused by the added height of the brass-pin through-holes. And leveling the bridge in the process (tilting it away from the sound hole) will help even more.

See! It all works perfectly!

But seriously, what do you guys think?

[BothHands]

Originally Posted by SRL

Just another name for the bridge doctor, and what Breedlove calls them.

Thanks, and thanks for your 'speaker cone' analogy in post #6.

[Piercast]

Originally Posted by BothHands

Thanks for your advice, Piercast.

The lower-bout dome/belly is about 1/4" high. Assuming the guitar top was flat when manufactured, I assume it can be returned to half-as-flat by the JLD Bridge Doctor. So I assume the JLD can flatten the belly by 1/8" and thereby lower the bridge (relative to the fretboard) by 1/8".

If I can lower string height at the saddle by 1/16" that should be fine. A 1/16" improvement would enable a straightedge atop my frets to rest atop my bridge. Acceptable alignment and good string height. But if a full 1/8" improvement is possible, I could increase the height of my saddles 1/16" and recover the lost break angle caused by the added height of the brass-pin through-holes. And leveling the bridge in the process (tilting it away from the sound hole) will help even more.

I wouldn't rely on this line of reasoning to make such assumptions. The top likely wasn’t flat upon leaving the factory and you have no way to know what the original normal curve was apart from comparing with another identical guitar that's freshly out of the factory, so…

Don't forget the BD will help pivot the bridge slightly, thereby lowering it in small increments. The lowering action will not be as dramatic as you imagine.

The numbers are certainly wrong, but the principle holds, though. Bottom line is you'll have to try the BD and see where it leads you depending on the particular guitar, its structural specs, bracing pattern, bridge plate, top stiffness etc.

And don’t believe for a minute that you can mill out the tops of the brass pins, that's what is holding the strings in place. I’d make sure to check with the manufacturer about what space is required behind the pins for the regular model. I’m pretty sure you'll end up with an insufficient break angle all over the bridge with the brass pins.

So for me, it’s a yes because it’s your only option. But the brass pins model wouldn't be my first choice considering the already compromised break angle. The BD is a very cheap way to try and rescue a guitar when a proper repair is not an option. If it fails (and I've seen more than a few where it didn't live up to expectations), well that's small change lost.

And don't forget, because we have not even touched on this… the top has moved for a reason, which should be addressed. Check for unglued or cracked braces, a damaged bridge plate having caused the bridge to pull the top, etc.

[Talldad]

Deleted this post as OP only seems to want to argue with people who mean to help.

[John Arnold]

In a modern factory guitar, the crack beside the fingerboard is seldom the result of under building. The OP describes an impact. The other main cause is overheating. If that crack is displaced so that the fingerboard side is pushed into the soundhole, it also indicates a shift in the neck block, which will cause the higher action. I would address that first, before any attempt is made to flatten the top.

[BothHands]

Originally Posted by Piercast

The top likely wasn’t flat upon leaving the factory and you have no way to know what the original normal curve was apart from comparing with another identical guitar that's freshly out of the factory, so…

Do you see a contradiction in the above statement? Clue: If I have no way of knowing, you have no way of knowing.

Originally Posted by Piercast

Don't forget the BD will help pivot the bridge slightly, thereby lowering it in small increments. The lowering action will not be as dramatic as you imagine.

Another broad statement. Every guitar is different, and their histories are, as well.

Originally Posted by Piercast

The numbers are certainly wrong, but the principle holds, though.

And a third broad statement. The numbers are wrong? Based on what?

Originally Posted by Piercast

And don’t believe for a minute that you can mill out the tops of the brass pins, that's what is holding the strings in place.

I disagree. As long as the pin's sidewall is tall enough to meet (and slightly exceed) the tangent of the circle represented by the string's ball end, the pin should retain the ball end. I'm certain I can shorten the pins to that extent, though I don't think it'll be necessary.

Originally Posted by Piercast

…the top has moved for a reason, which should be addressed. Check for unglued or cracked braces, a damaged bridge plate having caused the bridge to pull the top, etc.

As the only player for the past four+ years, I haven't noticed any movement...none that translates into a change in playability, and none that's caused a measurable change in the relationship between bridge and fretboard. Two days ago the local guitar tech's straightedge demonstration looked exactly like my own back when I made the new saddles years ago.

And I'm certain the tech/luthier who cleated the crack would have advised me of any such problems. He has a good reputation in his locale and charges accordingly (!).

What is your specific expertise, Piercast? Are you a luthier, or an expert acoustic guitar technician? You're making surprising assumptions, and I would like to know what qualifies you to make them.