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  #1  
Old 06-09-2019, 02:22 AM
DesmondWafers DesmondWafers is offline
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Default Neck angle question

Hello everyone, I just picked up a d35 and it sounds incredible. The action was pretty high when I got it, and I’ve sanded down the saddle a bit to get it lower and it’s sitting a bit lower than I’d like. This is a 2016 model so I’m hoping it’s not a neck angle issue, but from what I can tell it has the shallowest angle of all of my guitars. I tried the straight edge trick and it’s sitting a bit below the top of the bridge, but that’s very difficult to photograph, so here are some measurements.





Perhaps I’m just being paranoid because of all the talk of underset Martin neck angles recently, especially since I bought it used. I have a 00018 that also has a relatively shallow neck angle, but it has a bit more saddle than this one. Should I be worried?
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Old 06-09-2019, 02:39 AM
JKA JKA is offline
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No, you shouldn't be worrying. The action looks great and as long your you're happy with how it plays, forget about it and enjoy the guitar.
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Old 06-09-2019, 02:45 AM
ChalkLitIScream ChalkLitIScream is offline
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Hmm well the saddle height doesnt look all that great, however the important thing is the string height above the top, and that looks to be about 11mm, which is close-ish to the optimal height of about 13mm.

Your action is at about 2.5mm. If that's perfect for you, then I guess you can see where the guitar goes, but if you want it lowered even more, that will affect your sound and it wont be a good idea for the long run.

I find this is the issue with all commercial guitars. I like my action 1.5mm on the low side, but the saddles ALWAYS become too short, and I lose tone. If I were to adjust your guitar to my liking, the saddle would be short of flush with the top of the bridge!
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Old 06-09-2019, 03:54 AM
varmonter varmonter is offline
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like you said about the straight edge trick. if its below th bridge it needs a reset.
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Old 06-09-2019, 10:21 AM
redir redir is offline
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If that is 3/32nd at the 12th fret then you got nothing to worry about. It should go down to 2/32nd on the high E, ideally. At this point you still have plenty of string break at the saddle. The straight edge trick is a good way to determine if you need a reset but in your case since the action is good you don't. If the action was high then you would probably have to consider a reset. Hopefully you will be able to ride this out for years to come. You can only remove a little bit more on that saddle then the next step would be a reset.
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Old 06-09-2019, 11:26 AM
charles Tauber charles Tauber is offline
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Quote:
Originally Posted by redir View Post
You can only remove a little bit more on that saddle then the next step would be a reset.
Before that would be slotting and ramping the string holes.

If you are happy with the current action, there is adequate break angle over the saddle and you don't currently need a neck reset. Like most other guitars, someday you might, but not now.
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Old 06-09-2019, 12:49 PM
redir redir is offline
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Yup and slotting and ramping is a good idea on any guitar weather it needs a neck reset or not.
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Old 06-09-2019, 03:19 PM
DesmondWafers DesmondWafers is offline
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Thanks all for the advice, the action is about 2.3mm when I measured it with a flat rule (balancing it on a fret wasn't too accurate) so I think I'm in a decent spot. No Martin guitar I've ever owned, new or otherwise, passed the straight edge test, all were slightly below the top of the bridge. I am a Martin fan to the end, but I do wish they'd increase the neck angle as the shallow angle is a conscious decision if my guitars were any indication.
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Old 06-10-2019, 04:15 AM
Talldad Talldad is offline
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First and foremost, the sound, if you are happy then check the playability, still happy, go and make some great music.

The saddle on a guitar acts as a lever, the higher it is, the more leverage it has and hence the better the vibrational transfer from string to top. Typically around 1/2 inch (13mm) is a good target. Much taller than this you run the risk of deforming the top, much shorter and you can under power the guitar.

Have you checked the curvature of the neck, the relief? hold down bottom E at 2nd and 14th frets and check height above 6th fret, there should be just the slightest of slight gaps. If its big then consider tightening the truss rod. Ideally do this before you start playing with the saddle.
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Old 06-10-2019, 11:22 AM
Rodger Knox Rodger Knox is offline
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Quote:
Originally Posted by Talldad View Post
First and foremost, the sound, if you are happy then check the playability, still happy, go and make some great music.

The saddle on a guitar acts as a lever, the higher it is, the more leverage it has and hence the better the vibrational transfer from string to top. Typically around 1/2 inch (13mm) is a good target. Much taller than this you run the risk of deforming the top, much shorter and you can under power the guitar.
That's not exactly correct, the height of the strings above the top have very little effect on the power. There are two forces the strings exert on the saddle, one is vertical and is powered by the vertical motion of the strings. The other is horizontal, and is powered by the variation in tension as the string vibrates.

The vertical force is primarily responsible for power, and it is not effected by the height of the strings above the top.

The variation in tension (which rocks the saddle, and is affected by the height of the strings above the top) contributes very little to the power, but can have a significant effect on the composition of the harmonic content. That means it can effect the tone significantly.

Changing the height of the strings above the top has very little effect on power, but can have a significant impact on tone. Or it may not, depending on the values of a couple dozen variables, most of which are difficult to measure.
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Old 06-10-2019, 11:38 AM
Alan Carruth Alan Carruth is offline
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Talldad wrote:
"The saddle on a guitar acts as a lever, the higher it is, the more leverage it has and hence the better the vibrational transfer from string to top."

Yes and no. I've done a bunch of work and several experiments on this, and, as with everything about the guitar, it gets complicated, but the bottom line is fairly simple.

There are actually three different string signals that drive the top. The strongest one is the 'transverse' signal; the string vibrates 'up and down' relative to the plane of the top, and pulls the bridge along with it. This gets the top moving like a loudspeaker cone, which is the most effective way to make sound.

As the string vibrates the tension changes: it's high when the string is either 'up' or 'down', and lower in between, so this signal is at double the frequency (an octave higher in pitch) of the fundamental of the string. This 'tension' signal rocks the bridge forward and back, so that when the lower end of the top moves 'up' the area between the bridge and the sound hole goes 'down'. This is not a very effective way to produce sound, since the motion of the two areas tends to cancel out. Also, it's hard to move a top that way, since tops are braced to resist that sort of deformation. On top of all that (so to speak) is the fact that the tension change is a much smaller force than the transverse signal.

There is also a high frequency 'zip tone' signal; a compression wave within the string. This also pushes and pulls on the bridge to produce a rocking motion, so, again, it's not very efficient. It is, however, at a fairly high frequency, and often dissonant, so even a little bit of it in the sound can be audible.

Changing the height of the strings off the top doesn't alter the way the 'transverse' signal works, but it does change the strength of the 'tension' and 'zip' signals. When I measured the effects of changing string height off the top of a guitar (from 11 mm to 18 mm;don't try this at home!) there was a clearly audible and measurable difference in the character of the sound output. However, there did not seem to be any more actual power in the sound when the strings were higher off the top: the maximum amplitude from a 'standard' mechanical pluck was the same for a given string either way, as were the rise time and sustain. It makes some sense. There's only so much energy in a plucked string, and if you get a bit more at one partial, then there's less energy to go into others.

The bottom line there, then, is that you might prefer the sound quality with the strings higher off the top, and it could 'carry' better because of that high-pitched dissonant 'zip' sound, but there's no more power.

As part of that same experiment, I looked at the effect of different break angles. Basically, once you got to 'enough' more didn't help; changing the break angle without altering the string height off the top made no measurable or audible difference in the sound. As far as I can tell, something on the order of 12-15 degrees of break over the saddle should be 'enough'.

The greater the break angle over the saddle the more tipping force there is at the saddle top. This will tend to break out the front of the bridge: a miserable repair. Better to keep the break angle low.
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