Neck angle question

**reverhar** · Jun-15-2009, 9:40am

How does neck angle and bridge placement affect the tone of an instrument. I have a mandolin where the neck angle is what i would consider high. This neck angle, I guess, causes the bridge to be set high. In other words, I have to run the wheels of the bridge up pretty high to get the action at a reasonable playing level. How does this affect tone or would it matter?

**Bernie Daniel** · Jun-15-2009, 9:48am

reverhar: This neck angle, I guess, causes the bridge to be set high. In other words, I have to run the wheels of the bridge up pretty high to get the action at a reasonable playing level. How does this affect tone or would it matter?

The neck angle does influence the volume -- there have been many discussion strings on this topic in the past -- doing a search should get you a lot of information.

Also there are many experts and builders here who might comment on your issue but you should give them some idea of what height of action you consider reasonable -- also what kind of a mandolin are we talking about -- is there any top sag at all -- what gauge strings are you using? etc?

**Lefty Luthier** · Jun-15-2009, 9:54am

Neck angle is the most significant factor in bridge pressure against the soundboard. The greater the angle, the more pressure on the soundboard. On occasion, I am asked to build a mandolin with a greater string break angle than standard and usually handle this by extending the bridge base rather than turning the lift nuts higher. I doubt that you will hear much difference in tone when you raise the bridge saddle with the lift nuts but it does put a bit more bending stress on the posts when you chop a chord.

**reverhar** · Jun-15-2009, 10:03am

Originally Posted by Bernie Daniel

.
you should give them some idea of what height of action you consider reasonable -- also what kind of a mandolin are we talking about -- is there any top sag at all -- what gauge strings are you using? etc?

I don't have a gauge to measure action but right now the action is where I usually like it. There is no top sag and I am using medium gauge strings. I would consider the tone rather brassy and volume is ok. It does have a new bone nut that was done recently (replacement for ivory).

**Ken Roddick** · Jun-15-2009, 10:14am

Here is a link that is very informative on this topic.
http://www.siminoff.net/pages/simino...itcor_str.html
Hope this helps
Ken

**reverhar** · Jun-15-2009, 10:45am

Originally Posted by Ken Roddick

Here is a link that is very informative on this topic.
http://www.siminoff.net/pages/simino...itcor_str.html
Hope this helps
Ken

Thanks for the link. I suppose that raises this question due to increased neck angle = greater downward force on the top. To me, it seems as if the greater tension would lessen the top vibration which would create an end result of less volume and maybe changes in the tone. Would that be a correct assumption?

**Hans** · Jun-15-2009, 10:56am

There is too much and not enough of everything. I've made some low angle instruments that just barked and some high angle instruments that have done the same. Depends on how the top is loaded. From the looks of the bridge, you might could do with one of Steve Smith's (Cumberlland Acoustics) tallboy saddles.
The other factor in the equation is the riser block's height above the top. If it is quite high, your "break" angle is lower. Usually, about 1/4" to 5/16" is about the right height.

**reverhar** · Jun-15-2009, 12:14pm

Thanks Hans, I will contact CA about the tallboy. Right now the top of the bridge of the mandolin in question is 31/32 off the top of the mandolin. Seems pretty high to me. My other two mandolins are 3/4 and 7/8. Not a lot of difference but the one at 3/4 is the one I prefer. Volume and tone much better.

**barry k** · Jun-15-2009, 1:36pm

Steeper neck angle results in a higher break angle,(depends on top arch also) which then puts increased pressure on top, tailpiece, tailblock and rim area around tailblock. like Hans said high or low may or maynot effect tone, but it will definatly effect playability. I hate stiff feeling strings, too much tension cause this stiffness. It took me a few mandolins to get the combination of neck angle , bridge placement and arching that I was pleased with.

**Gail Hester** · Jun-15-2009, 3:02pm

From the picture, it appears that the neck angle is not the issue but rather the height of the neck set and as Hans said the resultant tall riser block.

**Martyweir** · Jun-15-2009, 3:32pm

Are you fishing for repair options here, or just looking for general opinions? There are alot of factors at play including plate thickness, overstand height, string break angle, as well as neck angle. The siminoff link is good reference to check your string break & neck angle & calculating top loading.

I just reset the neck angle on my first build and it made a world of difference. Hope I never have to do that again. In my case, I originally had a bridge height of around 1.15", which is WAAAAAYYY too high (beginner error). Before I reset the neck angle, It was tough to keep strings on it. The tone was sweet and woody in the mids before, but not loud, and there was no chop & not much bass to speak of. Tone was not very balanced. I had issues with fret buzz because I could never get the action high enough and the string tension was tough on fingers. After the neck reset the bridge height is about 5/8". I have a very similar sweet woody midrange tone, but I can dig in and get more low end out of it, and it is noticably louder. Chop is pretty potent now too. Overall, much more balanced & comfortable to play.

Your mando may have been designed that way. Some folks pick hands are pretty wicked & some folks mess with the bridge height trying to build foghorns, so who knows... If you are fishing for repair ideas: as suggested check the neck angle & height of the riser block. If the geometry is correct and you have enough clearance above the top & scroll, you could have a reputable luthier remove the fretboard & sand the neck to a lower angle to lower the riser block height. Much less invasive than neck reset...

If your not serious about doing anything with it, it should be just fine, but I'd keep an eye on top for splits & sagging down the road.

**reverhar** · Jun-15-2009, 3:34pm

Best I can tell, the riser block is around 3/8 which I would think would be on the high side. So, if we determine the neck angle is the issue, does that mean that the only way to resolve this would be a neck reset?

**barry k** · Jun-15-2009, 4:57pm

Thats probably not too high, but the combination of the two might give you what you have??.. best to take it to a repairman and have it evaluated, or play it and leave it alone.

**Rob Grant** · Jun-15-2009, 6:43pm

There have been two references to break angle increasing string tension (playability-wise) in this thread. I might be arguing in ignorance here, but break angle should only increase direct bridge to top tension. The actual string tension is constant to the pitch that the individual strings are tuned to. Of course a high action will mean that the string has to be pushed further (slightly increasing tension) to fret, but the actual string tension (at rest) remains the same. Therefore a higher break angle with a good action height should not really affect string tension. Am I wrong?

**John Arnold** · Jun-15-2009, 10:39pm

To me, it seems as if the greater tension would lessen the top vibration which would create an end result of less volume and maybe changes in the tone. Would that be a correct assumption?

It can stiffen the top, making it less bass responsive. Depending on the construction, there is a 'sweet spot' where the down pressure is enough to get efficient energy transfer, but not so much as to affect volume and bass response.

There have been two references to break angle increasing string tension (playability-wise) in this thread. I might be arguing in ignorance here, but break angle should only increase direct bridge to top tension.

Higher break angles increase the static tension in the string from the bridge to the tailpiece. The static tension in the vibrating string is not affected. But the dynamic tension is a different matter. When the mandolin is played, the string is pressed to the fret, and plucked. Both of these actions stretch the string, which in turn, stretches the 'dead' section of the string below the bridge. That is where the tighter feel comes from.

**Martyweir** · Jun-16-2009, 7:58am

Originally Posted by barry k

Thats probably not too high, but the combination of the two might give you what you have??.. best to take it to a repairman and have it evaluated, or play it and leave it alone.

Sounds like good advice. BTW, what kind of mandolin are we talking about here? Is it one of the 2 Gibson MM's in your profile?!?

**Hans** · Jun-16-2009, 8:57am

A riser block that sits 3/8" above the top (probably means the whole block depth to the rib is 9/16" if the top is 3/16" at the block) is a bit tall. I don't like to go over 5/16" and prefer 1/4". Nothing much can be done that won't cost you a bundle, but the tallboy bridge will keep the saddle from tipping, and get the thumbwheels back down to a reasonable spot.
This is a factor to watch for anyone looking at mandolins. Tall riser blocks, excessive neck angle and a saddle that's screwed up to the top of the adjustment are warning signals that the instrument might be built improperly.

**reverhar** · Jun-16-2009, 4:12pm

Thanks to everyone for their advise. I will continue to play with the setup on this instrument. I have changed strings again and lowered the action a bit and the mandolin seems to have gained tone, is not brassy as before, and has maintained pretty good volume. I also measured the break angle, if I did it correctly, and determined that it is around 14 degrees. All the specs seem to fall in the high range but not totally out of line so that the mandolin should not be damaged by excess tension on the top.