Pre-war neck angle

[Rickco]

Ive been looking at some pre war archtops. According to Bob Benedetto the distance at the bridge location should be 1" extending the fretboard top with straight edge to bridge location between top of plate and straight edge. I have looked at all my post '60s archtops and this seems to be the case.

However many of the pre wars I have seen seem to be lower,some by 1/2" but seem to still sound and play well. From inspection these guitars of different makers showed no signs of neck movement, everything tight at heel with no signs of repairs or separation, no sinking of top. Again these all played well, were all pre '40.

So my question is, is it common for a prewar archtop to have a lower neck angle?

I'm not a luthier so what am I not seeing. Im playing one with only 1/2" at said distance but set up and plays well. Ive dealt with reset and sunken top so I get that. These examples were solid carved Epi and Gibsons playing and looking fine but exhibiting this lower angle and it seems to be common in these 80+ yr old gits, or is this just a coincidence in the ones Ive seen.

By example I observed this on a '30s L7 I really wanted and played well but the lower angle and the bridge almost all the way down scared me off, I'm still wondering if I was being over cautious and underinformed.

[wintermoon]

Some prewar guitars were designed w more shallow neck angles but one of the main reasons for bridges bottoming out/action getting too high is necks pulling up over time under tension. That doesn't necessarily mean you'll see a seperation at the neck joint/heel.

[ThatRhythmMan]

It depends on the guitar. Epiphones need resets more often than the old Gibsons. I’m no expert on the construction, but Mark Lacey had explained this to me as due to the type of joint each used. He said that vintage Gibson archtops almost never needed resets. The one example of a Gibson that I took to him that did he was quite certain had too shallow of an angle from the factory.

The prewar guitars that consistently seemed to have shallow angles in my experience are L-50s, and that seems to be fairly consistently true of both those with fingerboards flush to the body and those with elevated extensions.


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[deacon Mark]

Yes, Gibsons rarely ever need a neck reset compared to other guitars. They seem to have that process down. The older Gibson in the 40s and 30's do usually have a shallower neck angle. It is not consistent and over time can change a bit but usually nothing that needs a reset. In fact, the only issue on some is getting pickup thin enough to go under the strings and clear.

My 38 L5 has a fairly shallow neck angle and a Dearmond works but fine but a full-size humbucker like a Kent Armstrong is too fat to clear. This actually common on older archtops and not necessarily because the neck needs a reset, it depends on what you want to do. I at one time thought shallow neck angles did not make always for the best of sound but now think the opposite in some cases. Normally a steeper angle you should get more punch and sound but over time I do have observed and heard otherwise. I would be interested on others take on the neck angle and sound. In my case the 38 L5 is a monster sound, loud and punching but with sustain and rounded equally bass and treble.

Both of my other acoustic Gibson archtops from last 25 years easily fit a full humbucker they have a BJB floater.

[sgosnell]

A higher bridge, thus greater break angle, tends to put more pressure on the top through the bridge. Whether that increased pressure helps or hurts depends a lot on the way the top is carved, IMO. Everything influences everything else, and so I'm not sure there is a set relationship between sound and bridge break angle. I'm fine with whatever the angle is, as long as I can get the action I want without fret buzz.

[JCat]

Look, there's an obvious relationship between bridge pressure, tone and feel. The steeper the break angle, the greater the bridge pressure. (If there would be no string break at all, a floating bridge would not stay put).

The greater the bridge pressure, the greater the compression of the top. When you turn those thumbwheels clockwise, the bridge may not raise a corresponding distance as the force presses the the top down. Also, the top tends to compress around the neck joint, (effectively pressing the neck joint down).

Over a long period of time, this compression may result in permanent deformation. At some point in time it's no longer possible to have low action keeping the neck straight, and this is when the guitar is due for a neck reset.

This is not only a matter of build quality, but also about storage, maintenance, strings and gauge etc.

This is how you validate that a guitar can be set up properly:
1. Set the neck straight using a straight edge.
2. Put a long straight edge over the frets, extending all the way to the bridge. Now, the straight edge must clear the top of the bridge (if not, the neck angle has gone flat...)

[deacon Mark]

Look, there's an obvious relationship between bridge pressure, tone and feel. The steeper the break angle, the greater the bridge pressure. (If there would be no string break at all, a floating bridge would not stay put).

The greater the bridge pressure, the greater the compression of the top. When you turn those thumbwheels clockwise, the bridge may not raise a corresponding distance as the force presses the the top down. Also, the top tends to compress around the neck joint, (effectively pressing the neck joint down).

Over a long period of time, this compression may result in permanent deformation. At some point in time it's no longer possible to have low action keeping the neck straight, and this is when the guitar is due for a neck reset.

This is not only a matter of build quality, but also about storage, maintenance, strings and gauge etc.

This is how you validate that a guitar can be set up properly:
1. Set the neck straight using a straight edge.
2. Put a long straight edge over the frets, extending all the way to the bridge. Now, the straight edge must clear the top of the bridge (if not, the neck angle has gone flat...)

The top of bridge, not thr saddle correct? I am asking to clarify?

[JCat]

The top of bridge, not thr saddle correct? I am asking to clarify?

Correct, the straight edge must clear the top of the bridge saddle.

[Rickco]

I was wondering if the distance from the string to the top of the plate would effect sound and if the 1" BB recommends is for tone. Sounds like the resulting pressure at the bridge would mitigate that...? When you raise the action on an acoustic archtop it generally sounds louder and when you put heavier strings which would increase pressure at the bridge. TRM mentions the L50 which was when I first thought about it since it seemed low by design but noticed it on early Gibs and Epis which didnt show any signs of neck or top movement and played well but with bridge almost all the way down to accommodate an action of 4/64 +- . I passed on an L7 I really wanted because of this concern. It was a '30s? picture frame with no signs of movement at the heel or top but bridge bottomed out at 4/64, very playable etc but not being able to lower action if anything moved scared me off...still wondering if that was prudent. Good info here thanks

[Rickco]

Quick add on, Texas Bills L12 picture of bridge exactly what Im talking about. (a few posts earlier)

[sgosnell]

I don't think the distance of the strings from the top makes much if any difference in the sound. It's the bridge that drives the top and produces sound.