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Hello!

I’m starting my first archtop. I’m an amateur with some experience building lutes, theorbos and classical guitars.

I will follow The Benedetto book and plans but I prefer a long scale (25,5”) and here is my first doubt. Since the f holes are aligned with the bridge center, must I make the the neck 1/2” longer or the 25” scale body could assume this difference moving the f holes to the tailpiece? Could this affect to the design?

I also have some doubts about the fingerboard radius. I love the low radius of my Larrivée OM-03 (I thing is compound 17-21”). The 16” of my Godin 5th Avenue is perhaps too much for my ideal, but still comfortable for me. Benedetto uses 12”, I don’t know if an archtop guitar benefit of a pronuncied fingerboard radius due to the repertoire or other factor. Any experience on this subject?

Any suggestion will be wellcomed.

Thank you for reading!

Juan, if you are making it for youself, go with the flat radius that you like. I have on at 12" and the archtop is at 10-16" or something. I don't notice the difference, but I don't play much, and never was a player.
As far as the longer scale. If you keep the same body, and bridge placement, you would have a longer neck, and more frets to the body. Is that a terrible thing? I don't think so. You could play around with the body, making it longer, scaling up everything, or seeing just how much lower the bridge would set, with a 14 instead of 12, or 16 instead of 14 feet neck.
The longer neck does mess with.The balance. The 16 feet neck on my 13" archtop seems heavy to me.
If you are playing classicals, maybe a shorter scale with bronze strings would be fine.
Maybe real players will chime in.

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Why be normal?

Yeah.... I bet those long arms get heavy, too.

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"Act your age, not your shoe size" - Prince

Thank you very much for share your experiencie. I will consider it [SMILING FACE WITH SMILING EYES]

Juan, just a couple of comments for what they are worth. First, I have only built two archtop style guitars - one is a 16 inch carved top acoustic inspired by the Gibson L5 but built with the help of Benedetto's book. The second is a 17 inch hollow body electric, which will approximately the same size as Bob's 17 inch guitars.



For both guitars I used Gibson "24.75" scale, both because I like it and because I'm set up to slot that scale. Both of my guitars have the neck to body joint at the 14th fret.

Assuming you will still have the joint at the 14th fret your bridge will move a hair under 1/4 inch farther into the lower bout. The head will move slightly more that 1/4 from the body. In theory moving the bridge will have some affect on the sound - I don't think you will hear it (and you don't have any reference). As you said, the points of the f-holes usually point to the scale location (ie the bridge) but I don't know of any reason that they need to be there. The f-holes do have a couple of functions besides letting the sound out, they very effectively weaken the top and let the center of the lower bout vibrate (you'll experience this as you do the voicing of the top). Moving them a quarter of an inch probably won't affect that much. You could always change the shape, many f-holes do not have the points. Our you could not move the holes but put the points back at the scale. One little thing the points are good for is if your bridge comes off while changing strings it gives you a starting point to put it back on.

Adding to the scale means the neck will be longer but should not be a problem with normal archtop cases. Mine is in a nice TKL case and there is 3 inches between the end of the head and the case.

As far as fretboard radius, just remember that if you are going to use a commercial bridge you might be locked into that radius. StewMac sells a couple of bridges, they are 13 and 15 inch radius. My necks are both 12 inch radius, they work fine with the 13 inch bridge. Compound radius necks can get more complicated because the flattening. The big advantage to compound radius is they don't fret out as badly on big bends - I don't think many archtop players do that. Otherwise use whatever you like.

Good luck with your build. If you have any questions let me know. I've got lots of pictures of the carved top guitar and its really a lot of fun to play.

The advice I got from a jazz player with a long experience in retail was that a 16” radius will be most likely to sell to a flat top player taking his first dive into jazz guitar while most experienced jazz dudes will prefer a 12”.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Nice tip, thank you very much. I come from the classical guitar world, then flaptops and now starting to learn jazz. My goal is to increase my solo repertoire. I think that a long scale will be more suitable to my playing (and to mi size!) but I uave doubts about the fingerboard radius since 12” is used by Benedetto and this mean surelly better for jazz playing technic.

Thank you very much for the detailed information, that is very valuable for me. And contratulation for this two beautiful guitars. I’m sure you are very satisfied with both instruments.

I’ll send you a PM with some questions. Thank you very much.


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Fingerboard stop: a mistery for me.

As much as I have tried, I cannot understand why the fingergoard stop that Benedetto explains in his book is necessary. I have read the description and seen the drawings more than ten times. I understand what it's for (to create a straight line between the fingerboard binding and the headstock binding). But I don't understand why it's necessary. Is impossible achive this straight line without it?

No, you need it to raise the bottom plane of the head to line up with the fretboard.

There are other ways to do it but you will not get the same effect.

Hello,

My archtop is groving erery day… a interesting adventure on unknown seas for me.

I’m measuring the neck angle before frettinng and binding. I’ve measured a neck angle of 5º and 1 2/16” between the straight ruler and the top on the bridge location (without frets). I think is too much. Any expert advice would be welcome!

The fretboard extension looks excessively thick. If you thinned it down, that would bring the neck down closer to a target of 1".

Yes, is already thinned down to 7/16”. The measurement I wrote is done with the extensión thinned. Thank you very much.

There's nothing holy about the neck angle that Benedetto shows in the plan; the object is to get the correct bridge height and, more importantly, sufficient, but not excessive, string break angle over the bridge. The greater the break angle the greater the down pressure on the top. This does not 'transmit more string energy to the soundboard', it just makes the top collapse sooner. I'd just change the neck angle a bit to get the bridge height right.

Some time ago I set up an archtop that I had made with a 'hook' tailpiece: 'L' shaped, with the foot of the L hooked over the tail end of the body. The line of the strings from the bridge top points to the pivot, and with the pivot below the level of the edge the strings can actually point down through the top, although, of course they don't actually go through. It was fairly easy to alter the pivot point, and thus change the break angle over the bridge. Increasing the break angle by lowering the pivot point didn't make the guitar any louder; just the opposite in fact. At a certain point as I moved the pivot down the sound just died. I think there was too much down pressure which just kept the top from moving freely.

In theory, the bridge should sit at the high point of the arch, but a 1/4" difference probably isn't going to matter much.

I understand, interesting info. So I will adjust a bit the angle in the neck part of the dovetail joint. Thank you!

It should be an 1" finished.
You still need to carve the bottom of the extension to the top and that will bring it down.You also might have to adjust the cheeks of the heel as well.

Thank you, the neck extension is already carved. Please, what are the cheeks of the heel?

The 'cheeks' of the mortice joint are the flat areas on either side of the tenon that bear against the sides and establish the angles.

I undersrand, thank you very much!

I'm much too late here because I think I see a radius at the nut there in your pic, but radius is personal preference. I wasn't prolific by any means, but I played in a jazz band throughout college. Radius isn't something I ever thought about, and prefer a 16-20' radius now on my steel strings.

Scale length is structural. Changes there will require forethought, understanding, and planning. I've only dreamed of building an archtop and don't understand the instrument at all in a way that makes me feel comfortable offering advice.

16” radius has been my choice. Thank you!

I wonder how this small pickguards are fitted to the body. Is there only two screws to the fingerboard side? And the rest is “on the air”?

Sometimes there is a bracket underneath the pickguard that attaches to the neck, and a felt pad underneath the rear of the pickguard to keep it off the top.

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"Act your age, not your shoe size" - Prince

It’s a style. Larger pick guards are supported by a bracket on the side of the guitar. Those thinner ones aren’t supported. Of course, there is a block that attaches it to the neck extension that gives it rigidity.

If you like that style, they work fine. It seems like it wouldn’t be rigid enough, but it is. Personally I found that I didn’t need a finger rest on my guitar. If you are building for yourself you can always leave it off and decide what kind, of any, you want later.


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Thank you very much for your reply. Yes, I’m building for me, and really I don’t will use the pickguard for to rest the finger but for supporting the pickup and its controls. I’m considering to install a Benedetto S-6.
This small pickguards perhaps let project better the sound across the f hole.