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Some of you may have seen the really innovative, beautiful work of Nigel Forster, the English luthier. He's come up with a unique approach to the archtop, one that utilized a “long neck” that held the strings at tension, like a neck-thru electric bass, and which was coupled to an arched body by a bridge that contacted the neck . [url="http://www.nkforsterguitars.com/instruments/archtop-guitars/"]You can see pictures at his website and a description of the idea here.[/url]

I thought Forster’s idea was interesting—it reduced stress on the top, and while it would likely have less volume I have yet to play a jazz gig without an amp. It looks like a design that would be relatively easy to build. You could change strings without changing the tension on the top. And plus, if I built it and it sounded lousy, I could blame the design, rather than myself!

Note: although I've built a few good solid body instruments, I have never built an acoustic guitar—never bent a side, never braced a top. Also while I have Benedetto’s book on building an archtop, this would be a different design. I decided this would be a “never mind the maneuvers, just go straight at ‘em” build. How else do we learn?


Below is an example of how the neck attaches. It's attached with machine bolts and sits on this angled mount. I just winged it on the angle. I have no idea what the angle is. It's roughly the same as the angle on my Guild archtop





Here you can see how the strings attach to the neck. I need to come up with some sort of cover that's less crude looking. Also that's a temporary bridge--i've since make a wider, thinner bridge that's well fitted to the top. But you can see how Forster's idea works




And here the hardware store 1/4-20 bolts. I need to inset them or buy something a little more classy looking




So it's strung up and roughly setup and I'm thinking about what I want to do. a little more top and back carving. I need to install the pickup.

For what it's worth, here's what it sounds like acoustic, recorded with a ribbon mic about three feet away

[url="http://chnm.gmu.edu/courses/omalley/archie%20raw.mp3"]Raw acoustic sound[/url]

Couple things to consider

1. It's a crude copy of a someone else's idea
2. I've never made an acoustic guitar before
3. the sound clip above is a raw unprocessed recording of a guitar with a rectangular, uncarved neck

I think acoustically it sounds surprisingly good. Since I recorded that clip I've finished the neck and done some additional to carving and setup. Today I'll start french polishing.

So Forster is on to something really cool. The neck angle can be adjusted--it doesn't matter if it's steep or shallow. The tension on the top can be controlled by the bridge and/or the neck mount. The top can be lightly braced because it's not bearing the pressure of the strings. It's relatively easy and the modular design simplifies finishing.

I wish I knew more about making a top, because I'm pretty sure I carved this much thicker than it needs to be. The first thing I've noticed is that if I increase tension on the top, it gets slightly louder and much more midrangy and barky, with less sustain. Its a really good sound for chunking out rhythm chords. If I back the tension off, it sounds more like a flattop. I'd like to try this again with a thinner top and some kind of specifically adjustable neck design, so the player could dial in the amount of tension on the top.

Oh here's an overall shot of the guitar in the white



I've since trued up the sides a bit and made the soundhole a little larger. The guitar is made out of some old cherry boards I had sitting around and a piece of spruce I bought a decade ago for a guitar I never finished

The sound surprised me, not bad.

I saw your description over on MIMF, and we've exchanged a few posts on a more general topic. I won't go over that again, but I am curious about the neck join. Did you really figure it out just from Forster's pictures? Amazing if you did.

What kind of neck block is under the neck and inside the body? Do you have pictures? How do the carriage bolts (or whatever those bolts are) pass through the neck block? Did you put inserts into the neck? Again, pictures?

You say you can adjust the neck angle, how? It would seem you have some kind of wedge that separates your neck-through and the actual body. Do you need to change that wedge to adjust the angle? How do you bring more/less pressure to bear on the bridge? Are the mounting bolts not fully tightened?

In short, if you have pictures and descriptions of how that neck attaches and is adjusted to the body I am certainly interested.

A good archtop is among the loudest of guitars. How does this compare to a standard archtop? Where does the pickup go?

_________________
http://www.cushmanguitars.com/.

A man who carries a cat by the tail learns something he can learn in no other way.
Mark Twain

Forster carves the spruce top in a neck-shaped concave curve, with the angle figured in, then sits the neck in that "cradle." I just tapered a piece of cherry, glued it to the back of the neck blank at @the 14th fret and then put in some threaded inserts. The machine screws are 3.5 inches long. If the local hardware store had something more elegant I'd have used it! Forster appears to use something like button head screws. In one of his guitars, he attaches the neck via screws in the fingerboard, which seem to be capped. It's hard to tell and I've been hesitant to ask him, since I've been copying his work in an amateur way.

The neck block is just a square of laminated cherry--you can see it in the picture below, where it's really oversized for the job. I beveled the edges after the picture was taken, because "professionalism!" It has three holes drilled through it


I can't adjust the neck angle, but I'd like to figure out a way to do so. What I can do is adjust the degree of pressure on the bridge by loosening or tightening the third, single machine screw. What I've noticed, though, is that despite the graphite stiffening rods I installed the neck flexes a good bit. The truss rod runs the full length of the neck and I haven't really experimented with it yet. I;'d like to figure a way to make the neck angle adjustable, maybe some kind of pivoting bolt arrangement within the neck block. Like a barrel bolts in the back and a machine screw in the front. It would also be easy to make a set of neck mounting blocks at different angles, sort of the way Taylor does those neck angle shims

I think this would be a great ting to try with a carbon fiber top!

Hard for me to answer on loudness. The player is the guy in worst place for judging loudness. It seems as loud as my guild artist award, a full size 16 inch archtop from 1978, but I would not take that to the bank. When I get it set up agin I'll try putting the two guitars in front of a mic and see what I can come up with.

I made this with the assumption that it would be acoustic for around the house, and electric for playing out. The pickup will go at the end of the fretboard, jazzbo stylee. I'm planning on using one of those Lace ultra slim acoustic pickups, which is @1/4 deep. output jack will go on the pickguard, so the whole neck/pickup assembly can be removed in one piece.

If I were to build another one of these, I would use a lower profile truss rod and put a fillet on top of it, and then I'd have room for a more typical end of fingerboard pickup. I sued a Stew Mac Hot rod because I already had one hand

It is a very interesting and unusual design. With no string tension on the body just about any body shape should be possible. Unlike most guitars the body neck joint is also under no string tension. Great first acoustic build!

_________________
http://www.cushmanguitars.com/.

A man who carries a cat by the tail learns something he can learn in no other way.
Mark Twain

I think I'll give it a try. One of the problems I encountered with the CF top is that CF isn't strong in compression. The dome holds its shape well, but the pulling of the strings from the tailblock tends to "accordion" the top. This "through-neck" idea would eliminate that problem.

It's important to me that an archtop sound good acoustically, otherwise you might as well build a solid body. I'm still not a hundred percent convinced by this design, but your sound clip is very encouraging.

What the heck! CF archtop is weird enough, why not make it totally unorthodox!

Here are a couple pictures of the finished guitar and a new soundclip, first with a pick and then fingers


http://chnm.gmu.edu/courses/magic/forster%20style.mp3

Sounds nice. How are the ergonomics with the strings that high above the body?

_________________
Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

They're not bad at all, although they might be with a bigger body. At some holding angles I notice the jump to chords at the tenth fret being a slight bit awkward but at others no issue. If I were to build another one I would consider making the neck angle slightly less steep. Or I could adjust this one. We'll see as time goes by.

One interesting things about this design is the neck angle does not affect tension on the top, which is controlled by the bridge.

But making the neck angle too shallow would mean having to either mount the input jack somewhere else or go to a mini jack for input. The tip contact of the input Jack is @ 1/2 inch above the top as it is. Forster puts the Jack in different places on his.

The other weakness of this design, which I'm still thinking about how to get around, is that there isn't a lot of room for a pickup. I have a pickup that will work well, but choices are limited. I'm not sure how Forster gets around this.

The truss rod runs the length of the neck--it's a bass truss rod--which makes it great for tweaking the action. But it means you can't recess the neck below the fingerboard, because the truss rod--I used a stew-Mac hot rod--needs to be covered to work. A little hard to explain. One approach might be a shorter truss rod. Or maybe a low profile rod sunk a little deeper with a fillet over it. I'm still thinking about it

I've been giving this design a lot of thought thanks to you. I too am stymied by the truss rod issue. With a truss rod running the length of the neck, it's hard to see how to mount a pickup. There is one super low profile pickup made by Lace. Not cheap, and I would hate to be limited to just one pickup choice. What pickup are you going to try to mount?

Looking forward to your further development of this.

I went with that Lace UltraSlim Acoustic pickup. It is pricey. I tried a "flatpup" from this guy, Humidor Guitars (http://humidorguitars.com/magnetic-ciga ... r-pickups/). Cool design, VERY thin but it was SO noisy I gave up on it. It sounded great as far as I could tell through the nonstop buzzing. The LAce pickup was pretty much dead quiet from the start.

Here's a clip, played through a ZT Amps lunchbox

http://chnm.gmu.edu/courses/magic/archamp.mp3

My daughter ran up and distracted me at the end and I stopped, but you get the idea

It sounds good, but the pickup BARELY fits. Barely, and I even cut the section underneath it down a little

On my guitar I glued the fingerboard on, then glued a facing made out of richlite planed down to the rest of the neck below the fingerboard, so the rod would have backing, like 1/8 thick.

Some ideas

1. LMII sells a low profile truss rod with a rectangular metal backing rod (not the right term) that does not need a fillet. I was thinking use that, sink it a little low, put a fillet in anyway under the neck, then shave it down to the metal rod where the pickup sits. But they don't make it in bass lengths. Stew Mac makes soemthign similar, also not in bass lengths

2. Use a facing of a thin CF/Graphite plate. Lke 1 mm. Strong, thin. You would know much better than me if that would work!

3. Add a metal plate of some kind

4. use a really thick fingerboard.

5. Use a shorter truss rod and a stiffer neck, e.g. laminated boards on edge

I can't tell what forster does, and I don't want to ask him--he does this for a living, and it seems wrong to ask him to give secrets away. Based on how his bridge saddles look, I think he uses a thicker fingerboard

Nigel Forster originally posted his build thread for these "Long neck" archtops on MIMF. I don't think he would be offended if his fellow luthiers were curious about his design. I've emailed him about the placement of the truss rod/pickup. I'll post back here if/what he responds.

Yes, I've made quite a few of these archtops now and yes, getting the pickup to fit height wise is an issue. Space is tight.

There are several ways to tackle this issue:

1) Slim pickups - I've used both the cheap factory and the hand wound versions of the Kent Armstrong slimbucker. There are a few other slim pickups out there too. Quite a few come out at about 7mm deep.

2) Sink the truss rod in deeper the neck at the saddle end and cap it above. I use easy to find (ebay) 2 bar, 1 way bass truss rods. Then you can cut into the neck by a few mm.

3) Wedge it - use a thicker fretboard at the saddle end. You can add a couple of mm if you start off with a thick fretboard. This does increase saddle height but since the saddle has no leverage on the soundboard this isn't a structural issue only an aesthetic one.

4) If the pickup has pole pieces (like the Johnny Smith pickup I use for "Carlos") drill the neck slightly under the poles to accommodate.

5) Combinations of 1, 2, 3, 4 and 5.

Acoustic volume - These are not designed to be acoustic arch tops - though acoustically they perform better than you'd expect for heavy, shallow instruments with no end to end compressive forces on the soundboard. They are far louder acoustically than all the semi acoustic guitars I've tried.

Rather, these are (in my opinion and in the opinion of their owners) a really superior semi acoustic guitar. They have bags more sustain than your average (or even above average) archtop/semi yet when amplified have a resonant and woody quality that you can only get from an acoustic body.

Neck angle - on this guitar the neck angle has no effect on anything other than playing position and aesthetics. The down force on the soundboard is created by the wedging action of the bridge between the neck and the top.
In short, the bridge is taller than the gap it fits into, and the neck (if you've chosen you materials wisely) is considerably stiffer than the soundboard. The result is down pressure on the soundboard, irrespective of neck angle. To repeat: the down force is created by the differential between the height of the bridge and the gap you put it in. It's a very simple system.

Truth is though these guitars are just too unconventional for most people. They just don't "get it." But some folk do. As a result unless someone well known plays them, the "long neck" archtop will always have limited market appeal despite being superior to much of what is out there. But that's fine, if you end up trying to please everybody, you end up making the same guitar as everybody else and there is enough of that going on already.

It's nice to see folk trying the design - hopefully doing so will help you to come up with new stuff of your own. You may learn something by copying, but once you have, I'd urge you to try some experiments. And if you're not sure how to experiment, develop your own aesthetic or progress with the design aspect of your work, there are lots of things to try in theluthierblog ebook. It's a $9.99 ebook with a lot of useful thought provoking stuff in it.

Here is a link:

http://www.amazon.co.uk/Luthier-Blog-Op ... thier+blog

Keep it up!

Nigel
http://www.theluthierblog.com

Thank you very much!

I'm not an archtop guy, but this is really interesting stuff. Is the bridge glued or simply wedged?

If the latter, presumably you could manipulate the tone by having various height bridges that you could swap in and out.

Or am I on drugs?

Steve

Bridge is just wedged in.
Yes, the amount of pressure on the top makes a significant difference inthe tone. More pressure makes it barkey and midrangey

Just an update for anyone interested. I made a second neck for this guitar, following Nigel Forsters suggestions for making pickup mounting easier. I used a low profile truss rod, routed the channel at an angle, and planed the fingerboard as a wedge. As a result I've got half an inch of clearance for a pickup at the end of the neck and I could get a little more.

This does compel ate neck construction considerably--I had to make two simple jigs for routing at an angle. At this point I'm still using a Lace UltraSlim Acoustic pickup, because it sounds really good. I'm tempted to try something else but if its not broke why fix it etc. You can make a pretty conventional neck and use the Lace pickup or maybe the new surdo pickup and get excellent results, or or make the fixtures for the angle/wedge arrangement.