StewMac tools

Looking for info on resophonics (spider bridge)

Please put your pickup/wiring discussions in the Electronics section; and put discussions about repair issues, including fixing errors in new instruments, in the Repairs section.

Looking for info on resophonics (spider bridge)

Postby Peter Wilcox » Wed Aug 03, 2016 9:00 pm

Shortly I'm going to start building both a round neck and a square neck guitar. I don't need plans, but any info, links, pics, drawings of builds would be helpful. I have Stewmac's guide (biscuit, not spider) and Gary Dusina's pdf, and have links to a couple of reso sites (that don't have much info on building them). I have a cheap Chinese square neck (with a sound well) and have upgraded it (new cone, flattened spider and cone ledge, made new nut, tweaked saddle slots), and set it up, so I'm somewhat familiar with its construction. I've never even seen a round neck reso, so this is new to me.

Some specific questions I have are the influence of body depth, solid vs laminate, sound well vs sound post design, baffle vs no baffle, dual sound holes vs single vs f holes, screens or no screens, types of bracing. Regarding a round neck guitar, I assume the fret board and saddles are radiused, with similar action to any steel string guitar. And that compensation is done by rotating the spider, so the scale length will be a little shorter, or the cone placed a little farther from the nut, than a square neck guitar.

Anyway, any info, links or opinions would be appreciated. Thanks.
Maybe I can't fix it, but I can fix it so no one can fix it
User avatar
Peter Wilcox
 
Posts: 871
Joined: Sun Jan 08, 2012 1:31 am
Location: Northeastern California

Re: Looking for info on resophonics (spider bridge)

Postby Brian Evans » Thu Aug 04, 2016 7:31 am

Paul Beard is a good source of information, he sells a kit and a plan. You need to be careful with neck angle on a round neck, my Goldtone Paul Beard signature has a wedge under the fretboard extension and the neck is on a decent angle to get the needed string height over the bridge. You are building a box with pretty thick wood, 1/4" or so, and bracing vs no bracing, sound posts vs baffle ring, F-holes vs a couple of round holes is all a matter of taste. My 1936 Dobro (Chicago made by Regal, Model 25) has a dovetail set neck just like a normal guitar, thick plywood body, no bracing or internal structure except for the ring the cone sits on, F holes, neck joint at the 14th fret, and it sound great, I play it bottleneck because the neck is bowed but the body is in perfect shape. So different builders try different things, but at the end of the day it's tough to say a soundwell is better than posts, is better than an open baffle. General consensus is that solid wood is not better than plywood, some of the best players preferred a plywood guitar. I personally think solid wood instruments got popular because when boutique luthiers started building resonators in the 1960's and 1970's they could get quality solid wood tonewood easier and cheaper than really high quality good looking veneer plywood, so they used it. People think that maybe maple is brighter than mahogany, but they can't reliably tell in an A-B test. The idea of tonewood is kind of moot in resonators because the idea is a solidly damped speaker box, so you can pick really pretty wood and go for the visual appeal without worrying about is it master grade spruce, or what thickness the top bracing is. The screens are there so you don't drop stuff inside the box, btw. No other reason, except maybe that they are shiny. Good forum here: http://www.resohangout.com/
Brian Evans
 
Posts: 516
Joined: Sat Aug 30, 2014 8:26 am
Location: Tatamagouche, Nova Scotia

Re: Looking for info on resophonics (spider bridge)

Postby Brian Evans » Thu Aug 04, 2016 8:06 am

Forgot: original Dobro's had around a 1 7/8" nut width and flat fretboards. Slot head until late 1930's. Mostly 12 fret neck joints, 14 fret option from late 1935 or so. The 12 fret guitars had a typical shape very similar in size to a standard classical guitar, while the 14 fret had the same size lower bout and just smalled-up the upper bout. Modern round neck resonators can have a cutaway. I personally find that my 14 fret Dobro lets me play slide up to the all-important 12th fret very easily, and my 12 fret PBR-CA with a cutaway lets me do exactly the same, so two great options that I would think about for a round neck. I would suggest the square neck be a 12 fret. Tuning - most square-neck players use high G tuning - GBDGBD, and heavy strings - .016 to .056 - which puts a lot of tension on the neck. Round neck players tend to use "Spanish" tuning, which I call low G - DGDGBD - which is a lower tension tuning and is great for slide with the same string set as square neck uses, or just regular guitar tuning with normal strings. I use a variation of Spanish tuning with a low E instead of the low D, since that gives me a nice minor 7 chord option.
Brian Evans
 
Posts: 516
Joined: Sat Aug 30, 2014 8:26 am
Location: Tatamagouche, Nova Scotia

Re: Looking for info on resophonics (spider bridge)

Postby Brian Evans » Thu Aug 04, 2016 8:20 am

Ha! I was questioning a comment I made about solid wood being cheaper and easier than really great plywood. My hardwood supplier makes very high quality plywood also. I can buy a 4 X 8 sheet of highly figured birdseye maple 1/4" baltic birch core plywood for $700. I can buy highly figured kiln dried 4/4 rough sawn birdseye or curly maple for $12 a board foot. I could buy $16 worth of solid maple (8" by 24" by 1") and re-saw it into a book matched top set or I could get 12 tops (16" by 24") out of the sheet of plywood for $58 per top. I never actually did the math before. They have cheaper plywood, mind you.
Brian Evans
 
Posts: 516
Joined: Sat Aug 30, 2014 8:26 am
Location: Tatamagouche, Nova Scotia

Re: Looking for info on resophonics (spider bridge)

Postby Peter Wilcox » Thu Aug 04, 2016 10:17 pm

Thanks Brian for your detailed reply - it's a help. I'm a recent member at resohangout - lots of opinions and not a lot of build info, and hard to figure who knows their stuff.

My question about solid vs plywood was because some opinions I've read are that plywood is better. I have lots of figured maple I'll be using, and I guess in the end it seems like it's a wash either way. Some say that different types of solid wood impart different sonic qualities to the instrument - hard for me to believe since they're so heavily built. I guess it's like the same argument about solid body electrics.

I'm still unclear about the round neck fret board and saddle - radiused? When you said the original Dobro had a 1 7/8 nut and flat, was that regarding the square or round neck? Also, it seems some have the fret board extension screwed to the top - for added bracing I presume. Slot head certainly easier to tune, but harder to make.
Maybe I can't fix it, but I can fix it so no one can fix it
User avatar
Peter Wilcox
 
Posts: 871
Joined: Sun Jan 08, 2012 1:31 am
Location: Northeastern California

Re: Looking for info on resophonics (spider bridge)

Postby Freeman Keller » Thu Aug 04, 2016 10:31 pm

Peter, Brian has given you a lot to think about - I'll add a couple of my thoughts. I currently own three reso's and a Weissie and play both lap and Spanish style slide. One of my reso's is a 1932 type 27 Dobro - its a round neck spider but I currently have it set up with a high nut and am playing it lap style.

Image

First, the square neck. As you know it will be strictly a lap player so make the fretboard perfectly flat, set the action about 3/8 from nut to last fret and don't worry about intonation (set the saddle at exactly the scale length). Buy your cone and spider and use them to lay out the geometry of the guitar. As far as body volume, sound well design, f or screen holes, my only recommendations are to listen to guitars and choose what you like. My 27 is cheap birch plywood, traditional sound well and a shallow body - it has the sweet singing tone that you expect of a traditional dobro. Ps, I'm running a Quarterman cone in it. I would consider doing a traditional neck stick to allow you to change the angle if you ever wanted to.

Image

As far as building a roundie, I think you need to answer some questions about how you plan to play it. Most of the time it will be Spanish style and may be either fretted or slide. If you are going to play mostly fretted then you MIGHT want a little more radius in the fretboard, if you will be using a cylindrical slide then you might want a flatter board. My metal body is 16 inch radius and I personally hate it for slide, I'm much happier with 20 or more inches (and a moderately wide neck).

You may want to consider compensating the saddle/spider/cone - I added a very slight compensation to my tricone because I do play it about 50% fretted (and the slide is the ultimate compensator LOL). I don't set the action particularly high on a roundie and I'm careful about picking strings that fit the tunings I use.

You have obviously chosen to build spiders for a reason - personally I think that is the right choice for a lap guitar but depending on the sound you want you might want to consider biscuit or tri cone for your roundie. I'm sure wood does matter but I think its like arguing wood for an electric guitar - the affect is overwhelmed by the choice of cone (pickups) and configuration. I think I have the right mix - wood spider for the dobro sound, the metal biscuit for delta blues and the wooden tri cone is somewhere in between - it has certainly become my go-to resonator.
Freeman Keller
 
Posts: 223
Joined: Mon Feb 27, 2012 11:34 am

Re: Looking for info on resophonics (spider bridge)

Postby Brian Evans » Fri Aug 05, 2016 6:45 am

Modern round-neck resonators typically have the wider fretboard but with a 20" or so radius. Enough to make it comfortable, but not enough to make it hard to play slide on. I believe my PBR-CA has a thoroughly modern bolt-on neck, and it has a radius. The 1936 Dobro has a flat board, is a round neck, but recall that they were dead cheap guitars in their day - definitely a "student model".
Brian Evans
 
Posts: 516
Joined: Sat Aug 30, 2014 8:26 am
Location: Tatamagouche, Nova Scotia

Re: Looking for info on resophonics (spider bridge)

Postby Freeman Keller » Fri Aug 05, 2016 11:49 am

Brian Evans wrote:Modern round-neck resonators typically have the wider fretboard but with a 20" or so radius. Enough to make it comfortable, but not enough to make it hard to play slide on. I believe my PBR-CA has a thoroughly modern bolt-on neck, and it has a radius. The 1936 Dobro has a flat board, is a round neck, but recall that they were dead cheap guitars in their day - definitely a "student model".


My 1932 type 27 was the least expensive of all Dobro (tm) models - birch plywood, no body binding, flat wide neck. It cost $27 new, an 18 series Martin was $18 at that time as I understand.
Freeman Keller
 
Posts: 223
Joined: Mon Feb 27, 2012 11:34 am

Re: Looking for info on resophonics (spider bridge)

Postby Freeman Keller » Fri Aug 05, 2016 12:25 pm

A few more random thoughts about building a resonator.

A square neck doesn't need a truss rod but build the neck "sturdy". When your action is a mile high a few thousands relief doesn't matter. A slot head with the tuner buttons facing up works well for tuning, I find a paddle head a hassle to tune while on my lap. You really don't need wire frets - on my Wessienborns I just inlay contrasting wood

Image

A roundie of course can be set up for lap play with a nut extender - its kind of fun to switch back and forth. Be careful of string gauges - so called "resonator" sets are designed for high bass G (also called dobro G) where the bottom strings are tuned up - that will be a fairly high tension which might be hard on the neck (and hard to fret).

Most of the time a roundie will be played a combination of fretted and slide - you need to decide what configuration and action works best for YOU. I prefer 1-3/4 nut, 20 radius and slightly higher than "normal" action (maybe 0.020 or so). I use mediums, change the first two to 0.014 and 0.017 and tune to either open G or D. Be very careful tuning up - watch your string gauges and break angle.

I think a roundie needs a truss rod but that can be problematic if you want to build a slothead. For my tricone I put the adjuster inside the body (like a Martin) and drilled an access hole thru the cone well - it is a real hassle to adjust (kind of like a Strat) but I've only had to do it initially.

Image

As I said before, most resonators have some sort of neck stick and the fret board extension is usually screwed down to the top (thats what the blocks are for in the picture). Hide the screws under marker dots I used a standard bolt on for the tricone - it has been adequate. Remember to provide some sort of access to whatever internal hardware needs to be taken apart for adjustments.

One of the big differences in building a resonator is that your starting reference is the cone/saddle location - both scale length and height. Its not like an acoustic where the bridge and saddle go on last so you have some wiggle room - once you cut that big hole you are locked in. I would suggest carefully laying out both plan and profile based on your actual hardware - factor in the radius of your string plane, clearance for the cover plate and palm rest, break angle to the tail piece (and its clearance on the cover plate). Most spider bridge saddle inserts are maple with an ebony cap - you need to file your string slots and there isn't much material to work with. Most of the time you will be futzing with the neck angle in conjunction with the saddle. A one piece saddle is slightly easier to work with but a two piece one lets you get at the tension screw which is valuable during setup.

I'll let you decide on woods, body size and shape and all those details. I'm sure that wood does color the sound but you see everything from plywood to some highly figured maple and they all sound good. I happened to use some highly figured koa but I was attempting to build a fairly outrageous guitar. As with any guitar, if you build to fit an existing case you'll save a bunch of money - a good resonator case will have a recess for the cover plate and palm rest and maybe for the tail piece. A square neck might need a special case for the neck. I had Cedar Creek build a really nice case for the tricone - 300 bucks and 4 months later....

Image

Do yourself a favor and make the top flat (back can be radiused). I made a couple of prototype cone wells while I worked out the details, including the rim that the cover plate mounts to

Image

Last, and far from least, share your build with us.
Freeman Keller
 
Posts: 223
Joined: Mon Feb 27, 2012 11:34 am

Re: Looking for info on resophonics (spider bridge)

Postby Peter Wilcox » Fri Aug 05, 2016 1:42 pm

Brian Evans wrote:Modern round-neck resonators typically have the wider fretboard but with a 20" or so radius. Enough to make it comfortable, but not enough to make it hard to play slide on. I believe my PBR-CA has a thoroughly modern bolt-on neck, and it has a radius. The 1936 Dobro has a flat board, is a round neck, but recall that they were dead cheap guitars in their day - definitely a "student model".


Thanks Brian - that's what I wanted to know. So it looks like either flat or long radius is the way to go.
Maybe I can't fix it, but I can fix it so no one can fix it
User avatar
Peter Wilcox
 
Posts: 871
Joined: Sun Jan 08, 2012 1:31 am
Location: Northeastern California

Re: Looking for info on resophonics (spider bridge)

Postby Peter Wilcox » Fri Aug 05, 2016 2:06 pm

Freeman - thanks so much for your great informative posts!

I'm sure I'll have more questions, but one that comes to mind now is determining the neck angle of the round neck. I'm assuming that a round neck can use the same build and components for the cone assembly as the square neck, and assuming that all similar cones will compress equally under a given set of strings and tuning, the saddle height above the top should be the same for each. However, since the break angle over the saddle from saddle to nut is greater for the round neck, this would increase the downward force component and tend to compress the cone more and lower the saddle. Conversely, since the string tension for the round neck is less, this would tend to elevate the saddle. I'm probably being too nit-picky and these offsets are negligible.
But this leads to my question - if I measure the height of the saddle above the top for the square neck, can I use this height (assuming I'm using the same components) to determine the neck angle of the round neck? (I'm sure I'll have to futz around with it anyway no matter how carefully I measure. :) )
Maybe I can't fix it, but I can fix it so no one can fix it
User avatar
Peter Wilcox
 
Posts: 871
Joined: Sun Jan 08, 2012 1:31 am
Location: Northeastern California

Re: Looking for info on resophonics (spider bridge)

Postby Brian Evans » Fri Aug 05, 2016 3:10 pm

My modern round neck has a neck angle of 1.5 degrees, more or less. It has a wedge under the fretboard extension. it has barely adequate string break angle over the saddle with the action at normal acoustic height (1/16" high E to 3/32" low E). Get your hardware, your tail piece, your cover and mock it up. Draw it full size, even. String tension has minimal effect on saddle height from cone deflection. If you build the top the same way, the same depth of ledge to mount the cone, the top of the spider will be in the same place, give or take a few hundredths. Don't forget the the saddles have a lot of height and are completely adjustable in the normal manner. You just notch the top for the strings and sand the bottom for height.
Brian Evans
 
Posts: 516
Joined: Sat Aug 30, 2014 8:26 am
Location: Tatamagouche, Nova Scotia

Re: Looking for info on resophonics (spider bridge)

Postby Freeman Keller » Fri Aug 05, 2016 9:53 pm

Peter Wilcox wrote:Freeman - thanks so much for your great informative posts!

I'm sure I'll have more questions, but one that comes to mind now is determining the neck angle of the round neck. I'm assuming that a round neck can use the same build and components for the cone assembly as the square neck, and assuming that all similar cones will compress equally under a given set of strings and tuning, the saddle height above the top should be the same for each. However, since the break angle over the saddle from saddle to nut is greater for the round neck, this would increase the downward force component and tend to compress the cone more and lower the saddle. Conversely, since the string tension for the round neck is less, this would tend to elevate the saddle. I'm probably being too nit-picky and these offsets are negligible.
But this leads to my question - if I measure the height of the saddle above the top for the square neck, can I use this height (assuming I'm using the same components) to determine the neck angle of the round neck? (I'm sure I'll have to futz around with it anyway no matter how carefully I measure. :) )


I don't think there is actually very much compression of the cone in a spider. I would lay out a side view of your guitar with the cone and spider you intend to use, the cone well depth, action parameters that you like for your style of play. Remember that if you have radius on your fretboard the saddle will too - that makes a very slight difference as you go across the strings. You get about 5/8 inch of saddle height on a new one but be careful about planning to us all of it - you still have to fit in the window of your cover plate and palm rest. Anyway, lay it all out and it will tell you where your static fret plane will hit your bridge (ie a straight edge on top of the frets). As you set the neck use that reference (kind of like we use the idea that the fret plane should hit the top of a flat top bridge). Don't lock the neck angle into place until after you've strung it up and confirmed that this is what you want.

Image

With most traditional resonators the neck stick is shimmed - either at the edge of the cone well as in the picture of my old Dobro or with "mushrooms" as in this picture of my Duolian.

Image

Anyway, feel free to ask any question that might be helpful - I'm happy to take measurements or go back to my records. btw - there are a couple of good sets of plans for various reso - might be worth while to have just for reference.
Freeman Keller
 
Posts: 223
Joined: Mon Feb 27, 2012 11:34 am

Re: Looking for info on resophonics (spider bridge)

Postby Peter Wilcox » Thu Aug 18, 2016 6:43 pm

I've been thinking (a dangerous process) about making the top for the square neck thick - 1/4" or slightly over. I'm going to use sound posts, not a sound well. The advantage would be that I could cut a 10 9/16" hole in the top, and a 10" hole in the tone ring, precluding having to cut or glue up a ledge in the tone ring (though no big deal), and still have clearance for the saddle/strings under the cover plate. It would also strengthen the maple (non-laminate) top, and possibly preclude the need for bracing. The disadvantage would be adding to the weight of the guitar, which is why I'd hesitate for a round neck. I don't know if or how it would affect the tone, since according to much of what I've read the top contributes very little or none to the sound (using the speaker box analogy).

Taking it farther, I could make the top 1/2" (yes, I have the wood to do it), cut the 10" hole and route a 9/32" wide ledge into that ~1/4" to 5/16" deep. Might not even need sound posts. Binding the guitar might be more difficult.

Maybe I'm missing something here. Any thoughts?
Maybe I can't fix it, but I can fix it so no one can fix it
User avatar
Peter Wilcox
 
Posts: 871
Joined: Sun Jan 08, 2012 1:31 am
Location: Northeastern California


Return to Flat-Top Acoustic Guitars and Bass Guitars

Who is online

Users browsing this forum: No registered users and 3 guests

Your purchase from these sites helps support the MIMForum, but only if you start at the links below!!!
Amazon music     Amazon books     Amazon tools     Rockler tools     Office Depot    

The MIMF is a member-supported forum, please consider supporting us with a donation, thanks!
 • Book store • Tool store • Links •