Replies to This Discussion

Permalink Reply by Rand Moore on February 22, 2014 at 12:10pm

Hi Michael,

Those are nice drawings and photos of your resophonic box guitar. I'm always impressed by your builds. I was wondering how you go about making the 4 rings that you glue together to form the well for the resonator cone. It looks like 3.6mm ply, and I know from using 2mm ply for sound boards that cutting straight lines in the ply with a utility knife is already pretty tough, not even considering how to cut a curved line like on a circle. Of course, you probably have a special jig for some wood-shop power tool (like a band-saw or something else I don't have), but I'd still would like to hear about it.

I was also wondering that if you glue the reso well to the sound board, doesn't that dampen the sound board? Or is that not important because we are relying more on the reso cone for amplifying the string vibrations? I've seen some builders build reso-boxes without a well. Does having a well improve the resophonic sound? Your thoughts?

-Rand.

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Permalink Reply by The Phrygian Kid on February 22, 2014 at 1:26pm

You can't get a bandsaw blade onto the inside edge of an internal hole like this, it'd need to be a reciprocating blade like a jigsaw or scrolly or otherwise you'd be looking at a router, drill or mill.... You're right tho, this is beyond a sharp knife

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Permalink Reply by The Phrygian Kid on February 22, 2014 at 3:22pm

ps. dampening the soundboard is not usually a consideration with resos, the opposite in fact,  the most expensive non-vintage resonator instruments one can buy today are carbon fibre jobs which are specifically designed to be as inert as possible, thereby 'stealing' less sustain and volume from the cone :)

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Permalink Reply by ChickenboneJohn on February 22, 2014 at 11:37pm

I cut my reso rings on the bandsaw with a home made circle cutting jig, or you can cut then out with a router. To make pukka reso instruments you are getting into the realm of needing a few more specialist tools than the simple hand tools that will suffice for a typical CBG. Resonator cone instruments act similarly to a loudspeaker enclosure, so the body actually needs to be stiff to support the cone and allow the it to vibrate..if there's too much flex in the top and the supporting structure you'll actually lose volume. Most top quality resonator guitars such as wood bodied Nationals are made with (high quality) plywood tops. You can't build a guitar with a National style cone like this without a well of some sort to support the cone. The "drop-in" cones like the Old Lowe ones are a totally different proposition, and simply sit in a cutout thru' the top.

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Permalink Reply by Michael Fred Johnson on February 23, 2014 at 12:52am

The rings on No.32 were cut using a home made hole cutter (see photo) the blade is a sharpened piece of broken hacksaw blade held in place by a wedge.I have also used  a router to cut rings on other builds.

I think you need a rigid mount for the cone/cover to let the cone do its job.The bottom ring provides a seat for the cone,the other rings determine the height of the cone and provide some thickness for the cover screws to bite into

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Permalink Reply by Rand Moore on February 23, 2014 at 2:16pm

So, if I'm building a reso-CBG, I need to use something stiffer for the sound board, otherwise the sound board will dampen the resophonic effect of the reso cone. Would this also be true for other "home-made" cones like paint can lids, metal cat (dog) bowls, metal pans and the like? I currently have a resonator banjo in the works and I'm using a round internal lid to a square cookie tin. I'm wondering if I should stiffen the sound board which is currently a 2mm thick piece of plywood veneer. At some point in the future (maybe this summer) I'd like to build a real resonator, probably with one of the Lowe cones. I haven't fooled with resonator CBGs since this fiasco:

You can read more about it in the "Hall of Shame" discussion group.

-Rand.

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Permalink Reply by Michael Fred Johnson on February 26, 2014 at 1:09am

This cat bowl reso has a 1/16" ply top which is braced like No.32 and sounds very similar.

I think whatever "cone" you use you will have to use mounting rings for fastening the cone in place,just to get a fix on the soundboard.

I'm sure you could do something with your fiasco,that looks a nice box 

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Permalink Reply by Mungo Park on February 27, 2014 at 6:30pm

The height is important you can adjust it somewhat with the bridge, so I calculate the height of the ring first and get the board to the correct thickness.

Then I cut the outside of a ring, drill holes in it to let the sound out then cut out the inside to make it a ring. Then I measure it on the neck and cut out the space that a through neck will fit.The neck is cut and another piece glued to it to get a low as possible in the box, Cut down the through neck part to be the same height as the ring, Fiddle it all together. I then put a support on the inside of the lid or the strings will pull and bend/break the lid with the tension on the cover plate.

 Here is a in shop sound demo:

http://www.cigarboxnation.com/video/reso-sound-like-a-banjo-sort-of...

Cheers Ron

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