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Improving acoustic volume.

Any tips or tricks for increasing the acoustic volume on a cb mandolin? I am using a metal bolt for the bridge. Would a hardwood bridge help? If so, is it better to have it thicker or thinner? Also. I have a through neck design that was glued onto the top. Would it create more volume if I were to remove the glue and file down the wood on the neck so it isn't contacting the top? Finally. On a through neck design is it beat to put the pickup on the actual soundboard or the neck (under the bridge?)

Thanks for your help

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Permalink Reply by Mark Kortuem on July 28, 2013 at 3:39am

This is what my bridges look like. A short popsicle stick, a 1/4" square of poplar, and a fret wire. I get satisfactory sound from this. I use a zero fret for the nut, and put a 2 degree tilt on the neck to raise the strings off the box. I use a combination of different fret sizes, and wood to get the action right. The volume of the box makes a big difference.

Permalink Reply by Jeff McFadden on July 31, 2013 at 7:16am

If you build a bridge like Mark shows herd you can drill through it the long way and put a piezo rod pickup inside it so the fret wire bridge bears down on it to carry the string vibrations through to the piezo. You can drill / saw a little downward slot through the wood of the bridge to you can hide the pickup cord down into the box.

First pic shows a piezo rod at full length, then one cut down to 3 string length.

I drill them in a drill press. Next time I'll drill it when the blank is bigger, before I cut it to final size and shape.

Last pic shows (not too clearly) how the bottom of the bridge wood is cut away to hide the wire coming out of the pickup.

Mark - do you file notches in your bridge fret wire?

Permalink Reply by Chuck Cobillas on July 28, 2013 at 4:00am

Mark,

I have only built 1 CB Mandolin but I used a resonator cone on it. Old Lowe makes and sells them, he is a member of CBN. I was totally surprised at the volume level using the reso cone. And my Daughter loves it.
Chuck

http://www.cigarboxnation.com/photo/albums/my-first-cb-mandolin-bui...

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Permalink Reply by Mark on July 28, 2013 at 6:15am

Thank you for the replies. Has anyone had luck with keeping the through neck from contacting the top? (Or should I expect it to improve )?

Permalink Reply by Ron "Oily" Sprague on July 28, 2013 at 7:34am

Mark,

It won't improve unless you do something. Unglue and relieve the neck beneath your soundboard. Give it about 1/8 - 1/4". You can add a strengthening piece of wood to the backside of the portion of the neck inside the box to compensate for any perceived structural weakening. You want that soundboard to vibrate freely, being driven by the string vibrations passing through the saddle and bridge. Plenty of builders, myself included, do it this way. Only other ways to improve acoustic volume are to use a bigger box + heavier strings + hardwood bridge + bone saddle + metal resonator + metal finger picks or thick plectrum + strum harder. And maybe thinning the top if it's too thick (3/16" is good, 1/4" can be too thick).

You'll get better pickup response, assuming this is a piezo pup, by attaching it to tht top directly beneath the bridge.

Permalink Reply by Mark on July 28, 2013 at 8:21am

Thank you Ron. Those were the exact answers I needed. Will post a response after I have run through the alterations.

Permalink Reply by Ron "Oily" Sprague on July 28, 2013 at 10:15am

Mark,

Glad to be of service. Post a vid, if possible before and after alteration, so we can hear the diff...

Permalink Reply by Randy S. Bretz on August 1, 2013 at 4:42am