I'm fascinated by acoustic properties.  If it makes a sound, I'm interested.  So when the news came across my Facebook timeline that an inventor made a guitar amp that increases sound levels of an electric guitar by 12 decibels...without using electricity, I went crazy!

Canadian company, DelSonix has just introduced a "speaker," known as the SD28, that is made of a hollow wooden pickup with a bottom-resonating cavity.  The contraption is clamped to the guitar's headstock. It picks up the instrument's vibrations, while a resonator projects the sound.

In a way, it's similar to a Victrola record machine, taking acoustic vibrations and amplifying them through a wooden tube and out into a cone.

DelSonix says the invention works with all electric guitars and basses (hmm...cigar box guitars?) and can increase loudness from 6 to 12dB, depending on guitar design. By rotating the resonator, guitarists can project the sound in specific directions, while the entire device rolls up into a 1-inch tube for storage.

The SD28 is available now. It costs $34 CAN ($24 U.S.) and ships to Canada, U.S., Europe, Australia and New Zealand.

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Clever idea , so it will only be a matter of time before we see home made versions appear! They reckon this to be £17 which seems a bit steep. Not sure if that includes carriage either.... In the meantime lean yer geetar against a nice wooden table for added resonance ! 

It's neat, but it's the guitar version of putting your smartphone in a bowl when you play music on it. Someone / some company will make a Chinese copy, um, version and sell it for $1.

Hopefully Sean someone will, I would be off to Poundland like a shot ! 

Has anyone in CBN tried this out yet ? I understand how it works with a solid body guitar, as the video demonstrates, but I'm guessing the more hollow the body , the less volume increase would be achieved . I'm guessing if you clipped it to the headstock of a J200 the volume projected from it's soundhole would be far louder than the sound from the cone ? I may be totally wrong, but thought I would put it out there ..... 


Volume from the headstock won't change the soundhole's volume one bit. The device uses part of the string vibrational energy that gets transmitted through the neck and headstock. It's akin to setting a tuning fork on your headstock (try it). It would only amplify the volume of the CBG box itself if it were attached directly to either the soundboard, which receives most of a string's vibrational energy through the saddle and bridge (rather inefficiently), or to some other portion of the box. That will be one of the experiments I will be trying out this weekend: adding a simple horn to the soundboard of a CBG. Resonators work almost, but not quite, the same way.

Thanks for the technicals Ron . Just did the tuning fork test and that makes sense now. 

Hmmm. Easy peasy, methinks. Relatively narrow wood hollow sound post (can build from available thin scrap, check), a longish pan head screw with a wing nut (yep, got a few in the tool box), and for the plastic horn, either 1) a folded transparency sheet (got some old ones somewhere around here), bit of Scotch tape to close the horn, or 2) a plastic kitchen funnel (several sizes and colors available), Super glued into a small hole drilled into your wooden hollow tube, or even cheaper, 3) a plastic milk jug or 2L soda bottle, with the cap screwed on. You cut the bottle in half to form a horn, and drill a small hole in the cap. The screw fits through the hole, and the wing nut tightens it all up. Then some way, like a clamp, maybe from the shop, or a plastic clothespin, to attach it to the headstock...

Piece o' cake. I can build all of these tomorrow afternoon for under $10.

But wait 'til you hear what can be done with a radical CBG design I came up with while building three variations on an electric guitar amplifier plywood passive DIY Sound Enhancer (of which I need to post pics and video files).


At this point ,us Brits of a certain age will have read Oily's last post and will have visions of Rhubarb , shakily hammering and sawing in his shed in the dead of night while Custard lurks outside with his hands over his ears and the birds on the washing line giggling :-D

The quick and dirty cigar box version - got a couple dB out of it ;)

OK, turtle, you and I need to have a private chat ;-).

What you've done is clamp essentially a Helmholtz resonator to your headstock. Shaping the dimensions of the box will result in specific frequency range reinforcement. Been doing a lot of reading on folded horns, Voight pipes, and transmission line speaker enclosures for passive sound reinforcement.

;) Oily.  Interested to see and hear what you come up with. 

This reminds me of a story Les Paul told about when He was a kid. He used a old Victrola needle and embedded it in his acoustic guitar bridge, then attached wires to the Victrola horn. He got the idea from the windows rattling when a train rolled down the tracks near his home.

Also check out the Stroh violin for a similar sort of thing.


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