Why Cutaways Make Guitars Sound Brighter | Explained by a Luthier

In this episode of DIY Guitar Making, I explain the two reasons why a cutaway on an acoustic guitar increases the treble response and decreases bass response. I also explain the concept of Helmholtz Resonance, and demonstrate the affect with a bottle of water.
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[@rabbani8613]

Can ww make a guitar with Spanish classic guitar models, that neck into the body? TU

[@short6691]

Awesome demo of Helmholtz resonance. A stiffer (glass) container would resonate louder as the flex of the plastic allows some damping. Interesting presentation on the guitar body shape impacts. My first ukulele (tenor) has a pineapple shape and I made it rather deep accidentally. I strung it “low G” and the lower end tone is awesome. Blind squirrel finds acorn! I don’t ever put non potable fluids in beverage containers. When I dilute Tru-Oil I use something not easily mistaken as a drink. While my shop has few visitors, my grandkids are occasionally in adjacent rooms…

[@johngriswold2213]

Doubtful in the extreme that the Helmholtz resonance has much to do with the supposed brightness of tone in a cutaway. The sound production of a guitar is almost exclusively produced by the lower bout, as Chladni vibration patterns will demonstrate, and much of that sound is produced outside the box. The sound hole allows the diaphragm of the soundboard to vibrate freely...were the box closed the energy introduced to the top by the vibrating strings would be quickly consumed by the necessity to compress the air contained in the box in order for the top to vibrate. I suspect you are right about the volume change inside the box, but the mechanism of blowing air across an aperture is very different than the vibrating string driven guitar top vibrations;)

[@RonSteinPhotography]

Awesome video and great channel! One thing though - please tune that guitar in the soundtrack 😂

[@walterrider9600]

thank you Eric . i had not even thought of that but sure . to off set that would or could it make a difference if you deepened the body ? say the body si 5 ' to 3 ' from top to bottom so take it to 8 ' to 6 ' would that compensate for the difference ?

[@smbrumbaugh]

Great video. It's something I never really thought a lot about with cutaways, but it makes total sense.

[@BMWHP2]

Thanks for sharing you knowledge with us.

[@RonSteinPhotography]

Hey why do you use such wide saddles off centre to the bass side? Very interesting!

[@cheapskate8656]

Good video. I dont think the bottle was a good way to explain it, although it was funny :) Basically the bottle was a wind instrument and the guitar isnt. I think the easiest explanation for a guitarist is to say. Strings are brighter when they are shorter (shorter scale length etc), strings are brighter when they are tighter, just turn the tuning key. The timber is like a wooden string, make it stiffer, shorter, tighter or thinner and its going to be brighter. Now we are comparing apples with apples.

[@muhin3137]

Guitar tops also play a great role in tone. Spruce top produces bright tone ( Tanglewood roadster or Yamaha f310) Mahogany top produces warm tone ( Tanglewood crossroad series)

[@singingflowers3418]

Super!!

[@dalgguitars]

both beautiful guitars! just fantastic.