great, you are talent in guitar making with physics

wow chuck very nice you got my attention

That is a beautiful-sounding instrument. The explanation you give in regards to how having an open/close sound port on the opposite side was very logical and a good explanation of how it affects sound quality. What I heard even when slit, was a difference in the tone, and resonance, and I would say even the sound pressure even while using only headphones. Thank you

@chuckmorrison

Жыл бұрын

Thank you, There is a huge harmonic difference between one hole in a sound box and two (on opposite ends). The differences are usually described in terms of tubes that are open on one end vs both ends. The harmonics available with tubes open on one end (like a standard acoustic/classical guitar, clarinet) are the odd multiples of the fundamental. So the root, 3rd, 5th, 7th, 9th, etc. In contrast, all the harmonics are available with tubes open on both ends (flutes, recorders, open organ pipes), so root, 2nd, 3rd, 4th, 5th, 6th and so on. I should do a video on this as it's very basic and important physics for musicians and builders.

@miguelacevedo1200

Жыл бұрын

@@chuckmorrison Thank you for your reply. As a fellow Luthier I appreciate your openness in sharing knowledge. I have used sound ports in some of the instruments that I have built but only since 2009 when I changed my approach to building. Your explanation of what you have done is very appealing and demonstrable. Thank you again for your beautiful work.

Thanks for sharing all these quirky and ingenious things you know/make!

I may be wrong, but it seems that if you continue finding alternate air frequency selectors (or meter the same tail whole), you may wind up with a tonal effect similar to the tone toggle switch on an electric guitar; choosing between bridge and neck pickups in that case. I hear the change in the brightness and that’s what strikes me about your idea. If you have built it as low-end air resonant as possible with all other channels closed, it seems a simple matter of size and placement to create interesting effects when brightening it up. Just an idea, but maybe to take it a little bit further you may be able to cross multiple air resonances in effects similar to the ripple and wake convergences seen on the surface of water, and maybe could get some beautiful oscillating tones and effects that way. I just came across your videos here and watched a couple, and I’m loving what you are doing, by the way. I’m a steel-string guy, but your ideas in your oak back and sides videos and the outcome of the sound are very impressive to me as well. Fascinating, and very appreciated.

@chuckmorrison

Жыл бұрын

Thanks for the response. I have built instruments with sliding and rotating doors as well as just holes plugged by corks. In each case there appears to be a point at which the overall tone of the instrument shifts along with the air resonance. I haven't found it to be anywhere near as reliable as a tone control on an electric, which is cutting off highs rather effectively. It's actually a kind of reverse tone control. Opening a second, opposing hole moves the main air resonance up and also adds (at least some of) the even harmonics of the fundamental air resonance (which are not available on a one hole air cavity). To the extent that the top and air resonances are coupled, the top resonance may stay the same, move up or move down. That will have an audible effect any way it goes and all this may induce soft, dead or loud notes. It gets pretty messy and it's not a simple if X then Y correlation. Now on steel string acoustics, raising resonances may not be the direction one wants to go. It's generally more important to get good bass response on a steel string. Classicals are generally the opposite, bass being pretty easy but good treble response being a challenge. Good, in these cases needs to be defined and recognized.

Chuck or Kenny !!!!

Hi man rlly appreciate sharing ur knowledge I’m a fairly new luthier, just wondering how you figure out what size to make the opposite hole to target specific frequencies?

@chuckmorrison

Жыл бұрын

I usually don't try for specific frequencies, but rather an audible difference in tibre. At least on instruments with a valve so I can move between the two. If trying to adjust the main air resonance (to make it higher) I'll start small (large enough to fit a reamer into it) and slowly enlarge the hole as I measure the resonance frequency. Note that changing the resonance of one of the critical 3 (air, top, back) will usually affect a resonance change of at least one of the other two. So it's a moving target that needs to be monitored as you go.

@lewiskay7184

Жыл бұрын

@@chuckmorrison thanks a lot that makes alot of sense to do but I can imagine if this spread alot more some of the more enginere oriented luthiers could do some rlly cool things

@chuckmorrison

Жыл бұрын

@@lewiskay7184 I'm sure they could. I don't think in math formulas, so I'll leave that to someone else.

I love this idea and how it resonates (pun intended) with the idea of the sound chambers in Egyptian pyramids. Question, is it possible to build a body that’s tuned to a range of resonance/frequency (with lower port hole opened/closed) or a body tuned to resonate with a particular note I.e. A? Thanks :)

@chuckmorrison

Жыл бұрын

I can't say I've had the opportunity to play any Egyptian pyramids. Any acoustic guitar body resonates to a particular frequency. The majority of classical guitars, for example, have an air resonance between F and A# depending on the size of the body, sound hole size and placement and the flexibility of the top and back. Adding the lower bout port hole raises that resonance. How much depends on the size and placement of the port. By including a plug or valve one is able to switch between the original frequency and the higher frequency. This can change the timbre of the instrument and also which notes are louder or softer (assuming you listen for that sort of thing). So to answer more simply, Yes. Not that you would want to tune directly to a scale tone.

Hard to tell without seeing the interior and the top bracing, but by moving the sound hole backwards and up it seems you have lengthened the effective soundboard, which usually terminates towards the bridge side of the standard sound hole placement. By adding several inches of length to the soundboard you hypothetically strengthen the longer wave length base notes while robbing nothing from the vibrating surfaces for the treble notes.

@chuckmorrison

Жыл бұрын

It would seem that way wouldn't it ? How much that is the case is dependent on the tightness of the waist, the bracing pattern and it's dimensions, the top thickness and I'm sure many other things I'm not thinking of right now. Note that the sound hole itself is part of the effective soundboard length in the standard (X brace) design. This can easily be seen in chladni tests where the node line (of the fundamental air and top resonances) extends to the center of the sound hole. Removing the sound hole stiffens that part of the top since it is now soundboard, not a hole.

@johngriswold2213

Жыл бұрын

@@chuckmorrison Think you are saying that the sound hole would be part of the effective sound board length if it were still there as top material, not hole (air). While the node line extends to the center of the sound hole the missing circular cutout can't move air. In a traditional X the long mode wave would largely be blocked by the stiff center joint and then terminated where the soundboard terminates into hole... in a Falcate much less so, and if the hole is moved out of the length of this wave and into an upper bout region that contributes relatively little to sound production possibly the least of all. Just learning this stuff and fumbling around some;)

@chuckmorrison

Жыл бұрын

No, that's not what I'm saying. Forget relocating the sound hole. In a Chladni test, the node line outlines the area that is actively vibrating (the anti-node) because the node is inactive and that's where your sand/glitter/metal filings/sawdust/pepper/whatever gathers. At the main (air and) top resonance, on a nicely responsive X braced top I see the node line form around the perimeter of the lower bout extending up into the waist area and joining at roughly the center of the sound hole. (obviously it ends at the outer edge of the sound hole, not inside it) It's a pear shape. So the soundboard area above the joint of the X brace and on each side of the sound hole is actively vibrating together with the lower bout as one unit. Since it's within the active area, the joint of the X brace must be vibrating too and not blocking it. If the top and/or bracing was too thick/stiff, then the pattern would be smaller. Do some Chladni testing to see how things actually vibrate and how patterns change with modifications to bracing, sound hole placement and other design changes. It makes a lot more sense than trying to figure out what I'm trying to say here.

That sounds better than a Martin

sounds more like your air resonance is down under 100hz not 220

@chuckmorrison

Жыл бұрын

Hmm, did I say it was ? I missed that. In a normal size guitar the air resonance is 100Hz +/- 20 hz and the top resonance is 200Hz +/- maybe 40Hz, at least from what I've been able to measure.

@jeffhigh2

Жыл бұрын

@@chuckmorrison Yes at 2.55 Yes I agree with what your expectations are