Hello Art - yes it is now pretty much a folded horn/wave guide acoustic guitar with multiple ports. Live and learn, these changes are a result of what I learned from the prototype. I believe this is the best sound. I also learned much about hot to manufacture this guitar.
I tried an experiment earlier with the speakers only onside an acoustic guitar. It sounded terrible. Much echo, very muddled, and sounded like it was "ringing". Almost like it was starting to feedback. I was hoping somebody could tell me why the folded horn works as well as it does, I believe directivity is critical. The vibration in the body is nice, but that is just a small portion of the sound. Plus the thin yet strong soundboard will project plenty of sound. Still learning, will cut the real thing hopefully in October. Thanks! Joe
I tried an experiment earlier with the speakers only onside an acoustic guitar. It sounded terrible. Much echo, very muddled, and sounded like it was "ringing". Almost like it was starting to feedback. I was hoping somebody could tell me why the folded horn works as well as it does, I believe directivity is critical. The vibration in the body is nice, but that is just a small portion of the sound. Plus the thin yet strong soundboard will project plenty of sound. Still learning, will cut the real thing hopefully in October. Thanks! Joe
I have researched sound ports and see these comments: "You do not lose sound out sound ports. On the contrary, the guitar becomes louder due to more air flow, and it becomes like a surround sound system. The sound ports make the guitar sound fuller, more balanced, resonant and extremely clear. The larger the sound port, the larger the advantage. Adding more sound ports increases volume, clarity, and brilliance in sound. The acoustic guitar is an inefficient instrument, and can be improved."
Please note that machining this guitar from solid maple, allows me to have 1/4" thick wall sections, a beast. If you tried to put this many sound ports in a standard acoustic guitar, it would likely collapse due to thin walls.
Again, the goal is to make the guitar body ring like a bell (have you ever rung a 100 year old cast iron bell? The sound travels for blocks, hence the church tower). The other goal is to make a soundboard as thin and strong as possible, so it moves like a speaker!
Please note that machining this guitar from solid maple, allows me to have 1/4" thick wall sections, a beast. If you tried to put this many sound ports in a standard acoustic guitar, it would likely collapse due to thin walls.
Again, the goal is to make the guitar body ring like a bell (have you ever rung a 100 year old cast iron bell? The sound travels for blocks, hence the church tower). The other goal is to make a soundboard as thin and strong as possible, so it moves like a speaker!
Joe,
"Ringing" like a bell may not be the best goal unless you want a very specific harmonic sequence based on the bell body's fundamental note.
The folded valleys in your guitar create multiple reflective paths for various resonant frequencies to exit through multiple "ports", which you appear to enjoy.
The "best" soundboard resonates the string's output, increasing it's sound volume.
A "good" speaker minimizes resonances so it can accurately reproduce it's electrical input.
Your multiple port collective area has probably increased the effective Fb (frequency of box tuning/Helmholtz resonance)well above the frequency where they could assist the lower strings fundamental or second harmonic response.
Upper harmonics do tend to sound louder..
Art
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I think great "sustain" like a bell may be more accurate, all frequencies produced by the guitar. I have heard this from Luthiers, and can hear it in my prototype, I believe this to be a very good improvement.
The folded horns are covered (not shown) over the speaker and middle part of the horn, but not on the outer folded horn, just below all the sound ports, so this affects the reflective paths. I think it would be difficult to produce an accurate analysis of this design. Is testing with good results, as I have heard, better in this case??
The soundboard resonating the strings output is correct. When I say move like a speaker, I mean would like to see some actual movement, like you do in a speaker, and you can not see in a soundboard, because it does not vibrate that much.
The port collective...don't understand completely, could you comment further please. Thank you! Joe
The folded horns are covered (not shown) over the speaker and middle part of the horn, but not on the outer folded horn, just below all the sound ports, so this affects the reflective paths. I think it would be difficult to produce an accurate analysis of this design. Is testing with good results, as I have heard, better in this case??
The soundboard resonating the strings output is correct. When I say move like a speaker, I mean would like to see some actual movement, like you do in a speaker, and you can not see in a soundboard, because it does not vibrate that much.
The port collective...don't understand completely, could you comment further please. Thank you! Joe
Having not shown the cover, assumed you had abandoned it.
The folded duct (not a horn, horns expand) is covered, then leads into a chamber (enclosure, box) with multiple ports. Port areas in a Helmholtz resonator/bass reflex enclosure sum collectively to one Fb (Frequency of Box tuning).
Your testing by ear, hearing "good results" may inform you, but we still have no idea what the response of the speaker system is compared to the guitar's acoustic sound.
The folded duct (not a horn, horns expand) is covered, then leads into a chamber (enclosure, box) with multiple ports. Port areas in a Helmholtz resonator/bass reflex enclosure sum collectively to one Fb (Frequency of Box tuning).
Your testing by ear, hearing "good results" may inform you, but we still have no idea what the response of the speaker system is compared to the guitar's acoustic sound.
Yeah, hard to see everything with the cover on (chamber divider), so mostly wave guide, but still have about 15" of horn at the bottom of the guitar, hard so see that taper also. Just finished programming today, so hope to cut next week if the machines are open. I will then be able to show better pictures with the full maple body. I can also test more with both speakers in the body, then of course test various mic/amp/speaker combinations...much to do, thanks for your comments!!
Folded Horn Acoustic Guitar
Check out the Folded Horn Acoustic Guitar with some actual manufacturing progress. The body is the most difficult component to manufacture, but it held up. Testing is next!
Check out the Folded Horn Acoustic Guitar with some actual manufacturing progress. The body is the most difficult component to manufacture, but it held up. Testing is next!
Just hand finished the three bottom thru shapes to match the body, not much else lately, busy at work. The speaker holes will now be easy to cut by hand, that is next. I also have the solid maple neck wood.
Is anybody familiar with Baltic Birch? I know this is used in speaker cabinets, and has good response on the high and low ends. I am going to test it for a soundboard. It is easy to get in large pieces at 1/4" thickness, which I need due to cutting all my short bracing in solid on a CNC machine, no larger glued on bracing. I have decorative details on the top that are functional, around the entire perimeter, to assist in more soundboard vibration/movement. Will see how that works. Sitka Spruce may be better, but hard to find larger and thicker. Thanks! Joe
Is anybody familiar with Baltic Birch? I know this is used in speaker cabinets, and has good response on the high and low ends. I am going to test it for a soundboard. It is easy to get in large pieces at 1/4" thickness, which I need due to cutting all my short bracing in solid on a CNC machine, no larger glued on bracing. I have decorative details on the top that are functional, around the entire perimeter, to assist in more soundboard vibration/movement. Will see how that works. Sitka Spruce may be better, but hard to find larger and thicker. Thanks! Joe
Folded Horn Acoustic Guitar
Updated Folded Horn Space attached. The new design still includes a horn, but it is more like a trumpet shape than a saxophone shape. Much more straight area, and then into a flared horn on the end. I made this change because I tested an actual prototype, and this works. I am very interested in acoustic analysis, but this has never been done before, so I am am very focused on what works. I believe the speakers that I can fit in my guitar do not have enough SPL to drive five foot long horns, especially if the horn starts small to get a large 3D taper. Starting bigger and tapering at the end works best. The multiple side ports really let the sound out. Each port is larger from the speaker to the horn, which is of course the largest of all (impedance matching works).
I appreciate the great comments I have received. I especially appreciate criticism based on ideas for improvements, that helps me learn. Comments welcome and thank you all! Joe
Updated Folded Horn Space attached. The new design still includes a horn, but it is more like a trumpet shape than a saxophone shape. Much more straight area, and then into a flared horn on the end. I made this change because I tested an actual prototype, and this works. I am very interested in acoustic analysis, but this has never been done before, so I am am very focused on what works. I believe the speakers that I can fit in my guitar do not have enough SPL to drive five foot long horns, especially if the horn starts small to get a large 3D taper. Starting bigger and tapering at the end works best. The multiple side ports really let the sound out. Each port is larger from the speaker to the horn, which is of course the largest of all (impedance matching works).
I appreciate the great comments I have received. I especially appreciate criticism based on ideas for improvements, that helps me learn. Comments welcome and thank you all! Joe
Joe,
What you have is not a horn anymore.
Baltic Birch is physically heavier and brighter sounding than Sitka Spruce.
What you have is not a horn anymore.
Baltic Birch is physically heavier and brighter sounding than Sitka Spruce.
Hey Joe K-that sure looks cool.
IF I had skills anda one-off, I'd try something goofy with steel strings, magnetic pickup, two Faital 4fe32 in parallel, mono TPA3116 amp with 20v tool battery (not sure how a brace/mount for the bridge might go-?) It would probably feed back to itself too easily unless the aperture were fairly rigid( ?) The neck extension into the body would tie to the back for bracing-dunno if the pickup should be floating or not.
IF I had skills anda one-off, I'd try something goofy with steel strings, magnetic pickup, two Faital 4fe32 in parallel, mono TPA3116 amp with 20v tool battery (not sure how a brace/mount for the bridge might go-?) It would probably feed back to itself too easily unless the aperture were fairly rigid( ?) The neck extension into the body would tie to the back for bracing-dunno if the pickup should be floating or not.
Attachments
Yes, I am considering bringing the horn back, but with a larger mouth and also sound ports, so it would be a Ported Folded Horn. If I leave it the way it is now, I could call it a Ported Waveguide.
I will cut the Birch soundboard this week or next, we will see how it goes. I may switch to Sitka Spruce or Cedar depending on the results.
I like the guitar concept with the large horn. I assume that is an electric guitar? Is it in production? Thanks! Joe
I will cut the Birch soundboard this week or next, we will see how it goes. I may switch to Sitka Spruce or Cedar depending on the results.
I like the guitar concept with the large horn. I assume that is an electric guitar? Is it in production? Thanks! Joe
hi Joe K.
regarding that crude sketch, I doubt if there are any guitar with built-in-amplifier using a "Karlsonized" chamber --perhaps none with the "Bo Diddley"
shape body as a self-contained acoustic electric.
Whether its a good idea is questionable-but could look cool.
Figuring out a means to brace and mount the bridge so there's no "bow" would be one thing to overcome---maybe extend a section of the neck all the
way down and to the body as to brace against the body's back and hold the lower strap button (?)
with 10 volts sine, 4fe32 is just hitting its xmax.
It would be easier for sure to do a reflex in a (semi?) hollow than a bandpass.
regarding that crude sketch, I doubt if there are any guitar with built-in-amplifier using a "Karlsonized" chamber --perhaps none with the "Bo Diddley"
shape body as a self-contained acoustic electric.
Whether its a good idea is questionable-but could look cool.
Figuring out a means to brace and mount the bridge so there's no "bow" would be one thing to overcome---maybe extend a section of the neck all the
way down and to the body as to brace against the body's back and hold the lower strap button (?)
with 10 volts sine, 4fe32 is just hitting its xmax.
It would be easier for sure to do a reflex in a (semi?) hollow than a bandpass.
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it might work as below
IMO the rectangular would look better with straight "V" vents vs curved.
having exit at thebottom of the body would help reduce reflectionswith top vents only.
with perpendicular mounting of speakers, the body would be awfully thick at nearly 5 inches for a 4 inch speaker
IMO the rectangular would look better with straight "V" vents vs curved.
having exit at thebottom of the body would help reduce reflectionswith top vents only.
with perpendicular mounting of speakers, the body would be awfully thick at nearly 5 inches for a 4 inch speaker
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Build a proto! Mine is about 5" thick, the only way to fit horns and speakers...I had it at 6", but that is just too large to hold comfortably.
Folded Horn Acoustic Guitar
Hello all - horn is back, but with much larger mouth. Many ports which are needed based on my testing of full scale guitar body. I show wave guide (just a 2D taper so not real horn) and also 3D real horn. The improvement does not look like much (16% vs 22%) but that is a 37% improvement from wave guide to horn, very much needed!
You can feel the guitar vibrations against your body when playing, I did not anticipate this, and I have never experienced this before. A true sonic machine.
Comments welcome. Art, what do you think of this ported horn, the damn thing works! Thanks! Joe
Hello all - horn is back, but with much larger mouth. Many ports which are needed based on my testing of full scale guitar body. I show wave guide (just a 2D taper so not real horn) and also 3D real horn. The improvement does not look like much (16% vs 22%) but that is a 37% improvement from wave guide to horn, very much needed!
You can feel the guitar vibrations against your body when playing, I did not anticipate this, and I have never experienced this before. A true sonic machine.
Comments welcome. Art, what do you think of this ported horn, the damn thing works! Thanks! Joe
Joe,
Played without amplification, my Ovation Elite hits over 85dB at one meter, over 100dB near most of it's body, 110 dB if measured at it's ports ("sound holes"), and I feel vibrations against my body when playing any acoustic guitar.
You wrote in your PDF: "Standard Acoustic Guitar 85 dB, Wave Guide 99 dB, Horn 104 dB"
Your measurements appear to be taken at the sound holes, which tells nothing about the SPL at your or a listener's ear. They also tell nothing of what frequency range is loudest.
Without hearing what your electric guitar sounds like at a given distance compared to an acoustic, can't think of much more to say.
How much does it weigh?
Art
Played without amplification, my Ovation Elite hits over 85dB at one meter, over 100dB near most of it's body, 110 dB if measured at it's ports ("sound holes"), and I feel vibrations against my body when playing any acoustic guitar.
You wrote in your PDF: "Standard Acoustic Guitar 85 dB, Wave Guide 99 dB, Horn 104 dB"
Your measurements appear to be taken at the sound holes, which tells nothing about the SPL at your or a listener's ear. They also tell nothing of what frequency range is loudest.
Without hearing what your electric guitar sounds like at a given distance compared to an acoustic, can't think of much more to say.
How much does it weigh?
Art
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Art - since the guitar is not complete, I can only play another guitar through a pickup and into these speakers and then through the guitar body, or an acoustic guitar song on my iPhone. I am only measuring the sound through the body. Once the light yet strong soundboard is added, it will add more dB in addition to what is measured now. Maybe I can find a way to get the guitar I am playing close to the body with horns and speakers, and get a combined dB measurement.
I can feel a standard guitar vibrate in my body also, but it is very minor compared to the vibrations through this guitar body, since it is more like a speaker cabinet.
This thing will weight at least 12 lbs. so yes the weight is a concern for sure.
Your Ovation Elite sounds pretty great for volume, given the bowl projections. That is a great innovation. It is interesting how some people are big fans of Ovations, and others not at all. What is the biggest concern there, tone? How is your tone? I had a friend that had an ovation years ago, but not sure what kind, the tone was different than wood.
Good point about dB at listeners ear. Without any measurements, the speakers through the horn are very noticeably louder that a standard acoustic guitar from a listeners point of view, which is to be expected with amplification. When I play the classic song "Stand Back" by the Allman Brothers on my iPhone through the small speakers not feeding the guitar body/horn, the higher frequency is louder of course, due to it being a small speaker. When I play it though the horn, it sounds like the bass player just turned up his volume, major increase in the lower frequencies. Plus that is Berry Oakley, so a phenomenal bass player helps. I am not sure why this happens, but it is great, because if it sounded like all tweeter, it probably would not be worth doing. Thanks much for your input, I appreciate it!
I can feel a standard guitar vibrate in my body also, but it is very minor compared to the vibrations through this guitar body, since it is more like a speaker cabinet.
This thing will weight at least 12 lbs. so yes the weight is a concern for sure.
Your Ovation Elite sounds pretty great for volume, given the bowl projections. That is a great innovation. It is interesting how some people are big fans of Ovations, and others not at all. What is the biggest concern there, tone? How is your tone? I had a friend that had an ovation years ago, but not sure what kind, the tone was different than wood.
Good point about dB at listeners ear. Without any measurements, the speakers through the horn are very noticeably louder that a standard acoustic guitar from a listeners point of view, which is to be expected with amplification. When I play the classic song "Stand Back" by the Allman Brothers on my iPhone through the small speakers not feeding the guitar body/horn, the higher frequency is louder of course, due to it being a small speaker. When I play it though the horn, it sounds like the bass player just turned up his volume, major increase in the lower frequencies. Plus that is Berry Oakley, so a phenomenal bass player helps. I am not sure why this happens, but it is great, because if it sounded like all tweeter, it probably would not be worth doing. Thanks much for your input, I appreciate it!
The Ovation Elite is near 6 pounds, a bit on the heavy side for me..
I'm a lousy player, so my tone is not great 😉.
Listen to Glen Campbell (RIP) for examples of how an Ovation should sound.
I chose to buy an Ovation because the fiberglass composite back material is more stable than wood over a wide range of humidity and temperature. I also like the distributed sound holes better than a single large "O" hole, more consistent results when using an external microphone as the guitar moves with playing.
Good luck completing your guitar, look forward to hearing it when finished!
Art
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