Folded Horn Acoustic Guitar Patent # 10,777,172

Joe K

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2021-08-14 12:12 am
Indianapolis, IN.
freddi - you Hornresp nailed it, I am getting 117 dB MAX from one horn only, imagine if there were two. Plus the I am not including the soundboard. My Guild acoustic guitar, which is a nice big dreadnought is giving me 85 dB, pretty standard. That is a major volume increase. You can really feel the sound moving through the guitar body (OK just a proto), never felt that before. The downside is I gave it too much base in the compression chamber, lows are very pronounced, but the highs are severely diminished. The crazy thing is I pull the exponential horn about a 1/2" out of the guitar body (straight wave guide) and the high end comes in, then another 1/2" and more high end. Its like you can tune this with these kind of adjustments. You could never do this with just a simple horn. Would love to hear from all and Art. Thanks! Joe
 

Joe K

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2021-08-14 12:12 am
Indianapolis, IN.
Art - you were also correct that the horn only gave it approx 7-10 dB increase from the speaker, but the speaker compared to the guitar alone, and the horn also included gave it the approx 30 dB increase. It is pretty cool that your sims are so accurate. What is hard to sim is the tone, it is really great. I say maple colors the tone, in a positive way, compared to plastic or other materials. A Stradivarius violin is 100% maple, same as my wood, there must be something there!
 
Art - you were also correct that the horn only gave it approx 7-10 dB increase from the speaker, but the speaker compared to the guitar alone, and the horn also included gave it the approx 30 dB increase.
Joe,

Without knowing what signal used, how you powered and measured any of what you wrote, not much to say, other than doubling speakers and power could add another 6dB at some frequencies, while possibly cutting that much at others :umbrella:

Question: How can you tell if you have a real Stradivarius violin?
Answer: The Stradivarius burns with a blue flame.

Art
 
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Joe K

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2021-08-14 12:12 am
Indianapolis, IN.
Art - test results are promising, what I like is feeling the actual vibration of the acoustic guitar (proto) in my arms, and if I put my ears on it, just for fun, wow. Violins are always completely excited due to the power of the bow, the entire body is always vibrating in complicated and beautiful ways. That is why the violin is considered the greatest musical instrument ever, and rightly so... I still believe the acoustic guitar is a great instrument, that just does not have the mechanical and acoustic power that an instrument of that size should be able to project, due to plucking and strumming, it can be improved. I will never come close to matching a Stradivarius, it is a dream instrument to me, but what is the blue flame?
 

freddi

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2005-08-16 4:21 pm
I played bass but briefly had a Takamine steel string guitar as a gift. A friend came over with a WWII era Gibson guitar - very beat looking. That Gibson had a huge rich room-filling sound while the Takamine, a small -compressed "tinny" sound. (it was a budget guitar)

I've never heard a classical nylon string guitar played in person and un-amplified so not much of a clue as to their dynamic range. (It sounds very wide in recordings - moreso than electric solid body -?)
 
Using "A" weighting on a dB meter, a "huge rich room-filling" guitar may read little higher than a junior size guitar, as frequencies below 1000Hz are rolled off.

On "A" scale, the Low E would read around 24dB below it's actual output, the second harmonic (the main output he hear from the lower notes) more than 12dB down.

Upper harmonics above 8kHz would also read low using "A" or "C" scales :violin:
 

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freddi

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2005-08-16 4:21 pm
Hi Art

with regards to the bass guitar, how do flatwound strings compare to roundwound? I assume the fundamentals are about the same but harmonics weaker. (is the distribution a lot different between the types?)

some years back I posted roundwound bass strings RTA spectrum but lost the files long ago.

I was young when the fret eating round wound arrived and don't care for the "Seinfeld" style sounds nor most music associated, but round wounds are about all I've used partly due to price.. In those days in my area, it was common for a bass player to have a 15" or 18" in a little folded horn and the roundwound probably helped the player identify pitch better in that situation.

Speaking of weak fundamentals and folded, it was crazy in the 60's and early 70's to see W-bins such as the Eliminator pulled to the front of a stage for club work.
 
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Yes, flatwound string fundamental level is about the same as round-wound, but above the second harmonic have progressively less output.

Unlike round-wounds, the string doesn't fill up with oil and skin grunge, so they will sound about the same for a very long time. I've heard original 40 year old nylon tapewound bass strings that probably sounded near the same as when new.
 

freddi

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2005-08-16 4:21 pm
I must be in the tinyest minority to not care for the upper harmonics from roundwounds sticking out full force and with constant "solos" - sound like a damn screen door spring and if wanted slapped bass - then old jazz bands and Willie Dixon style on an upright is an exciting sound. No tweeters with the round things - never a pile of piezo.

Roundwounds work well - I just hate those springy overtones and would take the sound of a flatwound with a pick from the Lawrence Welk orchestra over that of the snappy poppy Seinfeld stuff.

My basses are all metalneck Kramers (maybe for no good reason than some feedback resistance and look) and its interesting that some models were very lively with roundwound while others deader than Dixie. The body seemed to make quite a difference.

50 + years ago I had La Bella black nylon tapewounds on a Hagstrom and also tried on Precision - mixed feelings. My fave Fender was the Telecaster. (which of course looked like the first Precision)


hey Joe K - Stratotron seems to be doing well with his first directional prototype - a horn not real far off from what you are doing:

Shoulder slung, waveguide, synth beamer
 

Joe K

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2021-08-14 12:12 am
Indianapolis, IN.
Stratotron - wow, they could do a chorus line!

Emerson Lake and Palmer synthesizer great, others, maybe.

It looks like a pretty great idea, I would love to put a horn that large
in my guitar, real estate problem. I will comment, thanks!

I have learned that a speaker horn and a trumpet horn are the same
at the mouth, air impedance matching. At the throat they are very different.
A trumpet blows hard in one direction, a speaker moves back and forth. Of course you guys knew this, but I am learning.

My compression chamber was a total disaster - Art was right again!
I deserve it from using Google images, I am sure they suck also! I also removed the entire top of the horn, cut and doubled the horn size, and added a port. BAM! Sonic! I did a dB check on a Grand Piano, 105 db. If I sound good and don' t get buried by other acoustic instruments, a good start!
the sound was finally pouring out and sounding good. 105 dB easy!
 

Joe K

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2021-08-14 12:12 am
Indianapolis, IN.
To all my new friends: Art, freddi, PPR, Tubelab, jjasniew and others: thank you so much for your input. I love hearing the truth, good or bad! Not tonight, but later I am going to post CAD pics showing the design, with dB at all areas and driver specs. Maybe I will get lucky enough to have freddi do another Hornresp for me. I need to learn how to use that software. I can do CAD until the cows come home, we all have our strengths and weaknesses. I have some really great sound coming from my wood prototype now, and great volume levels, my goal. As the great Duke Ellington said "if it sounds good, it is good". I have the soundboard, two internal speakers, two five foot long folded horns (now open on top) and (8) ports. I don't know if the open horns can count as collimated sound beams (Art recent post). This guitar proto is a sonic machine, you can feel the vibrations in your body. I equate it now with a car stereo blasting in a car. Nobody can be inside a guitar, so open the windows and the rear hatch, BOOM. I think I was killing the SPL, live and learn. More to follow next weekend. Thanks! Joe
 

Joe K

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2021-08-14 12:12 am
Indianapolis, IN.
Folded Horn Acoustic Guitar

Hello gents - pdf attached showing updated Folded Horn Acoustic Guitar specs. Please provide feedback (no pun intended). I would love to hear from everybody. I will be cutting the full scale entire body soon, as shown. Testing with hard maple partial prototype has given me lessons learned. I have adjusted based on these results, and what I hear. Thank you! Joe
 

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Joe,

Your "folded horn acoustic guitar" has morphed into something quite different from the original concept.

I can imagine you would feel the vibrations in your body very similarly with your prototype as you would if you suspended a pair of the same speakers on a baffle inside an ordinary acoustic guitar, "playing Little Martha at close to highest level".

I don't imagine those vibrations resulting in much usable sound pressure level at a distance in front of the instrument.

What lessons did you learn testing the partial prototype?

Art
 

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