Thank you to freddi, Printer2, and weltersys. I appreciate your feedback very much!
freddi - the Hornresp shows I might be able to get up to 105 dB between 100 and 1000 Hz (generally the full frequency range of an acoustic guitar). That would be a wonderful volume increase, and that is only with one horn. I have two, so amplitude will increase as they are symmetrical (constructive).
Printer2 - I see your guitar output is 40- 75 dB, makes sense for a smaller guitar, pretty cool data.
weltersys - yes having the horns in the body, and loading the body with sound/vibration is a total unknown to me, we shall see how this sounds, will be a learning experience. Feedback could be a real killer, my biggest worry. dB output will be the real test, I agree this might be dicey, but I am still going to try. Keep in mind the horns provide much of the sound, but the soundboard will also provide as usual, the combo will be "interesting" as you mention.
This is a prototype. Given the CAD and CNC equipment I am using, I can redesign the horns to be elliptical or round, so much to learn, and so much to redesign after I have test results that might be successful and more importantly, failure modes. I don't see any reason why we should build a guitar exactly the same way we have been doing for more than 100 years, lets dream and see what happens!
freddi - the Hornresp shows I might be able to get up to 105 dB between 100 and 1000 Hz (generally the full frequency range of an acoustic guitar). That would be a wonderful volume increase, and that is only with one horn. I have two, so amplitude will increase as they are symmetrical (constructive).
Printer2 - I see your guitar output is 40- 75 dB, makes sense for a smaller guitar, pretty cool data.
weltersys - yes having the horns in the body, and loading the body with sound/vibration is a total unknown to me, we shall see how this sounds, will be a learning experience. Feedback could be a real killer, my biggest worry. dB output will be the real test, I agree this might be dicey, but I am still going to try. Keep in mind the horns provide much of the sound, but the soundboard will also provide as usual, the combo will be "interesting" as you mention.
This is a prototype. Given the CAD and CNC equipment I am using, I can redesign the horns to be elliptical or round, so much to learn, and so much to redesign after I have test results that might be successful and more importantly, failure modes. I don't see any reason why we should build a guitar exactly the same way we have been doing for more than 100 years, lets dream and see what happens!
if you were using say, 3fe22 then its Xmax is rated 1.83mm and around 7mm limit before damage.
That would get pretty loud (in places - hey Art - never seen that "what goes around comes around" gain before feedback calculator before)
I know pretty much nothing about guitars and very little about loudspeakers but if were trying such an endeavor with very small mouth T-lines. then would consider making the path length of on e of the horns half that of the other as to have the short horn's peaks fill in the dips of the long horn.
Look at the "Compound horn sim.
That would get pretty loud (in places - hey Art - never seen that "what goes around comes around" gain before feedback calculator before)
I know pretty much nothing about guitars and very little about loudspeakers but if were trying such an endeavor with very small mouth T-lines. then would consider making the path length of on e of the horns half that of the other as to have the short horn's peaks fill in the dips of the long horn.
Look at the "Compound horn sim.
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Well I don't know anywhere near as much as you do about Acoustics Engineering, so we are even. I will consider your approach because I trust what you say, and also because I thought it would be a good to have one of the horns stop short, and exit up to the guitar player. A very interesting idea, thanks! Any others want to comment?
Freddi,
With only two AA batteries, 3volts to work with (without voltage boost) the speakers are not going to be driven to Xmax, much less Xlim.
Then to make things more "interesting", the acoustic output is at time "0", and the output of the short horn/transmission line path, about 2.5ms (milliseconds) delayed, the longer, about 5ms delayed, which when combined will result in more cascades of comb filtering (peaks and dips due to outputs being in and out of phase).
Art
Freddi,
What Joe is trying to do “is make the acoustic guitar louder and also keep that beautiful natural acoustic sound.”
Unfortunately, using an internal microphone and (peaky) horn speakers won’t do either particularly well, and also would be far heavier than I’d like to play.
I’d favor the approach used by Lâg/HyVibe’s Smart Guitar, using something like Dayton Audio's DAEX25FHE-4 sound exciters, and soundboard/bridge transducers.
Programmable DSP (digital signal processing) would also be part of the package from the get-go, as getting a realistic acoustic sound with increased SPL requires volume dependent parametric equalization.
Having provided sound for many of the world’s best-sounding acoustic guitar players, using dozens of different mic and transducer mixtures, one show in particular really informed my take on what works for making the instrument sound natural, but loud enough to compete with louder and/or amplified instruments.
The gig was in in Rapid City, South Dakota at the Rushmore Plaza Civic Center, a 7500 seater with performances by Jackson Browne, Bruce Cockburn, Willie Nelson, Neil Young and Timbuk 3, who had exactly one song I knew, “The Future's So Bright, I Gotta Wear Shades”.
The “big names” used combinations of internal mics, transducers, and pre-amps on very expensive guitars, set up by great luthiers and sound engineers.
Other than for high frequency “air”, the internal microphones proved to be of little use, as the low frequency resonance of the guitars would simply be reinforced by the stage monitors, requiring the mic’s low end to be notched out to avoid acoustic and mechanical feedback, which could make the strings vibrate enough to require the performers muting them.
They all required extensive parametric EQ (and polarity combinations) to make them sound like a decent acoustic instrument, and get enough gain before feedback.
Timbuk 3 used a brand new (in 1989) off the shelf, inexpensive Takamine using transducers only. Although Takamine had been making acoustic electric guitars for 10 years, it may have been the first I’d heard.
With no sound check (time had been used up trying to get all those other guitars sounding decent..) the guitar player plugged in and played, and had by far the best sounding guitar of the show, with almost no outboard EQ required at all.
Art
What Joe is trying to do “is make the acoustic guitar louder and also keep that beautiful natural acoustic sound.”
Unfortunately, using an internal microphone and (peaky) horn speakers won’t do either particularly well, and also would be far heavier than I’d like to play.
I’d favor the approach used by Lâg/HyVibe’s Smart Guitar, using something like Dayton Audio's DAEX25FHE-4 sound exciters, and soundboard/bridge transducers.
Programmable DSP (digital signal processing) would also be part of the package from the get-go, as getting a realistic acoustic sound with increased SPL requires volume dependent parametric equalization.
Having provided sound for many of the world’s best-sounding acoustic guitar players, using dozens of different mic and transducer mixtures, one show in particular really informed my take on what works for making the instrument sound natural, but loud enough to compete with louder and/or amplified instruments.
The gig was in in Rapid City, South Dakota at the Rushmore Plaza Civic Center, a 7500 seater with performances by Jackson Browne, Bruce Cockburn, Willie Nelson, Neil Young and Timbuk 3, who had exactly one song I knew, “The Future's So Bright, I Gotta Wear Shades”.
The “big names” used combinations of internal mics, transducers, and pre-amps on very expensive guitars, set up by great luthiers and sound engineers.
Other than for high frequency “air”, the internal microphones proved to be of little use, as the low frequency resonance of the guitars would simply be reinforced by the stage monitors, requiring the mic’s low end to be notched out to avoid acoustic and mechanical feedback, which could make the strings vibrate enough to require the performers muting them.
They all required extensive parametric EQ (and polarity combinations) to make them sound like a decent acoustic instrument, and get enough gain before feedback.
Timbuk 3 used a brand new (in 1989) off the shelf, inexpensive Takamine using transducers only. Although Takamine had been making acoustic electric guitars for 10 years, it may have been the first I’d heard.
With no sound check (time had been used up trying to get all those other guitars sounding decent..) the guitar player plugged in and played, and had by far the best sounding guitar of the show, with almost no outboard EQ required at all.
Art
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Thanks much Art and Freddi - I agree horns can have problems and not everybody likes them. I sure would like to get a +/- 3 dB frequency response, and I am not getting that. In the guitar sweet spot of approx 200-800 Hz I am getting about +/- 5 dB. I will not know until I test, but it seems like that is not terribly bad, and that is just the horns, not the soundboard. I have heard that transducers work pretty well (Taylor uses them), so I will check that out, I could mix the two together. I have seen the HyVibe, that is a pretty sweet guitar. This is for unplugged situations. For playing in a large concert hall, the best I have heard is just a great external mic in front of the guitar.
an idea - would a hybrid nylon string with say a quarter to half inch of magnetic winding for the pickup and a low Z high fidelity bar/"rail" magnetic pickup do anything good in the quest to amplify these type guitars? (Has that already been done?)
Could little "magnetic coupling sleeves" be slid over regular nylon strings then cemented in place to make the hybrid string?
50 years ago I wound a low Z pickup and used a little mic transformer to step up. It was very "hi-fi" and needed no active stuff to work in normal runs of cable to my Traynor tube head - but it looked ugly as the form had been melted in places by a previous owner (looked like soldering gun marks) so it didn't go on my Precision bass.
It will be interesting to hear about Joe K's progress
Could little "magnetic coupling sleeves" be slid over regular nylon strings then cemented in place to make the hybrid string?
50 years ago I wound a low Z pickup and used a little mic transformer to step up. It was very "hi-fi" and needed no active stuff to work in normal runs of cable to my Traynor tube head - but it looked ugly as the form had been melted in places by a previous owner (looked like soldering gun marks) so it didn't go on my Precision bass.
It will be interesting to hear about Joe K's progress
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If a string has a "lump" you get many oddball overtones.
There was a practice of "prepared piano" involving things like paperclips on strings, and they sure made odd noises.
There was a practice of "prepared piano" involving things like paperclips on strings, and they sure made odd noises.
I prepared a piano that was in my college dorm floor lounge - buy putting a thumbtack in the end of each hammer. Ok, only some...
Everyone hated it.
I asked a physics prof there what I could do to make my electric guitar sound different. He suggested putting little lead crimp-on weights (used for fishing) at various places along the string length, not over the fretboard of course. I never tried it to this day; never seen anyone else do that either.
Everyone hated it.
I asked a physics prof there what I could do to make my electric guitar sound different. He suggested putting little lead crimp-on weights (used for fishing) at various places along the string length, not over the fretboard of course. I never tried it to this day; never seen anyone else do that either.
funky it would be
- how about an optical pickup?
ōPik—the optical guitar pickup by Light4Sound — Kickstarter
- how about an optical pickup?
ōPik—the optical guitar pickup by Light4Sound — Kickstarter
Interesting concept, but the Light4Sound pickup power supply says "150 milliamps at 9 volts", which is 1.35 watts, compared with basically no power required for a magnetic, moving coil, or piezo-electric pickup.
An acoustic guitar has wide dynamic range, a class D amplifier using 1.35 watts average draw could deliver in the 10 to 20 watt (or more) peaks. The bright LEDs and photo-receptors would probably use more power than the audio portion of a battery-powered guitar.
An acoustic guitar has wide dynamic range, a class D amplifier using 1.35 watts average draw could deliver in the 10 to 20 watt (or more) peaks. The bright LEDs and photo-receptors would probably use more power than the audio portion of a battery-powered guitar.
Joe,
+/- 5 dB over a two octave range is not "terribly bad", but not very encouraging, as it implies that some notes will sound half as loud as others without corrective equalization.
Are you using the Tectonic Audio Labs, Inc. TEBM46C20N-4B ?
What's the range between the low E (82 Hz) and all the harmonics extending well past 12kHz look like?
Have you compared the output sensitivity of the horns to the drivers mounted in a box of similar volume?
Art
Agree! I love to play slide on an acoustic guitar. I tune to open E at times, this is a big sound. Overtones eh? Well since this guitar will be filled with sound and vibration, the overtones will either be quite stunning or troublesome, so difficult to tell on this type of an instrument, that is somewhat new. Stay tuned!
I like your idea about an equalizer due to undesirable peaks. I will check out your suggestions, needs to be small to fit. I don't see a guitar getting up to 12kHz, am I missing something? Comparing to a box of similar volume, yes I need to do much of that, need the time, time ,time...
This picture is the finished wood from a CNC program ( 1,300,000 lines of code) to cut this prototype. The two pieces will be cut out and assembled to form the horn. There are two of these (symmetrical) in the guitar. Ask your horn player friends about the power of a horn. Blow a breath through a saxophone and fill a room with sound, same thing.