I stretched a few of the the graphs on the y axis, to make them more readable. You'll need to adjust the y scale span to cover less range, with more focus on the where the sound levels are. I also cut below 50 and above 6k on the x axis...fooling around using paint.net.
The common attribute I see is the sound craters some 30 db between the loudest frequencies, 300 - 700 Hz and 2 kHz, and then the 2-4 Khz is some 20 db down from those loudest frequencies. If you put the pink noise from phone through just a small guitar amp, same bed-plane measurement as your horns, would it also have this? Is this really due to the horn loading, or something else in the system doing that?
I'd like to see that the pink noise signal is flat electrically, across the frequency range of interest, say 50 to 10kHz. Unsure how to do that with the USB measurement mic.
The common attribute I see is the sound craters some 30 db between the loudest frequencies, 300 - 700 Hz and 2 kHz, and then the 2-4 Khz is some 20 db down from those loudest frequencies. If you put the pink noise from phone through just a small guitar amp, same bed-plane measurement as your horns, would it also have this? Is this really due to the horn loading, or something else in the system doing that?
I'd like to see that the pink noise signal is flat electrically, across the frequency range of interest, say 50 to 10kHz. Unsure how to do that with the USB measurement mic.
Last slide added is better resolution of first slide. Everything looks pretty consistent, about +/- 10 dB in 100 Hz - 1,000 Hz, but of course louder with the horns.
Note slide #7 even if more difficult to read shows good comparisons - wanted to get the entire range, hence not as easy to read. Note slide #8, from earlier, the horns are generally the same or better than the amp, still don't understand why the amp drops off so significantly at 450 Hz - ouch! I like your idea of pink noise thru amp only, I will do this, will be interesting. I am still going to test each string with guitar alone and guitar with horns. Need to be on the road at 5 AM for work today, will not be able to try this until the weekend, but fun stuff, thanks!
Also I want to test two piezo's together, one in each channel, because I like that sound. Will need to mess with the bridge saddle, not sure if that will work, but worth a try! I am also going to hang 150 lbs. from my neck head to test the strength/bend amount and resultant relief compared to strings. Plus I am ready to screw the chamber divider to the body, now that I am confident about neck setup. Let's rock, even in the morning! Joe
Note slide #7 even if more difficult to read shows good comparisons - wanted to get the entire range, hence not as easy to read. Note slide #8, from earlier, the horns are generally the same or better than the amp, still don't understand why the amp drops off so significantly at 450 Hz - ouch! I like your idea of pink noise thru amp only, I will do this, will be interesting. I am still going to test each string with guitar alone and guitar with horns. Need to be on the road at 5 AM for work today, will not be able to try this until the weekend, but fun stuff, thanks!
Also I want to test two piezo's together, one in each channel, because I like that sound. Will need to mess with the bridge saddle, not sure if that will work, but worth a try! I am also going to hang 150 lbs. from my neck head to test the strength/bend amount and resultant relief compared to strings. Plus I am ready to screw the chamber divider to the body, now that I am confident about neck setup. Let's rock, even in the morning! Joe
Hello JJ - recorded pink noise through Fender amp only, attached. Lower dB and flatter, but boy did it sound terrible, like static coming through a radio station not in tune. Constantly going from low to medium distortion over and over, not sure why. Totally different from all other pink noise recorded earlier, which could of course also be called distortion, but did not seem that way as the noise was very level, not up and down. I checked all my connections, they were OK. What gives? 🤔
Also showing Bose Waveguide Stereo with some general comparisons to Folded Horn Acoustic Guitar.
More info for Folded Horn Acoustic Guitar, this damn guitar sounded great tonight! Check out attachment and let me know what you think all, especially JJ and Art. I have some sheet metal screws that seem to work best, with a small tap drill, testing screws with wood just to be safe. Seems like #8 screws in .25" thick wood works best. Tascam recording next, did not have enough time this weekend. Ordered more rosewood fretboards, comparing these also. Cutting a third body on the CNC at work! Joe
Joe,
Your hate of the "so damn tinny" sound of your acoustic guitar's high "E" string may explain why you prefer the attenuation of the upper harmonics from the folded horn's acoustic bandpass filter.
You might also prefer the sound of gut or nylon strings...
Harmonic multiples of the "E" 329.63Hz fundamental frequency are visible in your RTA capture, the 16th harmonic (fourth perfect octave) at 5274Hz can be seen around -25dB from the fundamental.
Art
Yes agree Art, 25 dB is a lot of course, but for a harmonic four octaves higher it would normally be lower dB, but not that much lower, correct? How much lower "normally"? I have always shied away from high frequencies, prefer Greg Allman's voice over a strong soprano (although I really like Minnie Riperton).
I thought about nylon strings, might try that. What I would really like to see is the high E and also the B string be bronze wound like the other strings, have never seen any. I know the diameter is very small, and it would be difficult to do, but if somebody could pull it off, would have potential for sure.
I jammed for about two hours last night, and I really like the sound I am getting. It is so fun to play with the speakers turned off after that, and think what the hell happened to this guitar, I can barely hear it! Of course I am not young, so that is part of it also 🤣 . I have all my sheet metal screws preferred size after testing (#8) and will transfer holes from the body to the chamber divider and screw that on. Need to drill, self tapping screws put too much force on the wood, can crack it. I will also use these for the soundboard.
I will definitely get into the Tascam recoding equipment soon, so I can pass on some decent quality recordings. I bought some more 25.4" scale fretboards with mother of pearl, but I will need to add the frets in the precut slots. The fretboards I bought from on Amazon are junk. Thanks so much for your interest Art and all, I am up to 17,000 hits on this site. Oh yeah, and my third patent is due back with first round of corrections soon (Acoustic Waveguide Guitar). Similar of course, but with enough changes to get another patent - I hope! Thanks! Joe
I thought about nylon strings, might try that. What I would really like to see is the high E and also the B string be bronze wound like the other strings, have never seen any. I know the diameter is very small, and it would be difficult to do, but if somebody could pull it off, would have potential for sure.
I jammed for about two hours last night, and I really like the sound I am getting. It is so fun to play with the speakers turned off after that, and think what the hell happened to this guitar, I can barely hear it! Of course I am not young, so that is part of it also 🤣 . I have all my sheet metal screws preferred size after testing (#8) and will transfer holes from the body to the chamber divider and screw that on. Need to drill, self tapping screws put too much force on the wood, can crack it. I will also use these for the soundboard.
I will definitely get into the Tascam recoding equipment soon, so I can pass on some decent quality recordings. I bought some more 25.4" scale fretboards with mother of pearl, but I will need to add the frets in the precut slots. The fretboards I bought from on Amazon are junk. Thanks so much for your interest Art and all, I am up to 17,000 hits on this site. Oh yeah, and my third patent is due back with first round of corrections soon (Acoustic Waveguide Guitar). Similar of course, but with enough changes to get another patent - I hope! Thanks! Joe
The range of picks, strings and guitar bodies are endless, there is no "normal" that can be applied.
You would probably find that a guitar that sounds "half as bright" or "twice as bassy" has about 10 dB less top end than another.
If you want a speaker to reproduce the sound of either guitar it needs to have something close to flat response.
I might need a third speaker, not going thru the horns...also I need to test the port adjustment theory in REW. See what the trade offs are, totally sealed, half way open, all the way open, on my list. 🤔
Adding a high frequency driver and crossover would be an option, but you may find reversing the drivers with the port open would result in more high end output, though it still will have peaky response.
Arranging the drivers like a back loaded horn as Ian's Specimen Audio horns are, drivers pointed forward, would be a more "high fidelity" approach than your present configuration.
Arranging the drivers like a back loaded horn as Ian's Specimen Audio horns are, drivers pointed forward, would be a more "high fidelity" approach than your present configuration.
That is an interesting idea Art, I remembering considering that some time back, but never did anything as I can't mount from the other side of the wood wall, but I could flip the drivers and keep in the current position. I would likely need another mounting piece to make it fit.
Like it, on my list, easy to do (I think), and maybe some benefits as you mention. Thanks! Joe
Like it, on my list, easy to do (I think), and maybe some benefits as you mention. Thanks! Joe
OK flipping the drivers looks feasible, will get some output from REW. Easy change and very interesting to think about how this will affect sound. What do you think Art?
As I said, reversing the drivers with the port open would result in more high end output, though it still will have peaky response. Reversing the drivers with the port closed will reduce the horn's high end output.
Mounting the drivers on the guitar face and ducting their rear into the horn would probably be a better option.
A short parabolic reflector similar to half of a EV MTA-22 scaled up to the driver diameter (less the surround width), directing the output of the front of the driver to the face of the guitar would also be an option, and could increase forward gain over that of the direct radiator.
You have learned a bit from your pink noise experiments, but until you start measuring the frequency response with REW's sine wave sweep, with a known flat response amp set to a specific voltage, measured at the same distance and angle from the source, you won't be able to accurately determine what the response differences between changes are.
Art
Interesting options thank you Art. I did find out I can't flip the drivers, will not fit due to back of speaker features. I think I did try that before, it has been a while. I am going to measure the output from the back of the guitar (front of drivers), just to see differences, sweep may be needed as you say (on my list!), we shall see if highs are increased. The only problem with speakers on the face is feedback. I have learned that keeping everything under sealed 1/2" Baltic Birch WILL prevent feedback. The back ports do not contribute to feedback near as much, and now they are "sealed" (facing the floor). If they are open, they might feedback (not JJ's favorite!), will see what happens when measuring with mic from this area. I have seen many acoustic guitars with speakers on the faces, no horns, they all seemed to fail, as back of driver just went into open chamber, and front driver feedback is not tolerable, people have been doing this for decades, hence the horns that are promising! I know your ideas include the horns also Art, so different animal, but feedback is an absolute killer. And by the way, as I have said before, the horn output is less peaky than a standard acoustic guitar output, do not see how that is a problem by comparison.
There was a guy on this site that said feedback will be terrible and will kill this idea. He was almost correct, but 1/2" thick Baltic Birch and 1/4" Maple body saves the day. If you try this with a standard thickness guitar, it would feedback like a mother, and he would be absolutely correct, but not with the Folded Horn Acoustic Guitar design! I am curious why the electric guitar with speakers on face does not feedback, as these drivers are adjacent to the pickups, but seems to work, I do like that guitar. My guess is you can only go so loud before that does happen, and they had to limit the driver output, and also maybe add an anti-feedback feature (not sure if that even works well).
I have a Martin 25.34" scale steel template now, can do neck measurements accurately. The fretboards I bought with frets in them already are either the wrong scale (not specified, had to measure) or junk. I am going to fret my own rosewood fretboard, should be able to glue the fretboard on this weekend with the truss rod installed, then do the fretting, also chamber divider screwing. I am now very confident with scale length and intonation amount. Oh yeah and Tascam, yikes much to do, but so fun! I have to get back to work that actually pays money. 🤣 See pic, my office has been taken over by this project, so much better than a boring standard office! Joe
There was a guy on this site that said feedback will be terrible and will kill this idea. He was almost correct, but 1/2" thick Baltic Birch and 1/4" Maple body saves the day. If you try this with a standard thickness guitar, it would feedback like a mother, and he would be absolutely correct, but not with the Folded Horn Acoustic Guitar design! I am curious why the electric guitar with speakers on face does not feedback, as these drivers are adjacent to the pickups, but seems to work, I do like that guitar. My guess is you can only go so loud before that does happen, and they had to limit the driver output, and also maybe add an anti-feedback feature (not sure if that even works well).
I have a Martin 25.34" scale steel template now, can do neck measurements accurately. The fretboards I bought with frets in them already are either the wrong scale (not specified, had to measure) or junk. I am going to fret my own rosewood fretboard, should be able to glue the fretboard on this weekend with the truss rod installed, then do the fretting, also chamber divider screwing. I am now very confident with scale length and intonation amount. Oh yeah and Tascam, yikes much to do, but so fun! I have to get back to work that actually pays money. 🤣 See pic, my office has been taken over by this project, so much better than a boring standard office! Joe
You continue to equate a sound producer (a source of sound) with a reproducer (a loudspeaker), hence your problem in comparing the two.
Magnetic coil pickups in close proximity to steel strings electromagnetically convert their vibration into an electric signal, so are not subject to the acoustic gain before feedback problem associated with a microphone.
When the sound pressure level of a loudspeaker becomes loud enough to vibrate the guitar body enough to vibrate the strings, electro-mechanical feedback will occur. Any narrow-band feedback frequency may be "notched out" with electrical filters, but the more filtration used, the less the signal sounds like the original sound producer.
My answers for the great one - I mean Art, not Jackie Gleason 🤣 :
I agree producer (guitar) and reproducer (speaker) is not an apples to apples comparison. I am not confused about this. Since my product has both in the same instrument, I find this to be an interesting comparison, that is it. I am not into bullshitting people, so I would never use this type of specification in a marketing plan. And yes the results are interesting and helpful to me.
I did compare my guitar speaker output (reproducer) to another acoustic guitar through a standard acoustic guitar amp (reproducer), and overlaid them in REW as a comparison. I find this to be a legit endeavor, will use it for marketing, and will explain what I did. Yes my guitar speaker (reproducer) output is peaky, but it is LESS peaky than the acoustic guitar amp (reproducer).
I know people will also play the guitar and use their ears, their feel for the instrument, and feel the uniqueness of this guitar, with music pouring out of the entire body, and also make a decision based on these other outputs, all good.
I also recorded two different acoustic guitars and compared them. Also both peaky. It is an instrument, there is no way an instrument is going to be flat.
Now I do NOT have the ability to measure the guitar (producer) and compare it to the guitar speakers (reproducer), I just don't have the equipment. That of course would give me the true Frequency Response, like a high fidelity stereo would be rated. That of course needs to be as flat as possible, I agree. I have heard good output and need to focus on the build. I can't do everything. Now if somebody likes the product and asked me to do this would so it could be sold, would I? Of course! So maybe later if needed.
This is not a damn guitar kit, I am literally building it from billets of wood. This invention is crazy different, me thinks (and hopefully crazy good).
Regarding feedback, yes I agree with you, but I am talking about this specific instrument only. I agree mics are the best sounding and worst feedback possible, just can not control it in this instrument. Mag pickups do feedback of course, just like a guitar player facing the amp on purpose. Mine will only feedback at higher gain and with 1/4" wood separation from speaker to pickup. That is not acceptable to me. 1/2" wood, zero feedback - win!
Piezo's will also feedback. I had one connected and inched it closer to the speaker (a contact piezo) to pickup the vibration, get within 3"-4" on the same surface - BAM, instant feedback. Under the saddle piezo with 1/2" wood between it and the speaker, no problem. I must have an instrument that does not feedback at all. You can't just walk away from an amp with this instrument. If it feeds back, you are toast. Time to hit the shop! Joe
I agree producer (guitar) and reproducer (speaker) is not an apples to apples comparison. I am not confused about this. Since my product has both in the same instrument, I find this to be an interesting comparison, that is it. I am not into bullshitting people, so I would never use this type of specification in a marketing plan. And yes the results are interesting and helpful to me.
I did compare my guitar speaker output (reproducer) to another acoustic guitar through a standard acoustic guitar amp (reproducer), and overlaid them in REW as a comparison. I find this to be a legit endeavor, will use it for marketing, and will explain what I did. Yes my guitar speaker (reproducer) output is peaky, but it is LESS peaky than the acoustic guitar amp (reproducer).
I know people will also play the guitar and use their ears, their feel for the instrument, and feel the uniqueness of this guitar, with music pouring out of the entire body, and also make a decision based on these other outputs, all good.
I also recorded two different acoustic guitars and compared them. Also both peaky. It is an instrument, there is no way an instrument is going to be flat.
Now I do NOT have the ability to measure the guitar (producer) and compare it to the guitar speakers (reproducer), I just don't have the equipment. That of course would give me the true Frequency Response, like a high fidelity stereo would be rated. That of course needs to be as flat as possible, I agree. I have heard good output and need to focus on the build. I can't do everything. Now if somebody likes the product and asked me to do this would so it could be sold, would I? Of course! So maybe later if needed.
This is not a damn guitar kit, I am literally building it from billets of wood. This invention is crazy different, me thinks (and hopefully crazy good).
Regarding feedback, yes I agree with you, but I am talking about this specific instrument only. I agree mics are the best sounding and worst feedback possible, just can not control it in this instrument. Mag pickups do feedback of course, just like a guitar player facing the amp on purpose. Mine will only feedback at higher gain and with 1/4" wood separation from speaker to pickup. That is not acceptable to me. 1/2" wood, zero feedback - win!
Piezo's will also feedback. I had one connected and inched it closer to the speaker (a contact piezo) to pickup the vibration, get within 3"-4" on the same surface - BAM, instant feedback. Under the saddle piezo with 1/2" wood between it and the speaker, no problem. I must have an instrument that does not feedback at all. You can't just walk away from an amp with this instrument. If it feeds back, you are toast. Time to hit the shop! Joe
See attachment for closeup of Folded Horn at end of guitar. You can really see the horn open up.
Also posting my Folded Horn Acoustic Guitar Frequency Output (producer) vs. Fender Amp Frequency Output (producer).
I say mine is better, comments?
Also posting my Folded Horn Acoustic Guitar Frequency Output (producer) vs. Fender Amp Frequency Output (producer).
I say mine is better, comments?
OK I am on a roll tonight, screwed chamber divider on. Not easy because I can not see the waveguide shape when attaching, but worked well, very solid. Took the neck off and put it back on again, solid. The dovetail and screws are key. This is not some shitting flat neck that does not relocate the same way again.
I put the measurement mic under the guitar, at the drivers, same general REW output. Thought I would get more highs, but just the same (REW attached), and harmonics also the same. Not complaining, like the sound now, but a little surprised the highs do not have more dB.
The jazz chords sound great. Then I played a finger picking Beatles song and thought, hey what the hell is that sound, if I listen closely. Of course it is distortion, slight but there. As I have done before, I turned the bass and treble to zero on piezo amp channel, piezo pickup control, and mag pickup channel.
Distortion gone! The horns do it all, still sounded great! Let's rock!
I put the measurement mic under the guitar, at the drivers, same general REW output. Thought I would get more highs, but just the same (REW attached), and harmonics also the same. Not complaining, like the sound now, but a little surprised the highs do not have more dB.
The jazz chords sound great. Then I played a finger picking Beatles song and thought, hey what the hell is that sound, if I listen closely. Of course it is distortion, slight but there. As I have done before, I turned the bass and treble to zero on piezo amp channel, piezo pickup control, and mag pickup channel.
Distortion gone! The horns do it all, still sounded great! Let's rock!
Dying to hear you play your invention.
I wonder if the old trick we used to use at work, to avoid their silly email malware detection by simply renaming the extension of something we really needed to send; to .doc seemed to work there. Rename your recorded audio file to .pdf. You've posted so many .pdfs, who's going to know this particular one is really a .mp3? That way we can hear warts and all, without exposing yourself to the world at large "before you're ready" to present a professionally finished performance. You could do the same with recording the pink noise output; the we could run our own REW analysis on it..
Joe,
I still don't, and never will find your REW screen captures of random pink noise events to be a legitimate or valid comparison of frequency response.
Art