So there're 2 horns in the photo in post #18 😀
Another problem is: as the dispersion of horn would mostly be limited, so the sound radiating to audience would be very different from what it appear to the player.
For solving this, it seems a bent/folded horn is hard to avoid.
Another problem is: as the dispersion of horn would mostly be limited, so the sound radiating to audience would be very different from what it appear to the player.
For solving this, it seems a bent/folded horn is hard to avoid.
well I may also build it with the anchor point for the strings separate to the bridge, so that by raising and lowering the anchor relative to the bridge (with the bridge on the diaphragm) I can evenly adjust the pressure the bridge has on the diaphragm. if the anchor is at the same hight as the bridge, it will have very little pressure on the diaphragm, adjust the anchor down towards the body of the guitar to pull the bridge down onto the body, and there is more pressure onto the diaphragm. so I should be able to use whatever for the diaphragm 🙂
if I'm good, I will be able to adjust the anchor right up soon the strings don't even touch the bridge and the bridge and diaphragm should fall out because there is no strings touching them to hold them in! just to save time with experimenting with different diaphragm/bridge combinations... hmm..
if I'm good, I will be able to adjust the anchor right up soon the strings don't even touch the bridge and the bridge and diaphragm should fall out because there is no strings touching them to hold them in! just to save time with experimenting with different diaphragm/bridge combinations... hmm..
its been done -a modern approach to the Stroh guitar -(or six string horn-loaded banjolele) - look closely - perhaps you can contact the builder
Pin by Dave Copps on Ben Simon Guitars | Pinterest
Pin by Dave Copps on Ben Simon Guitars | Pinterest
An externally hosted image should be here but it was not working when we last tested it.
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I would use aluminum for the diaphragm, or something else light. A big issue will be counteracting the downward push of the strings on the suspension. Spring steel might be good for that. A trapeze and minimal break angle will reduce the downward push. It'll still likely be 10+ lbs to counteract.
what might happen if the diaphragm were just a 6" drum/banjolele head?
Amazon.com: Remo FA-0506-00 6-Inch Fiberskyn 3 Ambassador Drum Head: Musical Instruments
Amazon.com: Remo FA-0506-00 6-Inch Fiberskyn 3 Ambassador Drum Head: Musical Instruments
is all that pressure necessary? as I mentioned above, by having an adjustable string anchor, I should be able to adjust how lucky pressure is on the diaphragm
the compression chamber of the horn will be difficult to design if the diaphragm is to large, that's the only problem with a banjo head 🙂
not saying it won't be something to try, but after playing a banjo, I notice it is quite good at absorbing sound energy which hinders sustain.
I think maybe the bottom of an aluminium soda can may be an ideal start. it should handle just about any pressure the strings can dish out. 🙂
not saying it won't be something to try, but after playing a banjo, I notice it is quite good at absorbing sound energy which hinders sustain.
I think maybe the bottom of an aluminium soda can may be an ideal start. it should handle just about any pressure the strings can dish out. 🙂
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in contrast, the old Stroh violin had no appreciable weight upon its diaphragm as the phono-reproducer was connected with an arm from the bridge to where a stylus chuck would be
http://upload.wikimedia.org/wikipedia/commons/a/a2/Stroh_violin_up.jpg
http://upload.wikimedia.org/wikipedia/commons/a/a2/Stroh_violin_up.jpg
I think it makes sense for me to adjust the anchor so there is only just enough pressure on the strings to hold them firmly on the bridge. the more pressure the diaphragm is under, the more resistant the it is to flex. I'm still making my mind up about the best method and material to build the diaphragm from, but open to anything
The diaphragm material will need experimentation. Metal ones like a Dobro will have self stiffness but sound tinny with higher fs. Skin drumhead will sound warmer with lower fs. I still think you should try a speaker suspension as diaphragm and augment with supporting struts like Dobro to take brunt if string bridge pressure. If the diaphragm is large like a drumhead a compression chamber can still be low volume by making it flat with a hole for horn. It will operate like a BLH with direct radiator drum head for high and mids and BLH for bass. The advantage of using a real speaker is that TS params are known. Then maybe use sims conventionally but derive expression for equivalent power from mechanical vibration (probably milliwatts of mechanical energy).
Sorry for all the high res pics that are all out of order, I am having trouble getting the hang of this phone tap talk thing
sorry for the late reply, I've been pretty flat out with lots of things so I haven't really had time to post. This is where I'm at now. The body (in true speaker builder fashion) is made from mdf. It's dense, easy to work and should work well as a proof of concept. The horn is beyond imperfect! I realised half way through drawing it up that the lengths are way out, (the relatively straight sections need to be closer to twice the length) but it's drawn now and we'll see how it goes. The diaphragm is 4 inches made from 3 layer 0.5mm plywood, so I based the measurements on a 4 inch mid range driver. Clearly the ts parameters are completely off but I had no idea on how to even guess the measurements so I just went with that. The compression chamber volume is probably a little small, but it had to fit in the thickness of the mdf. It's made from Masonite (because it just happened to be the perfect thickness) and then coated with cyno (super glue) and cut and polished for a dense, shiny, smooth surface.
So that's what's I'm at. The compression ratio is around 7/1 so I'm hoping that does the trick. I just received some candle wax in the mail yesterday so this weekend I will melt that down and try to shape it onto the template so too make a mould of the internal of the horn and if I have time I will then put fiber glass over the top then remove the wax. This rear shell will be the bulk of the horn.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
sorry for the late reply, I've been pretty flat out with lots of things so I haven't really had time to post. This is where I'm at now. The body (in true speaker builder fashion) is made from mdf. It's dense, easy to work and should work well as a proof of concept. The horn is beyond imperfect! I realised half way through drawing it up that the lengths are way out, (the relatively straight sections need to be closer to twice the length) but it's drawn now and we'll see how it goes. The diaphragm is 4 inches made from 3 layer 0.5mm plywood, so I based the measurements on a 4 inch mid range driver. Clearly the ts parameters are completely off but I had no idea on how to even guess the measurements so I just went with that. The compression chamber volume is probably a little small, but it had to fit in the thickness of the mdf. It's made from Masonite (because it just happened to be the perfect thickness) and then coated with cyno (super glue) and cut and polished for a dense, shiny, smooth surface.
So that's what's I'm at. The compression ratio is around 7/1 so I'm hoping that does the trick. I just received some candle wax in the mail yesterday so this weekend I will melt that down and try to shape it onto the template so too make a mould of the internal of the horn and if I have time I will then put fiber glass over the top then remove the wax. This rear shell will be the bulk of the horn.
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Oh I didn't mean to post the last pic, but that's the paper the horn was drawn onto. Then I cut it out and transferred it to the mdf.
Nice work and great progress there. Have you considered using a spiral of foam core for the horn? It would be perfect for this application and help keep the weight down. It actually adds a lot of structural rigidity when coiled into a spiral. Nice compression chamber design. I suspect your diaphragm is too thick though. Can 0.5mm alone work? What about a carbon fiber disc? What about a tin can top?
Good luck!
Good luck!
My plan is to use a little down here and there to build a very rough shape of the horn and then coat it with wax. The foam is just there so I don't have to use so much wax. Once I put 3-5 latter's of glass over it, it should be rigid enough you stand on XD I then just melt or mechanically remove all the wax. The compression chamber is 11mm thick by just under 4 inches wide. If I remember, I'll measure the volume by filling it with fine dry sand and then measuring the volume of the remaining sand.
The diaphragm is relatively flexible, it may be thinner then that, I haven't really checked lol. But the best of my design is that the diaphragm/bridge assembly is only held in place with string tension. The anchor point, seen in the first picture at the bottom, can be raised or lowered via adjustment screws. So I can effectively raise the strings clear of the bridge so that that assembly can be easily removed without loosening the strings. Then I can try a carbon fibre diaphragm, the bottom of a soda can, you name it! When the diaphragm is stronger then 0.5mm thick ply, I can adjust the anchor to apply more downward pressure onto the assembly, which may or may not allow better transfer of acoustic energy. BUT ONLY EXPERIMENTATION WILL PROVIDE RESULTS!
I'm pretty excited XD
The diaphragm is relatively flexible, it may be thinner then that, I haven't really checked lol. But the best of my design is that the diaphragm/bridge assembly is only held in place with string tension. The anchor point, seen in the first picture at the bottom, can be raised or lowered via adjustment screws. So I can effectively raise the strings clear of the bridge so that that assembly can be easily removed without loosening the strings. Then I can try a carbon fibre diaphragm, the bottom of a soda can, you name it! When the diaphragm is stronger then 0.5mm thick ply, I can adjust the anchor to apply more downward pressure onto the assembly, which may or may not allow better transfer of acoustic energy. BUT ONLY EXPERIMENTATION WILL PROVIDE RESULTS!
I'm pretty excited XD
also, I may down the track build a second version, because I expect this build to be quite heavy and have other problems, but for now I just want something that works 🙂
unfortunately this project has gone on hold as I've have had other projects come up that have taken precedence. mainly installing and building the sound system for my new car. also I was trying a few techniques to build the horn buck, none of which where working, then the blindingly obvious came to me; clay. i build the horn out of clay, then fiber glass over it, pull the clay and fiberglass off the timber front, then pick out the clay. I'll try my best to prevent the clay from drying so it will be more easy to remove once the glass is set. i just need to buy the clay. I'm down to the old chestnut of having no time or money right now for it lol
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Hello ubza1234. I love your idea, very creative. I think you may see some very good results. I say this because I am currently building a Folded Horn Acoustic Guitar (U.S. Patent #10,777,172). It is similar to your idea, but not the same. I like the way you think, and I like that you have the courage to try, build it!! What do you have to lose? Also, might I suggest you consider getting a U.S. Patent (largest market). I learned how to write patents myself. It was very difficult the first time, but after that, not so bad. I encourage you to get the book "Patent It Yourself" written by David Pressman (Patent Attorney and Patent Agent) and David E. Blau (Patent Attorney). Best how to patent book I could find, really great. If you don't have the time, use a Patent Attorney. My build project has been a complete joy in my life, and also a wonderful challenge. Mistakes will be made, but so what, just solve the problem. I could go on forever, see attached PDF, hope you and others enjoy it. Please comment, or find my Folded Horn Acoustic Guitar link on DIY Audio! Thanks! Joe