Those guys make a guitar version that makes a lot more sense than the hifi ones (and of course that's what the OP is working on anyway). Horn Speaker and Amplifier | Specimen Products
Just as a followup, as an experiment I loaded the crunchy guitar-only intro to Rush's "Limelight" into Audacity and tried EQing the audio with a 24dB/oct highpass at 275Hz and a 12dB/oct lowpass at 1800, fairly well mimicking the response of the similar driver I'd found. The result: almost transistor radio - very disappointing. So I think I'll stick to the 5" Carbonneau speaker screwed into a small cylindrical enclosure made from a PVC cap and cleanout plug that I can just screw into a 6" cleanout fixture that I will adapt down to 4" right away with a flexible rubber coupling. I am not sure if that will be too small an enclosure or not but it's a starting point and at least the air volume will be many times the maximum air displacement from the cone. Also, I'm going to use a small PVC cap and cement to seal off the phone jack where the speaker input must penetrate the cap.
Trying a couple different compression drivers on a long folded horn that in theory should go down to around 80 Hz was also disappointing, response rolled off below 300 Hz.
Using a 5.25" Goldwood GM-85/8 (4" cone) the horn went down to 300 Hz, well below the driver's Fs (resonant frequency) of 470 Hz.
After drilling a couple 1/2" holes in the back of the speaker, and using around a 100 square inch compression chamber, it plays down to 75 Hz.
Very peaky response, rolling off steeply at 1800 Hz.
"Interesting" for guitar use.
Your 5" Carbonneau would work on this horn, if you are willing to pay for shipping, it's yours
.Art
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Notes
You may find the followin helpful:
1) At low frequencies, compression drivers are displacement limited by the close proximity of the diaphragm to the phase plug. Diaphragm displacement is inversely proportional to frequency squared (1/(f^2)).
2) The diaphragm is suspended by only a single compliance, the voice coil does not have a spider to further stabilize diaphragm excursion. As a result, a rocking motion may be observed at certain low frequencies.
3) Implicit in the use of a horn function is the trade of bandwidth for efficiency and pattern control. Typically the pass-band for clean output is about a frequency decade in width.
4) The reason you see few mid-bass horns in the at-home venue, is that to be effective, they must have dimensions comparable to the wavelength of the lowest frequency to be passed.
Regards,
WHG
You may find the followin helpful:
1) At low frequencies, compression drivers are displacement limited by the close proximity of the diaphragm to the phase plug. Diaphragm displacement is inversely proportional to frequency squared (1/(f^2)).
2) The diaphragm is suspended by only a single compliance, the voice coil does not have a spider to further stabilize diaphragm excursion. As a result, a rocking motion may be observed at certain low frequencies.
3) Implicit in the use of a horn function is the trade of bandwidth for efficiency and pattern control. Typically the pass-band for clean output is about a frequency decade in width.
4) The reason you see few mid-bass horns in the at-home venue, is that to be effective, they must have dimensions comparable to the wavelength of the lowest frequency to be passed.
Regards,
WHG
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OK, so it seems I'm probably right to dump the compression driver idea even though the plumbing interface for my application sounds very attractive.
weltersys - Intriguing creation there - it's tempting to take it off your hands just to play with it but I can tell you right now, even just bringing home this pile of 2" PVC pipe is NOT the direction things are supposed to be going in here at the ol' homestead. And I still have to buy at least $25-30 in parts just to start running tests.
weltersys - Intriguing creation there - it's tempting to take it off your hands just to play with it but I can tell you right now, even just bringing home this pile of 2" PVC pipe is NOT the direction things are supposed to be going in here at the ol' homestead. And I still have to buy at least $25-30 in parts just to start running tests.
Update with photos
Long time, no hear! By way of an update, I've been moving ahead with the 5" Carbonneau driver and just today I modified a 6" PVC threaded cleanout plug for the speaker to attach to. Here are two photos that show a test fit of the speaker with the hollowed-out plug. I had planned to use threaded inserts to accept screws to hold the speaker in place, but since PVC is so hard I had trouble finding a drill bit size that was large enough for the inserts to be able to be screwed in without breaking the inserts. Because the plug material is about 1/4" thick, I think I'm just going to drill and tap holes and secure the speaker with cap screws (with some red Loctite since these screws are going to be experiencing a lot of vibration).
I plan to cement a 6" PVC cap on top of this plug. I'll drill a hole for a phone jack and cement a 1-1/2" cap over that jack on the inside with the wires coming through a cement-filled hole so that the speaker jack isn't an air vent, and per a suggestion here I plan to glue some batting around the inside of the cap. So the completed assembly will be about the size of a paint can, just not as tall, and will screw right into a 6" cleanout socket.
Long time, no hear! By way of an update, I've been moving ahead with the 5" Carbonneau driver and just today I modified a 6" PVC threaded cleanout plug for the speaker to attach to. Here are two photos that show a test fit of the speaker with the hollowed-out plug. I had planned to use threaded inserts to accept screws to hold the speaker in place, but since PVC is so hard I had trouble finding a drill bit size that was large enough for the inserts to be able to be screwed in without breaking the inserts. Because the plug material is about 1/4" thick, I think I'm just going to drill and tap holes and secure the speaker with cap screws (with some red Loctite since these screws are going to be experiencing a lot of vibration).
I plan to cement a 6" PVC cap on top of this plug. I'll drill a hole for a phone jack and cement a 1-1/2" cap over that jack on the inside with the wires coming through a cement-filled hole so that the speaker jack isn't an air vent, and per a suggestion here I plan to glue some batting around the inside of the cap. So the completed assembly will be about the size of a paint can, just not as tall, and will screw right into a 6" cleanout socket.
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Here is the Carbonneau with the three PVC parts test-fitted together and a hunk of zip cord connected to the speaker for testing. There wasn't a lot of low end but there's no stuffing involved yet and there's certainly more than there would be from any compression driver. I've got about an inch and a half of room I can play with with respect to the cap on the bottom and the cleanout receptacle; I tried moving the cap around trombone-style to change the internal volume but it didn't make very much difference to how it sounded. In any case, I'll have something I can work with in short order.
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