Gorilla glue expands to much more than 4x when it isn't clamped. I have had some left over in a plastic yogurt container, with some water in the glue, so it cured.
A small amount in the bottom of the container foamed to more than fill the container. Much more than 4x.
The foam was pretty stiff, too.
Perhaps you don't need to completely fill in the cone anyway. How about 6 cardboard ribs, cut carefully to match the shape of the woofer. Glue them on with Gorilla glue.
Or even hollow paper ribs, glued to the speaker, to which you inject foam, making sure to have a couple of exit holes for the excess foam to expand out of.
Whatever you do, keep the dust cap free. It needs to be able to breathe or you could start a fire.
A small amount in the bottom of the container foamed to more than fill the container. Much more than 4x.
The foam was pretty stiff, too.
Perhaps you don't need to completely fill in the cone anyway. How about 6 cardboard ribs, cut carefully to match the shape of the woofer. Glue them on with Gorilla glue.
Or even hollow paper ribs, glued to the speaker, to which you inject foam, making sure to have a couple of exit holes for the excess foam to expand out of.
Whatever you do, keep the dust cap free. It needs to be able to breathe or you could start a fire.
Would a flat-coned 12" driver be able to play up to 1kHz with excellent fidelity? (assuming constructed using state-of-the-art methods bettering those of Seas/Scan-Speak/Audio Technology/ATC, if that's possible)
Assuming perfect-piston behavior, as seems to be a design goal with this flat diaphragm concept, a 12" driver could be expected to go up to 350Hz or so (WL = pi x dia.) before beaming/lobing started sneaking in to crash the party. If you wanna go higher with even off-axis response, you'd have to engineer some damped circumferencial decoupling into the diaphragm (often confused with resonant "breakup"--not at all the same thing!).
I'm surprised this thread it still going, the simple
answer to the question is because they don't work,
practical experience should tell you that or they'd
be all over the place in commercial lodspeakers.
🙂 sreten.
answer to the question is because they don't work,
practical experience should tell you that or they'd
be all over the place in commercial lodspeakers.
🙂 sreten.
That means an 8" driver should only be able to play up to about 550Hz before starting to beam???Bill F. said:
At least back in the seventies, (I don't know if they still they do), sound engineers used to put in a 6 dB rolloff commencing at 4,000 Hz on the records.
Of course, pop and rock music sound engineers can do what they want. Still, it was a widespread phenomenon.
Only one article I have read related it to the fact that at 4,000 Hz, the tweeter starts to beam.
As can be seen by this graph, the 60º off axis response starts declining right about 4,000 Hz for a 1" dome tweeter-the Peerless 811830.
Of course, pop and rock music sound engineers can do what they want. Still, it was a widespread phenomenon.
Only one article I have read related it to the fact that at 4,000 Hz, the tweeter starts to beam.
As can be seen by this graph, the 60º off axis response starts declining right about 4,000 Hz for a 1" dome tweeter-the Peerless 811830.
An externally hosted image should be here but it was not working when we last tested it.
454Casull said:
Yep! but the moving mass would have to be less than 30 grams! and have very little X-max, Atc drivers cross-over at 350 to 500 Hz, the paper cone is very light even with the dope. The larger surface area of a cone displaces more air so its effectively a big canopy, more friction slows it down smearing the sound you could say, 1000 Hz with a X max of say 25mm, i just cant imagine what that would sound like! It's best left to the small drivers unless you want a PA sound, Have you ever seen Mike Tyson play Ping Pong! Hes fast in his own right but not that fast!
Hey, before you guys lose your creative momentum here, let me quickly clarify that I don't think anyone is saying a flat-face diaphragm is intrinsically a bad idea, just that having perfect-piston motion as a design goal puts serious limits on bandwidth.
Here is a link to a very interesting (and long!) B&W white paper detailing the design process of all aspects of the Nautilus 801, including the drivers. The earlier nautilus drivers were designed in the perfect-piston school of thought, but that necessitated a 4-way design and placed limits on efficiency and dynamics (since smaller perfect-pistons are necessary for reasonable bandwidth). They discuss a few of the advantages of flat/domed diaphragms, not the least of which is avoiding cavity modes/diffractive re-radition of energy from neighboring drivers. IMO, the most interesting part of the paper is the midrange driver design and the unique methods they used to create smooth decoupling and damp resonances.
Anyway, lots of food for thought in that paper regarding flat diaphragms, perfect pistons, etc. to keep the creativity flowing. I agree with KW that the old-fashioned cone isn't necessarily the end-all-be-all of diaphragm design, so keep asking "what if..."
Here is a link to a very interesting (and long!) B&W white paper detailing the design process of all aspects of the Nautilus 801, including the drivers. The earlier nautilus drivers were designed in the perfect-piston school of thought, but that necessitated a 4-way design and placed limits on efficiency and dynamics (since smaller perfect-pistons are necessary for reasonable bandwidth). They discuss a few of the advantages of flat/domed diaphragms, not the least of which is avoiding cavity modes/diffractive re-radition of energy from neighboring drivers. IMO, the most interesting part of the paper is the midrange driver design and the unique methods they used to create smooth decoupling and damp resonances.
Anyway, lots of food for thought in that paper regarding flat diaphragms, perfect pistons, etc. to keep the creativity flowing. I agree with KW that the old-fashioned cone isn't necessarily the end-all-be-all of diaphragm design, so keep asking "what if..."
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