The best bass I have ever heard was with a metal cone woofer in a sealed cabinet with fiberglass stuffing. I suppose acoustastuff would work, all depends.
You don't need stuffing at low frequencies. The fundamental driver/box resonance works whether you do or don't. (lower than the standing waves)
Probably due to bad recordings. 🙄 Absence of resonances is often mistaken for a lack of liveliness or that kind of subjective descriptions. Make close range CSD or (better) BD plots with various damping solutions. Then judge if your ears don't fool you into liking those ridges and troughs.
True but the bass was still excellent sounding. I do think it can give a slightly cleaner sound probably by absorbing small resonances in the material.
Actually its probably because the material causes a backwave when the sound hits it due to an impedance change, as has already been discussed here. THis is basic stuff. This is why the wall surfaces of anechoic chambers are unevenly shaped, because it is more effective.
picowallspeaker,
There is no correlation between quantitative estimation and subjective evaluation. It is reprehensible to corroborate physical existence in an idea. The apprehension of the physical world is cumbersome, people take the easy way out.
markbakk,
The terms reflection, resonance, vibration, oscillation are being used arbitrarily. You would have severe difficulty methodically generating standing waves in speaker cabinets of any shape.
Oh no! Bad me! Yes, I should have specified cone emanations too but failed to do so.
The endless jaw-jaw continues and nobody has moved their tired self to measure a thing, least of all human audibility*. Isn't anybody blushing?
B.
* OK, that's redundant since everybody knows we are talking only about human audibility on this forum, I think.
True. But stuffing means a smaller box. Plus, the harmonic distortion products that excite resonances will be attenuated by stuffing (and lining).
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The cone is acoustically transparent at mid frequencies - unlike a well-made cabinet.
But agree about the jaw-jaw, which is rapidly getting very tedious.
"The cone is acoustically transparent at mid frequencies"
Don't know as I've ever seen stats for any cone, let alone all kinds of cones like the ones that come on drivers with cone assemblies weighing a half-pound (yes, 250 gr).
Now that should be real easy to test for anybody that can stick a speaker into their box. Say, isn't that the very test nobody has done here?
B.
B.
Don't know as I've ever seen stats for any cone, let alone all kinds of cones like the ones that come on drivers with cone assemblies weighing a half-pound (yes, 250 gr).
Now that should be real easy to test for anybody that can stick a speaker into their box. Say, isn't that the very test nobody has done here?
B.
B.
250 grams? Probably a very large cone. And how much do you think a comparably-sized piece of 18mm MDF weighs?
There isn’t enough room for a wave 😉 . The wedges in anechoic rooms indeed are designed to minimize reflections. But do you have any clue of the magnitudes we’re talking about here? With adequate materials for loudspeakers the reflection itself hardly matters. Whereas the change of acoustic impedance in the cavity as a whole matters very much, i.e. changes in the time domain are effectively reduced. So the cone ‘sees’ a lot more even (resistive) impedance.
The result is visible in the time domain, see the attached BD of a midrange with rather excessive damping of the enclosure. Even in this case not all cavity resonances were suppressed but given the level I then considered it OK. As you can see the cone indeed is rather transparent for these resonances, so keeping them low matters.
Attachments
Please enlighten because with my limited knowledge I fail to grasp this. Or should I consider your comment not relevant?
I don't many people here know much or anything about BDs. myself included. So please explain how you concluded the cone of an anonymous midrange is "rather transparent for these resonances" inside the box. Or are you just saying something obvious like the cone moves readily at its resonance?
And just how much of that racket noise inside the box leaves through the little mid-range cone and is audible to the human who is listening?
B.
The little cone won't weigh 250 grams (even if it did, it ain't MDF), and will be pretty flimsy, compared to a very heavy, braced and damped cabinet, and is held in place by a small coil in its centre. Why would you think it wouldn't be acoustically transparent in the midrange?
The racket inside the box will include resonances and echoes. Lovely.
Jaw. Jaw.
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B&W says they picked Rohacell for the diaphragm material in that speaker's woofer in order to reduce the amount of sound coming through it. The site seems to be down right now but both Google and Wayback Machine have an archive of the PDF.
Just food for thought.
https://web.archive.org/web/2019042...nloads/reference/bw/800_Development_Paper.pdf
B&W says they picked Rohacell for the diaphragm material in that speaker's woofer in order to reduce the amount of sound coming through it. The site seems to be down right now but both Google and Wayback Machine have an archive of the PDF.
Just food for thought.
https://web.archive.org/web/2019042...nloads/reference/bw/800_Development_Paper.pdf
Fair enough. It is a ZA14, close range (about 1cm) that I measured years ago. Wedge-shaped enclosure with two parallel boundaries. Unit mounted on a baffle 25cm wide and 100cm high. Measurement with cheap electret measurement mike on a Yamaha audio interface, single channel, ARTA software. Measurement I’m not completely sure here, with sine sweep, half-Hann window, gating is stated, 48kHz sample.
It is not the cone itself, that breaks up at 9k. Otherwise it moves like a piston, the measurement shows this. The unit is filtered band pass. I don’t have the measurements with lesser damping anymore, so you have to believe me here.
By the way, in my opinion these days one has no real excuse when stating that one has little understanding of BD or CSD plots, while suggesting one has knowledge of electro acoustics and perception in general.
To your last question: I don’t think that this specific resonance can be heard. That is why I endend up with it. The problem with perception is it’s adaptability. Worse resonances could or could not be noticeable, but only in true ABX tests the results count. I don’t have time or resources for frequent double blind testing. So I end up with results that, with my limited knowledge of perceivability (there has been done enough research) should be just fine for my listening room. That is again not the same as ‘just fine for any room’, I have performed listening tests in anechoic rooms and I know design objectives are not uniform.
markbakk,
You could consider my comment as irrelevant in the sense that it does not help resolve practical issues.
You could consider my comment as irrelevant in the sense that it does not help resolve practical issues.
Was the response of the driver flat to begin with? BD has its downsides, no sense making it more difficult.