Damp vibrations in speaker diaphragm material so it doesn't radiate as much crud.
Edit: Speaker cones behave like drum skins. There are patches of the surface that resonate and radiate. ENABL cuts down some of the energy that feeds these patches.
I think Bud has been applying the principle of phononic crystals but he doesn't want to go there.
http://www.google.com/search?q="phononic+crystals"&hl=en&num=30&lr=&ft=i&cr=&safe=images&tbs=
Last edited:
As likened to an automobile's suspension, the suspension is a system that separates one from the inevitable bumps and jarring irregularities of the road surface. Each team of engineers designs their system. You can end up with what is to some a boring floating on a cloud sensation, or a very busy, bumpy, jarring ride. Its a system of compromises.
Suspensions are now designed for a matter of personal tastes. Some like a silky smooth ride, but can tend to be floaty. Others, like to feel connected to the road and accept damped sensations of bumps which now sound like thuds in the road. Likewise, with speaker design.. How one implements their speaker design will do so according to personal taste because resonances can not be completely avoided. Not unless someone invents a practical mass-less system for moving air to replace the physical driver.
EnABL seeks the results for a certain mind set. B&W, for another. NHT, yet another. Each company has its signature coloration that finds itself in satisfied homes for those who agree with the results. There are some wrongs to be avoided by all. Boomy and squawky. Who knows? Someone may even like that.
No, they don't. Drum skins have (close to) no stiffness.
Bending wave propagation on rigid membranes is governed by
different parameters than wave propagation on drum skins.
As one of the consequences stretched skins do not have the
dispersion (wave propagation speed rising with freqency) of
bending waves on rigid membranes.
Just the modal patterns (node lines) of drum skins may be
similar to modal patterns on a rigid membrane.
The hypothesis would be easy to prove - just get a solid state amp, add a load of 2nd-order distortion - and hey-presto you've got a a SET! I doubt it would work, though. For me it is the crystal-clear and natural micro-detail and utterly convincing soundstage that keeps me my SET in the big rig. I love how it renders vocal "s"s so clearly yet without a hint of sibilance, how the shimmer of cymbals just sounds so delicate, detailed and right, how big choirs sound like lots of individual voices rather than hazing over (these aren't 2nd order distortion effects).
The closest I have got using solid state technology is my little Tripath amp which also has great micro-detail and comes dangerously close. But always that slight edge and not quite so "convincing". You've guessed - I'm a SET convert - after many long evenings swapping amps around.
When they are tuned up as they should be, some drummers have even stood on a drum. They become very stiff to touch with proper tuning tension. Much stiffer than a speaker cone. One exception, the bass drum heads.
My set...
Drummers have tried various placements of dampers to eliminate unwanted resonances. Some might say that they have their own version of EnABL. For it was one of the first things that entered my mind when I saw the pictures of EnABL applied to the cones.
Taut and stiff are two different things. A rope isn't stiff, but it can be quite taut, for example.
Tough crowd.
Typical cone material for a speaker is quite flexible as long as its not a metal. Many cones are even made of paper. Take the plastic typical cone material and make it into a drum head? And it will break within seconds of use. Make a typical plastic used for cones and make it into a rope? You'll get a slipperyrope.
An interesting point. Kevlar was the only speaker cone material I know of used also for a drum head. Problem was, it sounded dead. It was tough, but dead. (like some arguments I read here) Add to that, the Kevlar was not stiff until placed under tension on the drum.
Since I can not edit at this point.. This is how it should have read.
An interesting point. Kevlar was the only speaker cone material I know of used also for a drum head. Problem was, it sounded dead. It was tough, but dead. (like some arguments I read here) (smiling face that will not stay when submitted) Add to that, the Kevlar was not stiff until placed under tension on the drum.
Got to be careful! (tough crowd)
Last edited:
I don't care whether you call it "rhetorical", it's a stupid question. What does it even mean? What do you mean when you say an instrument "distorts"? What was distorted? Are you saying a bass drum is "supposed" to sound like a sine wave?
So violins are a "distortion" of some ideal signal? Faithful reproduction of violins would sound "dry" and "awful"? If so then violins sound "dry" and "awful", you can't have it both ways.
Gee, I've been playing drums for more than 30 years, and I don't recall ever seeing a drummer paint dots on his/her drum head to change the sound.
Yeah, I made a mistake. But the principle holds, I think: When EnABL is subjectively successful, sound that's feeding radiating areas on the diaphragm is damped. Thus less crud to mask or modify low level signals.
EnABL process is obviously arrived at empirically and the only theory based stuff I could find that resembles what Bud and Dave do is work done on phononic crystals.
I don't know if phononic crystals have application to what they're doing - it might just be damping caused by additional mass that has the effect they're so enthusiastic about but the similarity is remarkable.
EnABL process is obviously arrived at empirically and the only theory based stuff I could find that resembles what Bud and Dave do is work done on phononic crystals.
I don't know if phononic crystals have application to what they're doing - it might just be damping caused by additional mass that has the effect they're so enthusiastic about but the similarity is remarkable.
When you have a flexurally rigid and internally low damped membrane or plate, which is suspended
somehow at the circumference and driven somewhere (from the center in case of a usual driver's membrane),
then you will get modal behaviour when exciting that structure with frequencies high enough.
If you want to significantly modify that resonant bahavior, e.g.
- increase the frequency of the first mode above pistonic
(whole body) motion
or
- lower the Q of one or more resonances
- influence the shape of node lines of a certain modal pattern
...
you have to significantly alter the structure of the exciter/membrane/suspension system.
There are not so many things you can modify to achieve this, basically we have
- point of excitation (will not be changed, when modifying conventional drivers)
- distribution of stiffness on the membrane
- distribution of mass on the membrane
- distribution of damping (mech. resistance due to bending wave propagation)
- the mech. impedance of the suspension
In Systems which have very little internal damping, small amounts of damping or slight parameter
shifts may cause significant shifts in behaviour. But a usual paper cone e.g. with rubber surround already
has some internal damping.
Trying to change such a system using "homeopathic" measures in adding local mass, stiffness or damping
cannot be expected to change the behaviour on a level seriously exceeding say "usual manufacturing tolerances".
If you have a certain driver which has a prominent breakup mode - that may be one of lower order - you have
to to apply significant changes to the design.
If you want to address the problem by damping e.g. you will need a viscous coat, which covers at least a major
portion of the surface which has high velocity when the cone is vibrating in that specific mode, you want to modify.
That coat will increase also the mass of the membrane significantly, to show some effect. Some mass can be saved,
if you manage the coat to get more thick e.g. by using a coat of foam or a foamed contrained layer as a damper ...
Applying tiny dots of whatsoever material, which does not form a continuous coat and only has a small fraction of
the mass/stiffness or resistance than just the area of the surround which is glued to the cone will not do anything
significant.
I am not saying that it does nothing. But my bet would be like this:
Take 100 drivers from "standard" production quality, say fullrange paper cones of same type.
Define a quality measure say the "Q" of that particular resonance (which might shift slightly
in frequency by any measures taken).
Take one driver by chance and "EnABL" it, with respect to a major breakup mode, we want to adress.
>> I will most probably find one of out of the remaining 99 drivers, which has a lower Q in
that particular mode.
somehow at the circumference and driven somewhere (from the center in case of a usual driver's membrane),
then you will get modal behaviour when exciting that structure with frequencies high enough.
If you want to significantly modify that resonant bahavior, e.g.
- increase the frequency of the first mode above pistonic
(whole body) motion
or
- lower the Q of one or more resonances
- influence the shape of node lines of a certain modal pattern
...
you have to significantly alter the structure of the exciter/membrane/suspension system.
There are not so many things you can modify to achieve this, basically we have
- point of excitation (will not be changed, when modifying conventional drivers)
- distribution of stiffness on the membrane
- distribution of mass on the membrane
- distribution of damping (mech. resistance due to bending wave propagation)
- the mech. impedance of the suspension
In Systems which have very little internal damping, small amounts of damping or slight parameter
shifts may cause significant shifts in behaviour. But a usual paper cone e.g. with rubber surround already
has some internal damping.
Trying to change such a system using "homeopathic" measures in adding local mass, stiffness or damping
cannot be expected to change the behaviour on a level seriously exceeding say "usual manufacturing tolerances".
If you have a certain driver which has a prominent breakup mode - that may be one of lower order - you have
to to apply significant changes to the design.
If you want to address the problem by damping e.g. you will need a viscous coat, which covers at least a major
portion of the surface which has high velocity when the cone is vibrating in that specific mode, you want to modify.
That coat will increase also the mass of the membrane significantly, to show some effect. Some mass can be saved,
if you manage the coat to get more thick e.g. by using a coat of foam or a foamed contrained layer as a damper ...
Applying tiny dots of whatsoever material, which does not form a continuous coat and only has a small fraction of
the mass/stiffness or resistance than just the area of the surround which is glued to the cone will not do anything
significant.
I am not saying that it does nothing. But my bet would be like this:
Take 100 drivers from "standard" production quality, say fullrange paper cones of same type.
Define a quality measure say the "Q" of that particular resonance (which might shift slightly
in frequency by any measures taken).
Take one driver by chance and "EnABL" it, with respect to a major breakup mode, we want to adress.
>> I will most probably find one of out of the remaining 99 drivers, which has a lower Q in
that particular mode.
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.