The problems within the surface area inside the voice coil can be sorted quite easily.
This is a panel problem.
But it is the magnet , spider, and former , that I think is the main problem with this type of exciter.
As burnt says , I will carry on , on this subject on the other forum.
Steve.
This is a panel problem.
But it is the magnet , spider, and former , that I think is the main problem with this type of exciter.
As burnt says , I will carry on , on this subject on the other forum.
Steve.
The fact that "the speed of sound is much faster in a solid than it is in the air" has been brought up several times recently, and it got me thinking about what exactly is meant by the "speed of sound in a solid". And I realized only then the irony of our situation. And that irony is this: "the speed of sound in a solid" (as it is most commonly understood) is virtually irrelevant in the discussion of speakers!
Typically when someone refers to the "speed of sound" in a solid, they are talking about the speed of sound of a compression/longitudinal wave. However, when such a wave is travelling though a solid, the deformation of the solid due to this wave is so miniscule, that the only way you can typically "hear" the so-called "sound wave" is to put your ear directly into physical contact with the solid. So in the sense of being a wave that creates any meaningful level of sound, well, it's barely correct, I would say, to call such waves "sound waves". Being that these waves do not produce meaningful sound levels, the speed of such waves is largely irrelevant in the discussion of speakers.
Such waves might be reasonable to call sound waves in the sense that they are similar to sound waves in air, in that both waves are compression/longitudinal waves. But compression waves in solids don't produce significant compression waves in the surrounding air, and in that respect aren't really (significant) "sound waves" at all.
There are several types of elastic (or "sound") waves that can travel through solids. In addition to compression waves there are bending/shear waves, Rayleigh waves, Love waves, and perhaps others. But of these, only bending/shear waves typically have enough displacement to produce sound waves in the adjacent air. Hence, the speed of bending waves in solids is very relevant to the discussion of bending wave speakers.
On the other hand, the "speed of sound in a solid" in the usual sense, that is, the speed of compression waves in solids, which actually produce no significant sound, is largely irrelevant.
Eric
Typically when someone refers to the "speed of sound" in a solid, they are talking about the speed of sound of a compression/longitudinal wave. However, when such a wave is travelling though a solid, the deformation of the solid due to this wave is so miniscule, that the only way you can typically "hear" the so-called "sound wave" is to put your ear directly into physical contact with the solid. So in the sense of being a wave that creates any meaningful level of sound, well, it's barely correct, I would say, to call such waves "sound waves". Being that these waves do not produce meaningful sound levels, the speed of such waves is largely irrelevant in the discussion of speakers.
Such waves might be reasonable to call sound waves in the sense that they are similar to sound waves in air, in that both waves are compression/longitudinal waves. But compression waves in solids don't produce significant compression waves in the surrounding air, and in that respect aren't really (significant) "sound waves" at all.
There are several types of elastic (or "sound") waves that can travel through solids. In addition to compression waves there are bending/shear waves, Rayleigh waves, Love waves, and perhaps others. But of these, only bending/shear waves typically have enough displacement to produce sound waves in the adjacent air. Hence, the speed of bending waves in solids is very relevant to the discussion of bending wave speakers.
On the other hand, the "speed of sound in a solid" in the usual sense, that is, the speed of compression waves in solids, which actually produce no significant sound, is largely irrelevant.
Eric
Attachments
Eric,
What you just posted is correct, but now what axis do you have the shear wave propagating in? By definition shear waves can only exist in solids. Liquids and air can not support shear waves unless the shear wave is longitudinal, but shear waves are transversal waves by definition. So they can only exist in solids and propagate 90 degrees to the longitudinal wave which can propagate in liquids and air.
What you just posted is correct, but now what axis do you have the shear wave propagating in? By definition shear waves can only exist in solids. Liquids and air can not support shear waves unless the shear wave is longitudinal, but shear waves are transversal waves by definition. So they can only exist in solids and propagate 90 degrees to the longitudinal wave which can propagate in liquids and air.
Agreed, except that the speed of bending waves is related to the speed of longitudinal waves, and people may be referring to bending waves as 'sound' or 'source of sound' in the solid, without knowing the technical meaning of 'speed of sound in a solid'. To be unambiguous, we should say 'longitudinal' or 'compression' when we mean that. In many cases in discussions here, I simply assume people are talking about bending waves (unless they are one of the couple who apparently don't 'believe' in them, then I don't assume, and don't care). You can also get mode conversions upon reflection, so longitudinal waves can create sound that way.
Sound is propagated only in waves, whatever the medium it travels through. Sound travels in the medium, not on the medium. As we live also in that medium, air, we hear the sound. Our ears and the ear drums are also in the that medium, air. When you are under water, you'd hear sound coming in that medium, and at that time, your ears are in that medium. When you take the head out of the water, you stop hearing the sounds that was in the water. You hear the sound propagated in the medium you are currently in. We do live in air.
I doubt anyone here would disagree with those statements. Do you think that they are somehow contentious?
Then comes the question, how does a sound wave bend? That is, travelling within a medium.
Mean while I just did a quick little tweak to my most recent DML panels to change the way they sound. You can compare this (DML-5) vid with the DML-4 video. Which one do you prefer? Or can yawl even tell the difference?
Ussuns don't really care, we all like to share.
Refraction -- soun dfor example, spreading out through a hole, like whistling. Diffraction -- light turning in when moving from one medium to another, usually from air to more solid one.. Does sound too turn in, (or out) travelling from one medium to another? From a solid to air, in which we live in?
Merry Christmas, everyone!
Last edited:
Whistling isn’t caused by refraction. Light turning when moving between media is refraction not diffraction. And neither effect requires movement to a different medium.
Sure, two words should've been other way around. 🙂 Nice of you to catch the misplacement.
Diffraction -- for example, sound spreading out through a hole, like whistling. Refraction -- light turning in when moving from one medium to another, usually from air to more solid one.. Does sound too turn in, (or out) travelling from one medium to another? From a solid to air, in which we live in?
Merry Christmas, everyone!
Sure, the medium doesn't have to be different, the change of density the same medium would do...
Last edited:
homeswinghome,
Ussuns is just a funny slang word for "us" or "we", depending on whether it is used as direct object or subject in the sentence. I suppose it is somewhat like "Was ist los?" in German, which literally means "what is loose", but in use means "What's going on?".
Ussuns is just a funny slang word for "us" or "we", depending on whether it is used as direct object or subject in the sentence. I suppose it is somewhat like "Was ist los?" in German, which literally means "what is loose", but in use means "What's going on?".
Last edited:
Well, Paul, I understand what you’re saying. But what he’s not saying this time, but which is implicit in his thinking , is that sound waves travel through a medium (be it air, water, or solid) without any movement at all of the medium. So I fear if you agree with his statement, you may accidentally be agreeing to that concept. At least in his mind.
Eric