more fundamentalism

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julian2002 said:
isn't aerogel the least massy substance on the planet though?
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Not going into the realms of quantum physics, but the least "massy" element is hydrogen.. Praps we need an updated plasma tweeter using purified hydrogen at a molecular weight of 2.0158 (H2), and density of 2.0158g per 22.4 litres squared!
Beats the crap out of all those heavy metal lattices..
 
BerylliumDust said:
NS1000-sch01
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That doesnt show beryllium to be lighter than typical soft dome. As the thickness of the yammy dome is 0.27mm thinner. It appears the thickness to wieght ration for 'typical soft dome' is actually better than beryllium.


Beryllium thickness to weight ratio -
1:1

Typical soft dome thickness to weight ratio -
3:1

So if the typical softdome had a thickness the same as beryllium of 0.03mm the weight would be 0.01gms.

Without having the actual volume of the domes in question it is impossible to obtain a definitive ratio. But as it stand the information given appears not to support your claim of beryllium being the lightest material for tweeter domes.
 
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leonard smalls said:
LITHIUM
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Having seen lithium (like the other Group I alkali metals, it's soft, like putty) and its reaction with water (the official chemical description is "vigorous"), I'd prefer to avoid it...
 
sorry should possibly have said least massy solid with all the pedantry flying about - must be accurate mustn't we? ;)
cheers


julian
 
julian2002 said:
isn't lithium prescribed for various mental diseases
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It's commonly used as a treatment for bipolar disorder (manic depressive illness). It's not especially toxic in therapeutic doses. Beryllium OTOH is quite nasty, it's also carcinogenic.

Michael.
 
tones said:
Having seen lithium (like the other Group I alkali metals, it's soft, like putty) and its reaction with water (the official chemical description is "vigorous"), I'd prefer to avoid it...
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Ahh, but how do they slip it to "nutters" then (for want of a more politically correct term :D)..
And reactivity of group 1 metals increases up the group.. You should see what Ceasium does when it gets moist! And as for Francium (if you can find some) :eek:
 
leonard smalls said:
Ahh, but how do they slip it to "nutters" then (for want of a more politically correct term :D)..
And reactivity of group 1 metals increases up the group.. You should see what Ceasium does when it gets moist! And as for Francium (if you can find some) :eek:
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I believe they use a compound rather than the metal (at least, I hope they do...). Never got further than potassium, and that was vigorous enough (scooting across the surface at top speed - no wonder they form such stable compounds).
 
michaelab said:
To answer your question, they take pills.

Michael.
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My point being that reactivity of an element doesn't necessarily mean that that of it's alloys, amalgams or compounds is the same..

Also I use the term "nutters" in an affectionate way - I've got some friends who suffer from a number of mental illnesses raging from bog-standard depression right the way up to full-blown paranoid schizophrenia... They call themselves "nutters" in order to reclaim the word from those who would use it as an insult.. No offence intended - it's a usage similar to NWA's naming of themselves..
 
leonard smalls said:
I think you'll find that Beryllium is in group 2, with an atomic weight of 9.01218.. There is a group 1 metal which is quite a lot lighter, at 6.94 - that's LITHIUM...
Mebbe someone needs to produce a Lithium alloy tweeter for extreme ultra-lightness!.
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You are right, Leonard... I'm sorry! Lithium is indeed the lightest metal known to man... However it is NOT as rigid as beryllium.

For lithium we have:

Elastic modulus: 891 kg/mm2

Sound propagation: 6000 m/s

Thus, beryllium has the best rigidity/mass ratio. That is the most important thing...

leonard smalls said:
And fwiw, metal tweeters may be all very well, but having had experience of a Hartke 4x12" metal driver cabinet compared to an EV 15" paper cone cabinet for bass guitar, I stuck with the EV - warmer, deeper and less tiring..
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As you see, you use cone materials to have a specific sound... for a music maker that is ok... but for me to hear that warmer sound through my hi-fi I need accuracy, therefore I cannot add further warmth.

It is simple as that...
 
BerylliumDust said:
As you see, you use cone materials to have a specific sound... for a music maker that is ok... but for me to hear that warmer sound through my hi-fi I need accuracy, therefore I cannot add further warmth.

It is simple as that...
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I use the term "warmth" advisedly...
What I mean by it is the opposite of having your ears torn out by the roots, then salt and strong acid rubbed into the wound. In other words, I subjectively found the sound of metal cones to be a tad harsh:D (that's in a hifi as well as bass-bin context).
And subjectively is the only way we can describe things - after all, doesn't the very act of measuring a quantity change it?
The moment that humans are completely objective about anything I'll eat my own pooh!
 
I reckon the goal posts have been moved ....again .
The original quote was talking about cones .....

Why do you think I now like metal drivers? Because they have the best ratio stiffness/mass and thus they can accelerate and stop quicker, because they are lighter, and with less distortion (break-up modes), because they are also stiffer.
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Now , we are talking about the tweeter .
Theres a good chance that the titanium tweeter is very good , but what about the other cones ?
I bet they are not made from titanium :D and it,s these (to me) that are the more important (the mid range ) .
Now , it,s a good chance that these are just bog standard metal drivers that are rather old in design . So , I still think theres a good probability that these will colour the mid range (quack) and so won,t be acurate at all .
And will these metal drivers be lighter and more rigid than the W-sandwich as previously stated ?

ps ,
Lithium get my vote , but it,s not as nice as Librium ;)
 
leonard smalls said:
I In other words, I subjectively found the sound of metal cones to be a tad harsh:D (that's in a hifi as well as bass-bin context).
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I agree that there is a greater probability of metal cone speakers sound harsh because they are more transparent by nature and therefore they are more revealing of system faults...

Guitar and bass players do use distortion to create a sound type...
 
kermit said:
I reckon the goal posts have been moved ....again .
The original quote was talking about cones .....

Now , we are talking about the tweeter .

(...) And will these metal drivers be lighter and more rigid than the W-sandwich as previously stated ?
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Did you ever ask to yourself why JMLab use metal tweeters (even beryllium)? Why only the tweeters are from metal and the cones are not?

I can give you a clue... As tweeters are used to reproduce higher frequencies they must be quicker. Thus, they must be stronger and they must be definitely lighter... Since they are smaller they are also cheaper to produce.

The problem is that transients are brodband signals that combine many different frequencies and you need that same quickness, strength and lightness from a cone in order to be able to faithful reproduce when a drummer stick hits hard on the snare drum or when piano hammers hit hard on the strings.
 
malagahifi6kn.jpg


I heard the JMlab gran utopia and the Berillyn tweeter,it was the worst sound I have ever heard,I really didn't like this speaker,it was hard as nails,I'd had enough after three songs,my ears had tooken such a battering.
 
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