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Old 1st November 2008, 11:25 PM   #1
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Default volume velocity

can any 1 explain what does "volume velocity" mean?
and what it showes in sound effect?

and what does the corresponding diagram showes?
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Old 2nd November 2008, 12:35 AM   #2
OzMikeH is offline OzMikeH  Australia
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It is not a phrase I have heard before. I have been interested in audio for 15 years.
Where was the phrase used?
It might be from wrong translation. The words surrounding may give some more information.
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Old 2nd November 2008, 08:52 AM   #3
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Default Re: volume velocity

Quote:
Originally posted by bigcatdairy
can any 1 explain what does "volume velocity" mean?
Hmm. May I suggest you buy a book on acoustics & read it? You'll find it easier in both the short & long terms.

Volume velocity, is pressure / acoustic impedance. Sometimes also written as the CSA (of a source) * its velocity.

Interestingly, if you had typed 'volume velocity' into google, the very first hit would have answered this for you:
http://www.google.co.uk/search?hl=en...velocity&meta=
http://www.diracdelta.co.uk/science/...ty/source.html

I'm afraid the corresponding diagram shows nothing because you don't seem to have attached one.
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Old 2nd November 2008, 04:37 PM   #4
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Quote:
Originally posted by OzMikeH
It is not a phrase I have heard before. I have been interested in audio for 15 years.
Where was the phrase used?
It might be from wrong translation. The words surrounding may give some more information.
this phrase i heard from the article of martin j king on horn acoustic theory, said that the horn enclosure having a good efficiency bcoz the horn shape accelerates the "volume velocity". that's the doubt of me--what's volume velocity? what does it showes?
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Old 2nd November 2008, 04:42 PM   #5
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Default Re: Re: volume velocity

Quote:
Originally posted by Scottmoose


Hmm. May I suggest you buy a book on acoustics & read it? You'll find it easier in both the short & long terms.

Volume velocity, is pressure / acoustic impedance. Sometimes also written as the CSA (of a source) * its velocity.

Interestingly, if you had typed 'volume velocity' into google, the very first hit would have answered this for you:
http://www.google.co.uk/search?hl=en...velocity&meta=
http://www.diracdelta.co.uk/science/...ty/source.html

I'm afraid the corresponding diagram shows nothing because you don't seem to have attached one.

i search in google by the phrase "volume velocity", and read some of the articles, but none of them let me understand what is it, these article just told about how 2 calculate, or some other higher level of understandings, now i just like to know the fundamantal definition, or meaning.

liked to buy a book about that, but unfortunately books that i can buy here just in russian or ukrainian langue, not easy to read........
lol...........
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Old 2nd November 2008, 06:48 PM   #6
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What do you mean none of them tell you what it is? I told you what volume velocity is, as does the page I linked to: it's pressure divided by acoustic impedance. Another way of expressing it is as the flow of air in m^3/s and = particle velocity * area.

I think what's happening here is you're falling into the trap of worrying about mathematical phraseology before you've got the basic principles sorted out in your mind.

OK; some advice now. It might seem harsh; but you'll thank me in the long run. Do yourself a favour, show some initiative, and do some research on horns, as you are obviously interested in them, but are posting questions that could easily be answered by doing a little reading. There are many freely downloadable articles on the subject -run a search here on the forum for suggestions, and on the 'net. You'll find quite a few. Also (again): read an acoustics textbook. I find it very difficult to believe that you cannot order one via the internet from one of the many respected internet bookshops that deliver worldwide. The gains will be disproportionate to the cost, and remember you take out of this what you put in. The more effort you make in research, the more you'll get in results.

One thing to get you started: remember, most BLHs are basically variations on the bass reflex theme.
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Old 2nd November 2008, 08:27 PM   #7
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Volume velocity is a quantity in acoustics analogous to current in a circuit.

V=IR in circuits or I = V/R.

Air presents an impedance to a travelling wave. Pressure is analogous to voltage. Pressure divided by acoustic impedance is volume velocity as voltage divided by electrical impedance is current.

A horn provides an acoustic impedance match from high at the narrow end to low at the wide end in the same way that a gradually widening signal trace on a PBC can match from one impedance to another.

w
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Old 3rd November 2008, 02:22 PM   #8
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Quote:
Originally posted by wakibaki
Volume velocity is a quantity in acoustics analogous to current in a circuit.

V=IR in circuits or I = V/R.

Air presents an impedance to a travelling wave. Pressure is analogous to voltage. Pressure divided by acoustic impedance is volume velocity as voltage divided by electrical impedance is current.

A horn provides an acoustic impedance match from high at the narrow end to low at the wide end in the same way that a gradually widening signal trace on a PBC can match from one impedance to another.

w
got that!!

thanks guy a lot


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Old 3rd November 2008, 02:27 PM   #9
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Quote:
Originally posted by Scottmoose
What do you mean none of them tell you what it is? I told you what volume velocity is, as does the page I linked to: it's pressure divided by acoustic impedance. Another way of expressing it is as the flow of air in m^3/s and = particle velocity * area.

I think what's happening here is you're falling into the trap of worrying about mathematical phraseology before you've got the basic principles sorted out in your mind.

OK; some advice now. It might seem harsh; but you'll thank me in the long run. Do yourself a favour, show some initiative, and do some research on horns, as you are obviously interested in them, but are posting questions that could easily be answered by doing a little reading. There are many freely downloadable articles on the subject -run a search here on the forum for suggestions, and on the 'net. You'll find quite a few. Also (again): read an acoustics textbook. I find it very difficult to believe that you cannot order one via the internet from one of the many respected internet bookshops that deliver worldwide. The gains will be disproportionate to the cost, and remember you take out of this what you put in. The more effort you make in research, the more you'll get in results.

One thing to get you started: remember, most BLHs are basically variations on the bass reflex theme.
ok, thanks Scottmoose anyway~
like to tell is that i searched on the engine, and read some article, but not mean that i can understand at once. i ain't no talent anyway.
and, in order to show u initiative, i am going to make a blh model from carton boxes. then share with u guys, although little something like naive test
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Old 3rd November 2008, 03:46 PM   #10
GM is offline GM  United States
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Quote:
Originally posted by bigcatdairy

.........i am going to make a blh model from carton boxes.
Been there, done that, it's a good way to learn the basics of what does, doesn't work well if you lack the math skills as I do to get it out of the various textbooks required. There used to be a scaled down cardboard box Jensen Imperial BLH on the net, but if I saved the link I can't quickly find it now.

FWIW, a young David Weems did magazine DIY articles of various designs as far back as the '50s using cheap wide BW drivers and various inexpensive construction materials including Celotex wall insulation board. They were great projects for youngsters or others new to DIY speaker building and/or for an app where looks or potential for being damaged weren't design issues.

GM
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