http://www.diysubwoofers.org/sld/sealed1.htm
http://www.diysubwoofers.org/prt/ported1.htm
btw winisd has been compared with several other programs-its close.
http://www.diysubwoofers.org/prt/ported1.htm
btw winisd has been compared with several other programs-its close.
Try the book of Beranek
Actually, this is the first time for me in this forum. Your question regarding the real physics behind a loudspeaker is not simple, apart from some simple equations which can be seen everywhere around. My best guess would be the famous book of Beranek. Here, the elektro-acoustical model is presented and transformed into a equivalent elektro model. Good luck!
Actually, this is the first time for me in this forum. Your question regarding the real physics behind a loudspeaker is not simple, apart from some simple equations which can be seen everywhere around. My best guess would be the famous book of Beranek. Here, the elektro-acoustical model is presented and transformed into a equivalent elektro model. Good luck!
Hello Slackerbob,
I have those T/S paper in scanned version, courtesy of a member here (I think it was from f4rier). If my memory serves me right, it was in tiff format.
If you want it, I can send it to your email.
BUT, I don't have it now. I am now in my office and the paper is in my PC at home. Tomorrow, maybe I can send it to you.
Just tell me if ya want it to be sent to your mail.
Cheers,
I have those T/S paper in scanned version, courtesy of a member here (I think it was from f4rier). If my memory serves me right, it was in tiff format.
If you want it, I can send it to your email.
BUT, I don't have it now. I am now in my office and the paper is in my PC at home. Tomorrow, maybe I can send it to you.
Just tell me if ya want it to be sent to your mail.
Cheers,
SY said:
Duh…? What do you mean by that? A closed box system is simply a 2nd order mass-spring system and a BR/PR box a 4th order mass-spring system as far as it concerns the TS model. I don’t see why that is not solvable in closed form with regard to spl, impedance etc.
BTW it is not that difficult to model a speaker system by means of control theory with real masses and springs in stead of the electrical equivalent of Thiele and Small and many others.
Cheers
Someone asking for "physics equations" is probably not all that savvy on simulation and/or control theory.
Whenever sonmeone asks me how to model boxes, my first question is: "What do you know?" and next is "What do you want to know", and then I try to get them there.
While you might be able to program a box design routine without knowing Laplace transforms and circuit analysis, you aren't likely to do it without a lot of handholding.
Circuit analysis and Laplace transforms, and preferably dynamic simulation experience are what is required to roll your own and be confident that it is right.
For all others - www.diysubwoofers.org has all you need to know.
Whenever sonmeone asks me how to model boxes, my first question is: "What do you know?" and next is "What do you want to know", and then I try to get them there.
While you might be able to program a box design routine without knowing Laplace transforms and circuit analysis, you aren't likely to do it without a lot of handholding.
Circuit analysis and Laplace transforms, and preferably dynamic simulation experience are what is required to roll your own and be confident that it is right.
For all others - www.diysubwoofers.org has all you need to know.
This started with a request for formulas. He wants to use the formulas manually rather than use the ones in a computer program he has.
Will he end up with the same formulas either way?
It seems to me that the only advantage of that is to be able to be critical of the formula as you use it. Would a person able to criticize those formulas not be able to derive them?
Will he end up with the same formulas either way?
It seems to me that the only advantage of that is to be able to be critical of the formula as you use it. Would a person able to criticize those formulas not be able to derive them?
you have to realize there are a lot of assumptions made in modeling. like air density, uniform BL, Le, and Km for the speaker, speed of sound, no temperature change effects, and so on. the 1w1m efficinency rating is an example of this kind of modeling. the theory is that doubling power from 1 watt will result in 3dB more output from the speaker. this is ok for an approximation, but as you put more and more power to the speaker you will not get as much back. wood can flex, things get hot, the suspension may stiffen up, BL drops, air in the port gets compressed and fights back. so the basic model no longer applies completely.
As i've mentioned, there are modeling circuts. you may also want to research the theile-small parameters and what they are and how they are measured and ect...
As i've mentioned, there are modeling circuts. you may also want to research the theile-small parameters and what they are and how they are measured and ect...
Hold on,
Slackerbob just wants to dig deeper in the basics of what it is all about the “mysteries” of a loudspeaker. For this the work of Thiele and Small is mandatory reading as well as the old book on acoustics of Leo L. Beranek. But behold, the work of Thiele and Small is not so easy reading. If you finally understand T&S you are be able to swap the whole math in Excel and simulate it yourself or build your own models in PSpice. This is the real (and hard way) to get understanding what it is all about. Of course it is a simplified model and not exactly the real thing. But it is good enough as a tool and to make progress.
Reprints of the old articles of Thiele an Small are in this books:
http://www.audioxpress.com/bksprods/bookindexl3.htm
Besides the articles of T&S there is much more useful and interesting reading in them, so I strongly advise to simply buy these bundles. Just part 1 and 2 will suffice. The book of Beranek is also available from Audioxpress.
Cheers
Slackerbob just wants to dig deeper in the basics of what it is all about the “mysteries” of a loudspeaker. For this the work of Thiele and Small is mandatory reading as well as the old book on acoustics of Leo L. Beranek. But behold, the work of Thiele and Small is not so easy reading. If you finally understand T&S you are be able to swap the whole math in Excel and simulate it yourself or build your own models in PSpice. This is the real (and hard way) to get understanding what it is all about. Of course it is a simplified model and not exactly the real thing. But it is good enough as a tool and to make progress.
Reprints of the old articles of Thiele an Small are in this books:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
http://www.audioxpress.com/bksprods/bookindexl3.htm
Besides the articles of T&S there is much more useful and interesting reading in them, so I strongly advise to simply buy these bundles. Just part 1 and 2 will suffice. The book of Beranek is also available from Audioxpress.
Cheers
Guys,
Pjotr has a good advice. I've been wanting to buy those books myself, but considering the price of shipping and handling from US to my country, it doesn't make sense importing those books.
So, for you guys who still want the scanned copies of Thielle work, instead of sending it by email, I put it on my office server, voila:
http://f1.intelix.co.id/thiele1.exe
http://f1.intelix.co.id/thiele2.exe
It is a self extracting zip (jpgfiles). I've been trying to upload it on Friday at home, but internet connection through phone line was REAALLLY slow
. So, now that I've managed to upload it from my office, there you go.
For you guys who wants it, you'd better hurry up to download it. I won't put there forever.
The credits for those files goes to f4ier, a kind member of this forum. For f4ier, if you mind that I put those files for public, I will delete those files from my server.
Cheers,
Edwin Sianturi
Pjotr has a good advice. I've been wanting to buy those books myself, but considering the price of shipping and handling from US to my country, it doesn't make sense importing those books.
So, for you guys who still want the scanned copies of Thielle work, instead of sending it by email, I put it on my office server, voila:
http://f1.intelix.co.id/thiele1.exe
http://f1.intelix.co.id/thiele2.exe
It is a self extracting zip (jpgfiles). I've been trying to upload it on Friday at home, but internet connection through phone line was REAALLLY slow
. So, now that I've managed to upload it from my office, there you go.For you guys who wants it, you'd better hurry up to download it. I won't put there forever.
The credits for those files goes to f4ier, a kind member of this forum. For f4ier, if you mind that I put those files for public, I will delete those files from my server.
Cheers,
Edwin Sianturi
If you want to write a program or a spreadsheet and get a feel for the design equations, go to:
http://www.diysubwoofers.org/prt/
You will find all the equations you need under frequency response and power response sections.
For these simple formulas, a sealed box response can be had by setting the tuning frequency to 0Hz.
The Thiele/Small areticles are only going to help an engineer or someone who is quite educated in math. You have not indicated your education level, so anyone recommending the T/S papers is perhaps overesstimating your ability to absorb information. A casual reading of the T/S papers is responsible for much of the misinformation that you see out there on vented boxes. The alignment tables in Thieles 1961 paper are for undamped enclosures and therefore are not useful in any practical sense - although they were revolutionary in their time, firmly associating box design with filter theory.
Thieles undamped (Ql=infinity) B4 alignment has a Qts of 0.383 and a Vas/Vb of 0.707. When you have a Ql of 7, that equates to Qts=0.405 and Vas/Vb of somewhere around 1. A pretty big difference, eh?
Even for engineers, there are better references than Thiele or Small, although I wouldn't suggest not treading the originals. J.E. Benson wrote a great series of very technical papers that have been reprinted as: Theory and Design of Loudspeaker Enclosures. I wouldn't recommend these for anyone except someone who has completed at least three years of engineering or physics.
http://www.diysubwoofers.org/prt/
You will find all the equations you need under frequency response and power response sections.
For these simple formulas, a sealed box response can be had by setting the tuning frequency to 0Hz.
The Thiele/Small areticles are only going to help an engineer or someone who is quite educated in math. You have not indicated your education level, so anyone recommending the T/S papers is perhaps overesstimating your ability to absorb information. A casual reading of the T/S papers is responsible for much of the misinformation that you see out there on vented boxes. The alignment tables in Thieles 1961 paper are for undamped enclosures and therefore are not useful in any practical sense - although they were revolutionary in their time, firmly associating box design with filter theory.
Thieles undamped (Ql=infinity) B4 alignment has a Qts of 0.383 and a Vas/Vb of 0.707. When you have a Ql of 7, that equates to Qts=0.405 and Vas/Vb of somewhere around 1. A pretty big difference, eh?
Even for engineers, there are better references than Thiele or Small, although I wouldn't suggest not treading the originals. J.E. Benson wrote a great series of very technical papers that have been reprinted as: Theory and Design of Loudspeaker Enclosures. I wouldn't recommend these for anyone except someone who has completed at least three years of engineering or physics.
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