Well, on some books I read, they suggest tuning the port with the same freq as the driver's Fs, and other books suggest some other tuning methods, any ideas whats best?
Ilianh said:
Are you reading a bunch of old books from the fifties before the Thiele-Small papers came out? That was one of the theories around at the time when basically people were playing hit-and-miss with vented enclosures.
Sure it's a good idea to tune the enclosure to the driver's Fs sometimes-like when the driver's Qts is around .4 and the box volume is close to the speaker's Vas. This is the "classic bass reflex" that so many boxes are built on.
There are other setups where tuning to the driver's Fs is a good idea. However, there are other setups where it is not a good idea at all. Thanks to Novak, Thiele and Small, we can predict beforehand if it is a good idea to tune to Fs or not.
Yhea, your right, well many of the books I read are old, but they are using thiel-small parameters in those books and still saying that it should tuned to the box fs. The books ive read are from around.. 1960-70 (yhea... best i could find in lybraries...)
I dont really have the money to buy other books that the ones required from college right now, wich are not related to speakers at all 😉
Well, I guess i'll stick to what Winisc sais..
Thanx for the reply
I dont really have the money to buy other books that the ones required from college right now, wich are not related to speakers at all 😉
Well, I guess i'll stick to what Winisc sais..
Thanx for the reply
Thiele and Small's papers were published in the Journal of the Audio Engineering Society in 1971. Even then, speaker manufacturers didn't really adopt the vented box until about 10 years later.
The funny part is, while everyone gives credit to Thiele and Small for changing everything, Novak wrote a small article in the Journal of the Audio Engineering Society that basically told you everything you need to know about building vented boxes. He didn't go into such details about speaker configurations that required equalizers, etc. He also didn't go into "alignments"-that is Thiele's idea.
At the time that Novak wrote his article, speaker designers were able to make a sealed enclosure with a nice, flat response. That, they knew. On the subject of ported boxes, they were all over the place. "Tune to speaker's resonant frequency" said one engineer, followed by another flatly maintaining "Resonant frequency means nothing". What Novak did was to show how a sealed box, when configured a certain way, will give you a flat response when you port the box to a certain frequency.
This, the speaker designers could understand. Novak put the design of the ported box, which the engineers did not understand, in terms of the closed box, which the engineers understood very well. His method produces boxes which agree very well with the paper of Thiele and Small. He wrote his paper back in the fifties-years before Thiele's and Small's paper. He also pointed out the major advantage of ported boxes-the fact that the woofer must move considerably less to put out the same bass output that a speaker in a sealed box must.
Considering that Novak was an engineer at Jensen, which was one of the largest speaker companies in the world at the time, (and there were not that many speaker companies then), you would think that people would jump all over the ported box after Novak's paper. Forget it. They didn't. In fact, they still argued wrong theories, "Always tune to resonant frequency, etc." for years afterward.
As stated before, even Thiele's and Small's much more involved papers did not have an effect for close to a decade.
Thiele and Small eventually got the credit, but Novak had the whole thing figured years in advance.
The funny part is, while everyone gives credit to Thiele and Small for changing everything, Novak wrote a small article in the Journal of the Audio Engineering Society that basically told you everything you need to know about building vented boxes. He didn't go into such details about speaker configurations that required equalizers, etc. He also didn't go into "alignments"-that is Thiele's idea.
At the time that Novak wrote his article, speaker designers were able to make a sealed enclosure with a nice, flat response. That, they knew. On the subject of ported boxes, they were all over the place. "Tune to speaker's resonant frequency" said one engineer, followed by another flatly maintaining "Resonant frequency means nothing". What Novak did was to show how a sealed box, when configured a certain way, will give you a flat response when you port the box to a certain frequency.
This, the speaker designers could understand. Novak put the design of the ported box, which the engineers did not understand, in terms of the closed box, which the engineers understood very well. His method produces boxes which agree very well with the paper of Thiele and Small. He wrote his paper back in the fifties-years before Thiele's and Small's paper. He also pointed out the major advantage of ported boxes-the fact that the woofer must move considerably less to put out the same bass output that a speaker in a sealed box must.
Considering that Novak was an engineer at Jensen, which was one of the largest speaker companies in the world at the time, (and there were not that many speaker companies then), you would think that people would jump all over the ported box after Novak's paper. Forget it. They didn't. In fact, they still argued wrong theories, "Always tune to resonant frequency, etc." for years afterward.
As stated before, even Thiele's and Small's much more involved papers did not have an effect for close to a decade.
Thiele and Small eventually got the credit, but Novak had the whole thing figured years in advance.
I don't know how the library system works in Canada, but here in the USA, you can go to the librarian in any local library and ask them to get a certain book for you. If the library does not have it, they get it from a library that does. It might take a week or so, but they get it for you.
If they have that system, then I strongly advise you to get the following book: "Designing, Building and Testing Loudspeakers" by David Weems. I read it, and that book gave me most of my knowledge. I also read a couple of anthologies of Loudspeaker articles by the Journal of The Audio Engineering Society, but believe me, without Weems' book, I would never have understood most of those articles.
Vance Dickason's Loudspeaker Cookbook is supposed to be excellent, (I have not read it), but some have complained it is too technical for the beginner. Weems' book breaks it down so you can understand things well, including such things as how closed boxes and ported boxes work.
Ask your local librarian.
If they have that system, then I strongly advise you to get the following book: "Designing, Building and Testing Loudspeakers" by David Weems. I read it, and that book gave me most of my knowledge. I also read a couple of anthologies of Loudspeaker articles by the Journal of The Audio Engineering Society, but believe me, without Weems' book, I would never have understood most of those articles.
Vance Dickason's Loudspeaker Cookbook is supposed to be excellent, (I have not read it), but some have complained it is too technical for the beginner. Weems' book breaks it down so you can understand things well, including such things as how closed boxes and ported boxes work.
Ask your local librarian.
Kelticwizard,kelticwizard said:
Actually, most of Thiele’s work was in the 60’s but he did publish in 71. If we talk about the people who were fundamental to the circuit analysis approach to loudspeaker enclosures design, we must include Beranek with his book “Acoustics” from the early 50’s. Another notable is Benson who was also published in the 60’s and 70’s.
Rodd Yamashita
I have the Beranek book, although if I wrote down what I had to go through to get it, you'd think I was making it up. A good used book dealer might be able to come up with a copy for you, or try the web. A worthwhile addition if you can spare a few dollars.
Dickason is, in my estimation, for intermediate to advanced folks. I can see how it might be too much for a beginner, unless they were pretty tenacious.
No opinion on Weems.
I have a number of books that fall into the 'tune to driver resonance' category, but agree that the other methods are more refined. I see comments from time to time that even T-S is oversimplified, and that's it's time for another look at things, but all my current ideas are about cabinets, not drivers, so it won't be me becoming famous for finally solving the riddle of how to build a perfect speaker.
A couple of days ago, I had an idea that might make a tolerable variation on the acoustic labyrinth idea. Whether it will stand up to more detailed scrutiny remains to be seen.
Grey
Edit: Beranek is not for newbies...better to go for one of the others first. Incidentally, some of the old books are really great for having pictures of these gonzo built-into-the-house speakers that would cost more than all of us could afford even if we pooled our money.
Dickason is, in my estimation, for intermediate to advanced folks. I can see how it might be too much for a beginner, unless they were pretty tenacious.
No opinion on Weems.
I have a number of books that fall into the 'tune to driver resonance' category, but agree that the other methods are more refined. I see comments from time to time that even T-S is oversimplified, and that's it's time for another look at things, but all my current ideas are about cabinets, not drivers, so it won't be me becoming famous for finally solving the riddle of how to build a perfect speaker.
A couple of days ago, I had an idea that might make a tolerable variation on the acoustic labyrinth idea. Whether it will stand up to more detailed scrutiny remains to be seen.
Grey
Edit: Beranek is not for newbies...better to go for one of the others first. Incidentally, some of the old books are really great for having pictures of these gonzo built-into-the-house speakers that would cost more than all of us could afford even if we pooled our money.
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