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hybrid ported with rectangular conical horn

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jayam000 View Drop Down
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    Posted: 18 April 2017 at 3:42am

Normally the port is recatangular, square or round. here it is like horn. Any advantage?
If yes, then how to calculate the same. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bass*en*mass Quote  Post ReplyReply Direct Link To This Post Posted: 18 April 2017 at 9:42am
don keele, if i remember correctly, wrote a good article about flared ports and their influences etc.. lots of info online aswell as its still up to date tech, see new Lacoustics 218 subs for example..
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bob4 Quote  Post ReplyReply Direct Link To This Post Posted: 18 April 2017 at 12:20pm
Originally posted by bass*en*mass bass*en*mass wrote:

don keele, if i remember correctly, wrote a good article about flared ports and their influences etc.. 

except the port of this ported wbin is NOT flared at all, just increasing in cross-section. So none of that theory applies.    

some french guys have done research, with prototyping and measurements




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Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 18 April 2017 at 3:39pm
The flared port just reduce port shuffle noise. A noble idea for home audio when High SPL is not a factor. However in sound reinforcement, you would have to have a really piss poor design to have the port noise as loud as the woofer playing at high sound pressure levels.

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Elliot Thompson
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jayam000 Quote  Post ReplyReply Direct Link To This Post Posted: 19 April 2017 at 2:55am
Thanks for the nice information bob4 & Elliot Thompson.
Now if we want to impliment,  how to calculate?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote bob4 Quote  Post ReplyReply Direct Link To This Post Posted: 19 April 2017 at 5:44am
Originally posted by Elliot Thompson Elliot Thompson wrote:

The flared port just reduce port shuffle noise.


If you believe so, you should carefully read the aes paper that i linked      
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mobiele eenheid Quote  Post ReplyReply Direct Link To This Post Posted: 19 April 2017 at 6:12am
The easiest way is to simulate the port in Hornresp, as a single segment (S1, S2, L12) with the chamber volume (Vtc in cm^3) leaving the effect of the horn out. Then approximate the ports tuning by a straight port (Ap and Lp), so that you can simulate the horn as well, now using the segments for the horn.

I haven't read the AES paper yet but I'm pretty sure that, in this particular case, the effects aren't so immense, that it justifies you learning AkAbak to fully grasp it's influence on the whole.

Johan

- Edit -  Now that I've read the AES-paper, my advice remains unchanged ;)


Edited by mobiele eenheid - 19 April 2017 at 6:47am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 19 April 2017 at 11:19am
Originally posted by bob4 bob4 wrote:

Originally posted by Elliot Thompson Elliot Thompson wrote:

The flared port just reduce port shuffle noise.


If you believe so, you should carefully read the aes paper that i linked      

I am sorry I cannot take a paper seriously with tubes longer than the actual box it is residing in. It tells me automatically that the cabinet is so small that the tubes need to be longer than the actual enclosure in order to achieve low frequencies.

 

Ask yourself a question. How many times have you seen a Bass Reflex enclosure with ports sticking out of a box aimed for Sound Reinforcement?

 

This paper reaps Home Audio Setup as I mentioned in my previous post why such a method would be beneficial under low SPL conditions. Under High SPL Conditions in the Sound Reinforcement World which we all do, such methods are not going offer tremendous results for the majority of the sound stems from the loudspeaker, not the port. 

 

Not everything posted in AES is aimed for Sound Reinforcement.

 

 

Best Regards,



Edited by Elliot Thompson - 19 April 2017 at 11:25am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jayam000 Quote  Post ReplyReply Direct Link To This Post Posted: 19 April 2017 at 1:20pm
Thanks to all for nice guidance.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bob4 Quote  Post ReplyReply Direct Link To This Post Posted: 19 April 2017 at 1:34pm
Originally posted by Elliot Thompson Elliot Thompson wrote:

I am sorry I cannot take a paper seriously with tubes longer than the actual box it is residing in. It tells me automatically that the cabinet is so small that the tubes need to be longer than the actual enclosure in order to achieve low frequencies.
 

it's a small prototype for research….


Originally posted by Elliot Thompson Elliot Thompson wrote:

Not everything posted in AES is aimed for Sound Reinforcement.

Agreed (well, duh… Tongue)

Originally posted by Elliot Thompson Elliot Thompson wrote:

Ask yourself a question. How many times have you seen a Bass Reflex enclosure with ports sticking out of a box aimed for Sound Reinforcement?
  

while I'm not claiming that it's useful for PA, if you had read the blurb, you would have noticed that the nozzle shape yields notable improvements/stability in phase behavior at high input power:

Originally posted by Pellerin, Pollack, Mokerken Pellerin, Pollack, Mokerken wrote:

 we proved, with the help of the phase space representations, that well tuned nozzles ensure a better global dynamical stability even for very high feeding power in the case of a dipole configu- ration and the dipole moment is then an interesting physical property which allows to build complex di- rectivity patterns in the low frequencies.

  

I mainly wanted to point out that the nozzle port is about more than just reducing port chuffing.


I don't know about you, but to me this statement in the article's conclusions is an interesting one:

Originally posted by Pellerin, Pollack, Mokerken Pellerin, Pollack, Mokerken wrote:

 We demonstrated first that it effectively exists a second cutoff frequency under the well known Helmholtz frequency which could be exploited to design sources radiating in the very low frequency domain with dipole directivity patterns and that, in theory, this frequency could be decreased near zero Hertz. 
  

I don't see why any of these principles couldn't be applied to PA systems at some point.

Best Regards,

Bob



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Elliot Thompson View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 19 April 2017 at 3:15pm
Originally posted by bob4 bob4 wrote:

I don't see why any of these principles couldn't be applied to PA systems at some point.

Best Regards,

Bob





Because in the Sound Reinforcement Market we do not use a port larger than actual size of the enclosure in addition to the size of a loudspeaker in a reflex enclosure to attain greater SPL. The size of the cabinet makes a huge factor on the performance.

We will use a larger enclosure to extend the frequency response. We will use multiple drivers in order to increase the coupling effect to attain more SPL in which, will offer lower distortion than forcing one speaker to do all the work.  We will use woofers with the proper TS Parameters in order to attain optimum results.

Phase? I would recomend measuring the impedance plots of loudspeakers in free air offering various TS Parameters. Not even a sealed back driver will be in phase once it approaches its fs.


If you feel the author's idea is intriguing, build a Sound Reinforcement version of his Home Audio Bass Reflex concept, make the proper measurements and, post your findings.


Best Regards,



Edited by Elliot Thompson - 19 April 2017 at 3:16pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gen0me Quote  Post ReplyReply Direct Link To This Post Posted: 19 April 2017 at 7:25pm
Maybe the reason why port is so huge is because autor wanted to get flat response from strong speaker?
Haha is it still br or a miniscoop

Just a thought: could be good idea to design telescopic brs

Edited by gen0me - 19 April 2017 at 7:31pm
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