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Multi-Way Conventional loudspeakers with crossovers

Cardioid Bass
Cardioid Bass
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Old 13th May 2008, 07:44 PM   #261
Etienne88 is offline Etienne88  Sweden
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I am happy that both of you (Earl and John) come to an agreement despite quite a tough debate...!
Thank you for all the effort you put into it and thank you for a valuable result for the DIY community.

Earl, I wish you luck in shaking up some JAES people!

Regards,
Etienne
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Old 13th May 2008, 08:40 PM   #262
Salas is offline Salas  Greece
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Cardioid Bass
Quote:
Originally posted by augerpro
I hate to oversimplify this-just trying to wrap my brain around it- but are you two in agreement that for bass there is no advantage to any of these forms assuming you didn't just happen to place in the worst possible place? How about if you were running a woofer up around 200-300hz, any advantage to cardioid over monopole considering front wall reflections? From power response and polar response perspective are these forms still about equal-considering they are running up to 200-300hz? I should mention I ask these questions in the context of a 3 way design where the mid (and possibly tweeter) are dipole.

200-500Hz is better suited to cardioid.
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Old 13th May 2008, 10:02 PM   #263
gedlee is offline gedlee  United States
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Quote:
Originally posted by salas


200-500Hz is better suited to cardioid.

I completely agree since a dipole has rear radiation that is of no use and can only cause problems. Cardiod is attractive in this frequency range and if I ever do a Magna Summa I might consider it.
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Old 13th May 2008, 10:15 PM   #264
john k... is offline john k...  United States
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Quote:
Originally posted by salas



200-500Hz is better suited to cardioid.

Hi Salas,

I think that depends on preferences. What I do believe is that above 150 Hz or so constant directivity is desirable, be it dipole, cardioid or omni. At that point it becomes very dependent on the room and preferences. But as I develop the ICTA I may move away from a cardioid type woofer though I expect to keep the mids and top end cardioid. On the other hand, there is nothing wrong with taking the NaO II approach where the choice of cardioid or sealed box is in the hands of the listener.

Earl,

I checked the top plot on the right (number 3) against SE's FEM. The good news is that the agreement is pretty good. The bad news is that what I posted isn't the correct result. I must have mixed up some files or something. I'll have to recheck all the plots, again.
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Old 13th May 2008, 11:52 PM   #265
gedlee is offline gedlee  United States
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Quote:
Originally posted by john k...



Hi Salas,
Earl,

I checked the top plot on the right (number 3) against SE's FEM. The good news is that the agreement is pretty good. The bad news is that what I posted isn't the correct result. I must have mixed up some files or something. I'll have to recheck all the plots, again.

Then it was four versus six that I question. Some of our differences may come from damping. I prefer to use larger values than you are using because, to me, thats more realistic. In a real room there is more damping from the entire structure moving than you will ever get from wall treatments. Putting a value of impedance on the walls thus yields a vvalue far below my expectation.

You can find my raw data for the subwoofer study here. http://www.gedlee.com/archive.htm
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Old 14th May 2008, 10:53 PM   #266
ion is offline ion  Sweden
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Quote:
Originally posted by Graham Maynard
Comments made here by Lynn Olson would also relate to EQed dipole+monopole 'systems' generated cardioid bass.

http://www.diyaudio.com/forums/showt...2&goto=newpost

Cheers .......... Graham.
Pardon me,

I'd be grateful if you could specify which one of the 3500+ posts you are referring to. The link only goes to "newpost". Thanks!

And thank you Dr. Kreskowsky, Dr. Geddes and everyone else who has contributed to a interresting read!

/Jon
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Old 15th May 2008, 07:13 AM   #267
Graham Maynard is offline Graham Maynard  United Kingdom
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Hi Jon,

Posts 3546 to 3551 inclusive. I'll see if this works;-

http://www.diyaudio.com/forums/showt...72#post1506272

Cheers .... Graham
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Old 15th May 2008, 10:32 AM   #268
john k... is offline john k...  United States
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Quote:
Originally posted by Graham Maynard
Hi Jon,

Posts 3546 to 3551 inclusive. I'll see if this works;-

http://www.diyaudio.com/forums/showt...72#post1506272

Cheers .... Graham

If you are implying that the comments made by Lynn regarding minimum phase somehow apply to a cardioid made form an eqed Dipole +monopole you are mistaken. It will be minimum phase.


Earl,

I noticed that you were counting figures differently after I posted. All the figures agree pretty well with SE. You comment about damping is possiblity. I don't know exactly what SE uses as wall damping (admittance) models. It may be purely resistive or could include reactive components as well (but I don't think so). The user can select wall characteristics based onSoft and comfortable, mediud absorption, hard finish, steel panels. Obviously these are supposed to be "user friendly" terms.

Another issue to remember is that the model I am using, as you noted, is really only 1st order accurate applicable for small admittance. It is probably being pushed pretty hard at the beta values I am using. But the predicted behavior is still pretty reasonable, particualrly in regard to looking at differences between sources. I would not exect full FEM simulations to suddenly indicate that dipole behave totally differently than the simple model predicts.
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Old 15th May 2008, 12:56 PM   #269
gedlee is offline gedlee  United States
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John

As I said, how the damping is handled will make a big difference. It was a major portion of my thesis. I would suggest you look at the older Morse "Vibration and Sound" because in it he derives the exact expressions that I used. I find that discussion clearer than Morse and Ingard (in fact I find the entire earlier book clearer). I got mine used (first edition) from Amazon for less that the new paperbacks cost from ASA.
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Old 15th May 2008, 08:13 PM   #270
Graham Maynard is offline Graham Maynard  United Kingdom
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Above, John K wrote;-

>> "If you are implying that the comments made by Lynn regarding minimum phase somehow apply to a cardioid made form an eqed Dipole +monopole you are mistaken. It will be minimum phase." <<

( You know John - this snide remark is ridiculous ! )

I wrote;-
>> " Comments made here by Lynn Olson would also relate to EQed dipole+monopole 'systems' generated cardioid bass."" <<

because I thought Lynn's comments were relevent as he was pointing out aspects related to responses in TIME, not just amplitude and phase etc., for responses in time are also crucially relevent to cardioid response generation, and time aspects are not covered by many amplitude or phase versus frequency plots shown in this thread. Such standard frequency responses were also raised by Lynn in relation to waveform coherence !

I should not be expected to have to explain my thoughts to satisfy anyone's 'imaginings' about what I did not write about, nor think about !

Watch out - the *thought* police are about !

Cheers ...... Graham.
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