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Old 12th December 2010, 07:11 PM   #21
Rudolf is online now Rudolf  Germany
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Quote:
Originally Posted by mige0 View Post
Thanx - and what would you calculate from that ?

The green trace is the overlay of "inverse EQing" - this is not affected by any "opening factors" IMO (except I may add half of the mouth "diameter" to the path length probably).
Michael,
the behaviour of those frames is controlled by the geometry of the frame. That`s right. But what you measure is the behaviour of a resonating column of air. Please don't believe that both have the same length. All your horn simulations show that the influence of the horn contour does not stop immediately at the horn termination. Same for H, U, N ... frames. What you show in the green traces is quite naive compared to your horn sims IMHO.

You can do better for sure.

Rudolf
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Old 12th December 2010, 07:32 PM   #22
mige0 is offline mige0  Austria
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Default DFD / Deep Frame Dipole sub-woofer

Quote:
Originally Posted by Rudolf View Post
What you show in the green traces is quite naive compared to your horn sims IMHO.
sure I can look at those pipes as being horns, cavities, waveguides, diffraction alignment device, helmholtzresos or anything else - but I still don't get the point I'm afraid, with respect to superposition of dipole behaviour (green trace)

So - what you suggest in taking meaningful measurements ? - but keep in mind that I'm after optimization *not* after absolute accurate measurement - which is a fake under usual listening conditions anyway !
What is important is the trend and the underlaying principles.

So far I have not seen someone suggesting deep frame dipole sub's - have you?


Michael

Last edited by mige0; 12th December 2010 at 07:40 PM.
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Old 12th December 2010, 07:50 PM   #23
mige0 is offline mige0  Austria
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Default DFD / Deep Frame Dipole sub-woofer

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Originally Posted by Mike Mount View Post
Thanks for posting this... solidifying several ideas
that I have held a long time. great images...
Let us know, once you realize your ideas


Michael
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Old 12th December 2010, 07:56 PM   #24
mige0 is offline mige0  Austria
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Default DFD / Deep Frame Dipole sub-woofer

Quote:
Originally Posted by sendler View Post
Any ideas on the cause of the dip/peak at 160Hz of the N frame?
My guesstimate is it comes from reflections of the basket / magnet of the front chassis.


Quote:
Originally Posted by sendler View Post
Would you expect increasing the dimensions slightly to allow a golden ratio of 80*50*31 for each side of the deep ripol to smooth the wiggles 85-210Hz? And maybe a slight taper, somewhere in between straight and full conical which in this N frame is currently about 1:2. Taper at 1:5? Magnets at the throat or the mouth?
No idea - you have to find out by try and error, I'm afraid

Michael
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Old 12th December 2010, 08:29 PM   #25
Rudolf is online now Rudolf  Germany
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Michael,
I like your idea of taking nearfield measurements and superimposing them with a dipole "correction" to get an idea of the farfield response. That's a clever suggestion. Pity is your green curves are based on too simple assumptions IMHO - making the superposition results almost useless.
Quote:
So - what you suggest in taking meaningful measurements ?
I don't suggest new measurements. They are ok. They show what is to be expected.
Quote:
So far I have not seen someone suggesting deep frame dipole sub's - have you?
I haven't either. But since I'm no longer interested in frames deeper than 20 cm, I have not looked for any "deep frame dipoles".

Rudolf
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Old 12th December 2010, 09:02 PM   #26
mige0 is offline mige0  Austria
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Default DFD / Deep Frame Dipole sub-woofer

Quote:
Originally Posted by Rudolf View Post
Michael,
Pity is your green curves are based on too simple assumptions IMHO - making the superposition results almost useless.
Ahh ok, at least we are talking about the same thing (was not sure about).


I agree on that my green trace for the inverse EQing is a "simplified assumption" - especially when it comes to higher frequencies due to directivity issues - but for the intended pass band and roughly one or two octaves above ???

Quote:
Originally Posted by Rudolf View Post
But since I'm no longer interested in frames deeper than 20 cm, ..
That is why ?


Michael

Last edited by mige0; 12th December 2010 at 09:11 PM.
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Old 13th December 2010, 07:15 PM   #27
Rudolf is online now Rudolf  Germany
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Quote:
Originally Posted by mige0 View Post
Ahh ok, at least we are talking about the same thing (was not sure about).
My communication skills are at their worst when I presume there can't be a problem of mutual understanding.
Quote:
I agree on that my green trace for the inverse EQing is a "simplified assumption" - especially when it comes to higher frequencies due to directivity issues - but for the intended pass band and roughly one or two octaves above ???
Your H frame example shows the first dipole null at 420 Hz when it should be at ~310 Hz. That is "engineering thinking": Good enough for the application.

But I should not play the critic any longer. After taking some more time I find your combination of nearfield measurement and dipole interaction quite helpful for understanding something like the "ripole" response above the first peak for instance. I certainly have to withdraw that "almost useless" comment.

Quote:
That is why ?
Well, I don't use dipoles as real subwoofers, but need an upper frequency limit of 300 Hz in my application. There is nothing wrong with DFD - they are just not part of my personal design goals.

Rudolf

BTW: How did you get the green dipole function into ARTA. Calculating with EXCEL and importing the SPL values?
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Old 13th December 2010, 07:43 PM   #28
mige0 is offline mige0  Austria
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Quote:
Originally Posted by Rudolf View Post
BTW: How did you get the green dipole function into ARTA. Calculating with EXCEL and importing the SPL values?
After thinking along some more complicated lines first, I finally arrived at the point that with my PC setup its actually quite easy.

You just plug in an inverter VST followed by a delay you comfortably can dial in ms values, sum up with the original signal and you are done.


Green trace is a measurement of the sound card out in this configuration. Switching configurations is a breeze with Console.


Click the image to open in full size.

Michael

Last edited by mige0; 13th December 2010 at 08:02 PM.
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Old 13th December 2010, 07:49 PM   #29
mige0 is offline mige0  Austria
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Quote:
Originally Posted by Rudolf View Post
Well, I don't use dipoles as real subwoofers, but need an upper frequency limit of 300 Hz in my application. There is nothing wrong with DFD - they are just not part of my personal design goals.
For the part above the Deep Frame Dipole sub's - roughly 100 up to 300Hz I use a 18" nude.
According to SL's spreadsheet this should be good enough for almost 120dB.

The part below 100Hz is the really tricky one with OB.
Stig Erik did it with sheer Sd - sadly I do not have the place nor the funds to follow his path.

So I was wondering what possibilities there are for optimization and still stay dipole.
Of course a Deep Frame Dipole sub woofer is a different animal compared to nude speakers - but on a first glance, it seems to blend pretty - as seem to do "normal" H-frame woofers


Michael

Last edited by mige0; 13th December 2010 at 08:15 PM.
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Old 13th December 2010, 08:14 PM   #30
Rudolf is online now Rudolf  Germany
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Quote:
Originally Posted by mige0 View Post
You just plug in an inverter VST followed by a delay you comfortably can dial in ms values, sum up with the original signal and you are done.

Green trace is a measurement of the sound card out in this configuration. Switching configurations is a breeze with Console.
Michael,
Thanks for explaining. I really need to look more into "designed" signals.
Quote:
Originally Posted by mige0 View Post
For the part above the Deep Frame Dipole sub's - roughly 100 up to 300Hz I use a 18" nude.
According to SL's spreadsheet this should be good enough for almost 120dB
I am still "in clothes" - at least below the 300 Hz belt : 15" in H frames 40x40x40 cm

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