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Passive radiator design from scratch
Passive radiator design from scratch
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Old 13th October 2019, 11:18 PM   #1
Rademakers is offline Rademakers  Netherlands
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Location: Rotterdam, NL
Default Passive radiator design from scratch

Are there any guidelines to design a custom passive radiator from scratch?

My intentions are to make a honeycomb passive radiator membrane, resulting in a known Sd and mass (Mmd). I've several idea's for the suspension that I'd like to try out, that hopefully ends up with a ball park Xmax of 10 mm for the passive radiator.

My first try would be a 33 x 33 cm square membrane (1089 cm^2) with an Mmd translating to the equivalent of a port that is between 100 cm - 150 cm long (40 - 60 inch). This will be used in combination with a 12" PA driver, in an enclosure tuned to 50 - 60 Hz.

What I do not know at this point are the resulting Fs, Vas and Qms and the effect these will have on the performance of the passive radiator.

I've seen mention of the effect of the Fs on the passive radiator performance but nothing on the effect of the Vas and Qms. Any guidance is welcome
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Last edited by Rademakers; 13th October 2019 at 11:22 PM.
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Old 13th October 2019, 11:21 PM   #2
Galu is offline Galu  Scotland
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CraigSu posted this link in a parallel thread: The Subwoofer DIY Page - Passive Radiator Systems
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Old 14th October 2019, 09:45 AM   #3
Rademakers is offline Rademakers  Netherlands
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Thanks for the link, I've read it and it contained useful information on finding the Fs of the PR.

I did find this page: AE Speakers --- Superb Quality, Unforgettable Performance, Definitely.

Basically it says not to worry about the Fp too much and to make the Vap and Qmp as high as possible.
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Old 14th October 2019, 10:54 AM   #4
TBTL is offline TBTL  Germany
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Indeed. The relevant parameters for tuning are the cone area and moving mass. Vap and Qmp are limited by the desired property than the passive cone should not be able to move in any way other than forward / backwards, which usually is solved by using a suspension. Rocking modes can be a problem if no spider is used.

Last edited by TBTL; 14th October 2019 at 10:56 AM.
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Old 23rd October 2019, 07:46 PM   #5
ente is offline ente  Germany
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Hi Rademakers,

some basics about the measurement of passive radiators you will find on the Homepage of Klippel (https://www.klippel.de/fileadmin/kli...e_Radiator.pdf)

The effect of a variation of Qmp, Vap, etc. you can simulate for example with VituixCAD.

If your German is good enough I can send you a paper dealing with your questions.

Regards
Heinrich
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