2 different subs with the same port tuning - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 6 Old 03-23-2020, 09:09 PM - Thread Starter
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2 different subs with the same port tuning

Two drivers, one has an FS of 15hz and the other has an FS of 25hz, if both drivers are placed in two different enclosures with the same port tunings at 20hz, Will the driver with the 15Hz FS have a better response below 20 hz?
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post #2 of 6 Old 03-23-2020, 09:28 PM
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Quote:
Originally Posted by qguy View Post
Two drivers, one has an FS of 15hz and the other has an FS of 25hz, if both drivers are placed in two different enclosures with the same port tunings at 20hz, Will the driver with the 15Hz FS have a better response below 20 hz?
This feels like a trick question as I don't think you have provided enough information to answer.
There are multiple parameters that impact the low frequency output of a driver in a particular box. QTS, VAS, XMax, etc.
You would need to model both drivers using something like WinISD to answer the question.
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post #3 of 6 Old 03-23-2020, 10:15 PM - Thread Starter
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Lets assume everything else is equal will the driver with lower FS play better considering both are tuned to 20hz?

Will install Winsd later - thanks

Quote:
Originally Posted by DavidK442 View Post
This feels like a trick question as I don't think you have provided enough information to answer.
There are multiple parameters that impact the low frequency output of a driver in a particular box. QTS, VAS, XMax, etc.
You would need to model both drivers using something like WinISD to answer the question.
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post #4 of 6 Old 03-24-2020, 03:08 AM
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Will install Winsd later - thanks
Sooner rather than later.

Automation: Alexa- Harmony Hub- Wemo Dimmer Switch- Wemo Smart Plug BatCave: SY Triple Black
Video Image: JVC RS500- Sony UBP-800X- Chromecast- 125" wide 16x9 white over black spandex screen
Audio: 5.2.4 Marantz SR7011- (LCR) QSC 2180 - (Surrounds) (4) BIC FH6-LCR- (Atmos) (4) Dayton Audio B652 6-1/2-Inch- (Subs)2 23ishcuft ported HS24s 14-15Hz tune - 2 Devastator Minis B&C21ds115 - 4 PA460 in ported cabs 40Hz tune- FP20000Q- 2 Sanway FP10000Q- Crown XLS1500- . To be continued...
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post #5 of 6 Old 03-24-2020, 08:01 AM
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Lets assume everything else is equal will the driver with lower FS play better considering both are tuned to 20hz?
Well, everything else wouldn't be equal. Compliance and mass would be different, hence the different Fs'. The admonition to get familiar with WinISD is important because it will make the relationships between drivers and their parameters less mysterious, and let you compare and optimize based on your needs/goals.
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post #6 of 6 Old 03-24-2020, 10:23 AM
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You asked a question that has some different answers depending on what you assume.

What's that mean? To drop the Fs and keep everything else equal, the easiest way to is to add some mass to the cone. Then change other driver parameters as they falls out from the one change (compliance/etc); there is no such thing as two drivers with same everything except Fs.

Anyway, if we lower the Fs via added mass, it will have a little more output at tuning. Primarily this is a "normalized response" artifact, i.e. level matched. Really you have a touch MORE output right at tuning and LESS output up top as governed by increased mass.

Attached is a pic of an ultimax in 11cuft box tuned to 20hz, standard and a cone with about an extra pound of mass added to it.
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