Down Firing Subs


New member
Username: Shadowfox1290

Post Number: 1
Registered: Feb-06
first off what is the real advantage/disadvantage to this

i have an old 12" pioneer sub and it seems like you can onl;y "feel" it within 7-8 feet of it you can hear it but not really feel it beyond that is this normal
it is powerd by my reciever with 220 watts

Platinum Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 10894
Registered: Dec-03
firing the sub downward can use the vehicle to resonate the output.
you need a sub tht's designed to be mounted that way though. you need to calculate the "sag" of the driver's suspension to see if it'll work.

Percentage of Sag = 24,849 / ( Xmax * Fs²)
If Sag% < 5%, the driver may be mounted down (or up) firing. (Xmax in milimeters.)

*Glassie drops the knowledge

Silver Member
Username: Pelona

Post Number: 341
Registered: Dec-05
you got your sub powered by the reciever?

220 watts. Thats a pretty strong reciever you have there. LOL

Platinum Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 10908
Registered: Dec-03
that sub needs a deditaced amplifier.
no radio in a car will put out close to 200 watts.

Gold Member
Username: Tdeaton1021

Near Tampa, Florida USA

Post Number: 1744
Registered: Sep-04
i never knew that only some subs (probably most though) can be mounted up or downfiring

Silver Member
Username: Nocc1n


Post Number: 181
Registered: May-05
glasswolf is awesome

Silver Member
Username: Phuktupbasshead

Phoenix, Arizona United State...

Post Number: 404
Registered: May-05
you confused me on that equation there...
please clarify.
24,849 divided by (xmax in milimeters)? What's the *Fs for?
sorry, please explain.

Silver Member
Username: Solacedagony

New Jersey US

Post Number: 801
Registered: Oct-04
Fs - This parameter is the free-air resonant frequency of a speaker. Simply stated, it is the point at which the weight of the moving parts of the speaker becomes balanced with the force of the speaker suspension when in motion.
Can get that usually from the manufacturer's website.
Not sure about what format the Xmax should be in.
* = multiplying

So 24,849 divided by the quantity of Xmax multiplied by Fs squared.

"*Glassie drops the knowledge"
Haha GhettoGlassie in the hizzouse

Platinum Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 10981
Registered: Dec-03
what he said.
Fs is listed in the TS specs of the driver, available with the speaker or from the company's website most times.
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