why higher tuning for spl and lower for sq?

[dustybear300ex 10+ year member]

ive ben doing research on numerous sites and found this is the common rule of thumb. is this because when going for spl you would want more excursion so by having a higher tuning you allow the sub to unload. this seem dangerous for the sub but i cant see any other reason as to why this rule exists unless im missing something.

thanks

d

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[JimJ 5,000+ posts]

Lower tuning reduces the "hump" (i.e, peaky response) in the sub's passband that you get as a result of porting it. Playing around with WinISD will give you a pretty general idea of what's going on.

 

[2loud4u 10+ year member]

you dont need alot of excursion to get loud.

Good example.

Re xxx 06 vs Re mt.

The xxx has alot more excursion but the mt will bend it over when it comes to spl.

 

[GrnEydDvl 10+ year member]

I am no SPL master but one reason is the resonant frequency of most cars is higher than most people tune for SQ. SPL competitors take advantage by combining the free boost at the resonant frequency and the added boost at the frequencies right above the tuning frequency of the enclosure .

A ported enclosure playing notes well below the tuning frequency will not be loud at all. Unloading is a bad thing. Frequency response drops off dramatically below the tuning frequency.

 

[AndonD454 10+ year member]

Lower tuning reduces the "hump" (i.e, peaky response) in the sub's passband that you get as a result of porting it. Playing around with WinISD will give you a pretty general idea of what's going on.

x2

and same thing works vice versa.. spl guys tune high to increase the "hump", boosing output around a certain frequency (usually the desired result for competitors is a peak at/around the resonsnt freq. of the vehicle as was said earlier)

 

[dustybear300ex 10+ year member]

so there is a hump then a steep fall at both ends of the response? that was another thing i was not sure of with tuning to the cabin gain. how would the cabin gain number effect tuning for sq and how the box is designed. also, what is a common range of frequencies for spl competition?

thankyou for all the answers.

 

[CBFryman2 5,000+ posts]

1.) Vehicle Resonance is usually 40-60Hz

2.) Enclosures are more efficent at and just above the tuning frequincy

3.) It takes less air displacement at higher frequincies to get equally loud

4.) Subwoofers generally have greater mechanical power handleing at higher frequincies

 

[Duke 10+ year member]

Cabin gain is usually anywhere from 8 to 12 db per octave right?

 

[T3mpest 10+ year member]

yes, that would be considered "average"

 

[CBFryman2 5,000+ posts]

at resonance. you can generally say 6-12dB

Cabbin gain in the lowest octave (around 30Hz) is 100% dependant on vehicle type, design, interior, window slant and total volume.

Car interior = funky acoustics.