Free Air Resonance ?

[Crump]

The Fs of a sub, is that the htz that its loudest at? or is the box tuning more important?

[IH8PunkRok]

everything has a resonant frequency. that is what the fs is.

so say u tap the cone of the sub it will vibrate at the free air resonance.

i dont know what that information is used for in a normal box but in a tline thats wut u should tune to

[aznboi3644]

No...it is simply a number that tells you the resonant frequency of the speaker...everything has a Fs.

Peak frequency depends on enclosure and loading environment.

[Crump]

So how do you "make" your system hit the lows? what do you need to do. Just tuning the box?

[reinke]

find a woofers with a little bit lower fs and a higher BL factor

[Neo_frog]

Fs is the point at which driver impedance is maximum. 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. If you've ever seen a piece of string start humming uncontrollably in the wind, you have seen the effect of reaching a resonant frequency. It is important to know this information so that you can prevent your enclosure from 'ringing'. With a loudspeaker, the mass of the moving parts, and the stiffness of the suspension (surround and spider) are the key elements that affect the resonant frequency. As a general rule of thumb, a lower Fs indicates a woofer that would be better for low-frequency reproduction than a woofer with a higher Fs. This is not always the case though, because other parameters affect the ultimate performance as well.

[BJD3]

find a woofers with a little bit lower fs and a higher BL factor

Slight thread jack.

What exactly is BL? Like fs is the free air resonance, what does the BL represent?

Is there a topic where there is a list of what everything is? Search doesn't like short words.

[Neo_frog]

Slight thread jack.

What exactly is BL? Like fs is the free air resonance, what does the BL represent?

Is there a topic where there is a list of what everything is? Search doesn't like short words.

The magnetic strength of the motor structure. Expressed in Tesla meters, this is a measurement of the motor strength of a speaker. Think of this as how good a weightlifter the transducer is. A measured mass is applied to the cone forcing it back while the current required for the motor to force the mass back is measured. The formula is mass in grams divided by the current in amperes. A high BL figure indicates a very strong transducer that moves the cone with authority!

[BJD3]

The magnetic strength of the motor structure. Expressed in Tesla meters, this is a measurement of the motor strength of a speaker. Think of this as how good a weightlifter the transducer is. A measured mass is applied to the cone forcing it back while the current required for the motor to force the mass back is measured. The formula is mass in grams divided by the current in amperes. A high BL figure indicates a very strong transducer that moves the cone with authority!

So this would be the other side of the xmax argument? Where a sub transmits high amounts of energy to the air in a short stroke as opposed to a long stroke with less energy?

[Neo_frog]

So this would be the other side of the xmax argument? Where a sub transmits high amounts of energy to the air in a short stroke as opposed to a long stroke with less energy?

If you're referring to the XMAX vs SPL argument, increasing the magnetic field strength or the length of the voice coil in the gap will increase the rate of acceleration essentially yielding higher numbers.

When a sub is playing at the tune of the port, the air velocity spikes and the drivers hardly move so xmax is not always something to look for if you want SPL.