F3 (3dB downpoint)

[Subwoofery]

Hi Nick,
I need to know (or maybe I'm bored). This forum needs to wake up a bit. It hasn't been very active lately.

I would like to know what the MagV.4 yields in term of F3 in a 0.7cuft, in the nominal 1.0cuft and in a 1.2cuft.

Same question for the new to come BMv.2 in a 0.4cuft, in the nominal 0.5cuft and in a 0.7cuft.

Thank you,
Kelvin

[Electrodynamic]

Originally Posted by Subwoofery

Hi Nick,
I need to know (or maybe I'm bored). This forum needs to wake up a bit. It hasn't been very active lately.

I would like to know what the MagV.4 yields in term of F3 in a 0.7cuft,

53 Hz

in the nominal 1.0cuft

50 Hz

and in a 1.2cuft.

49 Hz

Same question for the new to come BMv.2 in a 0.4cuft,

50 Hz

in the nominal 0.5cuft

47 Hz

and in a 0.7cuft.

42 Hz

These are preliminary estimates on the BM v2, as the final proto isn't finished yet. These numbers were generated off of the T/S's from the first prototype. As you can see though, it will play low in the target 0.5 ft^3 enclosure and even lower in 0.7 ft^3 but with reduced power handling of course.

[Subwoofery]

Thx Nick,
I like comparing specs even if it doesn't tell the whole story.

I can see that the F3 specs on the BM was better than on the Mag. Does it mean the BM will drop lower than the Mag?

Can you please explain what F3 numbers really mean?

Thank you,
Kelvin

[Electrodynamic]

Yep, that means that the BM will play a tad lower than the Mag will before rolling off.

The F3 of a subwoofer system is the -3 dB point of the system. However, keep in mind that all of this is theoretical and you would only hear that subwoofer play exactly that low if you were listening to that subwoofer in an anechoic chamber.

Having the lowest F3 possible isn't always a good thing because if you have too much bottom end the subwoofer can sound really tubby due to the gain (transfer function) of the vehicle.

[bose301s]

So the Mag is down 3dB at 50Hz? That just doesn't seem right to me. If that's true what is the peak frequency of the Mag in 1 cube?

[Electrodynamic]

Yep, that's the way the numbers crumble. Odd isn't it? You know from personal experience how low it can play.

Peak frequency will depend on the vehicle it is placed in. Since it's still below a 1.0 Qtc, there isn't enough rise in the response to worry about.

[bose301s]

Originally Posted by Electrodynamic

Yep, that's the way the numbers crumble. Odd isn't it? You know from personal experience how low it can play.

Peak frequency will depend on the vehicle it is placed in. Since it's still below a 1.0 Qtc, there isn't enough rise in the response to worry about.

Yea, it plays low just fine, it just doesn't seem like 50Hz could be the F3 based on how low it goes, but I would have to assume you are right

[Electrodynamic]

Originally Posted by bose301s

Yea, it plays low just fine, it just doesn't seem like 50Hz could be the F3 based on how low it goes, but I would have to assume you are right

And that is exactly why I tell people that the coveted WinISD can give you a ROUGH estimate about performance. I mainly only use it for port calculations. You get to the point where you can look at a T/S sheet and know how the driver is going to react with power in certain enclosures...but it takes a long time to get there.

[Subwoofery]

Originally Posted by Electrodynamic

Having the lowest F3 possible isn't always a good thing because if you have too much bottom end the subwoofer can sound really tubby due to the gain (transfer function) of the vehicle.

That means that the JL 13TW5 and the Soundstream Stealth are not better woofers then even though they have lower F3 #s...

[Electrodynamic]

Originally Posted by Subwoofery

That means that the JL 13TW5 and the Soundstream Stealth are not better woofers then even though they have lower F3 #s...

It depends on how much lower they are. You see, that's the key; not to over-do anything. If their F3's are 20 Hz lower (in the 30's) than the Mag, then yes, they will have too much bottom end and it will be VERY hard to EQ out.

And a lower F3 doesn't always mean a better sounding woofer either (even if the lower F3 is within reason). Having a larger bandwidth (which again is a factor of inductance...especially on the top end) is a major asset when it comes to how the driver integrates / sounds.