Just hooked up my Tempest and I'm a little disappointed

VR3

So...

In a sealed enclosure, does the woofer just 'roll off' gradually?

Or?

Thanks for the 'informational' reply!

Dr. Spec

Yes, a sealed subwoofer (depending on the final Q) will roll-off at approximately 12 dB/octave (2nd order).

Of course, the addition of any EQ (common), or a HPF (also common) will affect the final Q and also the corresponding roll-off rate.

If there is a high pass filter installed, then this will cascade with the natural roll-off.

The Acoustic Visions MRS-10 sealed subwoofer I'm reviewing has progressively increasing EQ (to about 4-5 dB at 31 Hz), and also has a 1st order HPF at 31 Hz. So the roll-off above 31 Hz is a bit less shallow than 2nd order due to the EQ. And the roll-off below 31 Hz would be approximately 3rd order (18 dB/octave).

This was corroborated by the ground plane FR sweeps I conducted.

Doc

VR3

So...

The subwoofer you are reviewing now...

Rolls off gradually after 31hz, or does the EQ boost the frequency below 30hz to compensate for the roll off?

Wouldnt using an EQ to pump the drivers volume on the lower frequency put more strain on the woofer?

Dr. Spec

No, it actually starts to roll-off gradually at 40 Hz, ground plane.

The EQ is used to flatten and extend the response down to 31 Hz. The HPF then rolls off the response more steeply below 31 Hz.

The nice thing about sealed subs is that they roll off slower than vented units and they can take advantage of room gain to extend the response. If the room is smaller, the MRS-10 can be flat to about 25 Hz in-room, even though it starts to roll-off at 40 Hz ground plane.

VR3

That is pretty cool...

Thanks for the info

kingtut

I already sold the B&K amp, but it is a mono amp spec at 150w @ 8 ohm RMS and also produce 56 high current amp. Do you gentlemen think that the B&K has enough power to drive Codey's sub?