Hit Bottom

RSTERN

The svs bottomed out tonight watching loin king 1 1/2. Its in the begining @ 2:03 when the title and the 1 for the 1/2 drop in. About jumped out of my chair. Did not sound good The volume was not up that loud. But replayed after the kids were done watching and man that was deep, whole house shook.

Rob Stern

gatemplin

Have you calibrated the sub level?

Ceruleance

those SVS'... good for nothing.

RSTERN

Yes sub is calibrated to +3to 5dbs hot. Have listen to other movies louder like monter inc.and starwars I and II. This is one of the deepest sound I have heard.

Rob Stern

gatemplin

Isn't there a subsonic filter on the plate amp? Maybe it is set too low? The excursion at and above 20 Hz should be very low but below the tuning point the driver can unload.

Dr. Spec

Originally posted by gatemplin
The excursion at and above 20 Hz should be very low but below the tuning point the driver can unload.

Not quite............

The excursion reaches a peak both above and below the tune point.

For the 20-39PC+, the peak excursion above the tune point probably occurs at about 30 Hz. If that LK 1.5 hit was around 30 Hz, that could have done it.

Agree on the stuff below the tune point - SS filter should be set to 20 Hz and all ports should be open.

PS - You aren't the first to bottom out an SVS, and you won't be the last. All driver's have limits - even the dB-12. I agree, if you bottom a dB-12, the entire house is probably shaking at that point.

No one has been able to bottom a PB2+ yet..........it seems almost bullet proof.

gatemplin

Your right Doc,

I should have said just above 20 Hz, as in 21, 22. My EBS Tempest is tuned to 16 Hz but reaches its maximum excursion at about 21 Hz. From the description I assumed that it would have been a subsonic frequency since he wasn't listening very loud.

Dr. Spec

Very few DVDs contain true subsonic content. The Daredevil DVD in DTS is a legitimate recent exception, which has a bunch of high amplitude, short interval hits at 14-16 Hz during the barfight scene.

I re-read my post and the 20-39PC+ (which has a tune point of 20 Hz) is probably at maximum excursion at around 25 Hz (not 30 Hz).

Below 25 Hz, the vents begin to couple with the woofer, and excursion drops dramatically, with minimum excursion being right at the tune point.

Below the tune point, the woofer starts to decouple from the vents, and excursion starts to rise again. That's where the high pass (infrasonic) filtering comes in.

In the stock tune, the 20-39PC+ goes strong to about 17-18 Hz in-room before the high pass (infrasonic) filter cuts in.

It's pretty tough to bottom a PC+ below the tune point if the tune switch is at the proper setting.

Leaving all ports open and dropping the tune switch to say 12 Hz, is a recipe for disaster. Not only is the high pass filter setting lowered, but there is also some EQ applied at each setting to flatten and extend the response.

The combination of a lower high pass filter and EQ applied below the tune point can quickly bottom the woofer if strong subsonic signal content is present.

Doc