Sub tuning problem

[swgiust]

I have been working hard with my new SVS PB12-Ultra/2 sub. I have gotten my
levels almost perfectly flat +/- only about 4db from 100 to 20 hz. EXCEPT at
63hz. I am almost plus 12db at 63hz. 55hz is good, 70 hz is good. What could
be causing this and what can I do to fix it??

[Woochifer]

I have been working hard with my new SVS PB12-Ultra/2 sub. I have gotten my
levels almost perfectly flat +/- only about 4db from 100 to 20 hz. EXCEPT at
63hz. I am almost plus 12db at 63hz. 55hz is good, 70 hz is good. What could
be causing this and what can I do to fix it??

If you're not using a parametric equalizer, the response curve you got going is pretty good for a nonequalized setup. You should expect at least one large boomy peak if any of your room dimensions are less than about 25 feet (which is most typical rooms). These are just normal low frequency wave interactions when the direct sound combines with the reflected sound to create a peak at a specific frequency.

You can fix this by hooking up a parametric equalizer. Then you set up a parametric EQ filter with a center frequency at 63 Hz, a bandwidth of about 1/12 octave, and a level setting of -12 db. A Behringer Feedback Destroyer costs $100-$150 (depending on whether you get the new or previous model -- functionally for the parametric EQ they are similar) and will take care of that issue.

Another approach to even out your bass response would be to either buy or make your own corner bass traps. Those keep the bass waves from amplifying in the corners and interacting with the direct sound at full strength.

[EdwardGein]

Also try heavy duty isolation pads which you can get online for $135 each and seem to work

[Woochifer]

Also try heavy duty isolation pads which you can get online for $135 each and seem to work

Isolation pads will help minimize floor reverberations, but will not do anything to reduce or eliminate peaks at specific frequencies. Those peaks are caused by room boundaries and wave interactions, which isolation pads do not deal with.

[EdwardGein]

Isolation pads will help minimize floor reverberations, but will not do anything to reduce or eliminate peaks at specific frequencies. Those peaks are caused by room boundaries and wave interactions, which isolation pads do not deal with.

Yeah your right. Sorry I'm just in love with these because so far I haven't had any complaints in my new apartment on the second floor. What room did this guy have his problems in?
As Paul said, because my living room is wide open I've had no problems with my 220-400 watt sub whatsoever but in my enclosed normal sized bedroom, while my 100 watt sub was fine, the 200-400 better sub I bought to replace it was out of control and I gave up and went back to the 100 watt sub.

[swgiust]

The measurements I gave you were with a parametric eq. It is set almost exactly as
you stated. I do currently have some homemade tube traps in the corners. I have them
set all the way into the corner, should I move them out into the room more??

The room is 18x18 with a vaulted ceiling. I does have a 6ft wide opening (with folding
doors) that I can close. I have a 6ft tube trap in each corner, I also have some basic
sound panels at reflection points around the room. The flooring is hard wood covered
by carpet. The sub does sit directly on the hard wood though. This room has a crawl
space (about 5 ft) underneath.

Any more help is appreciated.

[kexodusc]

Swgiust - You can try narrowing the band and applying more cut. You should be able to apply a razor thin precision cut. I'm not sure what Parametric EQ you're using, but most that I've seen are anything but simple to work - might be worth a few tests at a certain frequency to make sure the gain or cut you are adding is in fact being processed and introduced to the signal.