High pass filter on music-only sub?

[KEW]

On the Home Theater Shack forum, Wayne Pflughaupt wrote an interesting review involving the PSB10-ISD. He added a high-pass filter set at 25Hz and got what appear to be major improvements in bass speed & detail.
Here is a link to that review.
http://www.hometheatershack.com/forums/svsound/790-face-off-svs-pb10-isd-takes-few-contenders.html

Here are clips referring specifically to the performance of the PSB10 before the filter:

Music References
Basia, The Sweetest Illusion
Track 1, "Drunk on Love," is my favorite music track for revealing low frequency detail. The bass guitar has a very prominent texture or "growl." Since there is a lot of mid-bass energy in the recording, it will come through on both the mains and subs. The test of a musical subwoofer, naturally, is how well it conveys the "growl." Ideally, it should be able to render the detail and texture as distinctly as what you hear in the mains. If not, you only get the texture from the mains, while it "runs together" at the supporting lowest frequencies. A good way to tell if the sub is "up to speed" with the mains is to turn them off and listen to the sub by itself.
...The SVS’ superior extension gave the bass line the solid underpinning the others were lacking. None of the subs could render the texture as well as my reference subs, although the SVS was slightly better in this respect than the others.

Manhattan Transfer, The Offbeat of Avenues
This under-appreciated Grammy nominated album includes some great tracks for bass detail. Track 2, "Sassy," features a series of quick staccato triplets in the bass lineat 0:23, during the intro before the vocals begin. At 0:58 and other places in the song, the bass line does a syncopated pattern on a single note, with only a few milliseconds of "dead space" occurring as each new note is struck. If a sub isn’t fast and precise, the pattern will "bleed" together and sound more like a single long note than several shorter ones.
...The PB10-ISD’s added extension gave it an authority the others lacked, but I still felt it was fairly loose compared to my reference subs.

Here is what he wrote after adding the high-pass filter:

The SVS’ superior extension, while certainly impressive and noticeably better than my own subs, seemed almost too much of a good thing with music – everything sounded "heavy." Considering that the EQ boost my subs have at 25 Hz also means they roll out pretty fast below that point, I wondered if that would make a difference with the PB10-ISD.

Conveniently, the AudioControl equalizer has an optional 18 dB/octave high-pass filter with available settings at 15 Hz, 25 Hz and 35 Hz. I switched it on to 25 Hz, and the effect on the PB10-ISD’s ability to render detail was simply astounding. Suddenly there was resolution and detail in spades!

I went back through my reference tracks one at a time and the resolution the PB10-ISD was now exhibiting was simply jaw dropping. Where there was none before, the subtle texture in Basia’s "Cruising for Bruising" bass line was all there, even better than with my own subs. The prominent low freq growl in the "Drunk on Love" track was more "growly," the texture more pronounced and tighter than I have ever heard. The staccato triplets and syncopated legato notes in Manhattan Transfer’s "Sassy" were also tighter and better defined than I’m used to hearing with my subs.

So, it seems when it comes to music the SVS may be a victim of its own success. Apparently its prodigious output at the lowest frequencies can obscure the amazing detail the sub is cable of rendering. In other words, the PB10-ISD's "problem" is being too good at what it does!

That article was from 2006.
Has anyone else tried this?
Recommendations on how to implement the high-pass filtration?
Do you think these comments would apply to the SB12-plus as well?
Thanks!

 

[AVRat]

Read the manual regarding the room compensation feature. It sounds like it may do something similar.

 

[highfigh]

One main reason for a subsonic filter is that if we can't hear it and it's not needed for the music, it wastes a lot of amplifier power, makes the woofer do things that it wasn't designed for (like go to 10Hz) and since it's not part of the original signal, it's not helping the music. Most recordings are mixed for some nominal level of quality, not the best equipment. Look at what sells the most to find out what they're mixing for. In the early days, it was for radio, then it was for decent (but not great) phonographs, then it was for decent but average car stereo and now it's for iPods and iTunes. None of these can reproduce the deepest bass, so they mix the music down using smaller speakers, like Yamaha NS-10 (they're in so many studios it's incredible). This means they'll never hear any sub-harmonic content unless they play it back on something that can play deep bass well. If they never do, they'll never hear it and not everything that's on the master is intended. A four string bass guitar has a low E string that's normally tuned to about 41Hz. If the strings are sharp or flat, the difference between that note and the same one played on another instrument (like a synthesizer), will produce the original note, plus the sum and difference, called 'beat frequency'. The closer they are to being "in tune", the lower the beat frequency will be. If they're 12 Hz apart, you suddenly have a 12Hz note trying to go through your system and speakers. If they're 3 Hz apart, you now have a 3Hz note. This is the reason older stereos had a low filter- warped records produce these same frequencies and cause the woofers to flap around or bottom out and can cause feedback. It's also why a pilot needs to make sure the props are spinning at the right speeds- if they hit the resonant frequency of the plane, it will shake apart and suffer structural failure.

What the subsonic filter did is remove frequencies that weren't audible and were causing the speakers to modulate whatever came through that was audible. If main speakers are run full-range and a sub is used in the system, the mains should have the sub-sonics filtered out. If the sub is vented, it should have this, too- frequencies below the port tuning are poorly damped and can cause the woofer to become completely uncontrolled. This isn't quite as bad when the woofers are in sealed enclosures because they don't go to the subsonic frequencies very well unless they're aided, electronically.

 

[KEW]

Read the manual regarding the room compensation feature. It sounds like it may do something similar.

Yeah, I'll be hooking it up this weekend and play with it some. I believe the room compensation feature is more gentle thn a typical filter, but I'll see what it does.
I got in touch with the author of the article I referenced and he now believes his result was more unique to the specific subwoofer he had and for the room he was in, but I'm still going to play with it. I'll let you know.

 

[KEW]

I still have not really tuned the sub, but on my SVS SB12-plus, I now have the room compensation control set to small and have the PEQ set at around 30Hz with the (cut) level at about 3/4 of max and the Q set very wide. These controls are not on the NSD models.

This made the difference between my subwoofer screwing up the music vs. contributing to the music. I suspect my room has a really dramatic resonant frequency in the low-mid 30Hz area which needed to be toned down. The results from these adjustments allowed me confidence that I would benefit from having the sub in my system (I was beginning to wonder).

 

[fredk]

Hmmm... Seems to me you are a good candidate for REW. Measure your room response and then set EQ to correct any specific problems. That will give you all the bass without room related nastiness.