Previous Thread
Next Thread
Print Thread
Rate Thread
Localized Sub
#70544 12/03/04 11:00 PM
Joined: Mar 2004
Posts: 1,056
connoisseur
OP Offline
connoisseur
Joined: Mar 2004
Posts: 1,056
I recently moved my subwoofer so that it is placed next to the couch, around 5 feet from the main listening position. I did this because it made the front look better (less clutter) and because Dr. Hsu recommended this given my room set-up.

After recalibrating, etc., I've noticed that I can now localize the sub sounds. My crossover is set at 80. In addition, even the lowest "noteless rumbles" can sometimes be localized.

I always thought that sounds lower then 120 Hz or so were not localize-able. Untrue? Any suggestions/discussion about why this is happening or ways to fix it?



Re: Localized Sub
#70545 12/03/04 11:36 PM
Joined: Feb 2003
Posts: 649
aficionado
Offline
aficionado
Joined: Feb 2003
Posts: 649
Same problem here. I've always thought that if I bought a receiver that allowed an 80hz cross (mine is fixed at 100hz) that might help offset the fact that my sub is so close. I'd be interested to hear any suggestions that don't involve repositioning the sub.


M22ti mains, EP175 sub, VP150 center, QS4 surrounds
Re: Localized Sub
#70546 12/04/04 12:31 AM
Joined: Aug 2004
Posts: 6,379
Likes: 7
axiomite
Offline
axiomite
Joined: Aug 2004
Posts: 6,379
Likes: 7
AFAIK this whole "can't localize below 80 hz" is like the "you can't see your screen flicker above 56 hz". It's a generalization, everyone is a bit different.

For low notes you're normally OK because the harmonics go through your regular speakers and the ear + processing in the brain take localization cues from the harmonics preferentially over the low notes so sounds seem to come from the regular speakers.

I am very far from an expert on this, but my first thought would be to take the subwoofer level down a tiny bit and see if that helps. It's been ~25 years since I studied this stuff but I believe there's a threshold effect here -- if the hf signal is over some threshold relative to the lower notes then your brain "votes the low notes off the island" when it comes to figuring out where the sound is coming from.


M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8
Re: Localized Sub
#70547 12/04/04 04:18 AM
Joined: Mar 2004
Posts: 139
veteran
Offline
veteran
Joined: Mar 2004
Posts: 139
I found the same when my sub was close to the wall. Turning it slightly so it faced the center of the room helped. Moving it away from the wall helped even more. My guess is that the sound waves were reflecting and colliding off the wall, creating sounds and frequencies that were easier to localize.

It might help to recalibrate everything again, if you haven't done so.

Re: Localized Sub
#70548 12/04/04 03:13 PM
Joined: Feb 2004
Posts: 418
devotee
Offline
devotee
Joined: Feb 2004
Posts: 418
I think it is because you can hear where the harmonic frequencies above 80Hz are coming from. If the sub plays an 80Hz tone, it will also produce sound on the harmonic frequencies of 160Hz and 240Hz. These first 2 harmonics will be reasonably strong, and they are frequencies you can easily locate.


M- M60s/VP150/QS8s/SVS PC-Ultra/HK630 Sit down. Shut up. Listen.
Re: Localized Sub
#70549 12/06/04 08:16 PM
Joined: Mar 2004
Posts: 1,056
connoisseur
OP Offline
connoisseur
Joined: Mar 2004
Posts: 1,056
So, if I can also hear the harmonic resonances, would it help to turn the crossover on the sub down?

Right now, the cross over on my Hsu stf-2 (downfiring woofer, btw) is taken out of the loop, and the bass management/crossover work is being done by the Yamaha.

Question - if I turn the cross over on the sub down to, say 100, will the sub still produce the 160 and 240 harmonics? I.e. is that a sound that the sub is producing, or is it a natural by-product of the 80hz soundwave?

Thanks.

Re: Localized Sub
#70550 12/07/04 02:38 AM
Joined: May 2002
Posts: 10,654
shareholder in the making
Offline
shareholder in the making
Joined: May 2002
Posts: 10,654
Adrien, in the past I briefly tried a sub located near the listening position and quickly put it back into the corner. Besides the bass frequencies themselves, moving the sub closer to you may make other sound more audible and localizable, such as mechanical vibration of the enclosure and port noise. Still another effect that I experienced was the psychological one of knowing that the sub was so close and not located near the mains.

On the question of harmonics, they can be both "natural", creating the characteristic differences in the sounds of instruments playing the same primary frequency, and harmonics resulting from distortion in the sub. The rolloff(typically at 24dB/octave)which the receiver crossover does is generally sufficient to keep a 80Hz crossover from being localizable due to higher harmonics, although of course there's no sharp dividing line at that particular frequency. Harmonics created by the sub itself as a result of distortion aren't reduced of course by a crossover in the signal feeding the sub, but it seems unlikely that a sub of the STF-2's quality would have high levels of distortion. My view would be to restore the original settings and location, but contrary to usual practice you can try activating the internal sub crossover. The STF-2 has a nominal 90Hz highest crossover frequency(Nousaine's tests have shown that these control markings are inaccurate on many subs), so you can set it there in an attempt to cascade the receiver and sub crossovers so as to roll off the sub output above 80-90Hz more rapidly.


-----------------------------------

Enjoy the music, not the equipment.


Re: Localized Sub
#70551 12/07/04 03:19 AM
Joined: Feb 2004
Posts: 418
devotee
Offline
devotee
Joined: Feb 2004
Posts: 418
Harmonic distortion is the addition of unwanted harmonics by your equipment. You have a high quality sub, and your aren't pushing it to it's limits. Harmonic distortion is probably not your issue.

The other harmonics are what cause a G on a guitar to sound different from a G on a violin. In other words, the harmonics are what give the instruments their individual "voices".

Your house also has a resonant frequency (as all structures do) that it will vibrate at when energy is applied to it, just like a tuning fork. Harmonics are also produced by that sound energy.

Any sound energy released will cause harmonics. Radio waves do it too. I believe that a vacuum is the only place where they do not occur.

John is probably correct here. The human brain is a wonderful thing. It takes data from multiple inputs, and makes it's own determinations. Maybe you brain hears the sound coming from the sub and can't localize it, but it can tell that the left side of your body is getting hit with SPL in time with the sound. It's just putting 2 and 2 together and getting the private school answer...

Last edited by Michael_A; 12/07/04 03:28 AM.

M- M60s/VP150/QS8s/SVS PC-Ultra/HK630 Sit down. Shut up. Listen.
Re: Localized Sub
#70552 12/07/04 04:24 PM
Joined: Mar 2004
Posts: 1,056
connoisseur
OP Offline
connoisseur
Joined: Mar 2004
Posts: 1,056
Thanks, guys. I appreciate the tutorial. It does help.

I was fooling around yesterday, and tried messing with the phase switch and volume. Granted, I haven't checked it out with any serious bass content from DVDs, but after awitching the phase, and turning the volume down a tick, the localization seemed to dissipate somewhat.





Moderated by  alan, Amie, Andrew, axiomadmin, Brent, Debbie, Ian, Jc 

Link Copied to Clipboard

Need Help Graphic

Forum Statistics
Forums16
Topics24,940
Posts442,457
Members15,616
Most Online2,082
Jan 22nd, 2020
Top Posters
Ken.C 18,044
pmbuko 16,441
SirQuack 13,840
CV 12,077
MarkSJohnson 11,458
Who's Online Now
0 members (), 558 guests, and 3 robots.
Key: Admin, Global Mod, Mod
Newsletter Signup
Powered by UBB.threads™ PHP Forum Software 7.7.4