[Nate Hansen]

 

Subwoofer placement is more art than science I sometimes think.  But gear like the Anti-Mode make it idiot-proof for decrepit old geezers like me.

It certainly is science. A good usb mic can be can for under $100 I think these days. Learning to use a mic and interpret the measurements will yield much better results than listening for what "sounds best" and randomly moving the subs around based on suggestions by others not based on data from the room in question.

[JLM]

Bass frequencies travel in waves, so in-room bass from a single source will never provide flat response beyond a single location at a single frequency, just basic physics.  EQ can't solve that.  Treatments can't solve that.  Just accept it. 

Using two subs at the opposite end of the room is only a start. 

Again look up "swarm" and Duke LeJuene here on Audio Circle.  Best, only "real", alternative:

http://www.spatialcomputer.com/page9/page10/page10.html

This is a miked "reactive" sub that is located at the back wall that does not connect to your system.  It produces real-time out of phase sound wave.

[Mudslide]

Bass frequencies travel in waves, so in-room bass from a single source will never provide flat response beyond a single location at a single frequency, just basic physics.  EQ can't solve that.  Treatments can't solve that.  Just accept it. 

Using two subs at the opposite end of the room is only a start. 

Again look up "swarm" and Duke LeJuene here on Audio Circle.  Best, only "real", alternative:

http://www.spatialcomputer.com/page9/page10/page10.html

This is a miked "reactive" sub that is located at the back wall that does not connect to your system.  It produces real-time out of phase sound wave.

You are correct about the waves and the need for multiple subs.  However, you are somewhat incorrect regarding  eq systems like the Anti-Mode.  They serve to smooth frequency response at the listening point(s).  The peaks and nulls can be and are smoothed with use of such devices at the places where people sit.  And that is..."real".   

That "spatial sub" looks to be interesting but requires further study with regards to feedback (signal delay) issues.  And it appears to smooth the FR at the sub, not the listening point.

[Tyson]

There are a couple of points that can be EQ'd that will tend to be consistent throughout the room.  Usually it's the one related to floor/ceiling height.  That's why I like Dirac so much - multiple measurement locations, so they can focus on the room modes that are consistent from place to place and softer on stuff that's specific to the listening position:

http://www.minidsp.com/products/dirac-series

[Mudslide]

There are a couple of points that can be EQ'd that will tend to be consistent throughout the room.  Usually it's the one related to floor/ceiling height.  That's why I like Dirac so much - multiple measurement locations, so they can focus on the room modes that are consistent from place to place and softer on stuff that's specific to the listening position:

http://www.minidsp.com/products/dirac-series

Tyson, how does that differ from what most mid-level AVRs already do...e.g. Denon, Yamaha?  I am able to take measurements all over my theater room with my Yamaha's YPAO and 'smooth the room' for my multichannel listening.

While I do this (because of "movie night" with friends), it is sub-optimal.  FR becomes ... averaged.  It roughens up a bit the really smooth FR capable when measurement is confined to a single point.  So for a solitary listener in his/her favorite 2-channel room, single point eq is ideal.  For multiple listeners, multiple point FR averaging is best.  (Or also best if one wanders around the room a lot while listening.)   

[Tyson]

Dirac is pretty sophisticated, way beyond most other EQ solutions:

http://www.dirac.se/en/solutions/home-audio/dirac-live/technical-description.aspx

[Nate Hansen]

While I do this (because of "movie night" with friends), it is sub-optimal.  FR becomes ... averaged.  It roughens up a bit the really smooth FR capable when measurement is confined to a single point.  So for a solitary listener in his/her favorite 2-channel room, single point eq is ideal.  For multiple listeners, multiple point FR averaging is best.  (Or also best if one wanders around the room a lot while listening.)   

The idea with a multi-sub setup is to have them placed in such a way (with the correct level,delay, and low pass relative to the mains) that you have a pretty consistent response across all the seats. Then you can eq the entire system as one and have a smooth response at most listening positions. Obviously the more seats you have the more difficult this becomes.

[Tyson]

The other option is to use OB subs that just don't interact with the room in the same manner as a sealed box sub.  Downside is that they don't pressurize the room the way a sealed sub does, so you never get that "I am under water" feeling.  On the upside, bass clarity and detail is unmatched in my experience (not even by a swarm setup). 

[JohnR]

Oh right. What he said ^^

I will add that OB subs are still not immune to placement and I think "nearfield" is mo butter.

[gregfisk]

The other option is to use OB subs that just don't interact with the room in the same manner as a sealed box sub.  Downside is that they don't pressurize the room the way a sealed sub does, so you never get that "I am under water" feeling.  On the upside, bass clarity and detail is unmatched in my experience (not even by a swarm setup).

I'm wondering if you are using speakers that are already OB like the Super V or 7, do you use more OB subs for the swarm or do you use sealed subs. And what does the quality of the swarm subs have to be since they are mostly being used to even out the bass in the room?

[Mudslide]

And what does the quality of the swarm subs have to be since they are mostly being used to even out the bass in the room?

Quality subwoofers, generally speaking, are more desirable.  You want articulate bass presentation.  Cheap subs tend to be 'thumpy' and single noted.  Driver overhang  (or resonance) causes poor note delivery.  With subs, get the best you can afford is my recommendation.

[Tyson]

I'm wondering if you are using speakers that are already OB like the Super V or 7, do you use more OB subs for the swarm or do you use sealed subs. And what does the quality of the swarm subs have to be since they are mostly being used to even out the bass in the room?

I've heard the Rythmik OB servo subs at RMAF at the GR Research room for several years - first with the Super V's, then with the Serenity Super 7's, and a year ago with the Mockingbird Audio line arrays.  In each case it was clearly and obviously the best bass of any room at RMAF.  And that was for 4 years running.  My good friend Mike (mgalusha) runs a swarm of boxed Rythmik servo subs in his dedicated audio room which I've heard many times as well.  As nice as his room is (and it is AWESOME), I still think the OB Servo sub bass sounds the best.