[Jmitchell3]

So trying to understand sub positioning as it relates to OB subs.

I understand with traditional enclosures, frequencies around and below 80hz are non-directional, and thus subs should be placed in the position(s) where the bass sounds best at the listening position.

However I’ve read folks here comment that OB subs should be placed away from all walls for best results.

So, with my ignorance on display, if frequencies below 80hz are non-directional why would placement of an OB sub be any different from that of a traditionally enclosed sub?

Thanks!

[mlundy57]

Open baffle design, bass or otherwise, relies on the time delay from the back wave reflecting off the wall to provide the spacial cues that give OB it’s large spacious character. If the speakers are too close to the wall, the time delay isn’t long enough and instead of a large spacious soundstage, you get a smaller muddied sound. Three feet is the minimum distance to get enough delay to open up the soundstage.

[Early B.]

Also, don't accept the conventional wisdom that bass below 80 Hz is non-directional. 

[Jaytor]

As previous responses have stated, you want at least three feet, ideally more, between the baffle and the front wall.  However, since much of the response to the sides is cancelled, placing them near the side walls is not a problem.

Fixed autocorrect issues.

[Captainhemo]

Also, don't accept the conventional wisdom that bass below 80 Hz is non-directional.

I will never  go back to non-stereo bass again


jay

[Jmitchell3]

Also, don't accept the conventional wisdom that bass below 80 Hz is non-directional.

🤨😭 the more i think i know the more the rug is pulled out from under me!

[Jmitchell3]

I will never  go back to non-stereo bass again


jay

Found these articles i thought were very good RE stereo subs and helped me a bit more with the ob vs sealed and single vs stereo explanations.

https://www.kenrockwell.com/audio/stereo-subwoofers.htm
https://www.kenrockwell.com/audio/how-to-connect-subwoofers.htm

[guf]

interesting. I followed Ken's suggestion and turned down my crossovers. i'm liking it. 

[Jmitchell3]

interesting. I followed Ken's suggestion and turned down my crossovers. i'm liking it.

I think the idea of “lowest crossover point” from Ken matches with Danny’s assertion that you generally want smaller drivers playing lower frequencies because their lower mass will have superior spectral decay when compared to the higher mass of larger drivers playing the same frequencies. By letting the mains play as low as they can we have those smaller drivers (smaller woofers than the sub driver) producing cleaner bass frequencies if they are able, only allowing that big sub driver to do what it’s meant to do....the extreme low end.

[poseidonsvoice]

I think this article is highly relevant and cites sources of individuals who have actually done bonafide research in the subject and not anecdotal assumptions and observations:

https://www.audioholics.com/room-acoustics/stereo-bass

Best,
Anand.

[Early B.]

"Stereo bass" is more of a practical term than a technical one. Most dudes with dual subs realize they're not actually getting stereo sound in the lower frequencies.

Dual subs transformed my system. It's similar to going from a two-channel amp to monoblocks.

Hard core audiophiles keep things separate, and that includes separating the bass duties from the main speakers. Some guys even install a separate electrical sub-panel for their audio gear. 

[Jonathon Janusz]

I think this article is highly relevant and cites sources of individuals who have actually done bonafide research in the subject and not anecdotal assumptions and observations:

https://www.audioholics.com/room-acoustics/stereo-bass

Best,
Anand.

Interesting article, for me particularly the discussion of the efficacy improvements in implementing stereo bass in rooms with acoustic false ceilings.  This might explain a reason why I got so tuned in to the concept in my own experiences early on in my own systems, championing the cause more strongly than the camp optimizing in room mono bass below 80Hz.

Reminiscing about a room I used to have, that room had a drop ceiling installed (long before I moved in) with fiberglass backed tiles in a grid, backed by a good foot or more of fiberglass insulation, with about another four or five feet of dead air space between the insulation and the true ceiling; in short, the room naturally (and unintentionally) had an acoustic ceiling as described in the article.  This suggests to me that for me, in that room, the effect of stereo bass was both greater and easier to discern than it might have been were the room more traditionally constructed.

Just another reminder that I really, really miss having that room.  It was flatly dumb luck, but that room completely by circumstance and chance did so many things so right I would have had a hard time designing a room as good from scratch!

[poseidonsvoice]

Early B,

I disagree with your assertion that most guys use the term
of “stereo bass” as meaning just 2 separate subs. I’ve met more than a few that believe in separate left and right bass channels. The multiple conclusions and observations are very interesting from the article I referenced. There isn’t a right or wrong. The answer is...it depends (on a whole bunch of stuff that isn’t obvious). The important thing I like about it was that research was done as opposed to castigating one idea for another. Perceptions are important and they should be respected but science of acoustics has really advanced in the past 20 years. The devil is in the details, and the article contains them.

Best,
Anand.

[Tyson]

I find that with bass, you can't locate where the sound is coming from by using your ears, but you can by using your skin.  You feel it as pressure. 

Try an experiment - keep your stereo speakers in their normal position in the front of the room and now put all your subs on the left side of the room, but only playing up to 80hz.  You'll be able tell the subs are on the left because you'll feel them.

Which is why, if you can only do 2 subs, the best place is in the front 2 corners.  But if you can do 3 or more, then a swarm approach is far superior to stereo subs.

[poseidonsvoice]

...

Which is why, if you can only do 2 subs, the best place is in the front 2 corners.  But if you can do 3 or more, then a swarm approach is far superior to stereo subs.

About 1 year ago, I used to think so. Then I started reading Greisinger’s articles (he’s a world renowned acoustic researcher). Now I know that the answer is : “It depends.” The article above goes through some of the details in about as laymen terms as one can put it because it isn’t simple to explain.

Best,
Anand.

[Tyson]

About 1 year ago, I used to think so. Then I started reading Greisinger’s articles (he’s a world renowned acoustic researcher). Now I know that the answer is : “It depends.” The article above goes through some of the details in about as laymen terms as one can put it because it isn’t simple to explain.

Best,
Anand.

He's right, with box based subs you have to choose between optimizing for flat frequency response in room using a swarm approach, or optimizing for the bassiosness effect from stereo subs.  You can't have both, not with box based subs.

That's one reason I love OB subs so much - because they don't pressurized the room like a box sub does, they are inherently less lumpy in their room frequency response.  Which means you can optimize for bassiosness and for in room FR response at the same time.

[poseidonsvoice]

He's right, with box based subs you have to choose between optimizing for flat frequency response in room using a swarm approach, or optimizing for the bassiosness effect from stereo subs.  You can't have both, not with box based subs.

That's one reason I love OB subs so much - because they don't pressurized the room like a box sub does, they are inherently less lumpy in their room frequency response.  Which means you can optimize for bassiosness and for in room FR response at the same time.

Tyson,

In my experience you can’t do both with OB’s ALONE either. And they are not inherently less lumpy in their FR. They do have a quicker decay (since they have 50% less output) which is seen in the waterfall and is the reason they are easier in the beginning to use. The measurements I have seen from colleagues including the NX Otica’s I have listened to, and experienced, showed that it needed additional subwoofers to get a flat FR. You couldn’t do it with just (2) Triple 12 inch OB’s in a large well treated room. Nope. The FR was still rough and non flat. This was after a ton of work with placement, EQ, etc.... (and you know I did!). The addition of monopole subs fixed the problem. I also saw this with other OB designs like Linkwitz, etc...OB is good with spatialization of bass and this has been confirmed by other acoustic researchers and loudspeaker manufacturers like AJ of Soundfield Audio.

Which leads up to Matthew’s other point. A point of significance. The use of stereo bass seems to be advantageous to those who like classical music and non amplified music (due to the spatialization). However, the stickler is this. With most recordings, the bass is recorded in mono. And moreover if you are a non Classical enthusiast, then a swarm approach with all subs running with a mono signal is subjectively better. And for theater, swarms are always better. Close miked “studio” recordings, my preference is swarm too.

But the differences between a properly optimized swarm “mono” bass setup and stereo bass is still small in the big scheme of things. And not all swarms sound the same just like a triple 12 inch OB Rythmik doesn’t sound like OB subs from other manufacturers (Spatial, Linkwitz, Pure Audio, etc...). So that accounts for big differences in perception imho.

So in conclusion with OB you can get bassiousness/spatialization but with OB plus monopole subs you can get bassiousness/spatialization plus a flat FR. With monopole subs in a swarm you can get flat FR easily and they cater more to the majority of recordings available today and for mostly non classical listeners.

Both if done right are not inexpensive in my experience. None of my subs use inexpensive drivers or amplifiers. The execution has to be done right, and of course with measurements 

Best,
Anand.

[Tyson]

Wait, am I understanding correctly that you are coming over to the dark (OB) side, at least partially?  Wait, wut?   

[poseidonsvoice]

Wait, am I understanding correctly that you are coming over to the dark (OB) side, at least partially?  Wait, wut?   

I did own OB subs once, Double 12 inch Rythmik’s actually. They were good. The Triple 12’s my colleague have are better.

All I can say is that I appreciate why there are enthusiasts for them. But even with a dispensable income they are not for me and not in my main system. This is due to my listening habits, SPL levels and favorite genres of music.

Best,
Anand.

[Tyson]

I did own OB subs once, Double 12 inch Rythmik’s actually. They were good. The Triple 12’s my colleague have are better.

All I can say is that I appreciate why there are enthusiasts for them. But even with a dispensable income they are not for me and not in my main system. This is due to my listening habits, SPL levels and favorite genres of music.

Best,
Anand.

I'm just messing with you man 

I agree too - musical choice will make a difference.  For me I'm about 90% classical so servo OB subs are a perfect fit.  What kind of music do you generally listen to?