Post by tonycamphd on Oct 6, 2024 16:26:46 GMT -6
A single sub in a small room is almost always problematic, "A bunch of unmatched subs" is INDEED a well known hit and miss undertaking while in the installation process, but you will CERTAINLY HIT at some point by moving them around the room. Matching multi-sub phase correlation is also NOT important (and potentially a detriment) as the cross over point at that low of a frequency has no bearing on mix decisions above it.
Low sub bass is a mono centered flood of omni directional waves regardless of sub count or positioning. Bass articulation frequency info is also way above the sub crossover point and has no real bearing on upper bass articulation, sub amps often have variable 0-180* phase rotation pots on them for that very reason.
"Stereo subs" is a misnomer, sub freq's sum to mono, dual subs (or more) is a more appropriate term, "stereo subs" in phase will cause greater problems by making deeper nulls and hotter hot spots in a less than perfect small room.
The use of 3 or 4 subs at various degrees of phase shift at lower spl's will fill in comb filtering voids and room nulls but can also increase amplitude of hot spots with constructive and destructive interference(again having little bearing on the phase of freq's above the crossover point), thats why experimentation is required to find the sweet spots.
The concept is tried and true for small to even larger rooms to smooth sub freq responce giving you what you desire at and around the listening position that would otherwise require a perfect room of enormous size.
That said i'd always have a bypass switch(even in a perfect room) to get the subs out of the way.
This multi subwoofer small room array is a tried and true well known technique, I certainly didn't come up with it but i've used it dozens of times at this point because it works a treat
The concept is not as excepted as you think, yes you have one expert who supports it but it is full of holes. 1. First it might fill the nulls might, because when purchasing subs you don’t know the phase response of each driver, most manufacturers don’t publish this. 2. Second at any particular wave length the drivers Will acoustically sum if placed within 1 wave length so multiple drivers are going sum as much as they are going to cancel each other unpredictably, basic and far far more excepted array theory, what every large scale arrayed live system either Quasi point source or Line array is based on. 3. LF IS NOT MONO, ask anyone who believes this at what frequency or room function it becomes mono, you will never get a straight answer it’s Omni direction which many confuse with mono.
Now here is a biggie 4. Subs operate above the crossover point , so you have a bunch of unlike drivers producing different frequency phase responses and distortion at rolled off levels all over the room! 5. Now if we except ATC’s premise at all that lower distortion in the upper bass is far more important this is very very bad we screwed.
Tried it listening panel was mostly Symphonic Bassists, Tuba, and percussionist, and classical pianist as well as large pipe organ player in other words 6. those who are very familiar with the natural sound of their respective instruments in the LF un amplified some brought recordings they were part of. All agreed there was more LF but no one preferred it to a well tuned well placed system with stereo subs, in both well treated and poorly treated rooms. 7. The number one response was that the stereo sub based system was more articulate , it lacked smear and was more naturally dynamic. We also had multiple different measurement systems set up. All using not just calibrated mics but those with individual on axis calibration files for that exact mic samples.
The only consultants driver or Speaker manufacturers I know who prefer the Swarm system is the papers author, I have asked many most just shake their heads. One other point except for Spl capabilities most preferred each sub being a single vs multiple driver subs due to the lack of even a small difference in phase, frequency or distortion causing even minor comb filtering due to driver manufacturering.
We also compared this approach to the EM long developed ELF system, everyone noticed the companding at higher SPL.
If I could ever reassemble this panel I would love to do a longer term test to see how power compression factors in.
A couple of manufacturers were present all hoping Swarm would win because it would possibly mean more sales.
1. it doesn't matter because i'd turn them OOP anyway
2. again, doesn't matter because they are OOP in the setup i'm talking about
3. technically any source coming from 2 spots isn't mono, but everything we do is about psychoacoustics, doesn't change perceived reality, subs hit mono
4. Simply not high enough to matter and if you can hear it you are crossed over way too tall
5. Not sure what you mean here, but the speakers don't create additive harmonics irrespective of what the recording gear is doing...., resonances maybe?
6. Subs aren't low freq's, they are sub freq's, not being flippant here, it matters.
7. I'd love to read this study, can you link me please? IME outside of a perfect room, 2 subs in phase causes more issues than not, but ONLY at the crossover point and below and that point should always be well below any articulation freq's where you could lose sight of audible phase issues
Not that it matters in reality, but I'd say the use of parallel compression, added distortion amongst other effects on low freq sources blow the whole phase accurate articulation claims completely out of the conversation.
That said i've installed 1/2 dozen of these multi sub systems over the years with a 100% success rate after quite a bit of fiddling, not a single sub was in phase with the next, even the models were not the same.
I DID say in my first post that always use with a bypass switch for much the same reasons people switch to auratones and other monitors as their mixing monitors, subs wear me out so fast but can also inject some adrenaline
