Seems to be a little turbulence in the air.
Subwoofer speed is in the room, not the box
First, if you like swarm, that’s fine, please start a thread somewhere else about how much you like swarm.
I want to talk about the impression that subs are fast or slow compared to planar or line sources.
The concern, and it’s correct, is that adding a subwoofer to say a Martin Logan or Magneplanar speaker will ruin the sound balance. That concern is absolutely a valid one and can happen with almost any speaker, not just speakers with tight dispersion control.
What usually happens is that the room, sub and main speakers aren’t integrating very well. Unfortunately for most audiophiles, it’s very hard to figure out exactly what is wrong without measurements or EQ capabilities in the subwoofer to help you.
So, there’s the myth of a small sub being "faster." It isn’t. It’s slower has worst distortion and lower output than a larger sub but what it does is it doesn’t go down deep enough to wake the dragons.
The biggest problems I’ve heard/seen have been excessively large peaks in the subwoofer range. Sometimes those peaks put out 20x more power into a room than the rest of the subwoofer. Think about that!! Your 1000 W sub is putting out 20,000 watts worth of power in some very narrow bands. Of course that will sound bad and muddied. The combination of sub and main speaker can also excessively accentuate the area where they meet, not to mention nulls.
A lot is made about nulls in the bass but honestly IMHO, those are the least of our worries. Of course too many of them can make the bass drop out, but in practicality is is the irregular bass response and the massive peaks that most prevent any good sub from functioning well in a room.
Bass traps are of course very useful tools to help tame peaks and nulls. They can enable EQ in ways you can’t do without it. If your main speakers are ported, plug them. Us the AM Acoustics room mode simulator to help you place your speakers and listening location.
Lastly, using a subwoofer to only fill in 20 Hz range is nonsense. Go big or go home. Use a sub at least at 60 Hz or higher. Use a single cap to create a high pass filter. Use EQ on the subwoofer at least. Get bass traps. Measure, for heaven’s sake measure and stop imagining you know a thing about your speaker or subwoofer’s response in the room because you don’t. Once that speaker arrives in the room it’s a completely different animal than it was in the showroom or in the spec sheet.
Lastly, if your room is excessively reflective, you don’t need a sub, you need more absorption. By lowering the mid-hi energy levels in a room the bass will appear like an old Spanish galleon at low tide.
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I don’t think it’s IMPOSSIBLE.... but very difficult to do this by ear or based on published specs or measurements. You must figure out what your main speaker is doing in room. I repeat, in room speakers are entirely different creatures. It’s like you go to the store, get a sweet puppy which tries to eat your eyeballs as soon as you get it home. IF you have a DSP based system, and only do the subwoofer, you often end up wiht very complicated EQ at the transition area, so, practically speaking, yeah it's nigh impossible. |
I agree and the way I achieved this is using an active crossover with 70 Hz low pass and high pass filters (4th order 24 dB Linkwitz-Riley) and biamping with a SWARM set up using 4 woofers.
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@erik_squires wrote:
The highlighted parts are important points I’ve tried to raise at numerous, previous occasions - certainly the aspect that many end up lowering sub(s) gain to suppress not only peak issues in the range here, and thus are deprived of sufficient low end presence and overall quality. To clarify on the corrective measure of peaks/nulls: it is my experience that nulls, which can be quite severe, require sometimes a fairly prodigious amount of extra power to be alleviated, and this can put a strain on the amp(s). At the same time peaks do the opposite to some degree, which may end up at least partly nullifying the added power demands from peaks, but from my chair this is usually not enough to keep nulls from being a potential power issue correction-wise, to the point even where the driver is also stressed.
First, if dispelling named myth is the goal then be prepared for a variety of suggestions on how proper subs integration can be achieved. I don’t yet SWARM myself (though down the road I’m contemplating a symmetrically set up DBA with smaller tapped horn, similarly tuned variants), and my intention was not to be the "SWARM missionary" here but rather to lay out the challenge with a more limited number of bass sources (say, no more than 2 bass sources). Yes, SWARM presents challenges as well, but personally I find 2 subs a mandatory outset for serious sub integration, and one that lends itself naturally with a main speaker high-pass above the 60-70Hz range (i.e.: where directionality sets in when not using absolute brick wall low-pass slopes) placed symmetrically to and (fairly) close to the main speakers with the subs configured in stereo.
Indeed they often are.
When you put it that way (and it’s a very good description of what great bass can sound/feel like) I’ll have to say very few ever get to experience bass like that. Such bass presentation only comes from prodigious effective air radiation area, loads of headroom (i.e.: very low distortion and thus ease) and excellent overall integration. However, with reference to your second paragraph just above I’d go further and say there is a particular design approach that aids the traits mentioned by you (even though you don’t want to get "specific"), and that’s horn-loading or a variation thereof; that particular "coming out of nowhere," omnipresent and liquid/smooth sense of the lower octaves that swell effortlessly with dynamic swings and don’t call unnecessary attention to itself is a definite quality of large, horn-loaded subs. Direct radiation with larger, or multiple smaller cones (remember, horns are force multipliers that make smaller cones deliver similar or even more total air pressurization) just make themselves and their cones known more predominantly - even to the point of becoming a distraction when you know the difference horns can make. It comes down to cones in horns moving very little to produce even staggering output, as well as the gradual impedance match of cone-to-air coupling of horns, with all that entails, likely in combination with the woofer cones being partly or entirely hidden in the horn path and thus prevents mechanical distortion and upper end harmonics to more readily enter audibility (effectively acting also as a low-pass filter). It’s more of an immersive, musical flow of low frequencies than the more ground-based and differently tactile sense of bass from direct radiators, to my ears. |
@erik_squires wrote: "Installing 1 subwoofer correctly is a big deal and a lot more work than most audiophiles want to do. Tripling the number of speakers (from 2 to 6) for SWARM is also a big deal for many. Failing to do either well is what makes for slow, mushy or overbearing sub experience." If you are using a single subwoofer, the location of that single subwoofer may well be, and often is, critical. But the more subwoofers you use, the less critical the location of any one of them becomes. Duke |
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