@avanti1960 got it right…. and building an inert cabinet for those massive low THD but high IMD woofers is not trivial…. but then cabinet movement = trash = output = “ efficiency “….. funny how systems engineering just creeps in…..
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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@erik_squires wrote:
Except with horns. The cabinet/horn does the heavy lifting, not the driver - very neat. When the driver has the sole burden to carry, you hear the effort, but it requires of one to have experienced the difference to assess its impact, and react on it. The next step, if one ever gets this far, is actually implementing horn sub variants in your home, but most would be intimidated by the sheer size demand of such solutions. @gdaddy1 -- Different ways to skin you cat. Implementation is key for whatever route is taken here, and being I favor active configuration from a DIY-approach setting filter values of both the mains and subs, high-passing the mains lends itself even more naturally; although housed in different boxes, each sub and corresponding main speaker channel is treated as a single L/R system. The important thing is we're happy with whatever path we're choosing. It seems you are, as am I. @sfgak wrote:
My point was that with a limited amount of bass sources both nulls and peaks are unavoidable, and not boosting the nulls here can certainly be an issue - just like failing to address peaks. Another issue comes from the lauded flexibility of placing, say, two bass sources diagonally to try and address room modes, which I've tried several times with countless filter permutations and room treatments without ever getting to a satisfying result (even with a fairly low XO-point). It may look good "on paper," but I far and away prefer symmetry of subs-to-the-mains placement with all that it entails. Sidewall placement, symmetrically, has proved is viable solution as well.
Unless the subs are placed fairly close to and symmetrically to the mains.
This is of course a cardinal point. I would never do with a built-in DSP/filter of a sub, instead using a Xilica DSP for both the mains and subs, actively, with elaborate filter settings and finely scaled adjustments.
FIR-filter would be helpful here, but using IIR-filters of the Xilica with 36dB/octave L-R slopes produces very good results. 48dB/octave slopes didn't fare as well sonically in my setup context. @tomic601 wrote:
Forest for trees, as they say; engineering only gets you so far when the physical framework is stunted as an outset. |
Well, I meant to talk about the enclosure, not how a driver is loaded out the front. I hope most people understood I was specifically comparing acoustic suspension to ported enclosures and not trying to extend that to horns as well. I thought that would have been clear since I was clearing up the efficiency of ported speakers myth. Sorry for any confusion. |
Thanks. I love the speakers. I know some don't like the voicing (bump up at ~4 kHz), but I'm mostly a relatively low-volume listener. I have a very odd shaped room with many non-parallel walls; not bothering to post because I'm moving to Europe soon and will have a more normal-shaped room. Current room has a few modes (left sub has a deep cut at 68 Hz and a very slight boost at 130 Hz, right sub filter cuts a bunch at 55 Hz and a tiny bit at 350 Hz). But with the subs where they are, I get "glorious bass" in and near my listening position. Every room is different, so it is possible that, when I get to my new home, I may be in a position to place the subs more symmetrically with respect to speakers and cross them lower than 70 Hz. As Erik points out, that might allow crossing at a lower frequency. But every room is different, so I'll measure, experiment with various configurations, and listen carefully in the new location. And just in case, I am building an audio conduit to a location that allows flexibility in sub placement, and that location is part of the dedicated audio circuit to help minimize the chance of a ground loop. |
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