Why set a sub to 60 if your speaker goes to 30? Go big or go home?
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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@bjesien : Because it sounds so much better. In almost all cases when users have a high pass filter they are astonished at how much better their main speakers sound passed high vs. passed low. The naive (without actual experience) is that you paid megabucks for your main speakers, so they should be much better than your sub which costs 1/5th or less. The reality is, almost always, that your main speakers perform so much better when relieved of more bass. |
My apologies I didn't read the whole post. I had a pair of Vandersteen 5's that had a high pass filter to just run the top portion in essence doing what you are saying here. Haven't tried to high pass any other speakers but I do know some of mine over the years sounded worse with a sub, some better. If they really do go down to 30hz (rare) I found I didn't want one. 34-higher, yes for sure. |
Hey @bjesien
I beleive you. The issue with subs, always, is integration. It is hard without measuremengs and nearly impossible with them. I applaud Vandersteen's use of high pass filters, but recognize how hard the rest of it can be before you get good results. |
@erik_squires wrote:
Either scenario (i.e.: peaks and nulls) in the extreme is one not to be desired. It’s their combination in particular that can tip the boat, but remember that corrected nulls require power; peaks don’t. So, peaks have one sitting with a surplus of acoustic power that can be counteracted with a narrow range of power suppression, whereas nulls have one in the need of actual, added electrical ditto. Thus, practically speaking power requirement can be the more predominant issue at hand. If a distributed bass array is not an option we are dealing with frequency irregularities in the bass in the first place, even with pairs of subs, and the damn thing about absorption is that to alleviate peaks sufficiently, on its own, it can have a damaging effect on the overall presentation in other areas. I always go about sparingly with absorption, and would rather have the rest of the corrective measures done with digital room correction and/or a more manual approach with frequency correction via a DSP - preferably actively. On the other hand excessive use of DRC has its own disadvantages, or so I find, and so in the end there may be an element of one needing to accept an extent of FR-irregularities with a limited amount of bass sources. Or, a DBA is called for, and one placed symmetrically to the mains rather than a mono-ed asymmetrical ditto.
Definitely agree on the high-passing of the mains higher than lower - not only does it more effectively relieve the mains from LF but it also has you go about the overall integration with the subs much more effectively when controlling the HP of the mains over a range as well, which is akin to approaching it more as a single speaker system per channel than simply adding on the subs to the mains run full-range. There’s this misconception generalizing that high-passing the mains higher (say, >60-70Hz) is more suited to Home Theatre than "audiophile" use, which goes contrary to my own experience. To my ears high-passing higher (with a fittingly higher subs low pass as well) is usually more suitable on the whole. With regard to "slow bass" I believe there’s some merit to considerations on overhang and/or group delay inherent to a design that will impact the presentation regardless of the integration with the room/FR-smoothness. |
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