Great thread by the OP as usual .... Interesting read...
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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My (limited) experience agrees with properly aligned bass being largely equitable across music genres, @phusis @mijostyn , but I found subs with considerable room gain become less predictable according to how a given track/album was mastered - variation in bass gain seems extreme for certain album versions. Specifically: this variation (in bass gain) does not seem to scale with genre, rather, it seems aligned with specific masters / remasters, some albums / versions having very low bass levels and others (at the same subs’ level) being far too high and exciting room modes that are not heard on other versions. This seems independent of overall SPL for the whole audible frequency spectrum, I should note - i.e., it doesn’t seem to be simply because some albums / versions are simply mastered louder overall. I could make up a rule that it seems more pronounced in stuff mastered for OST’s or something like that, but trying to ascribe a pattern would probably just be misleading and pointless. This tendency is pronounced enough that I’ve considered getting a Goldpoint passive attenuator or similar device from which to run my subs - reduce the # level dials to turn by 50%, but I’ve concern over running the inbuilt plate amps on high level (downstream of a passive attenuator) for each listening session. Thoughts? |
@phusis I have no experience with horn subwoofer. For most of us they are impractical do to size constraints. For sure distortion will be lower for any given size driver due to efficiency. They problem is low bass will rattle and resonate almost anything. IMHO is is much easier to make a small enclosure resonance free with clever design and balanced force construction. It will not come remotely close to the efficiency of a horn but is way more practical from a size perspective. You are doing exactly as I suggested for crossover and slope. The game is keeping the sub out of the midrange or you will have mud. You are running 85 Hz @ 36 dB/oct. If you move up to 100 Hz you will have to steepen the slope. I can change crossover points and slopes on the fly which is very helpful for AB comparisons. @audioquest4life The largest I would go is 15". The reason is the larger drivers have more trouble maintaining pistonic motion, they wobble. If you want more subwoofer use multiples of smaller drivers. Two 12's make a 15. Two 15s make an 18. So, go with four 15s. I use 12" drivers because the 15's would require a larger enclosure which will not fit in my situation and larger enclosures are more difficult to control from a resonance perspective. @gdaddy1 Rel is only interested in selling as many subwoofers as they can. Their method of implementation is worse than silly.
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@benanders The solution to your problem is digital bass management with room control, which is really speaker control. You can change the volume of the subs instantly with sliders for each individual channel on the computer. Room control will even out the frequency response of the sub with the best response at the listening position. I advance the volume of the subwoofers by 6 dB. with the crossover point and slope I use this gives live recordings the thump of the real experience at less than ear damaging levels and I do not change it at all for any given recording. These are choices that the mastering engineer makes and who am I to alter his art? Digital bas management uses measurements you make of your system. It sets the crossover point and slope, and aligns the subs with the mains in time and phase perfectly. After the system is set up it will be flat and your only adjustment by ear or feeling is relative volume. Low bass you feel more than hear. Go to a live jazz club and feel the bass and drums. That is what you want at home without being able to identify the subwoofers by ear. If you can hear the subs as individual drivers you need to rethink your integration. |
Is it just REL you think is silly or are all sub manufacturers silly? I just came back from the Tampa audio show and had this very discussion with SVS. They said they don't suggest higher than 50hz. Cutting off main speakers that are perfectly capable of producing deep base is something they don't recommend. Their words, not mine. Silliness prevailed.... I couldn't find ONE room where anyone cut the main speakers with high crossed subs. Not one. Many of the displays had NO subs and the speakers alone were more than capable of producing deep powerful (dare I say fast?) bass. Their display only used subs for home theater demonstration. 2 channel stereo was speakers only. So the question is...If the high pass method makes the speaker sound so much better, wouldn't every speaker manufacturer use this superior method? Are all these displays competing for high end sound missing the secret sauce that would make their speakers sound even better? Are they ALL silly?
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