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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.

erik_squires
benanders's avatar
benanders
234 posts
 
mijostyn

7,990 posts

@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.


@mijostyn I agree this would be the most typical solution. I even implemented a rather basic version that could be controlled with a smartphone app slider (and in real time IIRC). That was genuinely great for convenience, but required even higher dial setting on the plate amps than the passive preamp I tried. Literally no (digital) file I’ve played requires (level) dial setting past 3pm (most not beyond 1pm) for “glorious bass,” but certain newer recordings can easily shake the all-concrete room at same approx. gain (as measured for dB with subs off) due to bumps in some albums/versions bass frequencies…

 

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?

 

So I say I, I 😅 am the one to alter the art (italics in quote mine for emphasis). I think this may be the true discrepancy. I do not share a hands-off [the proportional frequencies] mindset, as the work of some masterings is just tailored for a bass environment I don’t recognize. I much rather not run plate amps near max to squeeze more convenient control over this (seems simply a psychological conflict of interests in my case - ease of control vs. concern over fatigue to sub amps); but again - I surely don’t argue this is the most conventional and hassle-free approach once subs are properly integrated.

This article helped my thinking on the matter; it was published about the same time I finally started realizing just how (file-/pressing-/master-) version-dependent music playback characteristics can be, before the mechanical / layout characteristics of the kit and room factor in. It’s also part of the reasoning I’m not bashful in thinking glorious bass doesn’t necessarily require taking whatever proportional level the (re?)masterer determined. Just my perception; subject to change without notice. 😉

 

 

clio09
3,356 posts
 

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?

If anything is silly its this statement. The better solution isn't always the one that the majority of manufacturers would choose to market or the one that consumers would choose to employ. It's been proven many times over with products across multiple industries. From a business perspective it's almost always about following the money.

I find it a bit strange no one to this point has brought up the amplifier in this conversation. If the amplifier could talk and express an opinion on filters, slopes, and frequencies, not to mention phase and damping we might be a bit surprised. After all its the amp that is coupled to the speaker.

Lastly, one of the reasons I actively bi-amp using separate amplification for the mains and the passive woofers is I still don't feel an amp, let alone a plate amp belongs in a box with the low frequency driver(s). I'm sure over the last several years the technology has improved but I still remain a bit stubborn here, as I once was about using subs altogether. Maybe I just need a bit more time.

erik_squires OP
16,147 posts
 

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?

@gdaddy1 

Well.... funny you should mention this, because they DO!  Look at it this way.  Every multi-way speaker incorporates high and low pass filters in their crossover.  Adding a subwoofer is no different in my mind than increasing the number of drivers in a box. 

It is precisely because I approach adding a subwoofer as a speaker maker that I always consider a high pass filter as part of the process.

audiokinesis
2,743 posts
 

@gdaddy1 wrote:  "I couldn't find ONE room where anyone cut the main speakers with high crossed subs. Not one... 

"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?"

Did you ask any of them why they chose to not high-pass filter their main speakers? 

mijostyn's avatar
mijostyn
8,570 posts
 

@gdaddy1 Subwoofer manufacturers are in business to sell subwoofers PERIOD.

They could care less about the performance of your system. Rel is handily the worst but the vast majority of them do the same half baked thing and supply their subwoofers only with low pass filters. Their reasoning is if they make things more complicated and expensive nobody would by their units. The sad thing is they are right. Digital subwoofer management has been around since 1995, invented by Radomir Bozevic (the Boz of TacT Audio). Some subs include a watered down version of room control but without a high pass filter they have no control over the main speakers which is 50% of the issue. Proper bass or subwoofer management has to know what the main speakers are doing to mate the two correctly in time and phase. Then there is the marked improvement in main speaker performance when you relieve them of the lowest octaves. This can only be done by direct measurement of a system in it's own environment. Any other way is wishful thinking which you seem to be very good at. 

There is, at this time, only one best way to integrate subwoofers into a system and that is with Digital bass management. There are now units available from MiniDSP and Anthem that are very reasonably priced. Benchmark Media Systems uses a MiniDSP SHD Studio with two of their DACs to run their own system and they get great results with it. (Dirac Live) For people who can spend more there is the Trinnov Amethyst and the DEQX units which will be available to the general public shortly. The Anthem STR preamp is 1/2 the price and a great performer.

@clio09 One of the best thing about digital signal processing is you can add subwoofer and eliminate the "bump". Full range speakers like ESLs benefit the most from a high pass filter. 

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