Subwoofer speed is in the room, not the box

mijostyn

8,010 posts

02-24-2024 at 08:48pm 

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Exactly, the horizontal array of subwoofers forms a horizontal line source. Who says a line source has to be vertical?

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That is a neat trick to use with lower frequencies ( = long-enough wavelengths in-room)! Especially considering the lateral boundaries ( = sidewalls) will be of similar/same composition ( = permeability / reflectivity to lower frequencies) more often than not.

I’m surprised that composition of room boundaries hasn’t come up yet. Of the subwoofer “speed” and surely overall performance, I’ve found it (in my limited experience) to have a profound effect on how multiple subs couple either together or with themselves (in the case of one sub per-Ch), due to variation in room (boundaries-mediated) gain.

I get incredible bang-for-the-buck-driver surface area due to all boundaries being 6” solid concrete, except the front wall which is basically floor-to-ceiling glass (behind softwood blinds) - so essentially, strong retention along all boundaries and minimal reflections from the front wall. Back wall is far behind listening area.

I suspect the ceiling, in particular, being equally reflective of low frequency, helps. Most sub frequencies should be more vertical line array-like behavior under normal height ceilings (~12’ or less) unless you go by 1/2 or 1/4 wavelength rule-of-thumb. A sub as a point-source (vertically-speaking) seems converse to how wavefronts should work, at least in nearfield, no? [Vertical reflections-mediated] room gain in this way should be considerably skewed anywhere studs and drywall are used over a slab foundation - highly unequal boundaries in the vertical realm for many (most?) listening rooms.

james633

820 posts

02-19-2024 at 11:13am 

Good thread, I don’t have a lot to contribute that has not already been said.
 

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I find it silly when people chase bigger and bigger speakers at sky high prices for better bass, but refuse to try an actively passed sub system.

Same sentiment here. Perhaps not “silly” so much as unnecessarily complicated. 😅

I think the main crux of this topic is the cultural inertia that floor-standing speakers enjoy, as the overall concept predates active subwoofers, especially active subs implemented and EQ’ed as > 1 unit. The exact topics as covered in this (highly informative) thread seem rare convo’s among folks employing line arrays, since many (hifi) examples do not reach very far below 100 Hz (mids/high drivers). Sub crossovers below 80 Hz accordingly and quickly become irrelevant for such cases.

“If subwoofers and main speakers are integrated correctly there is no reason to turn the subs up or down with any genre of music. A system that is tuned correctly does not care what genre you are playing. When I use the term , system I include the room in that category.

Most audiophiles are ball parking it with their ears which are extremely poor calibration devices. There is no substitute for measurement.”

I agree re: subs gain when correctly* implemented. With both music and movie reproduction I never change subs gain as it sits where it’s supposed to for overall balance, although I can understand if some would want to go bonkers with the subs gain lever to suit a particular mood and/or occasion.

With regard to measurements, they’re certainly indispensable in many regards and as an outset at least with some parameters, but to me it always comes down to fine tuning per ears as a last tweaking measure - if not in all aspects.

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.
Measurements and by-ear-fine-tuning both suggest things are good in my present setup (at least within the system-incl.-room constraints), but the level dials on my subs’ plates still get exercise almost every listening session for favored tracks with extremes in bass gain (I already know where the dials belong based on past tuning exercises).

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?

mijostyn

7,990 posts

02-20-2024 at 10:04pm

@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. 😉