I assume test is easy. If you stand up and vibrations are gone then sofa is not an issue?
That is very interesting indeed. Thanks for sharing.
This reminded me that drywall construction might vibrate as well. And these are very common in our homes.
One more thing. Once I measured all the possible locations for my stereo speakers. The optimal position (according to the FR) was 35 cm from the front wall. That leaves no room for a sub in a corner. If I move the speakers further from the wall, some dips/peaks would get bigger. My question is if this would be solvable with more subs or is it better to start with optimal stereo position and place the subs elsewhere?
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I'm after the highest quality sound I can obtain. The fact I need more sub power outdoors is pretty immaterial to me.
Ime/imo it isn't even debatable how much better bass sounds outdoors at proper clean SPL levels.
In fact the entire spectrum cleans up as the low end gains clarity from lack of reflections/modes/reverb, ..and when collocated subs are phase aligned with mains.
It's really so much better than indoors I can hardly bare to optimize indoors, and tend to wait for the occasions to set up outdoors to critically listen and optimize.
All that said, sure...indoors is an entirely different animal.
Rightly or wrongly, it seems to me there are two logical end approaches to subs indoors.
Either maximize modes or minimize them.
I realize minimizing modes takes considerable room planning and acoustic treatment expense. Perhaps seldom practicle/achievable.
(I had the luxury once of adding a 11,000cu ft room to my home that I designed ...LWH to the inch for optimized modal dispersion. Added absorption, diffusion, got a nice even RT60. Played with large bass traps.
Wonderful sounding room...corner stacked labhorns made the smoothest bass after trying lots of things....at least until the damn roof started resonating at high drive levels Lol....best laid plans of mice and men, eh?
Sure, I get the multiple sub approach as pragmatic. I just can't see it as best for trying to obtain ultimate sound quality.
Single vs multiple subs remind me of the contrast between line arrays and point sources (such as Danley) in the PA world.
The line arrays' multiple drivers' designed destructive interference do provide a fairly even coverage pattern, very pleasing,...but all you have to do is hear them side by side against a point source and you realize there's no contest.
It seems to me multiple subs, especially if adding to the multiplicity by not high-passing mains, works in similar fashion....designed destructive interference.
Anyway, just how I see it / hear it...best, mark
Did you consider Double Bass Array?(I had the luxury once of adding a 11,000cu ft room to my home that I designed ...LWH to the inch for optimized modal dispersion. Added absorption, diffusion, got a nice even RT60. Played with large bass traps.
Wonderful sounding room...corner stacked labhorns made the smoothest bass after trying lots of things....at least until the damn roof started resonating at high drive levels Lol....best laid plans of mice and men, eh?
Hi Don, yeah !
I've been following Danley since I built a bank of his Labhorn design, almost 20 years ago.
It's the kind of outdoor bass folks need to hear !!
Todd Welti (of Harman) comments here:
You are being redirected...
Red Spade Audio: Double Bass Array (DBA) bass integration
DBA require more room planning and seems suitable for de novo room constructions. Less practical for homes that are prebuilt. DBA's seem to be a very nice addition for home theater specific setups as well.
I haven't listened to a DBA personally.
Best,
Anand.
We will have to disagree on whether baas outdoors or in a large venue is better. I prefer the large venue, you the outdoors, that's a person preference (and it certainly is debatable.) At any rate this issue isn't pertinent since we are talking about bass in a small room, not outdoors or in a large venue.
The problem is that you can't do either for a given room. The number of modes in a given bandwidth is fixed by the room's volume and nothing that you do can add or subtract any modes without changing the volume. You can learn to control these modes however making them your friend. That's the best that you can do.
I'll stand by my claim that in a small room multiple subs or DBA (TBD) are the only ways to achieve the best LF sound quality. Which of these two works best, or if they actually result in significant differences subjectively is still an open question.
Your example is not pertinent since one is a HF situation and we are talking about a LF one. LF interference in a small room is inevitable, so you simply deal with it. The point source versus line array example simply has nothing to do with a multiple sub implementation.
Welti does not mention that in my letter to the AES editor about his first paper, I indicated that I had already been doing multiple subs for some years. His technique and mine are virtually identical except that I use off-line calculations and measurements to set the parameters and JBL does this all in one box. The price differential between our two methods is significant!!
Sure, plenty of room for each of us have our favorite bass space
I really don't see much difference between HF and LF....just waves of different lengths.
And I guess I don't see much difference between multiple HF drivers and multiple LF drivers....they all seem to add up to multiple arrivals.
As you say, inevitable LF interference in a room just compounds the multiple LF arrivals even further.
So I'm still led to think a line array and multiple subs share the principal of designed interference.
Thanks Mitch, this is an important point.
Notice how a "transition" is shown, meaning that both sets of characteristics hold to varying degrees. I would say that the example is a fairly small room, so the Fs is very high, about 300 Hz. in this example. The room does not have much LF damping (a typical problem.)
Notice how a "transition" is shown, meaning that both sets of characteristics hold to varying degrees. I would say that the example is a fairly small room, so the Fs is very high, about 300 Hz. in this example. The room does not have much LF damping (a typical problem.)
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Do you feel the same when there is nearfield summing of the elements, not some higher frequency effectively widely spaced line approximation that throws artefacts. (sorry, I seem to be short on words today)
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how so? one would think the behavior of waves to be constant but the interference introduced by boundaries would be different,no?
Yeah Mitch, second the thanks.
I'm familiar with Schroeder frequency. I got it to about 60 Hz in the room described earlier, the combination of room size and quite a bit of damping.
Had a pretty smooth RT60 across the spectrum of about 0.2-0.3 sec.
And yep, I totally get there is a transition zone, if for no other reason than RT60 variation by frequency. And then there's the shape of the room, and how does it connect or open up to adjoining spaces...lot's going on huh?
But you know, and I really don't mean to be belaboring or portraying any negativity to multiple subs..pls forgive if I come off that way....
It's just I've been trained to see strong 1/2 wave cancellations between any two subs, and nearly as strong 1/4 wave cancellations between each individual sub and its set of virtual subs created by its nearby wall/floor/ceiling reflections.
So when I picture adding all those cancellations on top of the room's modes...well, I just can't help but see a big mud bath...of what I've been likening to destructive interference...and I try to minimize the variables..
Anyway, I'm gonna shut up about all this...and maybe next time I'm setting up a uniform boxlike room, give multiple subs another try, via modeling, measurement, dsp adjustment, and of course listening
I think you are worrying about what's going on in the room as a whole? You only hear what is happening at your ears.
Hi Allen, yeah, I'm not sure either ..what you're asking
Re 'widely spaced line approximation that throws artefacts'....
My understanding is when line elements exceed somewhere about 1/4WL spacing they quit acting like a line, and start acting like multiple radiators with overlapping coverage zones.
So we hear multiple drivers make that phasing, whishing sound, when wind blows or moving our heads around.
Of course the above problem is greater when listening distance is further and more drivers are covering the same zone.
I'd think ideally we would want to be close enough to the line to hear only one HF/VHF unit (again assuming there is no true line coupling due to excessive driver spacing).
If we could be in a nearfield position where we have steady in phase summation of only a couple of units, I'd think that would OK (if we stayed still.)
Do you?
Does that make sense?
Lord I almost never worry about anything
Maybe cause I try to simplify things to where I have an honest chance to really understand, and thereby effectively ignore worrying complexity Lol
Oh, imho we absolutely hear more than what's happening at out ears...
Our bodies definitely add to hearing, picking up vibrations,
that our brain works into its magicry of what we call hearing..
Plus, the brain is such a perception modifier...have you listened to your speakers playing, through headphones and a measurement mic ?
The constast blows me away every time I do....