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"Stand Subwoofers" like the Genelec W371, Kii BXT, etc. Ideally with DSP & Multi-Drivers

Martin

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#22
LInkwitz was trying to design around the idea of having the sub as a stand

I think somewhere there was a measurement about vibration send up from sub to the main.
I have always liked the sound of the big Linkwitz speakers... You cannot beat a properly multiamped systems using DSP and active crossovers.

Martin
 
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#24
I think somewhere there was a measurement about vibration send up from sub to the main.
I can‘t remember if I have seen measurements about this, but I have seen this video:

Of course I don‘t know if they are placed on solid ground or on carpet, etc.
 

fredoamigo

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#25
$35K is the going rate for a good, low mileage 12 year old Porsche 911. Just got to know what you're getting into.

Martin
not in europe my friend ! here the price of second hand 911's is soaring ;)
 

hege

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#27
I can‘t remember if I have seen measurements about this, but I have seen this video:

Of course I don‘t know if they are placed on solid ground or on carpet, etc.
Nothing that some Sorbothane can't fix, assuming the subs hold steady on the floor. After putting few correctly specced bits between my Gennies and 18" BMS, there's absolutely zero vibrations coming though.. and the top of them does vibrately quite a bit when cranking. :)

bms4_2.jpg
 

AudioJester

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#28
I can‘t remember if I have seen measurements about this, but I have seen this video:

Of course I don‘t know if they are placed on solid ground or on carpet, etc.
The guy who put up that video posted on the LX/oplug forums that the issue was uneven floor surface. But, yes the premise of the bridge design by LX for the mids/tweeters was to avoid vibrations from the bass drivers/cabinet.
 

Bear123

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#29
Nothing that some Sorbothane can't fix, assuming the subs hold steady on the floor. After putting few correctly specced bits between my Gennies and 18" BMS, there's absolutely zero vibrations coming though.. and the top of them does vibrately quite a bit when cranking. :)

View attachment 49022
ZOMG MY SUBWOOFER TWIN! I think those BMS are amongst the top 2-3 best 18" drivers made! I have the pair that Josch Ricci at Data-Bass tested.
 

Winkleswizard

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#35
I think Rogers produced their AB1 subwoofer stand for the LS3/5a over 30 years ago and the "Puppy" subwoofer for the Wilson Audio WATT to sit on came out in 1990 iirc.
Interesting as I did research at the time (and it was not 30 years ago) and did not find much. Although I have owned some British speakers over time, did not come across Rogers in US. Am not nearly in the same market as Wilson Audio, so pretty sure it was not them. I recall the design was very modular and seemed well made. The design had some damping feature between the bass module and the monitor.

Internet search capability is much more advanced now and I have not been able to find my previous result. In response to the OP, my recent searches come across RBH frequently. RBH has an offering but is $10K per pair. While I get market-based pricing, I cannot rationalize them as a reasonable value :oops:.
 

JohnBooty

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#36
Even if it wasn't DSP controlled, a multi-driver stand could perhaps be calibrated with a MiniDSP and get rid of room nodes by emitting bass from a few spots for a more universal application that wouldn't rely in proprietary stuff and having all the speakers from the same brand.
This is a fine idea. I've been running my system this way for a few years and I'm very happy with it -- a pair of SVS SB-1000s as "subwoofer stands" for a rotating cast of bookshelf speakers. Due to awkward room layout this was kind of my only option but it's been very enjoyable.

One way to make this easier is to use a receiver/amplifier with a pre-out/main-in loop like the Yamaha A-S700 or the discontinued HK 3490. Using this you can wire up the MiniDSP for crossover duty inline with the receiver, and then continue to use all of the receiver's other niceties like input switching and volume control.

As for other examples, I know Selah Audio sells systems with this arrangement. http://noaudiophile.com/Selah_Mejor/

However you should refrain from this idea. The best position in a given room for a sub is very seldom identical to the best position for the sats, so either bass suffers or soundstage.
This is more true for "a sub", as in "a single subwoofer" than it is for multiple subwoofers.

With multiple subwoofers room modes are greatly mitigated, giving you placement flexibility.

Additionally, subwoofer output is typically a lot more localizable than people realize. Utilizing a 80hz crossover and 12dB/octave slope, you're still getting audible output (-10dB) up at 160hz which is localizable. One more reason to reduce the distance between speaker/sub when feasible. (Of course, a lower crossover point and/or steeper crossover slopes help with this as well)

It's true that "dual subwoofer stands" positioning may not give the max possible SPL compared to other positions. However, in my experience, a pair of subwoofers will have plenty of headroom to spare in most situations... a pair of decent $500 subwoofers is going to have no problems keeping up with pretty much any bookshelves in existence.
 

stevenswall

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#37
This is more true for "a sub", as in "a single subwoofer" than it is for multiple subwoofers.

-----

It's true that "dual subwoofer stands" positioning may not give the max possible SPL compared to other positions.
Would you consider the Genelec w371 to more like "multiple subwoofers" spaced a few feet apart? I think that's part of why I think it would work. If the stands each have two drivers, spaced as far apart as possible like on the W371, then a pair of those "towers" would be like having 4 subs.

Concerning crossovers, is there an advantage of a 12dB/octave slope? I choose 48 because it's the steepest, and would probably choose whatever the higher number is. I *think* this would also get rid of some lobing in 2 way monitors. Not sure what the drawback is or if there is one. (I don't believe it's time, because a DSP could time delay whatever was necessary.)
 

Bear123

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#38
Limiting sub placement to the same position as L/R is counterproductive and probably eliminates one of the main advantages of running dual subs.....improved sound quality due to a better frequency response resulting from *proper* positioning of the subs. Might as well just get towers that play lower.
 

suttondesign

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#39
My listening room is so small that not even a cockroach could hide in it.

Then again, our cockroaches in Panama can be quite large...

View attachment 49008
My god, that looks tasty. Do they have the nice white pasty insides?
 

JohnBooty

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#40
Folks in this thread dismissing "subwoofer stand" positioning, despite lots of well-regarded commercial examples and experiential evidence to the contrary. If this was such a flawed topology, why did we ever have tower speakers in the first place? By this logic, then every pair of tower speakers capable of putting out deep bass is fatally flawed.

Would you consider the Genelec w371 to more like "multiple subwoofers" spaced a few feet apart? I think that's part of why I think it would work. If the stands each have two drivers, spaced as far apart as possible like on the W371, then a pair of those "towers" would be like having 4 subs.

Concerning crossovers, is there an advantage of a 12dB/octave slope? I choose 48 because it's the steepest, and would probably choose whatever the higher number is. I *think* this would also get rid of some lobing in 2 way monitors. Not sure what the drawback is or if there is one. (I don't believe it's time, because a DSP could time delay whatever was necessary.)
I'm not familiar with those Genelecs. At first glance it seems like the dual drivers achieve some sort of dipole thing and I think the intent is that you wouldn't need more than one unit. I'm not sure if a second unit would be beneficial, detrimental, or merely superfluous.

As for crossover slopes, a steeper slope may cause audible discontinuity particularly off-axis as the subwoofer will have a different dispersion pattern than the speaker to which you're crossing it over. On the other hand a shallower crossover slope probably opens you up to some more phase/cancellation issues as in my "80hz @ 12dB/octave" example where the subwoofer's playing somewhat audible content all the way up at 160hz. Bit of a cop-out answer but ultimately it comes down to experimentation with one's room and equipment I guess.

The one thing I can say without reservation is that lower crossover points are always beneficial assuming the main speakers are capable enough.
 
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