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Post by Hair Nick on Apr 1, 2020 9:16:29 GMT -5
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Post by audiobill on Apr 1, 2020 16:22:19 GMT -5
Most bass or best bass?
Two very different objectives......
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ttocs
Global Moderator 
I always have a wonderful time, wherever I am, whomever I'm with. (Elwood P Dowd)
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Post by ttocs on Apr 1, 2020 16:25:03 GMT -5
When I want to get the most bass out of the room I just open the door.
edit: After watching the video, how do I give it 2 Likes? Very well explained, even though Lonnie was running out of ink.
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KeithL
Administrator
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Post by KeithL on Apr 1, 2020 16:53:13 GMT -5
Indeed.....
To get the MOST bass simply stuff your subs into the corners.... (The corner where two walls meet the floor or ceiling will yield the most room reinforcement possible.)
But, quite often, the result will be gobs of boomy and rather unpleasant sounding bass... But you will get lots of it...  Most bass or best bass? Two very different objectives...... |
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Post by audiobill on Apr 1, 2020 16:55:59 GMT -5
Yes, some will stuff subs in corners then use Dirac to flatten everything out , lol
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Post by donh50 on Apr 1, 2020 16:56:59 GMT -5
All I can think of is the singing fish on the wall plaque... Different kind of bass. Here is a link to the Harman site if you want additional reading material. Todd Welti's paper should be required reading for anyone considering placement, especially of multiple subs. www.harman.com/audio-innovationsHTH - Don |
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Post by novisnick on May 2, 2020 12:34:41 GMT -5
Question arises for a novis, I may be the only one asking but the answer may help many others.
Which Crossover slope do you use for music and is that slope different for movies (HT)? And why. I have read many pages and have used 24dB/Octave for a long time but am I correct in my choice?
Thanks
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Post by fbczar on May 2, 2020 15:59:50 GMT -5
Question arises for a novis, I may be the only one asking but the answer may help many others. Which Crossover slope do you use for music and is that slope different for movies (HT)? And why. I have read many pages and have used 24dB/Octave for a long time but am I correct in my choice? Thanks It depends on whether your subwoofers are sealed or ported and it depends on whether your speakers are sealed, ported, transmission line, etc. If they are all sealed then 12 db Octave is correct. If they are all ported then 24 db Octave is likely correct. If you are mixing speaker and subwoofer types your best bet is to experiment and listen. |
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Post by Gary Cook on May 2, 2020 17:26:07 GMT -5
Been thinking about the VSUB-1 for a while, not for a subwoofer but for a rear pair of Airmotive 4's. In my daughter's apartment they are located close by power outlets but I have to run interconnect cables to them around the room, over doorways, under windows etc. That could be avoided if there was full frequency range equivalent system, say a Virtual Copper Digital Wireless Full Range. She did have a Sonos wireless system before but its sound was just horrid hence the change to 5 x Airmotives (3 x 6's and 2 x 4's). I assume there must be some technical reason KeithL or Lonnie why subwoofer wifi is OK, but full range has some issues? Cheers Gary |
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Post by megash0n on May 2, 2020 17:30:32 GMT -5
Been thinking about the VSUB-1 for a while, not for a subwoofer but for a rear pair of Airmotive 4's. In my daughter's apartment they are located close by power outlets but I have to run interconnect cables to them around the room, over doorways, under windows etc. That could be avoided if there was full frequency range equivalent system, say a Virtual Copper Digital Wireless Full Range. She did have a Sonos wireless system before but its sound was just horrid hence the change to 5 x Airmotives (3 x 6's and 2 x 4's). I assume there must be some technical reason KeithL or Lonnie why subwoofer wifi is OK, but full range has some issues? Cheers Gary Are these the ones that do full range? I remember Keith going over this topic at some point. |
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Post by Gary Cook on May 2, 2020 17:35:45 GMT -5
Been thinking about the VSUB-1 for a while, not for a subwoofer but for a rear pair of Airmotive 4's. In my daughter's apartment they are located close by power outlets but I have to run interconnect cables to them around the room, over doorways, under windows etc. That could be avoided if there was full frequency range equivalent system, say a Virtual Copper Digital Wireless Full Range. She did have a Sonos wireless system before but its sound was just horrid hence the change to 5 x Airmotives (3 x 6's and 2 x 4's). I assume there must be some technical reason KeithL or Lonnie why subwoofer wifi is OK, but full range has some issues? Are these the ones that do full range? I remember Keith going over this topic at some point. Cheers Gary |
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Post by Boomzilla on May 2, 2020 23:56:39 GMT -5
I believe Mr. Mandara has over-simplified. If mass reduction were the biggest factor in achieving "fast" bass, then we'd all have subs powered by ribbon tweeters. Yes, it is true that larger cones have more mass, but if sufficient current (and magnetic field) can be applied to the woofer's coil, then the greater mass can be just as effectively controlled for a 21 inch diameter cone as for an 8 inch diameter one. And the 21 inch diameter cone can move a LOT more air.
I agree with Nick that subwoofers are very high distortion, and one of the greatest contributors to that distortion is cone excursion. For the same SPL, an 8-inch diameter cone has to have a LOT more excursion than a bigger one. Exponentially so, in fact. So it is a fact that a large cone, with low inductance and a strong magnetic field around the coil will need significantly less excursion to produce the same SPL as an 8" sub - AND the larger sub would play with a LOT less distortion.
So why don't manufacturers make big subs like that? In a word, cost. Low inductance woofer coils that can tolerate high current without excessive heating are expensive. High magnetic flux magnets are expensive. High-current amplifiers to power such drivers are expensive. And the larger cabinets that must have additional bracing are expensive.
So yes, two 8-inch subs are definitely better than one 8-inch sub, but two GOOD 15" subs will blow the 8" ones away.
Cordially, Boomzilla
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KeithL
Administrator
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Post by KeithL on May 3, 2020 1:26:05 GMT -5
I suspect that Nick neglected to completely dig into all the details behind that statement... ALL ELSE BEING EQUAL, with a motor assembly of equal strength, a lighter cone will accelerate more quickly.
It will also store less energy because it has less momentum...
I should point out that lack of acceleration is NOT the main reason why many subs sound "slow". An 8" woofer, producing a certain SPL level at 20 Hz, will be moving at exactly the same velocity as any other driver of similar size producing the amount of the same frequency.
And, to be fair, most subs have quite powerful motor assemblies, and powerful amplifiers, which are quite capable of accelerating their cone up to full deflection quite quickly. And, while it is an important electrical parameter, the idea that a voice coil with a lot of inductance will "slow down a woofer" is also a bit of a red herring.
The main reason a sub will sound "slow" rather than "quick" is that it stores too much energy... And, if a sub stores too much energy, when it is tasked with playing a short sharp sound, it will exhibit a lot of ringing after the sound stops... This will cause what was supposed to be a short sharp bump, or a pop from a drum, to spread out and sound more like "booooommmmmm" than a "THwaK!!!". And this is what most of us perceive as "sounding slow".
And, the heavier the cone, the more momentum it has, and the more energy it will store, and the longer that energy will take to dissipate.
In simplest terms, the ideal driver for ANY speaker would be massless, so all of the energy expended could be used to move air. And no energy would be wasted in accelerating the driver itself... And no energy would be stored in the driver that would need to be gotten rid of afterwards...
And, while there are lots of reasons why a woofer cone can't really get very close to that ideal, a lighter cone is still a closer approach to it.
You are also glossing over an other important factor.... A woofer is not anywhere near "a perfect piston being pushed back and forth by a motor".
A woofer cone is subject to an impressive amount of stress.... Therefore a woofer cone must be very stiff and strong to act even close to ideal piston and avoid flexing and deforming in ways that will generate huge amounts of distortion. The simple reality is that it is relatively easy to make a small cone strong and stiff... But, as the cone gets larger, making it equally stiff usually requires that it be make stronger, and thicker... and, in the end, heavier... The reduced excursion of a large driver has benefits in terms of reducing the need for extremely linear movements over large distances... This simplifies some factors involved in motor design.
But it imposes MORE complex requirements on the design of the cone and suspension.
I believe Mr. Mandara has over-simplified. If mass reduction were the biggest factor in achieving "fast" bass, then we'd all have subs powered by ribbon tweeters. Yes, it is true that larger cones have more mass, but if sufficient current (and magnetic field) can be applied to the woofer's coil, then the greater mass can be just as effectively controlled for a 21 inch diameter cone as for an 8 inch diameter one. And the 21 inch diameter cone can move a LOT more air. I agree with Nick that subwoofers are very high distortion, and one of the greatest contributors to that distortion is cone excursion. For the same SPL, an 8-inch diameter cone has to have a LOT more excursion than a bigger one. Exponentially so, in fact. So it is a fact that a large cone, with low inductance and a strong magnetic field around the coil will need significantly less excursion to produce the same SPL as an 8" sub - AND the larger sub would play with a LOT less distortion. So why don't manufacturers make big subs like that? In a word, cost. Low inductance woofer coils that can tolerate high current without excessive heating are expensive. High magnetic flux magnets are expensive. High-current amplifiers to power such drivers are expensive. And the larger cabinets that must have additional bracing are expensive. So yes, two 8-inch subs are definitely better than one 8-inch sub, but two GOOD 15" subs will blow the 8" ones away. Cordially, Boomzilla |
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Post by Boomzilla on May 3, 2020 4:49:21 GMT -5
...An 8" woofer, producing a certain SPL level at 20 Hz, will be moving at exactly the same velocity as any other driver of similar size producing the amount of the same frequency... Velocity - yes. But not at the same volume. The 4-cylinder engine in my Accord hybrid can turn the same RPM as the V8 in my neighbor's hot rod - but it doesn't produce the same horsepower. Bigger speaker cones need less excursion to produce the same room-volume (move the same amount of air). Everything else you say is (as always) spot on. Interestingly, one of the more innovative drivers I've seen was in a pair of three or four way Sony speakers I once owned. The bass driver itself was a flat plate with multiple voice coils attached to it, working in tandem. The rigid, but light plate was VERY well controlled by the multiple pistons and tended not to flex at all. The thing was so rare that I can't even find a photo of it on Google. I had to send the drivers off to get square surrounds custom made for the things. But I thought that the "rigid piston" concept was more fully realized in those speakers than any others that I've seen. |
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ttocs
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Post by ttocs on May 3, 2020 6:56:38 GMT -5
Interestingly, one of the more innovative drivers I've seen was in a pair of three or four way Sony speakers I once owned. The bass driver itself was a flat plate with multiple voice coils attached to it, working in tandem. The rigid, but light plate was VERY well controlled by the multiple pistons and tended not to flex at all. The thing was so rare that I can't even find a photo of it on Google. I had to send the drivers off to get square surrounds custom made for the things. But I thought that the "rigid piston" concept was more fully realized in those speakers than any others that I've seen. Were they something like this?  Kef and IMF had similar. |
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Post by Boomzilla on May 3, 2020 7:29:32 GMT -5
Were they something like this? Kef and IMF had similar. Similar, but not identical. If I remember correctly, mine were four-way systems in a much, much larger floor-standing walnut cabinet. The gent I bought them from said that they'd been a REALLY limited production, and that only a handful of them were ever sold in USA. |
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Post by bluescale on May 20, 2020 12:49:23 GMT -5
This video does a good job of explaining, in simple terms, why dual subwoofers are important in a room. What I would love to see is a video about integrating dissimilar subs. The example in this video was about utilizing a 15" and this 8" sub. That is FAR from a plug and play integration. This sub could be perfect as a mid-bass module in a larger system. Now that would be an interesting video topic.
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