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The making of: The Two Towers (a 25 driver Full Range line array)
The making of: The Two Towers (a 25 driver Full Range line array)
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Old 19th November 2019, 09:18 PM   #5301
daanve is offline daanve  Netherlands
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Quote:
Originally Posted by Juhazi View Post
A week ago I was at my friend's place listening and measuring AE 18" IBHT subwoofer, Mms 250g IB18HT - Home Theater Infinite Baffle Woofer - Subwoofer

Nearfield response was flat 20-1500Hz! It sounded nice and clean without xo, powered by 1200W ICEpower module.
That is what the 30W can do also (break up not until ~ 3 kHz):

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Old 19th November 2019, 09:20 PM   #5302
nc535 is offline nc535
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We could argue all day long about the woofer speed issue but the only thing that could/should resolve it would be a double blind test. Can you hear the difference between the two subs when they are eqed to the same freq response?

Consider that those long throw woofers with heavy cones and thus require strong motors, which results in high Le. That high Le leads to an early HF roll off making that kind of woofer less well suited for operation above 100 Hz.

At the same, I've seen slot loaded sub designs where the slot is designed to function as a horn (edit: and bandpass chamber) and provide gain just where the high Le is causing the response to start to roll off, thus extending the response without boosting the high end. That might be a problem at high output where the cone doesn't move enough to cool the voice coil.

So you really can go round and round on this. But if you want a true woofer instead of a pure subwoofer and select based on smoothness and flatness of response up to 500 Hz or 1 Khz or so, you will likely end up with a low Le woofer which correlates with having a light weight cone.
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Last edited by nc535; 19th November 2019 at 09:26 PM.
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Old 19th November 2019, 10:41 PM   #5303
BYRTT is offline BYRTT  Denmark
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The making of: The Two Towers (a 25 driver Full Range line array)
Think the speed problem is the relative difference in inductance data L(e) per band pass, so say woofer and tweeter band had same L(e) data the problem wasn't there or we can set XO point for woofer a tad low enough before its inductance start the climbing on the graph, low L(e) is one reason JoeRasmussen in his Helsinore build use those 7 inch SBA woofers to integrate with his tweeters because their L(e) is as low as 0,13mH.

L(e) is a distortion the higher the frq the bigger the time delay, but not shure our hearing can reconize the short time distortion listening to say one transducer at a time, but when summing two drivers with different L(e) harmonics as frq goes up can get out of timing no matter time sum is perfect in the low end so get it crossed below that point, most often transducers with advanced motors have improved L(e) numbers probably to help integrate with tweeters.

Think not wesayso should get any L(e) coursed speed problems as seen below : )

The making of: The Two Towers (a 25 driver Full Range line array)-wesayso_3-png
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Last edited by BYRTT; 19th November 2019 at 10:46 PM.
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Old 19th November 2019, 11:43 PM   #5304
HammerSandwich is online now HammerSandwich
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Originally Posted by nc535 View Post
that is why I was looking at 8"s configured like the array of 10's along the wall in your pictures with my array next to it and a layer of absorption (acting as an LPF for the sub) in front of it to absorb reflections from the array.
Clever idea! Using the damping for 3 purposes (add HD reduction from sub) is fantastic design.

Quote:
Originally Posted by wesayso View Post
But fast? 100 Hz is 100 Hz etc. You can't pay it faster or it would become 101 Hz (lol).
Funny. I'm stealing that when I get the chance.

I'm not a "fast bass" proponent, but there is another way of looking at it. Suppose you play a 50Hz sine at 83dB. Now turn it up to 95dB. How fast is the cone moving (cm/sec) in both scenarios? Could a lower Mms cone respond better in a dynamic situation, when the SPL isn't static?
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Old 20th November 2019, 01:57 AM   #5305
perceval is offline perceval  Taiwan
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Originally Posted by scottjoplin View Post
The 5 cycles was mentioned by Earl Geddes in respect to subwoofers and supposed directionality in a room, he commented that the wave had bounced around the room a few times before the pitch was perceived.
As I see/hear it, this is what most people attribute the "slow bass" moniker.
The multiple booming reflections arriving during a period of time takes the snappiness of it away.

So, most of the time, it is the room which is the culprit.
Adding a couple of bass traps will improve on that.

Of course, if one gets a very cheap sub that has no cone control and is flapping endlessly, then that distortion will also contribute to the perceived slow bass, but with any of the nice subs or woofers out there, without needing to spend outrageous amounts of money, it is very possible to get a very nice and tight sounding bass with placement, adjusting delays, some EQ because we usually don't have the chance to have the perfect room, and adding some form of bass traps to deal with that room.
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Old 20th November 2019, 03:12 AM   #5306
Robbintip is offline Robbintip  Netherlands
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Back when I knew even less of loudspeakers than now, I used to place my subwoofer at LP and then look for the place in the room it sounded 'best'. Then placed subwoofer at that spot. I had the idea that it worked, however the space beind 3rd dimensional, it could make for some very impractical subwoofer placement locations
To the contrary, if the room is very long, it might also open up some new subwoofer locations at the other end of the room. I'll be laughing out loud if this leads to new pictures of random stuff taking up space for his other half to get used to the idea

On a more serious note,
'Fast' bass, I think has to do with spectral decay/impuls response.
Hypothesis: At <25Hz, the 40ms(?) window to perception of these things as a seperate quality opens up...
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Old 20th November 2019, 04:37 AM   #5307
Robbintip is offline Robbintip  Netherlands
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For people looking for drivers: Keep in mind, that not every woofer needs the same excursion to achieve the same SPL. Xmax therefore is a number, but only one of many.

More about Xmax: value is defined as the maximum excursion that is within "reasonable" limits of distortion. These "reasonable" limits could be and often are: 10% THD. And that is, if the manufacturer adheres to the "standard" lol. This can not be considered reasonable for anyone that's serious with audio.

Klippel reports are valuable.
For high fidelity, I would prefer a driver which shows an absolutely flat klippel curve over 10mm, if it has a 12mm Xmax, over a driver that has 30mm Xmax but only shows a straight klippel response over 8mm.

When listening to music, I stay withing limits of the straightest part of the curve.
Under 15Hz, it becomes more difficult to hear with the ears alone. This is where I don't experience non-linear excursion as problematic. Movie effects can still be had while designing a system for music is what I'm trying to convey.

Also, it's usefull to keep output voltages in mind too when designing your boxes, subwoofer or not.
Click the image to open in full size.
Black= 2.83v, Blue = 33V. The lower two curves we are interested in (closed box).
I wonder if Klippel curves would differ too? I heard DUMAX might have answers to this.

@wesayso: Excursion linearity, power linearity, box size, phase and frequency response... MFB can lessen the strain on requirements, enabling more freedom in driver and design choices for subwoofers a lot. Take a look on MFBlabs.nl. When using MFB regard the lowering of distortion as a nice bonus ;-)

Also, I saw a couple of posts on ambient tweeters a few pages back.
Have you considered using a low shelving filter instead of low pass filters in your ambient speakers?
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Old 20th November 2019, 02:13 PM   #5308
koldby is offline koldby  Denmark
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Originally Posted by nc535 View Post
that is why I was looking at 8"s configured like the array of 10's along the wall in your pictures with my array next to it and a layer of absorption (acting as an LPF for the sub) in front of it to absorb reflections from the array.
Indeed a clever idea. Have you seen this implemented anywhere? I tried to dig a little around for some experience with such an arrangement, but could't find any. I might steel that idea, when I finally do my line array subs..
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Old 20th November 2019, 02:23 PM   #5309
nc535 is offline nc535
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Haven't seen it anywhere else. Straightforward analysis and thinking shows that it "should: work. Boundary interference calculator will tell you where the boundary nulls are for the HF array. Passive absorber calculator will tell you thicknesss of absorber to kill those nulls and then how much of the LF will pass through that thickness.
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Old 20th November 2019, 02:43 PM   #5310
HammerSandwich is online now HammerSandwich
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Originally Posted by Robbintip View Post
Black= 2.83v, Blue = 33V. The lower two curves we are interested in (closed box).
Are you certain that is correct?
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