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Post by gottavtr on Apr 20, 2013 2:26:39 GMT -7
Looky looky
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Post by ThomasW on Apr 20, 2013 6:35:59 GMT -7
Mgrs have offered big woofers since the 1940's. EV (Electro Voice) had a system that used a 32" driver. Thing was it had to be rotated every few months to prevent the surround from sagging.
One must be VERY careful with drivers larger than 18", reason being they're so large/heavy they become unwieldy to maneuver and are easily damaged as a result.
Doing anything with a 24" driver is a two person job.....
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Post by tinnears on Apr 20, 2013 20:32:28 GMT -7
I'll take six of them, please.
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Post by FOH on Apr 21, 2013 6:37:03 GMT -7
Those mammoth cones do present logistical issues. But I say bring them on. Problem is there exists a sweetspot in mfg of drivers, 18" is it. Much past that and expense barely justifies the effort, some have figured it out though. They've got to sell enough to make the price reasonable. Thomas is right, the big cones are nothing new. Mitsubishi has had the large 80cm(31"), and the enormous 160cm(63") driver. I'm not sure what's offered now, but like EV ... they had there big drivers too. Here's the 31" D-80 vented; Then the mammoth D-160, 63" monstrosity below; The D-160 is my avatar at the Data-Bass driver measurement/forum website.
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Post by mtbdudex on Apr 23, 2013 17:47:38 GMT -7
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Post by electrodynamic on Aug 9, 2013 19:52:21 GMT -7
Mgrs have offered big woofers since the 1940's. EV (Electro Voice) had a system that used a 32" driver. Thing was it had to be rotated every few months to prevent the surround from sagging. One must be VERY careful with drivers larger than 18", reason being they're so large/heavy they become unwieldy to maneuver and are easily damaged as a result. Doing anything with a 24" driver is a two person job..... Back in the early 1940's that may have been the case but we know about mass balance now so you don't have to worry about rotating the woofer anymore. Suspensions are a bit better too. IIRC they were using 4" spiders on large 21" drivers at the time. I think the Hartley was even smaller than 4". The SI 24" uses a multi-layer nomex spider that's 11" diameter along with a wide tall linear surround that is good for over 40mm each way before running into stress issues. If you are using an IB woofer in an attic or craw-space you have the room for a 24. All IB installs I have done have been in an attic but I know of some that were performed in a crawl space with good results too. Bring on Stereo Integrity's 24...no other single driver out-displaces it.
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Post by FOH on Aug 11, 2013 8:44:36 GMT -7
This driver is interesting, for sure. I appreciate you dropping by here.
I'm curious about the bottoming characteristics, can you share some details on how it's made? Does it run out of magnetic force, suspension limited, or does the VC/former encounter the back plate? I ask because I'm curious about re-coning services too, available?
I'm interested in any links you could offer up with DIY'ers utilizing these in any config, IB or otherwise.
Thanks for stopping by, I'd love to see Josh Ricci and Data-Bass measure one of these.
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Post by electrodynamic on Aug 11, 2013 19:31:09 GMT -7
This driver is interesting, for sure. I appreciate you dropping by here. I'm curious about the bottoming characteristics, can you share some details on how it's made? Does it run out of magnetic force, suspension limited, or does the VC/former encounter the back plate? I ask because I'm curious about re-coning services too, available? I'm interested in any links you could offer up with DIY'ers utilizing these in any config, IB or otherwise. Thanks for stopping by, I'd love to see Josh Ricci and Data-Bass measure one of these. Haha, I think Ricci would crap his pants if he got a hold of one of these. I'll shoot him an email to see if he's interested. It looks as if he's almost completely 18" subwoofers only...maybe we can break that. The speaker will bottom out via the bottom of the voice coil former hitting the bumped backplate. The drivers can be re-coned if someone burns one up. The suspension uses very large parts and every piece is very linear, not progressive, so the driver simply keeps going until you get a WHACK from the coil hitting the back plate. It would take a good bit of power to bottom it out using extremely low frequencies. Dare I say you might have to be trying to bottom it out to get it that far (like the Terminator theme song on the Telarc demo CD at full tilt). At that point you're getting a 24" woofer to move over 3.5" peak to peak.
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Post by FOH on Aug 12, 2013 6:25:21 GMT -7
[/quote]Haha, I think Ricci would crap his pants if he got a hold of one of these. I'll shoot him an email to see if he's interested. It looks as if he's almost completely 18" subwoofers only...maybe we can break that. The speaker will bottom out via the bottom of the voice coil former hitting the bumped backplate. The drivers can be re-coned if someone burns one up. The suspension uses very large parts and every piece is very linear, not progressive, so the driver simply keeps going until you get a WHACK from the coil hitting the back plate. It would take a good bit of power to bottom it out using extremely low frequencies. Dare I say you might have to be trying to bottom it out to get it that far (like the Terminator theme song on the Telarc demo CD at full tilt). At that point you're getting a 24" woofer to move over 3.5" peak to peak. [/quote] Thanks for the explanation. I'm always curious about bottoming characteristics, as being an IB owner there's so many infra pulses that one encounters, you've got to be ready and take steps to avoid damage. Myself, my IB aspect of my sub system is power limited. I'm not interested in a high pass, and I'm not interested in damage, ... therefore I took conscious steps to be power limited. Worry free, all around..all seven loudspeaker channels are active, .... I can't encounter any real limits and be in the same room. Myself, and I'm sure many others would agree, would absolutely love to see that big monster be ran through the paces! Then, pick a couple up and add to my IB capability. Thanks
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Post by electrodynamic on Aug 14, 2013 18:59:16 GMT -7
I didn't know if I should make another thread about this but we are raffling off one of our 24" IB subwoofers for a good cause. Here is all of the information:
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Post by twisterz on Aug 17, 2013 19:51:19 GMT -7
Stereo Integrity 24” IB Subwoofer
24" D2 Re: 3.7 Ohms Fs: 20 Hz Qes: 0.57 Qms: 12.2 Qts: 0.55 Le: 5.3 mH Sd: 212943.8 mm^2 Vas: 595 l BL: 23.6 Mms: 671 g Cms: 92.3 Sensitivity (1W/1m): 91 dB Xmax: 36mm
Recommended enclosures: 24": Infinite Baffle Cutout: 22 and 5/8’ths" OD: 24.5" Mounting depth: 13.25" Mounting flange to top of surround: 1"
Price: $699 plus shipping
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Post by FOH on Aug 18, 2013 7:11:43 GMT -7
It's nice to have Nick from SI stop by and keep us informed on his offerings, for sure. Perhaps Nick can elaborate, but it's my understanding that these T/S parameters may change in the final version.
I would enjoy seeing a build with drivers like these, but damn they would be unwieldy.
Thanks
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Post by electrodynamic on Aug 18, 2013 19:37:30 GMT -7
We are currently still developing this subwoofer. We have four different spider packs ranging from a "soft" pack to the normal "medium" pack (we also have some REALLY hard stuff that is not suitable for home audio) that we are using to build these prototypes. We can adjust Qts from the stock 0.7 to as low as 0.5 depending on what kind of response is desired and amount of power the customers has. The neat thing about developing this woofer and keeping the forums updated about our progress is you guys get to you see the changes / improvements. For instance, we will be using a coil for production that has half the inductance of what have published on the web site right now without sacrificing any Xmax.
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Post by electrodynamic on Aug 18, 2013 19:41:56 GMT -7
Here is the most recent video that we took when I brought our 3500 watt amplifier into clipping to show a little more excursion:
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Post by FOH on Aug 19, 2013 9:43:19 GMT -7
Thanks for that.
Merely estimating, but it would appear that if the 24" measurement is from outer edge of surround, I estimate 2.84 inches peak to peak travel in that video. This equates to 36.1mm excursion each way. Again, a very loose eyeball estimate.
Interesting comments regarding inductance, low inductance is good. How about efforts to linearize inductance across the stroke?
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Post by electrodynamic on Aug 19, 2013 19:51:00 GMT -7
Thanks for that. Merely estimating, but it would appear that if the 24" measurement is from outer edge of surround, I estimate 2.84 inches peak to peak travel in that video. This equates to 36.1mm excursion each way. Again, a very loose eyeball estimate. Interesting comments regarding inductance, low inductance is good. How about efforts to linearize inductance across the stroke? There is a thick inner magnet diameter shorting ring inside the motor and the huge aluminum spacer/adapter acts as a shorting ring on top of the motor. Like you said you want to linearize and lower inductance, not simply lower it, and you can actually over-shorting-ring a motor which causes an inductance spike which hurts more than originally intended. This isn't an XBL^2 motor, which is king of stabilizing and lowering inductance, but it is a very good sounding and good performing overhung motor. If Le was 11 mH and Re was 3 Ohms there would be an issue to address, haha. With Re and Le being a 1:1 ratio with the new coil I think are good to move forward with production.
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