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Multi-Way Conventional loudspeakers with crossovers

15 inch woofers: which have low moving mass?
15 inch woofers: which have low moving mass?
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Old 4th October 2009, 05:08 AM   #41
GM is offline GM  United States
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Quote:
Originally Posted by freddi View Post
re:Karlson - dunno if higher mass woofers are appropriate
Well, they are if you want a lower tuned K, i.e. its gain BW shifted lower for true (sub)woofer duty.

GM
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Old 4th October 2009, 02:04 PM   #42
angeloitacare is offline angeloitacare  Brazil
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Originally Posted by exurbia View Post
If you can find a pair I would recommend the Yamaha JA3882, it is not easy to use and won't work in Onkens. The magnetic circuit is 13 kG, 4" VC, mms of 52G. The ideal is horn loaded as it has ultra low Qts and reasonably high Vas.
This driver makes any other 15 I have heard sound fat and slow, it leaves the fabled 515 sounding like an 80 year old dog (if it were possible). This, in a pair of Altec 210 cabs. One side running the Yammies the other the 515's.
This is the best there is. Not that I am biased nor in the slightest one eyed. I will dig out the PDF and post it. If possible I will post some pictures as well.
http://audio-heritage.jp/YAMAHA/unit/ja-3882.html



型式 38cmコーン型ウーファー
公称インピーダンス JA-3882:8Ω
JA-3882B:16Ω
再生周波数帯域 30Hz~4kHz
推奨使用帯域 20Hz~1.5kHz
定格入力 150W
最大入力 300W
出力音圧レベル 102dB/W・m
ボイスコイル口径 100φmm
等価質量 71g
Qo 0.13
fo 30Hz
マグネット フェライト、2.9kg
磁束密度 13,000gauss
総磁束 367,600maxwell
推奨箱容量 約300L
外形寸法 直径390mm×高さ148mm
重量 11.6kg
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Old 4th October 2009, 02:26 PM   #43
elac310 is offline elac310  France
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Impressive; something (Mms??) says "71g".

It seems that the (Mms?) 58g version (but 66,6 mm voice coil?) would be the JA3881
http://audio-heritage.jp/YAMAHA/unit/index.html
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Old 4th October 2009, 03:06 PM   #44
exurbia is offline exurbia  Australia
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Default low mass cones

I have a cone and voice coil from the Yammie, no surround or spider. It weighs in at 51 Grammes. I allowed a couple of grammes for the part of the spider that would be moving, assuming that it wouldn't be very much.
So the Yammie spec may be correct as the surround would be another 10 Grammes at least.
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Old 4th October 2009, 04:00 PM   #45
freddi is offline freddi  United States
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15 inch woofers: which have low moving mass?
Quote:
Originally Posted by GM View Post
Well, they are if you want a lower tuned K, i.e. its gain BW shifted lower for true (sub)woofer duty.

GM
416 in Exemplar tuned K15 sound far better than woofers I've tried (Eminence built) with twice their mass. Those B&C in RAC-Fan's reflex pay a 6dB price in midrange sensitivity vs woofer with half the mass and are lifeless. Bulk for bulk a skinny pipe such as reverse tapered transflex would outperform K15 at at 40Hz. K might play cleaner in upper bass and are widerange with good coax or wideband. For a Karlson woofer I'd like an 18" with 5mm xmax, qts of 0.25, mms of 80g and xmax of 6mm
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Old 5th October 2009, 02:00 AM   #46
CLS is offline CLS  Taiwan
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18" with 80g Mms, that's pretty rare nowadays. These big guys are getting heavier and heavier. Over 200g Mms is commonly seen.

I remember EV DL18X had a very light cone, but it seemed no longer available.
http://archives.telex.com/archives/E...%20EDS.pdf
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Old 5th October 2009, 09:29 AM   #47
tinitus is offline tinitus  Europe
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15 inch woofers: which have low moving mass?
Quote:
18" with 80g Mms
You dont want bass ?

http://www.faitalpro.com/products/sc...p?id=151070100
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Old 5th October 2009, 03:05 PM   #48
freddi is offline freddi  United States
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15 inch woofers: which have low moving mass?
I didn't like the subjective quality of bass with 130g Eminence 18 in 8.2 cubic foot reflex - in contrast a 103g 0.25qts 18" Eminence in a little 6.4 cubic foot reflex sounded better - I did have fun with the 130g 18" in two k-couplers where the quality improved.

6.4 cubic foot RJ vented reflex with lighter 18" - I had two 8.2 and two 6.4 cubic foot reflex running - loud but not very musical
Click the image to open in full size.
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Old 5th October 2009, 03:21 PM   #49
GM is offline GM  United States
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Quote:
Originally Posted by freddi View Post
416 in Exemplar tuned K15 sound far better than woofers I've tried (Eminence built) with twice their mass.

K might play cleaner in upper bass and are widerange with good coax or wideband.
Freddy, you seem to be missing my point, all else equal, driver mass needs to increase with decreasing gain BW, so a different K alignment will be required for higher mass drivers.

Since you have a library of good measurements, sim the K15 as a 6th order BP and adjust it till its nominal response matches your half space measurements, then match it with a higher mass driver to find its optimum K alignment with the caveat here that 'optimum' is a personal choice. In theory, you can then scale the missing chambers and slot area. Do this with a variety of driver specs and a good enough design trend should emerge to maybe get enough folks to try them same as happened with the 'BIB' pipe horn.

That said, since tapped reverse tapered pipes (T-TQWT) approximate the K with an incredibly 'fast' final expansion, it seems reasonable to me that using Hornresp's TH Wizard to find the trend would be the way to go, then once David mods HR to allow reverse tapers to export to AkAbak, the missing chamber design details should become relatively trivial.

WRT K-coax designs, why not try a TH-coax since designing a TH has become such a relatively trivial pursuit? Mark K's UNHORN shows the basic design concept to mostly mimic a K15.

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Old 5th October 2009, 09:54 PM   #50
freddi is offline freddi  United States
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15 inch woofers: which have low moving mass?
hi GM - i don't have a BP simulator on this mac - any guesstimates to chamber sizes and appropriate driver? Freddy

inverse taper transflex with 295-070
http://www.youtube.com/watch?v=UJTctkDPKpE

Last edited by freddi; 5th October 2009 at 09:59 PM.
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