15 inch woofers: which have low moving mass?

[GM]

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

 

[angeloitacare]

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

 

[elac310]

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

 

[exurbia]

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.

 

[freddi]

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

 

[CLS]

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/EV/Drivers/EDS/DL18X EDS.pdf

 

[tinitus]

18" with 80g Mms

You dont want bass ?

http://www.faitalpro.com/products/schede/fhs.php?id=151070100

 

[freddi]

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

An externally hosted image should be here but it was not working when we last tested it.

 

[GM]

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.

GM

 

[freddi]

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

 

[CLS]

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 ....

This maybe overly generalized, however I'm still wondering if this is the reason that most people tend to prefer 15"ers. Almost all friends around me don't like 18"ers, they think they sound dumb and not any better in low end extension

 

[GM]

Greets!

Neat video presentation! BTW, I couldn't find a PE? 295-070 part number, but I thought the 295-080 to be their ~ JBL 2226 clone, so wondering if this is a typo.

Anyway, not sure which scenario I talked about that you're asking about and due to being 'up to my eyeballs' in a ~whole house restoration (amazing how much one can deteriorate over a 10 yr. period of neglect), don't have much time to devote to any hobbies beyond a few 'easy' responses for probably 6-12 mos. depending on how much grief my body gives me, so just 'ran the numbers' for an optimized (by my way of thinking) of the T(K)-TQWT you built for a frame of reference.

GM

 

[freddi]

295-070 was a short lived driver I carped about some years back with coated curvilinear cone - it works well enough in Bruce's Monolith and the 1-sheet inverse taper pipe but didn't sound very good as a direct radiator or in Karlson - my house needs a roof!

Dayton 295-070 105oz magnet, power = 250 watts, Voice Coil = 3 in., Spl=95.23dB, Re= 5.4ohm,
Fs = 26.4, Qms=8.25/Qes=0.300, Vas= 11.986 cu.ft., Qts=0.29, Le = 1.4mH, BL = 18.2, Xmax = 7.8mm, Sd = 132.7 sq.in.
weight ~20lb, no = 2.007%

thanks for the hornresp work - I'll have to save that and go back to my pc to see what happens - maybe for subs I should just do 15.5" inside width version of Cowan's 30Hz TH-?

 

[GM]

Yeah, mine too! Hopefully with a little help from my friends I'll get my workshop roof replaced Halloween weekend and siding soffit replacement soon after. Might even get to build some speakers before it gets too cold.

Bummer, looks good in a TK-TQWT when tuned to Fs..........

You're welcome!

??? Which driver for WC's TH?

Anyway, from these two sims it seems a simple TTQWT K-15 'wannabe' that covers the majority of its gain BW will need a 40-50 Hz Fs driver with ideally a HF mass corner that equates to a ~15.5" driver mounting width = ~218.71 Hz. Know of any, and any K-guys willing to gamble the price of a driver, materials to build a proof-of-concept?

GM

 

[kenpeter]

Zobsky has been talking up a tapped horn build. If you could convince him to try
something that size when he finishes his K12 builds, I got a Sigma18 he can borrow
for test purpose. And he also owns a killer University 15 woofer that might find a
use in a tapped horn or K loaded sub project...

Sigma 18 works in a K15, but no better than a 15. Running up on box size as the
limiting factor? Hoffmans's iron law etc etc...

 

[kenpeter]

A pair of KappaPro 10's has a good spec too. Especially if you want to keep
the waveguide narrower than 15 allows, and go long instead. I was thinking
something like this... With the upper 10 turned backward, and some overlap...

 

[GM]

Yeah, between using Prof. Leach's math to 'run the numbers' and HR to sim them, many TK-TQWT alignment combinations become possible to choose from before making any dust.

I haven't learned AkAbak yet to try and convert one to the K's multiple resonant chambers which will reduce the path-length considerably at the expense of relatively high wide BW group delay (GD). I'm hoping that a trend will emerge that will allow a simple design routine such as a 2:1 chamber/tuning reduction up to the front chamber to mimic an expo flare, then back to a 3:1 WRT the rear chamber Vb same as for an optimum two octave 6th order BP.

GM

 

[elac310]

Oberton

I've continued my search and have come accross a few interesting woofers, especially the OBERTON 15L400 Oberton Professional sound systems

This one looks very much like one that was made by German manufacturer Solton/Craaft before they stoped manufacturing speakers.

Mms is 56g
Fs still reasonably low: 43Hz
Bl is 16.8 which is more than enough to move the 56g and not too much to avoid over-damping.
Qts is 0.287 which is more than OK for bass reflex
Vas: 223 L

Those who like low inductive voice coils will be pleased to learn that this beast has only 0.62 mH (with Xmax 3.25 mm).

And it's an 8ohm speaker, so two units in parallel is possible

Rms at around 1.32 promises a detailed articulated bass even at low levels.

I did a few sims; this kind of woofer needs a large enclosure to reproduce bass. I'll have another look, I think I saw another model with Mms about 70 to 80g.

Chris.

 

[kevinkr]

Iconic Manufacturing (165 series) or Great Plains Audio (515 series) variations on the old Altec 515 family might also be of interest. They are expensive even before shipping, but I thought I would mention them. (I can recommend the Iconic 165-8G as I use it in my Onkens)

 

[elac310]

Thanks. The GPA were mentioned in an earlier post and I managed to obtain parameters from them (especially Mms). The Iconic pages have been under construction for years and as I can see, there is still no data available but I could have missed something.
Chris