Beyma 10MW/Nd

[Nordskov]

I know some of these drivers has been under the microscope before, but I can't find a review on this one.

Beyma 10MW/Nd:

350W RMS

Resonant frequency, fs: 47 Hz
D.C. Voice coil resistance, Re: 5.5 ohms.
Mechanical Quality Factor, Qms: 7.39
Electrical Quality Factor, Qes: 0.27
Total Quality Factor, Qts: 0.26
Equivalent Air Volume to Cms, Vas: 48 l
Mechanical Compliance, Cms: 273 mm / N
Mechanical Resistance, Rms: 1.72 kg / s
Efficiency, ho (%): 1.8
Effective Surface Area, Sd (m2): 0.0355 m2
Maximum Displacement, Xmax: 8 mm
Displacement Volume, Vd: 281 cm3
Voice Coil Inductance, Le @ 1 kHz: 1.7 mH

http://profesional.beyma.com/ENGLISH/pd ... 10MWNd.pdf


I know Qts is a bit small for the O10, and Vas too, but I'm impressed by the 8mm Xmax.
Maybe it'll work in some of the other designs.

[Bill Fitzmaurice]

The low Qts is a deal breaker, it results in poor bass response, rendering the high xmax as useful as the proverbial tits on a bull.

[Nordskov]

Can anyone provide me a good site explaining Thiele-Small parameters and their effect on the preformance of the driver?

Thanks

Nordskov

[Sydney]

http://sound.westhost.com/tsp.htm
This is a pretty "heady" article ( more about measuring than an intro ).
Loudspeaker Design Cookbook provides a good intro.
Hang on, I'll see if I can find a good appetizer ( instead of the main course above ) other forum members may have good ones for you.
Update:
http://www.speakerplans.com/page89.html
* Attention braniacs and tech junkies:
The following has a bunch of AES articles: ( too many to list )
http://www.readresearch.co.uk/html/articles.htm

[Nordskov]

http://www.speakerplans.com/page89.html

This is a good one, very thorough.
Now I know why a low Qts in general makes a crappy bass driver.

Thanks Sydney.


Nordskov

[Sydney]

Now I know why a low Qts in general makes a crappy bass driver.

I note sure if everyone of his conclusions are correct or his opinion ( no surprise there )
But other than that, I think the definitions and descriptions are valid.
I posted those links on Education section and hope if others forum members will find and add additional links.

[bgavin]

Now I know why a low Qts in general makes a crappy bass driver.

Almost all the JBL musical instrument and pro audio drivers are low Qts.

[Bill Fitzmaurice]

Now I know why a low Qts in general makes a crappy bass driver.

Almost all the JBL musical instrument and pro audio drivers are low Qts.

Which they generally offset to at least some extent with a lower fs than other MI drivers with higher Qts, so the net result is no worse on average than other drivers of similar sensitivity. But in any event the lesson to be learned is that very large magnets, high Bls and low Qts are not the way to better bass sensitivity; quite the opposite. You can still get very good bass output from low fs high Bl low Qts drivers, and do so in a small cabinet, but at the cost of sensitivity, which means you'll need lots of watts.

[Nordskov]

Ok, I guess Rome wasn't build in one day, and neither are my skills on speaker design.

Dammit. Just thought I had it!

Must keep my mouth shut - and my fingers off the board.


- The Novice