Please help me, to optimize this driver for TL sub

[christophorus]

Please help me, to optimize this driver for TL sub, here is T/L param:

driver dia = 10"
Fs=35,36Hz
Re=6,25ohm
Vas=39,16liter
Qms=8,36
Qes=1,85
Bl=8,5
Sd=363,2cm2

I can't get good result using MJK TL offset driver, it has big hump at 40Hz on SPL graph...

Is it not good driver for TL sub?

Thank you in advance for your help.

Chris.

 

[AndrewT]

Hi,
that high Q indicates that it may never suit any cabinet loading.

It might work very well in an open baffle (not infinte baffle=sealed box).

 

[pinkmouse]

Yes. Drivers are designed for certain uses, and though there is a little flexibility, you can't push them too far. You wouldn't use a Porsche to pull a trailer full of bricks would you?

 

[christophorus]

Thanks Andrew and Al,

how about lowering Qms to the level that can work for TL.
My driver has dual voice coil:

"When you run a single voice coil, it has the nominal single-coil Qes of 0.8.
So, with the second coil open, you'd have a Qes of 0.8, and a Qms (unchanged) of 6.5, for a Qts of ~0.7.
Now, when you short the second (unused) coil, it essentially acts as an electric brake.
This will manifest itself by lowering the Qms to the Qes of a single coil: 0.8.
So, you'll have a driver Qes (of the coil you're driving) of 0.8, and a Qms (of the shorted coil) of 0.8, for a combined Qts of ~0.4.
One coil driven, other open, Qts = ~0.7. One coil driven, other shorted, Qts = ~0.4.

Dan Wiggins
President Avatar Audio"

from:
http://www.google.com/search?q=cach...+lowering+qms+driver&hl=en&gl=id&ct=clnk&cd=1[/url]

so with Qes=1,85 Qms become=1,85 and Qts become=0,925!


or:
"I diluted bicycle grease with light machine oil and applied it generously on the spider. Measured T/S parameters again. Qms reduced by 28% (and hence, Qts), Vas increased slightly, Qes close to original."

from:
http://www.diyaudio.com/forums/showthread.php?threadid=61486)

so with Qms=8,36 it become=6 and Qts become=1,4 still high...

with first treat, the SPL graph suddenly looks soooo good!
F3 goes to 20Hz and big hump at 40Hz disappear!
The important thing is, it's very easy to do,
any comment, please...

Chris.