Please help me, to optimize this driver for TL sub

christophorus · 13th January 2007, 12:06 PM

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 · 13th January 2007, 12:13 PM

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 · 13th January 2007, 12:17 PM

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 · 14th January 2007, 11:41 AM

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=cache...=clnk&cd=1</a>

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:
Grease to Lower Speaker Q)

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.

13th January 2007, 12:06 PM	#1
christophorus diyAudio Member Join Date: Dec 2003	Please help me, to optimize this driver for TL sub 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.

13th January 2007, 12:17 PM	#3
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	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? __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

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13th January 2007, 12:13 PM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	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).

14th January 2007, 11:41 AM	#4
christophorus diyAudio Member Join Date: Dec 2003	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=cache...=clnk&cd=1</a> 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: Grease to Lower Speaker Q) 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.