Eminence LAB12 in a dipole woofer? - diyAudio
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Old 6th January 2005, 11:52 PM   #1
Hennie is offline Hennie  South Africa
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Default Eminence LAB12 in a dipole woofer?

Has anybody evaluated the Eminence LAB12 for use in a dipole woofer?

I can get hold of Eminence LAB12's (virtually new) but the seller lives some distance from me, so I cannot test them for noise in a dipole application. Apparently the Adire DPL12 was used as the basis for development of the LAB12. It looks like the LAB12 uses the same basket as the DPL12 with a heavier magnet. Vents under the spider as well as pole vent diameter seem to be the same.

Like the DPL12 it would probably have higher distortion in the upper bass range than the Peerless XLS, but I can get these drivers locally at a good price from someone who abandoned a bass horn project . Any other driver I would have to import myself and pay considerably more.

I would appreciate any comments.
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Old 7th January 2005, 09:47 AM   #2
mike.e is offline mike.e  New Zealand
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Although the lab12 has physically more magnet,the electrical control is the ~same.

I think that vent noise becomes a problem below 50hz and more so to the subsonic frequencies.

Cheers!
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Old 7th January 2005, 10:15 AM   #3
Hennie is offline Hennie  South Africa
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I was also concerned about Qms which is very high.

Some figures:

Peerless XLS 830500 : Qms = 3.7
Adire DPL12 : Qms = 11.16
Eminence LAB12 : Qms = 13.32

So Qms is somewhat higher than for the DPL12. Can anybody tell me what happens when the DPL12 is driven into over excursion? (Is Qe lost?). What happens to the restoring force? Is it possible to damage the driver this way?

I've heard about a "suck out" effect that can cause a driver with high Qms to get stuck at over excursion with a sustained overdrive signal because it does not have enough restoring force, but I have not experienced it myself....

I assume the LAB12 will behave similar to the DPL12 under over excursion.

It seems the LAB12 has much lower inductance than the DPL12 and presumably better upper bass response.
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Old 8th January 2005, 09:30 AM   #4
mike.e is offline mike.e  New Zealand
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Quote:
I've heard about a "suck out" effect that can cause a driver with high Qms to get stuck at over excursion with a sustained overdrive signal because it does not have enough restoring force, but I have not experienced it myself....
Ive heard of a different effect But I think that the most recent drivers dont suffer from the following. Infact my dad referred to it, as a problem on ported boxes with a pressure differential and floppy surround causing distortion[on old speakers I guess]

Relax about Qms, it is insignificant compared to the Electrical control- Sure the Bl is reduced as excursion increases and some DC offset maybe present,but the woofer doesnt get 'stuck' -just turn it down al ittle in volume! Youl require many woofers to achieve the same SPL as a sealed or ported box with dipoles.

Quote:
It seems the LAB12 has much lower inductance than the DPL12 and presumably better upper bass response.
But if you filter low,at say 70hz does this matter.
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