Venting Voice coils

[Robh3606]

Well I am going to quess you vent through the voice coil cap like the old Altecs. Didn't they vent through the cap vs. the manget. Used felt or a fine mess cloth??

Rob

[Maron Horonzakz]

Oh God......No wonder California Is 4 hours behind everybody else.

[Maron Horonzakz]

A good solution Rob !!!!!!!!!!!!!

[edgewound]

Well I am going to quess you vent through the voice coil cap like the old Altecs. Didn't they vent through the cap vs. the manget. Used felt or a fine mess cloth??

Rob

Yes Rob, that's right...Altec did. The problem with that... was an air leakage point that makes enclosure tuning a more manual process. The vented magnet is a much better means of cooling the voice coil by forcing more air over it through the pressure of the dust cap. The vented cap is an afterthought, to reduce chuffing and aid cooling...but Maron was asleep in class that day .

[Maron Horonzakz]

Yes...But I did graduate...

[Robh3606]

Hello Edgewound

Air leakage??? From where?? I thought they had essentially a sealed spider like a JBL. Were they vented as well?? Didn't know that. I am looking at an Le-14A and if you closed the magnet like the C version and vented through fabric like the C how would you get air leakage through the spider??? Is it porous so it breathes???? I always figured they had resin on them so they didn't. Never tried blowing air through one to see.

Rob

[edgewound]

Hello Edgewound

Air leakage??? From where?? I thought they had essentially a sealed spider like a JBL. Were they vented as well?? Didn't know that. I am looking at an Le-14A and if you closed the magnet like the C version and vented through fabric like the C how would you get air leakage through the spider??? Is it porous so it breathes???? I always figured they had resin on them so they didn't. Never tried blowing air through one to see.

Rob

Through the spider, through the coil....the spider is somewhat porous, and the vintage Altec spiders are quite lightweight to get the Fs down and the efficiency up. Anywhere you open airflow on the front of the speaker cone, you get a leakage point.

[Maron Horonzakz]

Tannoy did it.

[Robh3606]

Oh OK

So JBL's approach avoids that. If you look at the newer low power compression drivers they have vents into the space under the spider. It makes sense they are porous to help move air around the coil.

Cool

Rob

[Maron Horonzakz]

And TAD does that...

[edgewound]

Tannoy did it.

That's right...with Dual Concentric...so does Radian Co-axials, P.Audio and McCauley Co-ax's....and Eminence Co-ax's.

That has nothing to do with the original question in this thread of how to vent a voicecoil former....like a D/K/E series JBL.

I you havent noticed, Maron, most aftermarket voice coils being used for these JBL speakers don't have a vented voice coil former....so that makes them different from factory OEM.

I've learned that from experience..not reading Voice Coil Magazine that was ordered to stop publishing for a time because they got in trouble for publishing Patent Office art without permission.

That's why my subscription stopped...and I've attempted renewal...again...But I knew your brilliant solution even without Voice Coil Magazine...and so did Jim Lansing...that's why his company chose to vent the magnet.

[edgewound]

Oh OK

So JBL's approach avoids that. If you look at the newer low power compression drivers they have vents into the space under the spider. It makes sense they are porous to help move air around the coil.

Cool

Rob

Literally...cooler

Doug Button told me a few years ago at a NAMM show... when he designed VGC drivers, they manage heat so well that they tested them in the factory with 3000 watt amplifiers. I've had 2241's in my shop that got so hot the cone caught fire. People think that they are indestructable...not so.

[Maron Horonzakz]

Yes ....Yes I worked for Mcdonnell Douglas/ Boeing who also got in trouble with copyright with Janes fighting ships. But I didnt resign.

[Robh3606]

So vented coil form like the this guy here.

Rob

[edgewound]

Great pic...that's exactly it. As the cone moves outward, the vacuum sucks the hot air off the coil to be expelled out the vent on inward movement. The aluminum dome also acted as more of a heat sink to deal with the heat also.