pole vent clearance

[wenn_du_weinst 10+ year member]

no it doesn't, the Venezuela basket is one I forgot about. A pole vent does not increase cooling. DD and Sundown will both back me up on this as well multiple other manufactures. Gap vents work much better if it ''needs'' to have motor cooling. The vents have much more to do with noise and pressure then any other reason.

 

---------- Post added at 10:32 AM ---------- Previous post was at 10:31 AM ----------

 

also OP I deff recommend deadening your enclosure.

 

[Kangaroux 5,000+ posts]

no it doesn't, the Venezuela basket is one I forgot about. A pole vent does not increase cooling. DD and Sundown will both back me up on this as well multiple other manufactures. Gap vents work much better if it ''needs'' to have motor cooling. The vents have much more to do with noise and pressure then any other reason. 

---------- Post added at 10:32 AM ---------- Previous post was at 10:31 AM ----------

 

also OP I deff recommend deadening your enclosure.

You can PM corey then and ask him yourself cause apparently he's lying to me.

 

[rodburner 10+ year member]

also OP I deff recommend deadening your enclosure.

No worries. All that 1/8" steel is reinforced,sprayed with rubberized undercoat and lined with multiple layers of rubber/asphalt pipe wrap I use at work. It's DEAD.

 

[wenn_du_weinst 10+ year member]

You can PM corey then and ask him yourself cause apparently he's lying to me.

You mean Corey (sundownNY)the guy who doesn't build subwoofers for a living he only does it as a hobby?

 

[RAM_Designs 5,000+ posts]

Pole vents are mostly for keeping the dust cap from flying off due to too much pressure buildup.

 

[wenn_du_weinst 10+ year member]

Pole vents are mostly for keeping the dust cap from flying off due to too much pressure buildup.

you have any idea how many times my btl dustcap hit the roof? lol

 

[OmegaBunny 10+ year member]

you have any idea how many times my btl dustcap hit the roof? lol

Nope, how many and be as accurate as possible.

 

[hispls 5,000+ posts]

It increases air flow directly to the coil with it plugged. It will push and pull cool air instead of having a dead spot around the coil like pole vented subs do. The vent is to release pressure from under the dustcap and increase efficiency and to reduce noise. That is why you usually see big spl subs with small or no vents. I know sundown had a pole plug option on the nightshades for a while.

So plugging pole vent is less efficient, yet big SPL subs use small or no vent and putting duct tape over a vent gains half a dB on the meter in most applications? This doesn't seem logical.

I admit that cooling benefit is probably small at best, but I have yet to see a woofer with this feature that doesn't claim it as a cooling aid at least in their marketing. I also think that most woofers with pole piece plugged don't really have enough space in the gap for air to flow around the coil quick enough to fill the space opened up at excursion and more likely the air between the pole piece and dustcap is just compressed and rareified (sp?) more so than actually circulating in and out of the space within the coil (that is of course barring vents in the top plate or possibly at the top of the coil)

 

[sundownz Pro Seller]

So plugging pole vent is less efficient, yet big SPL subs use small or no vent and putting duct tape over a vent gains half a dB on the meter in most applications? This doesn't seem logical.
I admit that cooling benefit is probably small at best, but I have yet to see a woofer with this feature that doesn't claim it as a cooling aid at least in their marketing. I also think that most woofers with pole piece plugged don't really have enough space in the gap for air to flow around the coil quick enough to fill the space opened up at excursion and more likely the air between the pole piece and dustcap is just compressed and rareified (sp?) more so than actually circulating in and out of the space within the coil (that is of course barring vents in the top plate or possibly at the top of the coil)

Thermal analysis and heat transfer

Marketing pole vents as cooling dates back to the era of non-vented stamped frames, IMO... where there was literally NO way for air to get out of the driver aside from a vented pole or vented dust cap (I have some 1973 Sansui woofers with a vented dust cap, solid pole, and non-vented frame).

You can use a pole vent as part of an overall cooling scheme (our motors usually use a small pole vent as part of the overall system) -- but a large pole vent in and of itself is usually extremely ineffective at cooling down a voice coil. There are methods to enhance the effectiveness of a more "average" size vent but you will find with a given sub if you simply plug up the pole vent and you have a vented frame that cooling generally increases drastically.

There is an efficiency sacrifice... 0.4 dB on the NS v.1 motor in my setup and more with a tighter gap sub like an RE MT due to the huge amount of compression of the air going on (which causes a high velocity as well... good for cooling) -- which we cancelled out by venting the former. Of course... venting the former did sacrifice SOME of the thermal gains we made... but the opening area of the former vents was less than the opening area of the pole vent so a good bit of thermal gain remained.

Solid cores do have more issues with dust caps popping off from the pressure which is one of the other reasons why I typically prefer a system that incorporates at least a small pole vent (there are other reasons which I won't get into here as I consider them a bit of a trade secret). I also like to utilize gap venting in many designs that are not depth restricted as well (solid cores also have the advantage of not needed any room for venting behind the motor).

 

[SPLaudio 5,000+ posts]

totally depends the motor if using a pole plug will aid in cooling. most motors that are current yes a pole plug helps. with a pole plug you can make it into a shorting ring too.

plugging a pole will lower the sen of the driver and have more "mechy" noise though.