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stephens30228
05-26-2012, 11:52 AM
I was curious, Buck designed me a box for my single DD9512, the speaker is mounted on top and the slot port is faced backwards, my question is, if the inside height is 8 5/8", and the speaker mounting depth is 8", is that enough room below the magnet or no? I have never really ran into this problem, thanks.

Falcons
05-26-2012, 12:18 PM
if Buck designed that bo specifically for you and that woofer, then you wont have any problems.

stephens30228
05-26-2012, 03:12 PM
Thats what I figured, but I wanted to confirm before I kept putting the box together, I don't know hwo the airflow below a mounted sub works, but he isn't answering his texts, and he hasn't been online today so I figured I would get some input.

keep_hope_alive
05-26-2012, 06:32 PM
if the sub has venting in the middle of the magnet (i.e. a large hole in the middle) then you may be concerned. if it doesn't have venting like that then you are good to go.

stephens30228
05-26-2012, 08:05 PM
It has a small hole in the middle. But I have never seen a speaker without one.

Buck
05-27-2012, 01:27 PM
There will be 1.375 inches between the magnet and the wall.

Moble Enclosurs
05-27-2012, 03:25 PM
The other question now would be, what kind of compression exists and is the design ported to allow any form of noise to exit the enclosure? Noise, not sound by the way. Usually, you want to keep the distance of the drivers rear venting/cooling area about 1/2 to 1:1 ratio of the drivers effective diameter as a general rule to be safe in any layout of a design. The distance from the rear of the sub to the port is not as a concern either, though that has been mentioned by a few in the past as far as noise is concerned.
The good news is, normally the noise that is induced is that of much higher oscillations than the frequencies that do exit the port efficiently, and the noise is usually dampened from having major harmonic interference and is not heard as well outside the box than inside the box. Much like how a reverse tapered tline reacts to high frequency dissipation at the port opening.

SO, if the distance of the rear of the sub in relation to the velocity at the opening/vent is less than equal, the chance of that being an issue is increased. The best bet, if the understanding of those figures is minimal is to follow the general rule mentioned above where power is less of a contributing factor and reduces the chance of any noise issues in or outside of the box.

Hope that helps.

stephens30228
05-27-2012, 03:31 PM
The other question now would be, what kind of compression exists and is the design ported to allow any form of noise to exit the enclosure? Noise, not sound by the way. Usually, you want to keep the distance of the drivers rear venting/cooling area about 1/2 to 1:1 ratio of the drivers effective diameter as a general rule to be safe in any layout of a design. The distance from the rear of the sub to the port is not as a concern either, though that has been mentioned by a few in the past as far as noise is concerned.
The good news is, normally the noise that is induced is that of much higher oscillations than the frequencies that do exit the port efficiently, and the noise is usually dampened from having major harmonic interference and is not heard as well outside the box than inside the box. Much like how a reverse tapered tline reacts to high frequency dissipation at the port opening.

SO, if the distance of the rear of the sub in relation to the velocity at the opening/vent is less than equal, the chance of that being an issue is increased. The best bet, if the understanding of those figures is minimal is to follow the general rule mentioned above where power is less of a contributing factor and reduces the chance of any noise issues in or outside of the box.

Hope that helps.

I'm going to put this politely as possible... What in the hell are you talking about? I got lost quick. I guess that's why y'all make the money for designing boxes huh? Lol

Moble Enclosurs
05-27-2012, 03:39 PM
lol, yea. true. But basically, if you have the rear vent/cooling port too close to the box, and you put enough power into it, it will make noises. Those noises are higher "frequencies" than what the port couples with, so they usually are not heard as well outside the box because they are restricted in the box and lost before they make their way out, but in some cases it is audible. And to not have those problems, the rule I mentioned is the key to reducing those issues.

The reason they make noise it because of the pressure. Try pushing too much air out of a certain space and it causes enough pressure to make noise or chuffing sounds as some call it. The only compression you want in the box is that of the port beginning (not the opening unless it is smaller than the inside of the port), and the compression to control the sub the way it wants to be controlled to maintain the right response output with the power it uses. That is where the main efficiency comes from in a box, is the compression and the reduction of distortion and noise or any unwanted factor.
What we are talking about here is the unwanted factor of too much compression in a small area that makes noise that can be heard outside the box. You don't want that. :D

---------- Post added at 03:39 PM ---------- Previous post was at 03:39 PM ----------

I gotta leave, brb later :D