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post #1 of 4 Old 05-08-07, 11:03 PM Thread Starter
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Port location?

I am designing my next speaker project, a 3-way system, and it wants to be ported. My center channel ended up with the ports on the back because I didn't leave enough room on the front baffle, and had built most of the box before the speakers and ports arrived.

In the new speakers I will be using 2 ports. The box is tuned to about 50hz. I think I want to put the ports on the front baffle of these floor standing speakers, but I am open to hearing what the prevailing wisdom is.

My options are;

Front, Back or sides, and where vertically, top, bottom, middle, some combination?

Paul
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post #2 of 4 Old 05-10-07, 03:50 PM
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Re: Port location?

Please understand that I am no expert whatsoever, so if someone comes along and says otherwise, they should probably carry more weight than my opinion..

I'd put the port in the back, if for no other reason than I wouldn't want any of the potential chuffing from the port to be pointed at me. I think the sides are usually feasiable since the width is often not enough for the length of the port needed -- there may be other reasons, this is just what I could think of off the top of my head.

So, unless you plan on putting the speaker right up against a wall (which is usually a bad idea anyway), I'd put the port in the back.

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post #3 of 4 Old 05-10-07, 04:20 PM Thread Starter
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Re: Port location?

Putting the ports on the back makes the cabinet shorter, which is good, since the design currently has a height of about 45".

How far from the wall is the minimum with ports in the back? My cabinet will be 16" - 18" deep and placing it near the wall will be unavoidable.

BSD (Baffle Step Defraction) is the main reason for keeping the speaker away from the wall. This phenomenon is generally dealt with in the xover. Most speakers' xover curve are attenuated with the assumption that the speaker will not be against a wall. When speakers designed thusly are placed against the wall they sound boomy or bloated at the bottom. This is what I understand based on my reading.

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post #4 of 4 Old 05-10-07, 05:01 PM
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Re: Port location?

Quote:
aceinc wrote: View Post
Putting the ports on the back makes the cabinet shorter, which is good, since the design currently has a height of about 45".

How far from the wall is the minimum with ports in the back? My cabinet will be 16" - 18" deep and placing it near the wall will be unavoidable.

BSD (Baffle Step Defraction) is the main reason for keeping the speaker away from the wall. This phenomenon is generally dealt with in the xover. Most speakers' xover curve are attenuated with the assumption that the speaker will not be against a wall. When speakers designed thusly are placed against the wall they sound boomy or bloated at the bottom. This is what I understand based on my reading.

Paul
The "rule of thumb" regarding ports and walls is to make sure they're at least the diameter of the port away from any wall (inside or out).

I understand the BSD arguement -- but I thought there were more reasons. Not that I can think of any of them mind you, but it's just what I kind of have at the back of my brain (such as it is ).

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