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Old 14th March 2013, 03:41 AM   #31
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Originally Posted by Inductor View Post
I don't know, I can not predict that. You can go perhaps to the next chapter on room acoustics and calculators. You can read, test and simulate I guess.
By the way when you mention your room you forget the most important measurement the height of the room. Also important are the type of construction and sound absorption materials like windows and carpets in percentage of the area/side. Example: a sound studio is different from a bathroom.
Room Acoustics
Acoustic Calculation Tools
Port Calculation
How well do 3" inch flared ports do?I can tune two 3" inchers lower for deeper bass if needed.
Would I lose SPL or they would have more port noise?
1. two 3" ports 17" long tuned to 18hz
2. two 3" ports 15" long tuned to 19hz
Sub Driver should arrive eventualy Amp Ill order when I decide port size
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Old 15th March 2013, 12:16 AM   #32
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currently I'm deciding between a Flared port & a Vented port
Crossover is build into plate amps correct?

Sub-woofer itself should arrive tomorrow
rest of parts Ill order sometime soon after I start box.
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Old 23rd March 2013, 04:44 PM   #33
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Location: Cascais
Do you have the subwoofer already (Stereo Integrity HT 15")? Does it look good?!
Now ports size (internal diameter/length) they are related to the tunning frequency. That's a constraint of the bass reflex type of enclosure. Very low tunning frequency gives a gigantic almost impossible port length (several feet). To work in the limits of the practical, one dimension of the enclosure would be the max length of the port, that's what I have in mind. I need to know the 3 dimensions (of the enclosure) available or the one for the port you choose to be located (H, L or D internal of the box).

Now (example) for a Ported = 5ft³ tuned to 22 Hz
(5ft³ = 141.58L)
(note: the problem with tunning FB = 16.9 Hz is a port so many feet long that it doesn't fit inside the subwoofer enclosure and it's quality is bad.)
Max tunning frequency FB = 20 Hz.

So this is very critical if you do or don't have the space inside the box for this port. (When you don't have the electronics to modify the output curves of a speaker) The best bet, in this case, is to make say an ideal box with ideal (or more practical in this case) tunning with higher Fb.

It doesn't matter if you use a box from 3.5ft³ (99L) to 6ft³ (170L) it takes a max. tunning of 20Hz for a close to ideal alignment and with this driver.

1. Let's say 5ft³ (141.58L) tunned to FB = 16.9 Hz (ideal),
port 4", length ~20", air speed very high @70.4 m/s (max. 25.5 m/s).
(very difficult to work with the low frequency tunning)

2. 5ft³ tunned to FB = 20 Hz
port 4", length ~14", air speed very high @95.8 m/s (max. 25.5 m/s).

3. (Now with 2) 2 ports 4":
port 4"(x2), length ~29", air speed high but better @47.9 m/s (max. 25.5 m/s), results in a very long and bad port length.

4. Let's make another test with the port with a rectangular port:
port 1"x20" (HxW), length 15", air speed very high at high volumes 95.2 m/s@115.0 dB but ok at low volumes 13.7 m/s@98.2 dB.
So, I would use this alignment with this port if testing assure me it's ok.

5. Let's make yet another test with another rectangular port an different alignment:
Ported = 5ft³ tuned to 18 Hz
1"x20" (HxW) rect. port, length 19" (L), air speed high at high volumes 78.5 m/s@115.2 dB, ok at low volumes 15.4 m/s@101.1 dB.

So, after all this is my last simulation for such an alignment and the dimensions of the port system with the Stereo Integrity HT 15" in response to your PM.
Quote:
what type of Saw do you need or Drill attachment for a 14"cutout?
When you buy you need a jigsaw with wood blades. (Google)
How to Choose the Right Saw for the Job
Quote:
I was probably going to use 7ply or birch Plywood since MDF is more expensive & a lot heavier less durable.
Any wood glue probably works.
Make it (more) thick for such a big monster woofer.
Use wood glue (make sure it's approved for wood not paper glue, contact or another kind).
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Old 23rd March 2013, 04:49 PM   #34
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Location: Cascais
Same content here from OP.
Sealed vs Ported sub??
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