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Old 12-06-2016, 02:33 PM   #1
mossman

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Does Box Shape Matter?

I was thinking of getting a little creative with a vented enclosure I am designing, but was wondering if too many angles and blunt edges are a bad idea. Nothing too crazy, but I basically wanted to have an L-shaped box to save space in my trunk. Like so...

http://i63.tinypic.com/28i3zfa.png

Last edited by mossman; 12-06-2016 at 02:48 PM.
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Old 12-06-2016, 02:56 PM   #2
basicxj

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Yes and no, but mostly no.

Ideally you would avoid perfect cube shapes, and would have enough room behind the magnet for venting (with subs that use a pole vent for cooling). I don't believe the IDQ8 v4 is one of those.
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Old 12-06-2016, 02:58 PM   #3
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Quote:
Originally Posted by basicxj View Post
Yes and no, but mostly no.

Ideally you would avoid perfect cube shapes, and would have enough room behind the magnet for venting (with subs that use a pole vent for cooling). I don't believe the IDQ8 v4 is one of those.
Just to be clear..."no" meaning it doesn't matter? In other words, the L-shaped design I am proposing should be fine?
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Old 12-06-2016, 03:09 PM   #4
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Quote:
Originally Posted by mossman View Post
Just to be clear..."no" meaning it doesn't matter? In other words, the L-shaped design I am proposing should be fine?
Many of the vehicle specific enclosures on the market are oddly shaped (and some of those work very well).

Keep in mind the job of the port is to take energy from the rear of the sub's cone and utilize it to reinforce that from the front...sometimes the shape and positioning of the port is the way it is as that energy from the rear is out of phase and can actually reduce output when combined with that from the front of the woofer- the reflections engineered into the port bring that back into phase as it exits the enclosure, for more output than sealed and more output than some ported designs.

I've built both sealed enclosures and ported enclosures with good results, but as for the science of getting things as optimum as they can possibly be with ported I usually don't take too many liberties with a proven design. One of CAF's ported box gurus will be more valuable to you in that regard, as like mentioned before I usually prefer to go small sealed and pour the power on. Power is cheap these days, and the way I normally use a sub, it isn't likely to see enough power to burn things or break things.
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Old 12-06-2016, 03:17 PM   #5
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To counter that point, most of the tricks I've learned since my first install back in '81 (before internet forums like this one existed) were the result of trial and error and lucky experiments, with some paying off more than other ones .

(you can find out if the design works for the price of a sheet of MDF and your time)
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Old 12-06-2016, 03:28 PM   #6
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Alternate:

http://i50.photobucket.com/albums/f3...psthi8llfx.png
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Old 12-06-2016, 03:31 PM   #7
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Quote:
One of CAF's ported box gurus will be more valuable to you in that regard
Sorry, but who is CAF?
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Old 12-06-2016, 03:44 PM   #8
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Quote:
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Sorry, but who is CAF?
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Old 12-06-2016, 06:28 PM   #9
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I'm also thinking of using two ports as opposed to one. According to this calculator, two 4"x1"x 15.82 inches long slot ports would give me the same tuning as one 6"x1"x 10.65" long port. The calculator actually gives me a length of 10.95" for the length for one, but the manufacturer's spec sheet I am using says 10.65" for 40 Hz and 0.75 cubic ft enclosure.
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Old 12-10-2016, 04:24 AM   #10
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Try a Passive Radiator in your setup. You might like it.
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Old 12-12-2016, 12:46 PM   #11
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I'll be going with a sealed, trapezoidal-shaped enclosure in order to preserve the most trunk space. The front panel will be 28" wide, the back panel will be 20" wide and the box will be 18" tall by 9" deep (exterior dimensions) for a net displacement of 1.1 cubic ft per ID's recommended enclosure volume.

Last edited by mossman; 12-12-2016 at 12:55 PM.
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Old 12-27-2016, 01:39 PM   #12
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Box is finished and I hooked up the sub (IDQ10) yesterday. It is undoubtedly louder, extends lower, and hits harder than the IDQ8, but I have lost some response on the higher end of the spectrum. My test discs don't have enough granularity for me to give exact numbers, but it seems that the response drops off rapidly after 50 Hz. Below that it booms, but above sounds weak. Should I try going with the smallest recommended enclosure volume to see if that will restore the 50 to 80 Hz range? If I had to compare the two, I'd say that I prefer the IDQ8 over the IDQ10 when in their respective enclosures. However, I do like the added kick/punch that the 10" has. So if I can get the IDQ10 to reach higher like the IDQ8 does, I would be happy with that.

Reminder that I have my IDQ10 in a sealed 1.1 cubic ft enclosure and the smallest recommended enclosure size is 0.6 cubic ft, which is what I am considering trying next. I am using a Sundown 100.4 amp to deliver up to 320W rms. Additionally, I believe my alternator needs to be upgraded because the sub gets significantly louder when I turn the engine off.

IDQ10 frequency response (yellow line = 0.6 ft^3, green = 1.1 ft^3):

http://i64.tinypic.com/oqy805.png

...or should I go with two IDQ8's since I prefer their frequency response. Will the combined surface area of two 8's give me more kick/punch than a single 10? If so, that may be the winning combination for me.

Last edited by mossman; 12-27-2016 at 01:57 PM.
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Old 12-27-2016, 01:54 PM   #13
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Try throwing something inside the enclosure to displace some air and adjust the woofer's response...a phone book, a brick, something you can measure the displacement of and subtract from the enclosure's known volume to get an idea of what the final volume is and how it affects what you are hearing.

Put a multimeter across the amplifier's power and ground connections to measure DC voltage and see what is going on when output increases/decreases with ignition off and with engine running.
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Old 12-27-2016, 02:18 PM   #14
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Quote:
Originally Posted by basicxj View Post
Try throwing something inside the enclosure to displace some air and adjust the woofer's response...a phone book, a brick, something you can measure the displacement of and subtract from the enclosure's known volume to get an idea of what the final volume is and how it affects what you are hearing.
Good idea. I'll do that and see what effect it has.

Quote:
Originally Posted by basicxj View Post
Put a multimeter across the amplifier's power and ground connections to measure DC voltage and see what is going on when output increases/decreases with ignition off and with engine running.
I've done that. The voltage stays about the same (12.5V), so I'm guessing the alternator just can't deliver what the amp needs. The stock alternator is 130A at who knows what RPM. I found a Mechman alternator with 240A output, which I believe is near idle.

I forget, will a sub in a smaller enclosure need more power than a large enclosure or vice versa?

Last edited by mossman; 12-27-2016 at 02:20 PM.
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Old 12-27-2016, 02:26 PM   #15
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Quote:
Originally Posted by mossman View Post
Good idea. I'll do that and see what effect it has.



I've done that. The voltage stays about the same (12.5V), so I'm guessing the alternator just can't deliver what the amp needs. The stock alternator is 130A at who knows what RPM. I found a Mechman alternator with 240A output, which I believe is near idle.

I forget, will a sub in a smaller enclosure need more power than a large enclosure or vice versa?
If the alternator is being current-starved, I would expect to see that in the form of a voltage drop measurable with your multimeter. A clamp-style meter will allow you to observe the difference in current going through the circuit with ignition off/engine running.

A smaller enclosure will sound "punchy" in the form of increased upper bass energy, but does so at the expense of lower bass energy...it will need more power to reach maximum output down low compared to a larger enclosure (which is generally more efficient). With small adjustments in enclosure volume, the differences in efficiency are also small.

Does your vehicle's head unit have a speed-sensitive volume circuit? The RNS-510 head unit in my VW had that, and I found that to be annoying and turned it off in the settings.
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