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Old 22nd September 2008, 11:55 PM   #1
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Default Big speakers in none ported enclosures.

I have a Fane Colossus 18 inch 600 WRMS speaker.
It is recommended that I use a ported enclosure.

As I need to move the speaker around then I need to keep it as small as possible. This is fine but precludes the use of a port.

Will I do any damage to my speaker using a none ported enclosure ? The only air leakage into the enclosure will be through two quarter inch jack sockets on the side of the enclosure.
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Old 23rd September 2008, 12:04 AM   #2
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no it won't damage your speaker but you won't get much bass out of it (assuming the jack sockets are plugged when you use it)

The back pressure in the cabinet will prevent the cone from moving enough to develop low frequencies.


...but I always thought that, given a particular speaker, the ported cabinet would always be smaller than the sealed cabinet for optimum LF response??
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Old 23rd September 2008, 12:08 AM   #3
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Quote:
Originally posted by Iain McNeill
no it won't damage your speaker but you won't get much bass out of it (assuming the jack sockets are plugged when you use it)

The back pressure in the cabinet will prevent the cone from moving enough to develop low frequencies.


...but I always thought that, given a particular speaker, the ported cabinet would always be smaller than the sealed cabinet for optimum LF response??
There is no room at the front around the speaker for a port.
I suppose I could put one on the back of the box if it was kept simple.

Would a simple hole do the job or would it need a pipe ?
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Old 23rd September 2008, 12:15 AM   #4
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Quote:
Originally posted by Iain McNeill
I always thought that, given a particular speaker, the ported cabinet would always be smaller than the sealed cabinet for optimum LF response??
Rarely. Just depends on the driver. A Qts well above .40 often requires a large sealed cab. Very low Qts drivers (like under .2) often require tiny vented boxes, but those don't usually provide much low freq response anyway.

In the case of this Colossus 18, I'm guessing low freq response will be VERY limited in a sealed enclosure, and that boosting the low freq way up via EQ to overcome that probably wouldn't be a good idea for anything other than a personal application in a person's home, given that Xmax is probably limited to 5-10mm. However, an optimum vented cabinet for it will most likely be fairly large. A sealed cab would probably be very small, but not have any low freq output to speak of.. at least not without a lot of EQ, which will hinder max output substantially.
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Old 23rd September 2008, 12:20 AM   #5
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Originally posted by BHTX


Rarely. Just depends on the driver. A Qts well above .40 often requires a large sealed cab. Very low Qts drivers (like under .2) often require tiny vented boxes, but those don't usually provide much low freq response anyway.

In the case of this Colossus 18, I'm guessing low freq response will be VERY limited in a sealed enclosure, and that boosting the low freq way up via EQ to overcome that probably wouldn't be a good idea for anything other than a personal application in a person's home, given that Xmax is probably limited to 5-10mm. However, an optimum vented cabinet for it will most likely be fairly large. A sealed cab would probably be very small, but not have any low freq output to speak of.. at least not without a lot of EQ, which will hinder max output substantially.

I want to use the speaker in a mobile disco environment so it needs to be as loud as possible.

Would a simple opening on the rear of the box allow in enough air to get sufficient bass ? Or would this pollute the sound from the front ?
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Old 23rd September 2008, 12:22 AM   #6
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Quote:
Originally posted by nigelwright7557
There is no room at the front around the speaker for a port.
I suppose I could put one on the back of the box if it was kept simple.

Would a simple hole do the job or would it need a pipe ?
Doesn't work that way.
First of all, you need to figure out which Colossus 18 you have, as there are currently several (4 I think?), and there might have been even more in the past. Check this link here: http://www.fane-acoustics.com/proseries.asp

Once you figure out which one it is, you need to download the PDF and enter the TS specs in WinISD Pro or something similar to simulate an optimum enclosure.

If you're trying to put it in some sealed enclosure of an unknown size, there's a small chance it might work OK by selecting the right diameter and length of PVC pipe (or whatever) and making a corresponding hole in the cabinet. Chances are slim though. If it's an old sealed cab for a single 18", it's probably too small.

First things first.. figure out which Colossus 18 it is and model it.
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Old 23rd September 2008, 12:32 AM   #7
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I downloaded Win ISD.

I need a 4 inch diameter hole with a 4.16 inch pipe to vent the enclosure to get a decent response.

Thanks for the help, Nigel
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