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Old 21st October 2002, 12:55 AM   #11
Wizard of Kelts
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Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
Sealing the vents of the Euro shut-thereby making it a closed system-actually is a very good move.

Three cubic feet-as opposed to your 2.1 cu ft-is a very popular size for DJ cabinets. Here is what your 2 cu ft sealed cabinet looks like against a 3 cubic foot ported cabinet.

The 2.1 cu ft sealed cabinet is in red.

The 3 cubic ft ported cabinet is in green.


See how little difference there is? By sealing the cabinet, it just so happens that you come very close to the performance of a ported cabinet 50% larger!

Usually ported cabs give deeper bass, but not in this case.

The only issue left is the fact that the greater movement the sealed cabinet requires might muddy the midrange somewhat. That is a debate going on among audio fans-many claim that the difference is not hearable. It is up to you to decide.

I am not trying to convince you to keep the Euros, only pointing out that by sealing the vents shut, you might actually have gotten the bargain you hoped for when you bought them. Of ocurse, if you simply don't like the sound, by all means get rid of them.
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File Type: gif eminence beta 15 2 ft closed, 3 ft ported.gif (5.4 KB, 251 views)
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Old 13th January 2003, 04:10 AM   #12
Wizard of Kelts
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Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
Default Re: Reply to Keltec Wizard

Quote:
Originally posted by Bull
Yes i did try stuffing all 4 vents with fibreglass wadding,which i had spare from the loft insulation which was recently re-newed.

I sounds much tighter and cleaner,but only one problem,it makes the driver more like hell,and i didn't want to push it too much,otherwise i was afraid the suspension and cone might tear.
A sealed system will always make the cone move more, because the cone provides all the bass output in a sealed system. In a ported system, the vent provides most of the deep bass.

However, I shall show you the Eminence Beta 15 can easily work in your cabinet sealed and there should be no problem with excessive cone excursion.

The Eminence Beta 15 you have has a linear excursion of 4 mm and a mechanically limited excursion of 23mm-almost a full inch.

I just called Eminence about another matter, and asked about their excursion ratings. Those ratings are for both directions. In other words, going from front to back, the Eminence Beta 15 has 8 mm linear travel and virtually two full inches mechanically limited travel.

What you want in your speaker is up to you, of course, but it is unlikely that you could push this unit past it's mechanical limits with your cabinet sealed.

In the following thread is listed the volumes of air a sealed speaker must move to produce certains SPL's at various frequencies. The lowest frequiency your speaker will reproduce is 60 Hz. It helps to hit F11 when reading this chart.
Volume Displacement For SPL Chart

The Eminence has a cone area of 132 sq inches. With a one inch mechanical excursion limit, it can move 132 cubic inches of air.

132 sq inched for 60 Hz produces an SPL that is so high, it is literally off the chart!! However, one quarter of the Volume Displacement, (32 cubic inches) produces a whopping 117 dB SPL at 60 Hz. That is about the limit of your 150 watt into the Eminence. And the Eminence still has 3/4 of it's voice coil to go before you chance damage!!

Again, it is your speaker, do what you wish. But if cone excursion was preventing you from this box as a sealed system, you now know that there should be nothing to worry about.
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