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Old 19th July 2008, 09:25 PM   #11
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Default Re: Re: Re: Home made cabinets require drivers and x-over. Any recommendations?

Quote:
Originally posted by aim


Brett I believe the volume is as follows: -
12 206.25 cubic inch or 200 024.599 95 cubic centimeter (they're big!)
The book indicated that these are to be sealed enclosures and no cutouts have been made so far. My budget is going to be in the 300 mark to fix out both speakers; Im sure I can get a decent setup for this (well I hope)

Those dimensions you posted earlier (31" x 17.5" x 22.5") are the inside? That will give the 200 litres you quoted. I thought they were the outside measurements, that giving you about 150 litres internal.

I would look through the Eminence spec sheets and try a few of the likely drivers in Unibox. This will be tedious, but will give the most accurate results. To start you are looking for a driver with a high VAS and a Qts above .40 (for sealed).
Finding a driver that works in that box should be relatively easy, as there should be several to chose from.
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Old 19th July 2008, 09:54 PM   #12
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Choose the horn first because this will subtract from the internal volume. Once you know what you're left with then do as MJL says.

What's the intended use?
critical listening, home theatre, mobile DJ, Rave system?
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Old 20th July 2008, 01:28 AM   #13
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Agree with MJL and Iain. The 3015 or 3015LF would be my first WAG for 150L sealed. The 3015LF does really well with 4 x 4" ports as per the Eminence cab suggestions (~120L). I'd add the ports and tune them for the box, but make them able to be closed off easily so it could be used stand alone or with subs.

I'd also add a mid as 15 + 1" systems always sound lacking in the upper mids to me. An 18Sound 6ND410 would be a first suggestion.
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Old 20th July 2008, 10:26 AM   #14
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Hi guys,

OK, I should probably have made this point earlier but this system is for outdoor parties in my 31 tipi (a mini rave system). Im not going to be listening to classical music on this setup

Ive taken a look at the Unibox spread sheet and its impressive but I think its a bit too fine detailed for me as Im not constructing a hi-fi setup. I dont expect miracles from this simply reasonable sound quality and loudness. I may choose to add separate speakers if Im missing quality in the mid/top end.

My main concerns are that the end result is 4 or 8 ohm load per channel that the x-over point is manageable by both the HF compression driver and the bass driver.

MJLYou are right they were the outside measurements and these cabs are made from ply with a slight inset on the front (about 1). I would agree with the 150 litre assumption.

So looking at the eminence site again Im currently thinking about:-

Bass driver Eminence KAPPALITE 3015 Useable range 40Hz to 4kHz 8 Ohm. 450W

Horn - Eminence TI2000 - 2 - 284 x 246 x 257mm (although this is a push to fit as in its huge)

Compression driver - Eminence PSD:3006 - 2 - Useable range 500Hz to 18kHz -8 Ohm -80W

X-over Eminence PXB2:1k6 - 1.6kHz Slope 12dB/octave LP

Does this sound OK?

As both driver components are 8 ohms will the x-over ensure an 8 Ohm load to amp? And will it also reduce the power to the HF driver else itll pop.

Thanks again
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Old 21st July 2008, 06:42 PM   #15
aim is offline aim  Wales
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No one like to comment on this selection?

Its a very common setup to have an 8ohm driver combined with an 8ohm HF driver but the impedance is usually still 8 ohms for the whole speaker. How does this happen as I can't see a way of doing this with series or parallel wiring!

Also, with x-overs, I assume that a resistor is used to reduce the power to the HF driver is this used to maintain impedance @ 8 ohms and if so surely this would require more power from the amp to due to the loss? Anyone like to explain?
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Old 21st July 2008, 07:11 PM   #16
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Quote:
Originally posted by aim

Ive taken a look at the Unibox spread sheet and its impressive but I think its a bit too fine detailed for me as Im not constructing a hi-fi setup. I dont expect miracles from this simply reasonable sound quality and loudness. I may choose to add separate speakers if Im missing quality in the mid/top end.

Hi,
One of the reasons why you would want to properly model a driver for a given box size is excursion. If you run out of excursion at 7 watts and your system is capable of 250 watts, that's bad news.
Unibox is for every type of speaker, not just the hifi kind.

Here's how the Kappa looks in a 150 litre vented box. F3 at 42Hz, maximum power handling within excursion limits: ~200watts. The Kappa really should be in a smaller box, around 90 litres. This would give better power handling and tighter bass response.
Vent would be 15cm diameter, 6 cm long.
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Old 21st July 2008, 07:25 PM   #17
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Here is the Kappalite 3015LF (the LF added to the end). Better suited to the size box you have. This will handle 500 watts before you run out of excursion.
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Old 21st July 2008, 09:31 PM   #18
aim is offline aim  Wales
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Quote:
Originally posted by MJL21193
Here is the Kappalite 3015LF (the LF added to the end). Better suited to the size box you have. This will handle 500 watts before you run out of excursion.
Thanks ever so much MJL... The reason I didn't choose this driver was due to the limited 1.5khz (40Hz-1.5kHz) usable range. The 3015 have a better sensitivity (I think) @ 100.8 and a usable freq. between 40Hz-4kHz (better for the x-over and HF driver selected). Although I must admit I've not considered the excursion.
Do you think that the 3015LF would still be the better choice?

I plan on using these speakers in conjunction with 2 18" single scoop bins giving me plenty of low end. I don't plan on using these on their own.

Just going back to my point earlier, with the proposed 8 ohm drivers (both 15" and 2" HF) would the x-over ensure a 8 Ohm per channel load on the amp? I'm not 1-00% on this and there's not much info available on the Eminence site.

Thanks again!
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Old 21st July 2008, 09:35 PM   #19
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Oh... and also, I'm 100% sure that these boxes were designed to be sealed, not vented. They came from an Eminence design book as such. I worry about cutting holes in them just in case I'm shooting myself in the foot
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Old 21st July 2008, 09:49 PM   #20
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yes, the XO will ensure constant(ish) 8 ohms across the entire band.

In a parallel XO, the cap blocks low frequencies to the tweeter by going high impedance while the inductor blocks high frequencies from the woofer by going high impedance at high frequency. So at any frequency (except the XO frequency, of course) there is only one driver effectively in circuit.
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