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Critical mass ul12 for 12" db, what do u think? (Read 3587 times)
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Critical mass ul12 for 12" db, what do u think?
11/04/09 at 09:52:26
 
I have just picked up a critical mass ul12. Was going cheap so I grabbed it. Just wondering what peoples thoughts are on building a 12" db for it. Loud, low and with decent sq is what I'm after. Any input is muchly appreciated. Cheers
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dank
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Re: Critical mass ul12 for 12" db, what do u think?
Reply #1 - 11/05/09 at 14:55:14
 
Found this on-line:

Subwoofer Size: 12”
RMS Power handling: 2500 Watts (undistorted power)
Peak Power handling: 5000 Watts
Recommended Box Volume: 1.2 cuft. (Sealed)
Weight: 16.6 lbs
Motor Type: Dual Gap / Internal NEO Magnet
Voice Coil Type: Ultra-High Temp Dual Coil (Made in the USA)
Voice Coil Diameter: 3”
Voice Coil Impedance: 1.5 ohm nominal per coil
Xmax (one-way linear excursion): 36 mm (3” peak-to-peak)
Maximum Excursion (one way): 46 mm (Almost 4” peak-to-peak)
Sensitivity: 96.7 db (2.83V / 1m) (coils in parallel)
Fs (Klipple-LSI): 31 Hz
Qts (Klipple-LSI): 0.81
Vas (Klipple-LSI): 47.7 Liters (1.68 cu ft)
Price: $2799.99


One thing that jumps out at me is that they give the sensitivity in units of (2.83V / 1m) rather than (1w / 1m).  Parts Express is doing this too.  The units are equal if you are talking about an 8 ohm speaker, but if the speaker is less than 8 ohms the (2.83V / 1m) units make the speaker look better than it really is.  This speaker, with two 1.5 ohm voice coils in parallel, has an impedance of 0.75 ohms.  This would mean that 2.83v across 0.75 ohms is equal to 10.67 watts.  The spec should read: Sensitivity: 96.7 db (10.67w / 1m) (coils in parallel),  which would translate into 86.4 db (1w / 1m), or 96.7 - 10log(10.67).

Compare with a 12" Dayton Series II that has proven itself to work well in a DB12:
RMS Power handling: 275 watts RMS
Voice coil diameter: 2-1/2"
Impedance: 8 ohms
SPL: 92 dB 1W/1m
Fs: 30 Hz
Qts: .35
Vas: 4.52 cu. ft
Price: $96.65


If I do the math for the max SPL I get 86.4 + 10log2500 = 120.4 db for the ul12 and 92 + 10log275 = 116.4 db for the SeriesII.  I'm no expert, and I have never even heard a sub similar to a ul12, but my guess is that you are paying dearly (in power) for the low Vas of 1.68 cubic feet and you really don't need that low a Vas for a DB12.  I might also guess that a 20% scaled up DB10 might work just as well and be half the size when you are done.  

BTW how much did you pay for the ul12? and what amp are you planning to drive it with?

DanK
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HT-EXT
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Re: Critical mass ul12 for 12" db, what do u thin
Reply #2 - 11/05/09 at 19:34:17
 
I haft to agree with DanK. I looked at the specs over and over again and really would not choose the DB12 for that sub unless I was shooting for SQ only. I not saying it would not put out some good SPL but with that kind of X-max the port is prolly going to be the limiting factor for max output.

I have been proven wrong more than once and never tell anyone that an idea is bad unless bodily harm is involved. You don't know what it will sound like until you build it.

I am currently having luck with a wedge oriented design and you might want to think about a seal enclosure/half wedge. The half wedge would prolly work better with that type sub and output should(more than likely) be better. SQ might not be as good but still better than average. Just my two cents hope it helps.



HT-EXT
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« Last Edit: 11/05/09 at 19:38:36 by HT-EXT »  

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0Hz-20kHz please
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Re: Critical mass ul12 for 12" db, what do u think?
Reply #3 - 11/07/09 at 11:49:05
 
Hey thanks guys, yea it's going into a hatch so savin space is good! I was fairly keen on building a 12" db because of spl, but if u think it will probably be less than a scaled up db10 or half wedge I will Check out those ideas. I was planning on running it with two response precision 1000w rms @ 1ohm monoblocks, one per coil. I will add a cap to it or maybe one cap per amp not sure yet. Let me know what ur ideas on the half wedge turn out like. And where can I find out info to scale the db10 up for the ul? David
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