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Old 13th June 2008, 03:58 PM   #1
plenk is offline plenk  United States
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Default Best Sq sub setup

I have been building some test configurations with diamond d3s and trying to find the best sq setup. It sounded pretty good with it sealed in a .77cuft box with no fill, but I was trying to get it punchier and cleaner by experimenting with some isobaric setups. I read somewhere that isobaric push/pull configs don't actually cancel out the 2nd and 4th order harmonics as good as regular push/pull. The only advantage of them is 1/2 box size. Any input on this? Thanks.
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Old 13th June 2008, 09:49 PM   #2
jol50 is offline jol50  United States
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People I see are using sealed or IB for SQ. IMO the right sub and install can work great but I want to run IB subs and midbass to play under about 300Hz....subs under say 40. And then playing a sub under 40Hz leaves little room for audible distortion especially if it is in a trunk/etc., and that is typical for SQ setup. Then again I never had much issue with distortion in a decent sub setup I am much more worried about higher frequencies. But yes, getting a sub to play flat if you run it higher is a challenge and good excuse to run DSP. An adjustable slope crossover can help. In the old days we ran 10s IB and used to run them up to ~80Hz, but at a reduced output to fill in midbass. It was work to get it just right so you did not have boom out of the subs. If I run a sealed it is usually larger than spec and stuffed about 3/4 full. I rarely have room for a ported that can get as low as I want to get.
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Old 14th June 2008, 12:01 AM   #3
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If you want punchy and clean and your not too worried about maximum SPL, my favorite is a sealed box with a Qtc = 1 used with a Linkwitz transform.
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Old 14th June 2008, 12:50 AM   #4
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Another vote here for sealed.

No port noise, or worrying about perfect box tuning. Just get the right size box, and you get clean lows, real simple.
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Old 14th June 2008, 04:02 PM   #5
plenk is offline plenk  United States
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yeah iv done the sealed boxes, I was wanting to go even cleaner and punchier than 1 in a sealed box. Isnt a Q of .707 more ideal than 1? I dont know if a more linear freq slope is better sounding than one that stays around 0db loss as long as possible and then drops off quickly at low freq. So far, nobody has been able to answer that, so thats why Im just building the boxes to see what sounds better.
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Old 14th June 2008, 05:44 PM   #6
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Quote:
Originally posted by plenk
Isnt a Q of .707 more ideal than 1?
You can read about the Q of sealed enclosures here.....

http://www.geocities.com/kreskovs/Box-Q.html

With a Q = 1 there will be a peak in the response. When used with a Linkwitz transform to acheive a Q = 0.707 the peak will be removed and the low end extended all while keeping the "punchy-ness" of a Q = 1 alignment.
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Old 15th June 2008, 09:35 PM   #7
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Quote:
Isnt a Q of .707 more ideal than 1? I dont know if a more linear freq slope is better sounding than one that stays around 0db loss as long as possible and then drops off quickly at low freq.
Well stated question. Yes, 0.707 is more "ideal" in theory because of the lower ripple Anonymous1 spoke of.

In practice, the best between small variations depends entirely on your taste and the music you listen to. It also can be seriously affected by placement and equalization. If you're going to add boost in any form, the resulting system Q is completely different.

For subwoofers I prefer:

either the shallower slope of a low Q system;

or an arbitrarily higher Qts (0.9-1.4) with an electronic Q-correction circuit and plenty of power to recover the lower octaves.

Often, neither is practical and a compromise is necessary.

There is no substitute for your own experimentation. If you have the time and means, I strongly encourage you to do so, draw your own conclusions and share them with us!
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Old 21st June 2008, 09:19 AM   #8
amc32 is offline amc32  United States
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lets not forget phase shift and group delay
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