Will this work getting a great response out of a subwoofer? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 11 Old 01-09-2004, 06:57 PM - Thread Starter
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Will one of these ideas work getting an improvement to a subwoofer sound?

1) Boosting the low end of where the subwoofer starts showing a drop in decibals in the frequency curve? If so, how many decibals would be considered safe. Example, If subwoofer curve starts dropping say 5 decibals between 20hz and 25hz, just boost the low frequency by around 5 decibals with the equalizer say by using a parametric equalizer such as the BFD feedback destroyer and leave the rest of the bass range (25 to 80hz) flat.

2) Raising the overall volume/decibal level of the subwoofer and instead of boosting the low end (20hz to 25hz) by five decibals, lower the rest of the frequency range (26hz to 80hz) by five decibals to flatten out the response curve? say from 25hz to 80hz using a parametric equalizer such as the BFD feedback destroyer.

3) How about a combination of the two... Boost the low end by a few decibals and lower the gain of the rest of the frequency range by a few decibals to "even out the sound".

I can't be the first guy in the world to think about this and probably won't be the last....

Please don't say just get a HSU or SVS sub. I can't see myself buying a subwoofer that I have to mail back to return if I don't like..... I would have considered an HSU sub if Compusa had them in stock at the local Naperville, Illinois store and could just "buy" one off the shelf even though they have a pretty ****** return restocking fee policy.... Do any stores sell the HSU sub locally.... or is it just direct mail/internet? I don't want this paragraph to be the main topic of conversation....

By the way, I currently own the Definitive PF15TL+ subwoofer purchased locally and still have a couple weeks before it is mine "permanently"..... I own one of the digital Radio Shack meters, but haven't had the time to meter the sub yet. I also own a BFD destroyer and have been thinking about how to set it up and if it is really worth it at all......... My room size is on the small size (15' by about 10'6") even though my speakers aren't! I have 4 feet tall Infinity Quantum 2 speakers as my left and right and an Infinity Quantum 3 speaker as my center channel. I listen to music about 50% and movies about 50%. Serious movies with the subwoofer cranked up only when no-one else is home or when friends are over maybe 5%..... Almost every guy I know loves loud movie impact :D while almost every wife I know doesn't.... :( What's up with that?
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post #2 of 11 Old 01-09-2004, 09:45 PM
 
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Ok, your first 3 options are all the same. You just go about it in different ways. But they achieve exactly the same results, with the same costs in all ways.

You will need ample power for the sub to be able to handle that low bass, you may reach the limits of the amp, and/or the driver. A subwoofer can only do so much before it starts to reach it's limits, bottom out, the amp runs out of steam, it get's sloppy, you get port chuffing, etc etc.

EQing can definitley help sub performance though. But it isn't a way to turn any sub into a miracle sub. It's best used in getting flat response for the room.

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Please don't say just get a HSU or SVS sub. I can't see myself buying a subwoofer that I have to mail back to return if I don't like
Get an SVS or a HSU. You won't return it. ;)

Also try audioenvy to find a possible owner near you so you can audition one if you want.
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post #3 of 11 Old 01-10-2004, 01:33 AM
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First off, I agree with Chris. I built a 318l sonosub with a 15" Tempest and there truely is "no replacement for displacement."

That being said, you can do wonders with a Behringer Feedback Destroyer and your Def Tech sub. If you haven't played with the BFD much yet, start at http://www.snapbug.ws/bfd.htm and read it twice. Once you understand the basics, it becomes very easy to input your filters. Next, get Tony Gomez' fantastic Excel spreadsheet here . For a smaller room like yours, go to hometheaterforum.com and do a search for 'house curve.'

In a nut shell, you can use the BFD to have your sub's output rise ~10db from 100 Hz down to 25 Hz or so. If you're willing to spend a few hours, the difference is nothing short of amazing.

P.S. You'll want do it when the wife/SO/kids are gone. The last time I calibrated mine, the cat got sick and glared at me for a week. :eek:
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post #4 of 11 Old 01-10-2004, 03:25 PM
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If you can help it, NEVER boost the sub doing EQ---always cut---always.
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post #5 of 11 Old 01-10-2004, 03:30 PM
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audioguy,

On what basis do you give out that recommendation?
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post #6 of 11 Old 01-10-2004, 05:03 PM
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Ez-v, because trying to EQ a null just throws power into the void. Find the best placement first, then EQ down the peaks. Anything else is just a waste of power.

As to the Def Tech sub, I'd get a HSU STF-2. It'll play louder and lower and cleaner than the 15" DT sub.

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post #7 of 11 Old 01-10-2004, 06:12 PM
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Audioguy is right, what you need to do is lower the other frequencies, NEVER try to boost using the EQ, your sub will be several dBs quieter, but it will reach deeper, which is what you want.

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post #8 of 11 Old 01-10-2004, 07:21 PM
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An boost by a mere 3dB is asking for double the power from the sub's amp.

So near the deep end of 20hz, an almost inaudible boost of 3dB is asking alot from the sub amp and driver........... I too don't recommend any boost.
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post #9 of 11 Old 01-10-2004, 08:31 PM
 
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The cut versus boost thing i understand, but it's misleading. After EQing your sub flat, you'd then want to calibrate it to the correct output. Thus either way, you stress the amp and driver. If you cut the highs to get it flatter, you will lose output. Then you'd raise the overall volume and you're right back with the same problem as boosting the lows.
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post #10 of 11 Old 01-10-2004, 09:45 PM
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Zactly. Boost and leave the overall the same or cut and raise the overall. Either way, you want/need Xdb @YHz requiring Z Watts.

I am serious...and don't call me Shirley.
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post #11 of 11 Old 01-10-2004, 10:53 PM
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I agree with everyone above. Adding a few db of boost in a narrow range shouldn't tax the amp any more than raising the overall level. However, if the dip in response is due to a room null, you're sacrificing headroom and won't see any improvement at that frequency anyways. I always assumed that's why conventional wisdom is to EQ with cuts, not boosts.
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