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Old 16th August 2004, 06:07 AM   #11
memito is offline memito  United States
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no, inches, I thought I put inches. It's a JL 12w6v2-d4
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Old 17th August 2004, 01:12 PM   #12
Hayden is offline Hayden  Australia
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your sub will give a little boom in its hits
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Old 17th August 2004, 01:21 PM   #13
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Default Re: Boomy Sub

Quote:
Originally posted by memito
I have a 12" sub in a sealed box. I built the box to specification for the sub. I thought that sealed boxes were supposed to make the bass have a "punch" to it instead of a "boom". I'm not a big fan of the boominess that subs can produce. Anyways, I stuffed the box with polyfil and the boominess is still there. Is there a way to get rid of the boominess without replacing the box? The box is in my trunk facing towards the back, not towards the front. Someone told me that if I turned the box to face the inside of the car it would help out. Any suggestions?
If Qtc exceeds 1, you will get a booomy bass - also in a sealed box.

What is Qts, VAS, and free air resonance for this driver? And how big i the sealed box?

I will then explain why you have a booomy bass.

Br.

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Old 17th August 2004, 02:00 PM   #14
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Whilst in the main you are correct, the Q is only relevant around the resonant frequency. If the box is sufficiently small such that the resonant frequency is high and out of the passband, then it is not of importance. Some car subs with their small boxes operate in this fashion.

If the low-pass filter (Hz as the original poster calls it) is set to 80Hz and finds it boomy, pushing it up to 100Hz will only make things worse.

If the Hz control referred to by the original poster is not a low-pass filter but a bass boost control, try reducing the boost and/or the frequency.
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Old 17th August 2004, 04:09 PM   #15
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Quote:
Originally posted by richie00boy
Whilst in the main you are correct, the Q is only relevant around the resonant frequency. If the box is sufficiently small such that the resonant frequency is high and out of the passband, then it is not of importance. Some car subs with their small boxes operate in this fashion.

If the low-pass filter (Hz as the original poster calls it) is set to 80Hz and finds it boomy, pushing it up to 100Hz will only make things worse.

If the Hz control referred to by the original poster is not a low-pass filter but a bass boost control, try reducing the boost and/or the frequency.
You must have a quite "petite" box in order to get the resonance out of the passband. Imagine a box at only 5 litre, the driver data is Qts 0,3, VAS 50litres, f0 30Hz. With these data you'll get a resonance at 100Hz and a Qtc = 1. How small should we make it - 1 litre? 1 litre result in a Qtc = 2 and a resonance at 200 Hz - only one octave higher.
Higher Qtc also result in a steeper roll-off downwords. The steeper roll-off, the more power is required to maintain the level down to i.a 30Hz. A Qtc=1 means 24dB/oct roll-off - calculate how much power needed at 25Hz to keep the same level as at 100 Hz. 48 dB - means 250 times more power at 25 Hz versus 100 Hz?

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Old 18th August 2004, 09:41 AM   #16
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I did not check the driver T/S data. You are of course right

Higher Q only affects the slope immediately after resonance. As you get further down it will ALWAYS revert to the same 12dB/oct no matter what the Q. However, the 'affected' slope can often be quite well into the passband even when used in the Under Resonance Principle as outlined in my previous post, so yes it does matter.
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Old 18th August 2004, 06:10 PM   #17
memito is offline memito  United States
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Here are the specs for my sub:
Fs=25Hz
Qes=.480
Qms=7.1
Qts=.45
Vas=79.9 litres
Xmax=.65 in
IW/Im=85.9 dB SPL
Sd=77.8 in
Re=6.75 Ohms

My box has a volume of around 1.25 ft
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Old 18th August 2004, 06:31 PM   #18
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Ahh, antiresonant gave me misleading parameters.

By my calculations, you have a Qtc of just over 0.8 and F3 of 40Hz. That shouldn't be particularly boomy.

Play with your tone controls and filters. Set all your headunit levels and tone to zero/flat. 80Hz should be a good starting point for sub low-pass filter. Now set your amp level so you can hear your sub OK, then add a little bass boost if necessary.
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Old 20th August 2004, 02:16 PM   #19
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Quote:
Originally posted by memito
ok, this is what I have on my setup, a hifonics brutus driving a 12" jl. The Hz is at 80 and I added about 6db of gain. This amp has a remote "volume" control, which i don't know if it controls the actual volume or the gain (i've been reading that gain and volume are not the same). So what you guys are saying is that if I go from 80 to 100 on the hz and lower the gain it'll have more of a punch?
Its sound like your subwoofer has a high Q, you will need a smaller box or less air space as it would seem like there is very little loading on the cone, just reduce the internal volume and refit the driver and check the sound again.

With music not a test tone, choose something that has natural sound and not something electronic.

Always Always have your tone controls flat, no bass boost nothing, nada, zip.

The remote gain must be plugged in! or else the amplifier will run at maximium gain and sound terrible.
You have to remember that your car adds gain as well so adding more will give a boom effect, oh boy.

The subwoofer only starts to work at 80Hz so having its crossed over higher a waste of power, as i would hope your normal drivers would be able to cross over well with your subwoofer.

Who does like boom woofers?

I know, def folk!
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Old 20th August 2004, 05:38 PM   #20
djQUAN is offline djQUAN  Philippines
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Quote:
Originally posted by Paradise_Ice



The subwoofer only starts to work at 80Hz so having its crossed over higher a waste of power, as i would hope your normal drivers would be able to cross over well with your subwoofer.

Who does like boom woofers?

I know, def folk!

so you're saying I'm deaf?
wel,, I only have two 10's but they go boom when I need them to but they also sound real good when I listen to the right music.

www.djquan.angelcities.com/ride.html
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