I want a subwoofer flat from 10hz-40hz

[Audiophilenoob]

Originally posted by mwmkravchenko
Yep the back chamber is the room volume. The front chamber is the box volume. It can be done bud.

Mark

Originally posted by Cloth Ears


The only way you're going to be able to get 120dB, exactly flat, from 10Hz-40Hz, in 20cu feet or less, is by electronic means.

What I mentioned will give you flat (within 3dB - I challenge you to be able to tell any difference at 110dB), and if you put 3 of them together you've used about 26 cu feet and 119dB. A little extra power, some minor electronic flattening (you're low-pass at 40Hz will probably do this anyway) and you'll have your 120dB anechoic. In your room (somewhere) you might be able to find 130dB do to room loading - probably if you stick your head in a corner. But I doubt you would know it, as 10Hz will only make it uncomfortable to breath and cause a bit of balance loss. It'll probably shake a few things, though.

daddy likes

I can live with electronically flattening it out ....

[Audiophilenoob]

Originally posted by mwmkravchenko
Yep the back chamber is the room volume. The front chamber is the box volume. It can be done bud.

Mark

4th order bandpass correct???

JI can't seem to make this actually fuction very well

[454Casull]

I'm thinking a Linkwitz Transform filter for a crapload of high-power, high-excursion subs would do it. Don't feel like doing any calculations, though.

[simon5]

130 dB at very low frequencies are not that dangerous for hearing. It could be dangerous for health I don't know. I should bring my SPL meter in a club someday. I'm quite sure the SPL is stupidly high in the 120s...

I will use these Titanics since you seem to want to use them.

[simon5]

Originally posted by 454Casull
I'm thinking a Linkwitz Transform filter for a crapload of high-power, high-excursion subs would do it. Don't feel like doing any calculations, though.

It would work, but he only have 2400W to work with, so ported is the way to go.

mwmkravchenko, according to Adire, room gain is more like 2 dB per octave for the usual room. I built a subwoofer using that rule of thumb and it was flat in room down to 16 Hz as designed when measured with a RadioShack SPL meter.

[Audiophilenoob]

Originally posted by simon5
130 dB at very low frequencies are not that dangerous for hearing. It could be dangerous for health I don't know. I should bring my SPL meter in a club someday. I'm quite sure the SPL is stupidly high in the 120s...

I will use these Titanics since you seem to want to use them.

I just can't think of a woofer to buy that can do this....

the tumult isn't out nor is the maelstorm...

I can get RE to build me a "special" MT

[simon5]

Checked with the Titanic.

2 Titanic each in their 15 cu.ft boxes with 900W would do around 127 dB in room at 10 Hz. The rolloff is a bit higher than wanted, because you get 131 dB at 40 Hz.

I'll use the Acoustic Elegance AV15 in the next simulation, it's the same price for better performance.

[Cloth Ears]

130 dB at very low frequencies are not that dangerous for hearing.

I'd have to do a bit of research, but I thought that sub-hearing sounds at 125-130dB can have the same effect as someone slapping their hands over your ears - it can rupture the ear-drums. I'm not sure that it will deafen you, but will cause problems with your ears which can be the same thing.

From a quick scan, the following are the 'health' regulations:
Continuous dB Permissible Exposure Time
85 db 8 hours
88 dB 4 hours
91 db 2 hours
94 db 1 hour
97 db 30 minutes
100 db 15 minutes
103 db 7.5 minutes
106 dB 3.75 min (< 4min)
109 dB 1.875 min (< 2min)
112 dB .9375 min (~1 min)
115 dB .46875 min (~30 sec)

I remember the "Mythbusters" doing a show on low frequencies - surrounding one of them with a stack of subbies and pumping sounds from 8-80 Hz at volumes from 100dB to 160dB. They got the dude to wear ear proctection after the first test at 100dB.

[justinc]

I did a quick calculation using a lt and the ascendant atlas 12" since thats what paramaters i had on hand. in 2 20cuft boxes with 5 12"s each and 2400 watts you can get 126db flat down to about 5hz in room... I would assume you could get something similar with other readily available drivers such as the av12 or the tc2+

[BassAwdyO]

This thread is reducilis...

you dont want 130db@10hz... 110db@10hz gets scary. You will probably break something(although it may have nothing to do with your stereo). Perhaps your eardrums.... Although I dont believe infrasound is as damaging to the ears as some suggest.

Dont say the REXXX18 wont do 10hz because it has a high Fs... Believe me... it will do 10hz just as well(if not better) than an old school adire tumult 15 which has a much lower Fs. Excursion, displacement, and cone area are all that matters below 20hz. Throw the rest out the window.

On the issue of room gain... Just like SPL competetion cars there is a point where the bass you blast into the walls stops coming back and starts getting transfered into other things... 130db Is above that point I do believe