How low to go, ht sub

[Pashley]

Originally Posted by GM

Look at the charts in the thread I posted. Red is where the most bass is, ...
GM

Thanks! I did not scroll far enough to see the charts the first time I looked at your link, but did when i looked again. Very interesting.

Looks like some movies have nothing much below 25 Hz, quite a few have significant energy down to 15 or so, and almost none have much below that. So a reasonable first guess at f3 for a sub in this application is 14 Hz. Then look at models & costs, decide whether a compromise is necessary.

My question is answered.

[Pashley]

Originally Posted by norman bates

wow.
I think F3 27hz ported is fine..................
Especially at 120db !!!!

But I do appreciate a good low sealed system also.
Maybe someday I'll try a 20hz ported.......

My eye is on the epic 12's either sealed (3ft3) with 12db of boost to make F3 around 25hz, or twice the sized box but ported at 25hz.
I know the ported will be cleaner, but the sealed should go way lower adding a nice low level feeling.

Or a pair of dayton 390hf in a sealed qtc .707 (11ft3 total) giving fsb=fs=31hz.

My main left & right speakers are ported with 28 Hz f3, or 20 with the manufacturer's EQ. if i add a sub, i'll want f3 at or below 20 Hz.

[Tordenguden]

Bass requires room and space. But you will be able to enjoy the feeling of a subwoofer, if the membrane is bigger than 12", and you have two. I have two subwoofers with XXLS 12" driveres in their each 95 liters of closed volume. This is enough for me. But i would like a pair of 15" SB acoustics in aprox 150 liters. I heard a pair like this, and with proper DSP control and powerfull amps, it feels like the room is breathing. But it needs to be done with care, or else it will simply sound like af boom-box. But if you succeed, you will experience most music with a new sence og life. Bass heavy music will sound deeper, greater and with gentle authority. And with bass light music, it will sound like the subwoofer dosent exist - like it should.
Not simple or easy - but possible.

Just MHO

[m R g S r]

Something to think about. If you've never heard powerful 15hz (felt as well) then you won't miss it. But once you experience it in full force, then go back to watching a movie without it (that contains the sub sonic stuff) you'll really want it that much more

[chrisb]

don't ignore GM's advice about maintaining integrity of not just the drywall in the room, but of the building structure itself when attempting to reach "reference" levels of very LF impact/ explosions SFX etc, - IIRC he or others have anecdotes to share on the subject.

[chrisb]

Originally Posted by m R g S r

Something to think about. If you've never heard powerful 15hz (felt as well) then you won't miss it. But once you experience it in full force, then go back to watching a movie without it (that contains the sub sonic stuff) you'll really want it that much more

some might disagree with the second part- after the worst 2+hr movie experience in recent memory (Prometheus, prefaced by opening feature trailer for the latest episode of Dark Knight saga), the last thing I'd want to attempt to reproduce at home is the overwhelmingly obnoxious balance of "reference" bandwidth / SPL

[m R g S r]

I didn't say overpowering the mains, just a full presence of low distortion 20hz

I love the new Dayton 18" ref sealed sub I just built with some EQ down low. It's just there, adding to the sound, not in your face obnoxious. There's a difference.

But this sub setup, compared to my 30hz (2) 12" ported box, is more enjoyable when it really has the output down low. That is what I mean I'm not even talking about at levels where you can really be bothered by it, but at low level listening as well. It sounds much more "complete"

[GM]

Originally Posted by Pashley

Thanks!

So a reasonable first guess at f3 for a sub in this application is 14 Hz.

You're welcome!

This is what I chose back when U-571 was thrilling folks, but today my first choice would be multiple low Fs, Qt sealed spread around the room as required to minimize room peaks/nulls with the size/qty. of drivers determining how much output at ~14 Hz and below my house can tolerate [not a lot as I learned the hard way ].

GM

[GM]

Originally Posted by chrisb

........the last thing I'd want to attempt to reproduce at home is the overwhelmingly obnoxious balance of "reference" bandwidth / SPL

I resemble this remark! I don't know what movie was playing [had a car chase involving a Jeep-like vehicle?] at the local BrandsMart HT 'room' [open on one side], but if this electronically derived 'boom' with no sense of realism is typical of newer movies, I'll limit my next sub system to pipe organ symphonies and high pass it for the 'blockbuster' bass movies.

GM

[bjorno]

Originally Posted by Tordenguden

Bass requires room and space. But you will be able to enjoy the feeling of a subwoofer, if the membrane is bigger than 12", and you have two. I have two subwoofers with XXLS 12" driveres in their each 95 liters of closed volume. This is enough for me. But i would like a pair of 15" SB acoustics in aprox 150 liters. I heard a pair like this, and with proper DSP control and powerfull amps, it feels like the room is breathing. But it needs to be done with care, or else it will simply sound like af boom-box. But if you succeed, you will experience most music with a new sence og life. Bass heavy music will sound deeper, greater and with gentle authority. And with bass light music, it will sound like the subwoofer dosent exist - like it should.
Not simple or easy - but possible.

Just MHO

Hi Tordenguden,

Only looking for a place to land these suggestions:

b

PS: They too would add an 'image', like subs that don't exist - like they should.