I do not think I need a sub for music. My main speakers are Thiel cs 3.5 with a -3 dB point of 28 Hz. They come with an EQ that makes it 20 Hz. I've tested with music (Doors, Pink Floyd etc.) and cannot hear a difference with/without the EQ.
For home theater, I think I want (need?) a sub. Run the mains without EQ, play with preamp's variable crossover to find a point (probably in 40-60 Hz range) that works well.
First guess at design is sealed boxes with two 15" or four 12" drivers and a Linkwitz transform (Linkwitz Transform Subwoofer Equaliser) to get low enough cleanly. I won't know exactly until I do some modelling.
How low is it useful/necessary to go in HT? Presumably it would be possible to design something that goes down to, say, 8 Hz but I suspect that would be silly.
For home theater, I think I want (need?) a sub. Run the mains without EQ, play with preamp's variable crossover to find a point (probably in 40-60 Hz range) that works well.
First guess at design is sealed boxes with two 15" or four 12" drivers and a Linkwitz transform (Linkwitz Transform Subwoofer Equaliser) to get low enough cleanly. I won't know exactly until I do some modelling.
How low is it useful/necessary to go in HT? Presumably it would be possible to design something that goes down to, say, 8 Hz but I suspect that would be silly.
Now, small but i want to design something that will work in a large living room eventually. Up to, say, 6 by 10 m with 4 m ceiling.
Are you saying clean reproduction to 20 Hz is all one needs for topnotch HT? I thought sound effects went somewhat lower.
5.1 and 7.1 source material (movies mainly) makes a meaning for a separate sub. The .1 (LFE=low frequency effect) channel has up to 120Hz content mixed in too, specially in movies. That's why many sub plate amps have a switch for LFE, which bypasses the highpass filter.
AV amps (the dsp) have the option in speaker configuration to drive LFE to all speakers, if you don't have a sub. But then you can easily clip your amp or break your drivers when the dino jumps or cannons fire.
LFE in movies means that you must set up your system (AV receiver/dsp and sub-amp) differently for best performance/quality of 2ch music and 5.1 or 7.1 music and movies. Or have two different systems just in case you don't remember to change the setting's every time! Personally I have a HT system in the living room and two separate systems in the home theater room
AV amps (the dsp) have the option in speaker configuration to drive LFE to all speakers, if you don't have a sub. But then you can easily clip your amp or break your drivers when the dino jumps or cannons fire.
LFE in movies means that you must set up your system (AV receiver/dsp and sub-amp) differently for best performance/quality of 2ch music and 5.1 or 7.1 music and movies. Or have two different systems just in case you don't remember to change the setting's every time! Personally I have a HT system in the living room and two separate systems in the home theater room
Budget? If you were considering two double 15" boxes (it's unclear from your post how many cabinets you want) then maybe you would consider two of these boxes...
http://www.diyaudio.com/forums/subwoofers/221660-new-ht-subwoofer-dayton-ref-18-a.html
$250 each driver, wood glue stain etc, looking at right around $400 per box. $800 for a pretty powerful clean 20hz output! (Assuming you already have sufficient amp power and ability to EQ down below 40hz).
http://www.diyaudio.com/forums/subwoofers/221660-new-ht-subwoofer-dayton-ref-18-a.html
$250 each driver, wood glue stain etc, looking at right around $400 per box. $800 for a pretty powerful clean 20hz output! (Assuming you already have sufficient amp power and ability to EQ down below 40hz).
How, low, loud for a given room size depends on how much of the LFE gain BW some movies have: The New Master List of BASS in Movies with Frequency Charts
For some folks this means output to near DC, so huge IBs or at least multiple sealed EQ'd, with kilo power feeding them. At this level, the ability of the room's, building's construction to handle such acoustic output becomes a major issue as to what the practical limit is.
GM
For some folks this means output to near DC, so huge IBs or at least multiple sealed EQ'd, with kilo power feeding them. At this level, the ability of the room's, building's construction to handle such acoustic output becomes a major issue as to what the practical limit is.
GM
I don't know. Part of that depends on how low it is useful to go for the HT LFE channel. Do movies normally include useful content below 20 Hz? How far below? Is a -3 dB point of 18 Hz likely to be good enough? Or 12? Clearly the lower I go, the more drivers, power & expense. What i am asking is how low it is useful to go.
I probably want two cabinets for flexibilty in placement, preferably not huge. Ideally, each a single 12" or 15" or a pair of 10" or 12". even that i am not sure of yet because I do not know what I'm aiming at on the low end.
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.
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.
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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.
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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.
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
Not simple or easy - but possible.
Just MHO
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
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"
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"
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
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
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