Maybe you should take this over to diyaudio to see if one of the geeks there will engage. This isn't hi-fi in a living room, it's more a sound reinforcement problem, and that's a lot different animal. I have done some stereo speaker design and started to dive into this but in the end don't really have a lot to add, other than I agree with VolvoHeretic that a 6" driver is going to get lost in a room volume of that size.
In reply to jwagner (Forum Supporter) :
I did, at the same time I posted here. So far, no replies.
It's hard to explain in a short post, but you kinda have to take the published numbers with a grain of salt. You can tweak volumes and ports to "stretch" the frequencies of the driver, of course with a diminishing return on quality.
My setup is two C-notes for the L and R, an 8" Acoustics Research sub (300w, passive radiator), and a Polk center channel. When I do 5.1, I have Acoustics Research satellites behind, but I rarely prefer 5.1.
The C-notes tune down to 43Hz, and will make sound down to 30hz, which is mostly because whoever designed the enclosures and ports capitalized on going larger than recommended. It stretched the frequency response below the driver's recommended 50hz bottom end. I set the high-pass to 120 hz to better suit the C-notes, and the sub is low-passed at about 100hz, and it easily handles down to 23hz.
I mention all of that to say this: It's a bit easier to get a smaller sub to play low than it is to get a big sub to play high. That sounds counter-intuitive, but with respect to picking mids, it will be a hard task to jump from 18" to 6.5" and be able to fill the freqs in the middle. If you end up not being able to fill those midbass freqs, you may end up needing to add something like a 10" or 8" midbass, which is super extra. The single 8" in my living room absolutely pounds. If I went to a 10", I would likely have to lower the high pass on the satellites to fill in the mid bass that the 10" can't do, and I risk trying to drag the satellites into a range where I can get the SPL, but SQL will suffer.
I think you'll have an easier job with a higher excursion 12 and a proper ported box. You can pretty easily get infrasonic with a 12. Added bonus, it won't need 5 cuft like an 18 might.
Curtis73 (Forum Supporter) said:It's hard to explain in a short post, but you kinda have to take the published numbers with a grain of salt. You can tweak volumes and ports to "stretch" the frequencies of the driver, of course with a diminishing return on quality.
My setup is two C-notes for the L and R, an 8" Acoustics Research sub (300w, passive radiator), and a Polk center channel. When I do 5.1, I have Acoustics Research satellites behind, but I rarely prefer 5.1.
The C-notes tune down to 43Hz, and will make sound down to 30hz, which is mostly because whoever designed the enclosures and ports capitalized on going larger than recommended. It stretched the frequency response below the driver's recommended 50hz bottom end. I set the high-pass to 120 hz to better suit the C-notes, and the sub is low-passed at about 100hz, and it easily handles down to 23hz.
I mention all of that to say this: It's a bit easier to get a smaller sub to play low than it is to get a big sub to play high. That sounds counter-intuitive, but with respect to picking mids, it will be a hard task to jump from 18" to 6.5" and be able to fill the freqs in the middle. If you end up not being able to fill those midbass freqs, you may end up needing to add something like a 10" or 8" midbass, which is super extra. The single 8" in my living room absolutely pounds. If I went to a 10", I would likely have to lower the high pass on the satellites to fill in the mid bass that the 10" can't do, and I risk trying to drag the satellites into a range where I can get the SPL, but SQL will suffer.
I think you'll have an easier job with a higher excursion 12 and a proper ported box. You can pretty easily get infrasonic with a 12. Added bonus, it won't need 5 cuft like an 18 might.
you're not kidding on the 18" matching to smaller drivers. Here is my basement setup (I don't use it too much as the 58" tv is over 20' away and it is too small given the distance. The wiring has been cleaned up since. The speakers are Overnight sensation MTMs and the subwoofer is a driver from JTR speakers in a sealed 2x2x2 cabinet made out of 1.5" thick MDF. It's powered by a 1500watt rack mounted amp.
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