18 inch subwoofer

[boomer28]

I have 2 klipsh rf3. Anyway i like the sound of these speaker but now i want more powerful sub. I want to buy two 18 inch subs because i want to put them stereo. Is it possible to do something like this in a room of 400 square foot? Where should i locate all the speakers? Have you heard about people doing that kind of "crazy" project and what they think about it?

[lynnm]

Running two subwoofers will not do much if anything to enhance the stereo imaging simply because the bass frequencies are essentially omnidirectional. I also think that running 2 18s in a room of 400 square feet will likely degrade the the overall tonal balance of your system. I suggest that you start with a single unit and if you still feel a need for additional bass you can always add another.

If your system really is deficient in bass you should experiment a fair amount with speaker placement before adding even one sub. Proper speaker placement can dramatically improve the sound of almost any system.

[TBrennan]

Well 2-18s will give better dynamics and lower distortion than a single 18. With direct-radiating woofers you can never have too much cone area.

They need not be overwhelming; afterall one can simply adjust them for proper output.

[dantfmly]

----------------

On 5/1/2004 6:01:36 PM lynnm wrote:

Running two subwoofers will not do much if anything to enhance the stereo imaging simply because the bass frequencies are essentially omnidirectional. I also think that running 2 18s in a room of 400 square feet will likely degrade the the overall tonal balance of your system. I suggest that you start with a single unit and if you still feel a need for additional bass you can always add another.

If your system really is deficient in bass you should experiment a fair amount with speaker placement before adding even one sub. Proper speaker placement can dramatically improve the sound of almost any system.

----------------

i diagree two subs does help imaging. I have replaced my two smaller subs with one larger sub. (all i could afford). Yes you can not pinpoint the sub but you can tell what area it is coming from. When i had two subs the bass was more even across the room. it just was not as loud. i hope i can get another some day. 400 square feet is a little small for two 18's in my opinion though. Go with two twelves. It all depend though on the brands that you are looking at.

[boomer28]

Thank you for the advices. I've been thinking about your comment and to begin i will get just one 18" and maybe i will get another one if i need more bass. Anyway i have tried the 12" klipsch sub of reference serie and it was not enough for me. The 15" sub of klipsch was unfortunately not available at my local dealer.

[DrWho]

i'd have to say that two subs definetly has more potential to sound better than just one...there is less cone movement to produce the same volume (reduces modular distortion) and non-symmetrical placement opens up a lot of options with fighting room nodes and all that.

for what it's worth, i've always been able to detect imaging with subwoofers. i know sound isn't supposed to be directional below 80Hz, but i've always been able to tell where the bass is coming from. I'm also of the belief that we hear with more than just our ears (ie, our skull, nasal and oral cavities, and even our skin and stomache).

anyways, having two subs should never sound worse than having just one, but in the end it's all about how you implement them into your system. if you're on a tight budget, i'd suggest getting one high quality sub versus two of lower quality. but if money isn't an issue, then totally go with two...or maybe even 3 (there was a study a while back that determined that 3 subs out-performed an array of 80 subwoofers. i could find the technical article for anyone interested)

[chops]

Just curious, how does 3 subs out-perform 80 subs?

Also, it is true that you can have one sub or 13 subs in any size room and still have it sound good. It all depends on how you have the gains and crossovers set. I've got twin - dual 15" subs in my system, and it sounds perfect, not overpowering. (check out my System Profile)

One more thing, I was just wondering what brand of 18" sub you are thinking about going with. Again, I'm just curious.

[DrWho]

----------------

On 5/4/2004 7:29:54 AM chops wrote:

Just curious, how does 3 subs out-perform 80 subs?

----------------

the 80 subs were a line array across the front wall...the 3 subs were positioned near (not in) the front corners on the front wall and one in the rear middle. the 3 subs were able to obtain a flatter frequency response (due to placement) and the 3 subs were also able to achieve the same SPL and sensitivity. the additional subs in the line array didn't increase output that much because the room almost acts like a compression unit and keeps the SPL from getting any louder (gotta love room nodes and destructive interference). now that i think about it, im not sure it was 80, but more like 18...either way, the test concluded that the addition of subs beyond 3 was starting to waste money, because the modular distortion decreases less as subs increase and the max SPL doesn't increase much. keep in mind, this was all done inside a moderate sized room where there's a lot more factors than a wide open space (like outdoors). If we were outside, then no way would 3 compete with 80, but we have to remember that we're dealing with a room here. in larger rooms, i can even see 5 being applicable. it's typically good to have odd numbers of subs and avoid perfect symmetry because you want to activate as many room nodes as possible because it actually provides the flattest response. odd numbers by nature help to prevent activating the same sets of room nodes.

anyways, i think i might as well hunt down that article again as it's very applicable to the topic however, the link is on my pc back in chicago (im in grand rapids now) so i'll hunt it down over the weekend if i have time/remember. i've also got another link that talks about this topic as well (it's even got cool animated diagrams if i remember right), but it discusses more about room placement and the placement of multiple subs.

btw, you mentioned an 18" sub...i don't know of many "home-use" subwoofers that are that large. that said, i want to warn you that any "pro-audio" sub isn't going to have the deep low end that you're after; even if it's 18." professional subs are designed to project far and be loud...the standard approach to accomplishing this sacrifices the low-end extension. so you're looking at around a 40Hz cut-off with the majority of nicer pro subs. the majority of your good home subs will get you down to 30Hz no problem with "only" a 15" driver. I currently own a pair of mains with 12" subs that go down to 20Hz in my room (yes i know lots of cone movement, but that's life).

anyways, i might also suggest that you post your same question down in the powered subwoofers section of the forum...there you'll probably be bombarded with a list of subs to try (i might as well throw in the svs plug-in since no1 else has yet). www.svsubwoofers.com a few B4-Plus subs from them should do the trick and never forget the ever friendly DIY projects...i forget what they're called, but something like the tumult or earthsaker or something like that is very popular right now in the DIY world. (not to mention great bang for the buck).

[chops]

DrWho....

If adding more woofers in a given room does not increase the overall SPL because of "compression" in that room, then why with car audio, if you want to go louder, you add more drivers and power?

A vehicle is always going to be smaller than any room in a building, and the more drivers and amps they add, the louder it gets.

Bag End, and Velodyne make 18" subs. Unfortunately, those are the only two I can think of. Definitive Technologies has a pair of BP3000TL towers with built-in 18" subs.

[avman]

the biggest 'problem' w/deep bass in this 400 sq.ft. room is the room SIZE!

IMHO-you CAN'T get deep bass in that room due to the physics of bass wavelength.

i am basing this on something i recently experienced:

in my ht room,my RSW-15 makes great bass,both loud and deep.

in our somewhat smaller pj room,the RSW-15,while turned up more,and pumping harder,the bass IN THAT ROOM is not as loud,or as deep,as it is in my ht room.

now,at the store,if you go down the hall,or in the warehouse,you can feel and hear the deepest bass frequencies.

so, i would suggest one or two QUALITY 12" subs,as a larger sub's lower frequencies would be 'wasted' in that room,and 'tightness' and 'accuracy' wouldn't be as good.

avman.

[CECAA850]

Do yourself a favor and check out the SVS's. There are tons of reviews and specs all over the web. They also have a no questions asked return policy, but I've never read of someone using it (although their B-stock must come from somewhere). I am not affiliated with them but I do like to pass along a good thing when I see one. They are pretty awesome. Carl

[J.4knee]

"Do yourself a favor and check out the SVS's."

Ditto

[JJJeffries]

Locate either a Velodyne ULD-15/2 or a Velodyne ULD-18/2 and you will never look back.

The 15 is flat to 14hz and the 18 to 12hz. Both have a 400 watt servo power amp.

I auditioned both and settled on the 15. I have owned it since 1989 and had Velodyne update it in 1998 and I love the feeling it gives.

Trust me on this. Velodyne is a solid company and when used with horns or any loudspeaker in my opinion is the finest sounding subwoofer on the market.

A friend brought over Carver's 1200 watt sub and it didn't move us like the Velodyne did.

Best,

Craig

Broadcast standard equipment. Too numerous to mention!

[formica]

----------------

On 5/4/2004 5:26:30 PM DrWho wrote:

the 80 subs were a line array across the front wall...the 3 subs were positioned near (not in) the front corners on the front wall and one in the rear middle. the 3 subs were able to obtain a flatter frequency response (due to placement) and the 3 subs were also able to achieve the same SPL and sensitivity. the additional subs in the line array didn't increase output that much because the room almost acts like a compression unit and keeps the SPL from getting any louder

----------------

The phenomenon they experienced was probably due to placement issues as you mentioned and not the actual quantity. To fully pressurize a room would require tremendous power... although it is true that as you approach it, the subwoofers would become less efficient (SPL per Watt).

----------------

On 5/4/2004 5:26:30 PM DrWho wrote:

it's typically good to have odd numbers of subs and avoid perfect symmetry because you want to activate as many room nodes as possible because it actually provides the flattest response. odd numbers by nature help to prevent activating the same sets of room nodes.

----------------

I'm not sure which article says that, but an odd number of asymmetrically subs is no more advantageous that correctly placed even number of subs. Distribution of room modes is highly placement dependant. The article you mention reminds me of one published by Todd Welti for Harman International entitled: Subwoofers: Optimum Number and Locations The objective of the test was to produce the smoothest response and not necessarily the loudest with 1 to 50 subwoofers.

The ironic part is their conclusions are the opposite of those you mention... where an even number of symmetrically placed subwoofers in THEIR rectangular room performed best. Like you said, it's highly placement dependant.

OTH, a single sub is easier to tune for most people...

Rob

[bill rawls]

Let's see...400sq/ft room.....80 subs@at least one sq/ft footprint.....oh well, if some is good, more is better and too much is just enough.

Bill

[popbumper]

----------------

On 5/7/2004 3:28:47 PM J.4knee wrote:

"Do yourself a favor and check out the SVS's."

Ditto

----------------

Thirded - ABSOLUTELY check out SVS! Man, two 18's in 400 square feet? Ouch!! I have one SVS 12" (20-39PCi) in 400 square feet, and am VERY happy with it. In checkout with the Avia disk, I get useful output down to 30Hz, much less below that, but the wall hangings rattle at 24Hz. Pretty neat to see/feel it in action with test tones, gives you a better idea of what the sub is really "capable" of in the room size.

Popbumper

[popbumper]

Formica:

What a GREAT paper about subs! I read it fully and saved it for future reference. Looks like another sub may ultimately be in my future. This stuff is "crazy nuts" addicting. Thanks for sharing that!!

Popbumper

[TBrennan]

never mind, pearls before swine and all that.

[DrWho]

----------------

On 5/5/2004 6:38:36 PM chops wrote:

DrWho....

If adding more woofers in a given room does not increase the overall SPL because of "compression" in that room, then why with car audio, if you want to go louder, you add more drivers and power?

A vehicle is always going to be smaller than any room in a building, and the more drivers and amps they add, the louder it gets.

Bag End, and Velodyne make 18" subs. Unfortunately, those are the only two I can think of. Definitive Technologies has a pair of BP3000TL towers with built-in 18" subs.

----------------

for the sake of brevity, im gonna respond a bit on the blunt side but wanted it to be known that im trying to be polite...anyways, "car audio" and "home audio" are two completely different environments. the biggest difference most relative to this discussion is that the low frequency energy isn't trapped inside the car. in the home, the walls are sturdier and help to keep more of the energy inside the listening environment (thus the reason we have room nodes). now with one well placed sub, we have one set of room nodes; and for every listening position there will be specific dips in the frequency response. when we have two well placed subs, the goal then becomes to have the dips in the frequency response to occur in different places for each sub, which evens out the overall frequency response. as more subs are added, more and more gaps are filled. now if we add another sub in hopes of filling another set of gaps, then the overall SPL isn't going to increase as much as you might think because the extra energy from the next sub is going to be used up inside the gaps of the other subwoofer. now since it's practically impossible for a second sub to amplify only in the gaps, you are definetly going to get a noticeable increase in SPL, but only in the frequencies that both subs are playing in. also with the addition of subwoofers, you're going to introduce new dips in the frequency response due to cancelation from frequencies out of phase with each other. and don't forget that this is very dependent on the listener's position as well...every position in the room is going to have a slightly different response and the dips in and peaks in the frequency response are going to vary greatly and the phase issues are going to be different in every location as well. it is very possible that a second sub makes a world of difference at the main listening position, but at another seat in the room, a second sub could actually make it worse! this is why multiple subs starts to get really annoying and hard to dial in. well this part has already gotten too long, but i hope it makes enough sense. if not, i might give it another go (or find a bloody link)

----------------

On 5/7/2004 10:11:59 AM avman wrote:

the biggest 'problem' w/deep bass in this 400 sq.ft. room is the room SIZE!

IMHO-you CAN'T get deep bass in that room due to the physics of bass wavelength.

i am basing this on something i recently experienced:

in my ht room,my RSW-15 makes great bass,both loud and deep.

in our somewhat smaller pj room,the RSW-15,while turned up more,and pumping harder,the bass IN THAT ROOM is not as loud,or as deep,as it is in my ht room.

now,at the store,if you go down the hall,or in the warehouse,you can feel and hear the deepest bass frequencies.

so, i would suggest one or two QUALITY 12" subs,as a larger sub's lower frequencies would be 'wasted' in that room,and 'tightness' and 'accuracy' wouldn't be as good.

avman.

----------------

again, i don't wanna come across as arrogant or rude in my brevity...

first of all, the room size shouldn't determine the lowest frequency that you will be able to hear. you don't have to be a wavelength away in order to hear the frequency. we can all hear 80Hz in headphones can't we? and that wavelength is 12 feet long (somebody correct me if my numbers are wrong). i don't want to get too much into this, but i did want to claim that you can hear very low frequencies, even if your room is small...the only thing is that the smaller the room, the more uneven the low notes will sound (which might sound worse than if you didn't even play those low notes to begin with...thus why a smaller sub could sound better).

secondly, as long as the diameter of a driver isn't more than 1/4 the wavelength of the highest frequency it's trying to play, then the driver itself is not too big (im not sure if 1/4 is the correct ratio, but i'll just go with it). another key ingredient is that a larger diameter driver doesn't have to move as much to play lower frequencies. all that said, as long as the diameter of your subwoofer supports up to 80Hz (you could probably cross over anywhere between 45 and 80 with your mains), then the largest diamter subwoofer should be the most tight and accurate (aka, less modular distortion because the cone is moving less). the dampening factor is also gnerally higher with a larger diameter woofer which also helps with the amp/speaker relationship (less flutter).

----------------

On 5/8/2004 1:16:50 AM formica wrote:

----------------

On 5/4/2004 5:26:30 PM DrWho wrote:

the 80 subs were a line array across the front wall...the 3 subs were positioned near (not in) the front corners on the front wall and one in the rear middle. the 3 subs were able to obtain a flatter frequency response (due to placement) and the 3 subs were also able to achieve the same SPL and sensitivity. the additional subs in the line array didn't increase output that much because the room almost acts like a compression unit and keeps the SPL from getting any louder

----------------

The phenomenon they experienced was probably due to placement issues as you mentioned and not the actual quantity. To fully pressurize a room would require tremendous power... although it is true that as you approach it, the subwoofers would become less efficient (SPL per Watt).

Though im not sure, i think i remember reading that you start to experience room pressurization around 110dB...granted this will be very room specific and it's only when you start to experience it. this factor really shouldn't matter since 120dB should be considered more than enough volume (since you go deaf after that) and we can already come very close to that with any single subwoofer, let alone a few.

you also run into destructive interference as more subs are added and that's probably a larger factor than the room's pressure.

----------------

On 5/4/2004 5:26:30 PM DrWho wrote:

it's typically good to have odd numbers of subs and avoid perfect symmetry because you want to activate as many room nodes as possible because it actually provides the flattest response. odd numbers by nature help to prevent activating the same sets of room nodes.

----------------

I'm not sure which article says that, but an odd number of asymmetrically subs is no more advantageous that correctly placed even number of subs. Distribution of room modes is highly placement dependant. The article you mention reminds me of one published by Todd Welti for Harman International entitled:

Subwoofers: Optimum Number and Locations

The objective of the test was to produce the smoothest response and not necessarily the loudest with 1 to 50 subwoofers.

The ironic part is their conclusions are the opposite of those you mention... where an even number of symmetrically placed subwoofers in THEIR rectangular room performed best. Like you said, it's highly placement dependant.

OTH, a single sub is easier to tune for most people...

Rob

----------------

well that site didn't work for me so i didn't get to read it, but i find it interesting that they suggest even numbers of subs 'symmetrically' placed (and i have no doubt that both articles are equally credible in their results). Again, it seems very room dependant and there's an infinite number of placements to be tested. personally, i don't think there's a golden rule for the number of subs one should use. i do feel though that it's easier to find good placements for odd numbers of subs (particularly 3 subs) based on the way most home audio environments are laid out (but that's just my opinion which basically means nothing) as long as you're activating as many nodes as possible, then you're off to a great start (but you're off to an even better start if your room doesn't even have room nodes to begin with!)

from experience, i've found that subs placed under/near the mains image much better and thus sound better...i know you're not supposed to be able to localize frequencies below 80Hz, but you can always feel from which direction a sub is coming from.

now as a disclaimer, i don't mean to come across as an expert on the subject (i reread this post before posting and i felt i might come across that way)...im just trying to express my understanding of the situation and im hoping that someone else can come along and tear me apart if my understanding is wrong (i'll prob put up a fight though) anyways, i hope this proves more beneficial rather than annoying.

[Jim Cornell]

I have a Klipsch TSCM folded horn, fully enclosed Cinema Klipschorn bass bin, loaded with 1 EARTHQUAKE MAGMA 15 inch dual voice coil sub.

Powered by a Hafler 400 watt amp.

Its between my Klipschorns, and i have the sub bass evenly spread out in the room.

Now if there where only more TSCM bass bins available, it would be nice, these are rare, and not seen very often.

What i will do, is use the sub loaded bass horn as a sub, and the top section of the TSCM as center, Klipschorns front, and Cornwall rears.

Ill have to get a bigger place to see this happen, in the meantime, i enjoy these setup with 2 systems, 1 is 2 channel H/T, and stereo using heresys and cornwalls, the other is my Klipschorns on the long wall, with the TSCM bass horn, as well as the TSCM top section as center for 2 Channel, as well as 3 channel stereo.

All i can do for now.

Regards Jim

PS this is all in a 15X16 foot room.