multi-subs

joe logston

here is an article on multi-subs. i use 5 subs myself.

http://hometheatersound.com/features/videonoise/vn_20010301.htm

its a good article read it all and you make your own decision

thanks

Aaron

This guy total forgets about bass management in his article. If you have your center channel (or rear surrounds) set to SMALL, the bass from that channel will be redirected to the LFE channel. It seems to me that unless you have speakers that are capable of at least getting into the 40Hz. region, it would be pointless to add a subwoofer to each channel. Use bass management and add a second LFE sub or get a better single one. I can't even imagine the phasing problems with 5 subs.....

Aaron

joe logston

yes i set all my speakers to large that have the subs, i still get lfe out put in mono off my yamaha rx-v1 receiver. yes the phasing is a problem but you set it up right you can elimate that problem.

read the new hometheater mag about the (fly in theater toured)
that system haves 16- 15" subs and 9 speakers about two per channel they say that they dont play it loud they play it right.

Aaron

I'd be interested to see an equipment list of your HT.

Aaron

mantis

5 Subs in 1 room.............I would shoot myself in the face with a BAZOOKA before I WOULD ATTEMPT to set all that up.Damn one sub is hard enough to get right let alone multible.
I have setup as much as 2 sub's in one room for theater.The front and back of the room I don't care for,One in each corner of the front array is ok but difficult,One on each side tends to fight eachother..........enter into stacking on top of each other.This seems to work very well.A tip I got from THX(thats all of you like to kick)I tried this one my last 2 sub install.It was 2 B&W asw2500's with a complete CDNT line powered with a B&K avr307.Man what responce I got out of that Install.I should of took pictures of the room.It was a converted Barn house,very pleasing and comfortable.The room was high but the sound was great.

RuSsMaN

I don't know if it would be a phasing issue or not. I kinda like joe's thoughts on this one (see Tyrone's theater in system showcase).

A powered sub on each channel, why not. **** phase, set em all to 0, adjust gain and xover accordingly....

By doing this, in a VERY rough example, have you not turned, lets say RT35's into RT2000's or better? Overkill, maybe, but there is some basic logic to having more subs, working LESS (ie, more efficently) therefore achieving more...as far as quality goes.

Truth be known, for the average listener (non-audio-schmo), in the average room, 1, $300 jbl 10" sub will offer up all the LFE they could ever want or need.

The only thing that bothers me, is the 'powered' part of the sub equation. I think if you had a sub on each channel, it should have a driver and network (lowpass) to match to the speaker on that channel, and be passive (driven by the same amp as the speaker on this channel). Especially for if you are using a high quality main amp/amps.... That little plate amp can't hold a card to the, lets say Adcom 5 channel, or Marantz monoblocks you are running for the other speakers.

Interesting topic though......for those of you who are old enough, you will remember the pre-powered-sub days....when speakers were built full range, and you didn't need no stinkin' subs.....

Cheers,
Russ

joe logston

ok , here it gose , got 2 psw-650i use them with 2 rt-7 for the mains, i run speaker wires from aragon 4004 mark 2 amp to subs then to the rt-7 i have the rt-7 on top of the 650s with pedestals. then for the surounds i use rt20p that haves powered subs with the jumpers connected with a denon poa 2400 amp, thats 4 subs. then i have a 15" powered sub as a placement sub. thats 5 subs, on the 15" i run line level rca off my yamaha rx-v1 from the the two mono lfe out puts, to the r & l rca inputs on the 15" sub. i know how hard it is to set up . i been banging my head for a long time, all i can say its hard, but i got it real close to perfection now. the bottem end is awesome.
and i can here all of the highs & meds real clean and clear, every little nuaince in the music, it realy suprise me how it cleaned up the sound stage its not any louder but cleaner sound

thanks

juice21

i am very pleased running dual HSU vtf-2's. one front and one rear. never even thought of stacking them as mantis suggested, although i think i've seen a pic. somewhere on the net where someone stacked two vtf-2's on each other now that i think of it. one driver firing up into the other firing down. wonder what kind of results that would actually produce?

RuSsMaN

Compression, works only with bottom firing subs, enhances overall spl, and gives one hell of a punch. Some high spl car systems are setup in a similar push-pull method.......

Cheers,
Russ

Aaron

But it's not like the Juice's HSU subs would be coupled together in the same box like in car audio.....

Aaron

juice21

Aaron

OK, in that case I guess they are semi-coupled. Why is it a good idea to have the woofers fighting against each other? I could see it helping if they were 180 degrees out of phase of each other, because then they would be helping each other. I've seen opposed woofers used in isobaric subs, but that makes sense since they're in the same enclosure and forcing air out of a (huge) port.

Aaron

juice21

yeah, i am also a little leary if that configuration will give said desired results...

Aaron

The more I think about this the less sense it makes. I assume the subs in that picture are sealed, right? I don't think it would make any sense otherwise. I think I'll retract my statement about the subs helping each other if they were 180 degrees out of phase. I really don't think that would make much difference. Now if you have multiple drivers in the same enclosure firing the same direction (in phase), that makes sense. Argh! Somebody explain this right now!

Aaron

juice21

I assume the subs in that picture are sealed, right?

actaully, the hsu vtf2's are ported. actaully dual ported. there is a port on either side of the enclosure. each one comes with a plug. 2 ports open = maximum output (32hrz), 1 port open = maximum extension(25hrz).

mantis, or anyone, can you shed some light on this method...

johnnyamerika

A while back I suggested building a system of basically 5 cs400i's and 5 PSW650s (or other sub for that matter). I still think that would be a kick **** combo, to have 5 true full range signals blowing your pants off. One sub is good...but there's nothing like feeling the bass coming from all sides.

Sure, they say bass is non-directional, but I have old-school, full range, kick ****, big 'ol JBL moniters in my surround position, and you can tell where that rumble is coming from. You can also feel it.

I'm with Russ, gimme some huge, bulking full range speakers, a'la the 70's....my JBLs are proof that they don't go out of style. For a while I was thinking about replacing them with RT35s, but I'm totally happy with them. They rumble my couch from either side

Aaron

actaully, the hsu vtf2's are ported. actaully dual ported.

OK, now stacking them like that makes absolutely no sense. Somebody better explain this before I start PMS-ing.

Aaron

RuSsMaN

Aaron, why would the subs being ported or not, make a difference in stacking. Not doubting your logic, just looking to understand it.

Cheers,
Russ

mantis

Here all I'm gonna say on the sub's all over the place......
Take some room acoustic classes,at least research it,test all these cool idea's and post back real results.
America......more is more.Bigger is......BIGGER.

juice21

mantis, can you shed some light on the 'theory' behind stacking subs? you mentioned it as a tip you got from THX and that you've used this method in your last two installs, i am just curious to the logic behind this set-up. not doubting it, just curious...

Aaron

Aaron, why would the subs being ported or not, make a difference in stacking.

Hmm, I'm thinking about it this morning, and it's not making sense. There was some logic behind it yesterday when I wrote it, honest. I was thinking something along the lines of treating the interface of the two subs of a kind of "port." But then if each sub was also ported, it would somehow depeat the purpose of creating the stacking port thing. Oh hell, it doesn't make sense any more.

I'm going back to my original logic. If you put the subs 180 degrees out of phase with each other they should be able to help (reinforce) each other. I just can't see how opposing woofers (in phase) would not cancel, or at least reduce, each other's output.

Aaron

RuSsMaN

I don't know one way or the other, but seems to me, if they were OUT of phase, the would cancel each other out. In Phase, they might create a higher pressure (SPL) between the two drivers.

Cheers,
Russ

mantis

Juice,
stacking to sub's on top of each other...........
The output comes from the same location,providing more energy into the room.The way the low notes carry in a room,carry one way and one way only.They peek and dip a couple of times depending on the size of the room.
Sound is just pressure.The way the pressure effects the room is all about placement of the sub.It starts here and ends there.
seating is also effected, if you sit in a peek, the out put is high, if you sit in a dip, the output is low.There is another way to increase dips in pressure levels.By placing a sub there to boost of push a carring wave to maxamize it's effect can have promising results.Very difficult to set up.I perfer 1 sub over 2, but the stacking thing really worked out.They rean at the same phase and level.Stacked on top of each other as they would sit on the floor.Front firing sub's they are.

goingganzo

when you change box types too you have to change your phase if you have a front flirting sub and a bandpass sub that fases into the box you have to have your sub out of phase if you have mutible subs the easyest setup is on the same wall

RuSsMaN

Anyone have any idea what the last 2 posts said?

Someone translate, I'm drunk and lost......

Cheers,
Russ

mantis

Russ, when you sober up you should read again.
I hope it helps.

RuSsMaN

Originally posted by mantis
.By placing a sub there to boost of push a carring wave to maxamize it's effect can have promising results.Very difficult to set up

Sober?

-R

mantis

I thought you said you were drunk and couldn't understand because of it.

RuSsMaN

For the most part, I may have alcohol in my blood stream at any given time, but some posts just don't read right...

Trying to make sense of it all, I get mad, I get glad, you know.....

Cheers,
Russ

mantis

Yeah...I know.