Need help setting up mulitple subs

[pietsch288]

Here are my questions- I have 4 svs cs ultras all running off of a ep2500. I am running them basically as though they are 2 seperate subs---2 of them are dead center of the back wall and the other 2 are almost dead center of the front wall (one on each side of the canter channel ...so about 2 feet apart). I am running each SET in series to get a aprox 8ohm load (with both sets hooked up the amp see's 4ohm) and then bridging the amp for 2400w @ 4ohm. Ok here's my question-----When I hook up the front subs positive to positive negitive to negitive and do the exact same with the back subs I get an almost perfectly flat line with my sms1 with almost no EQing.
But when I reverse the back 2 subs (front subs are positive to positive neg to neg---- rear are negitive
to positive positive to negitive) ........I get a lot higher DB at certain freq (huge spike @ 25-28) but the freq response is very poor. So which way is correct flattest response or most overall DB but EQ it flat. I feel like I'm "in phase" when I have the most output.... but why am I getting the best responce "out of phase". Which way is correct????
please help......thanks

[thxgoon]

I'm at a loss of words for a good explanation but technically either way is correct. Commercial subwoofers have phase swithces on them for integrating with the mains and it's always whatever setting sounds best is the proper set up. As you've found there are trade off's to each way, in the end it's up to you.

Try moving the subs around the room. Corner locations help with the low frequencies and a cheap eq like the BFD can smooth out problems.

[Sonnie]

If you are closer or farther from one set of subs or the other, generally out of phase will sound better and produce a flatter response. If they are equidistant from your listening position, generally they will need to be in phase. At least that is my experience and was my situation in my testing of moving subs around in my HT room.

I had two subs up front, one in each front corner... and one large LLT sub in the back... drivers spaced far apart in a box that was 8' wide, so almost like having them in each rear corner, but about 2' out from the actual corner. I also had issues with cancellations and ended up crossing over the rear a little lower than the front.

It took a lot of experimenting and tons of measuring over and over with various phase settings, but ultimately, since my front and rear subs were equidistant from the listening position, they remained in phase producing a response that did not need equalizing, although I let Audyssey adjust it a little bit.

[Sonnie]

Btw... I combined your threads ...

[pietsch288]

So loosing a little impact but gaining an almost flat responce is the way to go? For the most part there is no write or wrong?

[pietsch288]

I am using an SMS1 for eqing and xover duties. I'm letting my denon 2808 audyssey set up phase between the subs and the mains. My room is 15.5w x 28 x 9.5. I'm just wondering about subs. I'm looking for the cleanest most accurate bass (LFE). As you can see I have a small room with alot of sub and I'm growing a little tired of too much sub sound (seems a little boomy). But there is no substitution for the feeling the subs make (I tried buttkickers but didn't like them). So now I'm just making sure I'm setting them up by the book.

[thxgoon]

If you want them set by the book, their levels should be as flat as possible and matched to the level of the mains. This doesn't always result in room shaking or satisfying bass. Adding a house curve to your eq settings can help you get that low end without sounding 'boomy', though I don't know how to apply it to the SMS.

Also, double check the phase and distance settings set by the Audyssey. Sometimes they can be a bit wacko

[pietsch288]

So this is how I've ended it as of today, and pretty sasified. I'm running the svs's @ native hz (20hz---all ports open), I've got the shelf (house curve) set flat from 20hz-32hz and sloping @ 48db per octive after 32hz. It seems like I'm xover very steep but I have my mains runnning down to 40hz (klipsch rf7's). Besides when I get around 30db per octive I get too much sound out of the subs (which is what I was trying to avoid). I do feel like I could use more 16-20hz, but its probably because I'm so used to the bass overpowering everthing. Allmost forgot I decided to split the front 2 subs (I have one in each front corner) and kept the back 2 dead center of the back wall and they are what I would consider "out of phase", but that is by far the best sounding (and feeling) bass I have yet to find in my system.

[thxgoon]

Sounds good

[Sonnie]

Sounds like you got it worked out.

Post us a screen shot of your response from the SMS-1.