Dual Subs

[GregBe]

Originally Posted by erict

Jomari, not sure but isn't your example supposed to be the other way around

I am sure he meant to have the numbers the other way around, but even in that example, the crossovers are close enough to each other, that they might interact in some strange way, so turn the crossover on the sub all the way up.

[jomari]

Originally Posted by GregBe

I am sure he meant to have the numbers the other way around, but even in that example, the crossovers are close enough to each other, that they might interact in some strange way, so turn the crossover on the sub all the way up.

heres a better example

Receiver: 60hz
Subwoofer is set at 130hz

we have a gap between 60hz and 130hz missing (aside from the roll-offs of course), this is a lot of information being lost.

you guys get the picture.

[GregBe]

Originally Posted by jomari

heres a better example

Receiver: 60hz
Subwoofer is set at 130hz

we have a gap between 60hz and 130hz missing (aside from the roll-offs of course), this is a lot of information being lost.

you guys get the picture.

You did it again

[erict]

Originally Posted by jomari

heres a better example

Receiver: 60hz
Subwoofer is set at 130hz

we have a gap between 60hz and 130hz missing (aside from the roll-offs of course), this is a lot of information being lost.

you guys get the picture.

I guess what I'm trying to say is if you set you're receiver at 80hz and you're sub at 60hz then there will be a hole, right?

[jomari]

hmm. lemme quote bd on this instead, he says it better...

im quite busy at work, and wish i can further this discussion. sorry lads, prioritizing right now...

per BD...

Avoid an Audio Hole
A low-pass crossover frequency will block high frequency sound above the cutoff level. A high-pass crossover frequency will block frequencies below the cutoff level.

Typically, on many new recievers, the LPF ONLY affects the LFE channel (the ".1" channel), not the bass redirected from the other 5 or 7 channels. That is why you normally set it to 120Hz to make sure you receive all the information that the producers intended to put in the LFE channel. However, if the implemented LPF in the receiver affects the redirected bass from the other SMALL speakers, do not adjust the low-pass frequency too far below the high-pass frequency. You could end up with an audio hole in between the low-pass and high-pass frequencies.

However, remember that crossover networks cut frequencies progressively. As a result, if, for example, the high-pass frequency for the small speakers is set at 100Hz, and you set the low pass frequency around 80Hz or 90Hz, you will most likely be ok. If, however, you set the low-pass frequency around 60Hz to 70Hz, then you would most likely end up with an audio hole. Can you really hear the difference? I will leave the decision up to you.

crossover settings

[StimpsonJCat]

The reason the crossover on the sub needs to be all the way up is you want the AVR to determine the crossovers. His last example was backwards.

If you set the crossover on the sub lower than the highest crossover from the AVR you will lose the information between the two. Also you will lose any LFE that is above the subs crossover. You should turn the subs crossover off or set it as high as it will go. (If the sub has a true LFE input it won't use the sub's crossover at all).

[jomari]

Originally Posted by erict

I guess what I'm trying to say is if you set you're receiver at 80hz and you're sub at 60hz then there will be a hole, right?

yes. an a-hole as bd mentioned it. audio hole.

[jomari]

Originally Posted by StimpsonJCat

The reason the crossover on the sub needs to be all the way up is you want the AVR to determine the crossovers. His last example was backwards.

If you set the crossover on the sub lower than the highest crossover from the AVR you will lose the information between the two. Also you will lose any LFE that is above the subs crossover. You should turn the subs crossover off or set it as high as it will go.

Ding ding ding! we have a winner!

man, you guys are harsh arent you.

thanks for clarifying that up stimpson...better said that i can...

im at work!

[erict]

I think it all makes sense now

[GregBe]

Originally Posted by jomari

man, you guys are harsh arent you.

Nah, just having fun.

[Fors*]

Hey, give the "other guy" a break, doing this from work isn't always the easiest thing to do! You start getting....

[350gt]

Originally Posted by jomari

first off, get a spl meter if you can afford one. its a great investment, and ive never heard anyone say its not worth 50 bucks.

in regards to the LFE input, it wouldnt matter anyways IF you turn your subwoofers crossover setting to its maximum point, meaning if it has a parameter of 30-130hz, you want to set it at 130hz.

your crossover settings on the receiver should dictate what the subwoofer is receiving. this is more important.

a big mistake a number of people tend to do is to have a 'hole' in there LFE frequencies by having crossover points set on both the receiver and the subwoofer.

for example
Receiver: 80hz
Subwoofer: 60hz

you are basically missing the 61-79hz worth of information being filtered out to a void. this is why we want the sub to be set at 130hz or its highest crossover point, and have the receiver do the filtering for you.

does this make sense?

EDIT:

heres a link for our sticky on this topic, created by someone called 'big daddy'

crossover settings and subwoofers

great starter course for reading.

Ya this is the one I bought:
http://www.radioshack.com/product/in...ductId=2103667

Just didnt have the patience at the time to play with it.

Okay on the JBL I have it turned all the way up, but on the def. tech. it has a high and a low crossover. Do I turn the high all the way up too? Also what about the varible phase alignment, Do I leave that at 0?

Sorry for all the questions, I read all Big Daddys thread awhile back, but I just get confused.

And BTW I watched part 5&6 if band of brothers and it sounds great. It added a little deeper effect but what I like the most is how my couch shook when the mortars and artillery where blowing up. Wasnt boomy like I expected and barely noticed it was there until all hell broke loose.

[jomari]

Originally Posted by 350gt

Ya this is the one I bought:
http://www.radioshack.com/product/in...ductId=2103667

Just didnt have the patience at the time to play with it.

Okay on the JBL I have it turned all the way up, but on the def. tech. it has a high and a low crossover. Do I turn the high all the way up too? Also what about the varible phase alignment, Do I leave that at 0?

no ones answered this part yet? hmm.

anyways, first off, congrats on your spl meter purchase. at least thats a first step into getting it properly calibrated.

second, im not much of a guru when it comes to subs, but i think i can advise
high pass - 120hz
low pass - 80hz.

i think.

stimpsoncat, fos, and bd can confirm if ever.

again, im at work, so thats an already valid excuse if people wanna play pick on the other guy game again.

[erict]

Originally Posted by jomari

no ones answered this part yet? hmm.

anyways, first off, congrats on your spl meter purchase. at least thats a first step into getting it properly calibrated.

second, im not much of a guru when it comes to subs, but i think i can advise
high pass - 120hz
low pass - 80hz.

i think.

stimpsoncat, fos, and bd can confirm if ever.

again, im at work, so thats an already valid excuse if people wanna play pick on the other guy game again.

Can we have fun again It's all good

[Yeha-Noha]

Originally Posted by Big Daddy

Placement of the two subs is very important. Research has shown that the best positions for tow subs are:[LIST=1][*]Middle of the side walls.[*]One in the middle of the front wall and one in the middle of the rear wall.[*]The two right and left front corners.

Hi BD. I have a PA 120 sub with a second one on order that should be here by Friday or the Tuesday after Labor Day weekend.

Your placement guide has caused me to reconsider what I intend to do. The only locations I can place the subs are in the middle of the front wall and in the middle of the left side wall. The left corner is occupied by a corner style fireplace. The right corner of the room is about another 15 - 20 feet away and is actually in the dinning room, so that corner is out of the question too. I can only get one sub in the front, next to the right front speaker. My room is 30 x 20 x 15 (vaulted ceilings).

Will I end up with a weird bass response by placing the subs thisway, one in the left side middle and the other in the front middle?

The PA 120's have a variable phase control from 0 to 180 deg. Will I need to adjust that as well?

Would I just be better off stacking one sub on the other in the front middle?

[tbizzle]

Originally Posted by rwojtalewicz

The only locations I can place the subs are in the middle of the front wall and in the middle of the left side wall. The left corner is occupied by a corner style fireplace. The right corner of the room is about another 15 - 20 feet away and is actually in the dinning room, so that corner is out of the question too. I can only get one sub in the front, next to the right front speaker. My room is 30 x 20 x 15 (vaulted ceilings).

Will I end up with a weird bass response by placing the subs thisway, one in the left side middle and the other in the front middle?

Since you have no pics or diagrams, that's gonna be hard for BD to address. The available positions sound like they look like this.



If so, those sound like good spots. BUT, I don't think that anyone, including BD, can tell you that they will sound good there. You're gonna have to experiment with the positions yourself. You said your room is 30x20, that's a pretty big room. There may be some other spots that you can fit them in there, just don't put the subs right up against a wall. Leave a foot or so in between, otherwise the subs can sound too boomy or muddy.

Originally Posted by rwojtalewicz

Would I just be better off stacking one sub on the other in the front middle?

I probably wouldn't do that. Part of the point of having 2 subs is that you can space them out around the room and the room will have uniform, smooth bass. If there are any dead spots around the room, especially a seating position that isn't against or near a wall, having 2 subs can help hit those spots. Check out BD's post on positioning. Having them across from each other is optimal

https://forum.blu-ray.com/showpost.p...68&postcount=2

[Yeha-Noha]

Originally Posted by tbizzle

Since you have no pics or diagrams, that's gonna be hard for BD to address. The available positions sound like they look like this.



If so, those sound like good spots. BUT, I don't think that anyone, including BD, can tell you that they will sound good there. You're gonna have to experiment with the positions yourself. You said your room is 30x20, that's a pretty big room. There may be some other spots that you can fit them in there, just don't put the subs right up against a wall. Leave a foot or so in between, otherwise the subs can sound too boomy or muddy.




I probably wouldn't do that. Part of the point of having 2 subs is that you can space them out around the room and the room will have uniform, smooth bass. If there are any dead spots around the room, especially a seating position that isn't against or near a wall, having 2 subs can help hit those spots. Check out BD's post on positioning. Having them across from each other is optimal

https://forum.blu-ray.com/showpost.p...68&postcount=2

Your diagram shows the right idea, but off a little bit. The sub on the left side wall is about 1 - 2 ft from the corner FP. The other sub along the
front wall is about 9 ft from the corner FP. You sort have drawn the reverse placement diagram. The couch is about 2/3 of the way to the back wall from the front wall.

I was questioning whether or not that is preferred or favored position. If not, would the bass thus be lacking or too much in general terms. Just like in the sense that if you put a sub in a corner, it will tend to sound louder and probably boomier. I was looking for qualifying words in a similar sense for the position where I'll have may subs positioned. My reasoning was that if a sub in the corner is bassy and boomy, then a sub in the middle of a wall might be the opposite: lacking bass and thin. That was my main concern, in words as such describing what might tend to happen.

I might be able to just squeeze in a foot distance from the wall to the subs, but will probably be slightly less. This is a living room and not a real HT room. A big box that far from the wall just won't get my wife's approval. The same goes for my tower speakers. The surrounds are mounted right on the walls.

Tbizzle thanks for taking the time to make that diagram. I'm at work tonight and thus unable to make any diagrams like that.

[Big Daddy]

Originally Posted by rwojtalewicz

Hi BD. I have a PA 120 sub with a second one on order that should be here by Friday or the Tuesday after Labor Day weekend.

Your placement guide has caused me to reconsider what I intend to do. The only locations I can place the subs are in the middle of the front wall and in the middle of the left side wall. The left corner is occupied by a corner style fireplace. The right corner of the room is about another 15 - 20 feet away and is actually in the dinning room, so that corner is out of the question too. I can only get one sub in the front, next to the right front speaker. My room is 30 x 20 x 15 (vaulted ceilings).

Will I end up with a weird bass response by placing the subs thisway, one in the left side middle and the other in the front middle?

The PA 120's have a variable phase control from 0 to 180 deg. Will I need to adjust that as well?

Would I just be better off stacking one sub on the other in the front middle?

The following diagrams demonstrate the generally accepted positions for multiple subwoofers. These positions are suggested after years of research at the National Research Council of Canada and at Harmon International. The two best positions are the middle of the front walls or the middle of the side walls. The next best position is two in the front right and left corners. The last option is to place one in the the front corner and the other one in the rear corner, diagonally oppositie of the front one. You may have to turn the phase of the rear one to 180 degrees.

If you place the subs in any other position, you may increase the risk of phase cancellation. It is a good idea to sit at main listening position with an SPL meter and play some music with heavy bass. Change the phase of one subwoofer to get the loudest bass.

I am not a fan of stacking the subwoofers. You may get louder bass, but you may also end up cancelling some frequencies. The idea of having two subwoofers is not to get louder bass. It is to get even and smooth bass across the room for all listening position. I would rather have two subs in the following positions and on risers.

For additional information on using multiple subwoofers, read A Guide to Subwoofers (Part II): Standing Waves & Room Modes.

Very Good



Good



Best



Best

[tbizzle]

Originally Posted by rwojtalewicz

My reasoning was that if a sub in the corner is bassy and boomy, then a sub in the middle of a wall might be the opposite: lacking bass and thin. That was my main concern, in words as such describing what might tend to happen.

I might be able to just squeeze in a foot distance from the wall to the subs, but will probably be slightly less. This is a living room and not a real HT room. A big box that far from the wall just won't get my wife's approval. The same goes for my tower speakers. The surrounds are mounted right on the walls.

Tbizzle thanks for taking the time to make that diagram. I'm at work tonight and thus unable to make any diagrams like that.

Haha no problem man. As for the sub on the wall, I think it should sound as good as if it was in a corner. It might seem to have a little less output than a corner, but not necessarily. Subs generally don't sound boomy by being in a corner, it's when they're too close to the wall that it can get boomy or muddy.

LFE waves like to interact with walls, so a sub should be placed near one as opposed to in the middle of a room. At least that's my understanding of it, I'll let the pros chime in on this stuff though [edit: BD swooped in while I was in the bathroom ]. I'm just speaking from personal experience I've had with this stuff in the last year and from with what I've learned here on the forums.

[Yeha-Noha]

Originally Posted by Big Daddy

The following diagrams demonstrate the generally accepted positions for multiple subwoofers. These positions are suggested after years of research at the National Research Council of Canada and at Harmon International. The two best positions are the middle of the front walls or the middle of the side walls. The next best position is two in the front right and left corners. The last option is to place one in the the front corner and the other one in the rear corner, diagonally oppositie of the front one. You may have to turn the phase of the rear one to 180 degrees.

If you place the subs in any other position, you may increase the risk of phase cancellation. It is a good idea to sit at main listening position with an SPL meter and play some music with heavy bass. Change the phase of one subwoofer to get the loudest bass.

I am not a fan of stacking the subwoofers. You may get louder bass, but you may also end up cancelling some frequencies. The idea of having two subwoofers is not to get louder bass. It is to get even and smooth bass across the room for all listening position. I would rather have two subs in the following positions and on risers.

For additional information on using multiple subwoofers, read A Guide to Subwoofers (Part II): Standing Waves & Room Modes.

BD, those diagrams are just fantastic and that's an understatement actually.
I have an idea of what I can expect in a qualitative sense. It looks like my arrangement will be a hybrid between good and best.

You read my mind when you said putting them in other positions might run the risk of phase cancellation. That's what I was concerned about.

Well, I do have some bass heavy music that might do the trick. If I detect phase cancellation, I'll use the variable phase control on my subs and watch what happens on my SPL meter. BD, that was an excellent suggestion.

No, I'm not going to stack them. I was just stirring the pot.

You have been most helpful and so was your guide to subwoofers: standing waves and room modes.

BD, thanks again!