Sub Placement Idea 700 series subs

[EAmin]

I'm really lovin' my 700 series HT/Home Audio system. However, the bass from my sub doesn't sound quite right --- kinda sloppy at times. I feel it is not very controlled when playing music, especially when playing multi-channel music. I know my ASW750 is a good sub, so it must be where it is placed.

I've fiddled with controls on the sub, but it doesn't seem to help much. It fixes the bass for music, but then I lose the punch for HT. And I very much enjoy feeling the bass in movies.

I currently have 703 mains, HTM7 center and Sig7NT in-walls mounted on the ceiling in a fairly large room. I was wondering if I needed to look at a smaller sub in the front like the ASW700, moving it away from the corner it’s currently in. This would hopefully give me that more controlled bass for music. I would like to keep my ASW750 and maybe move it to the rear to add to that punch I love in scenes from Master and Commander.

What do you think about me using an ASW700 and an ASW750 with my setup? Is it too much bass? Is the speaker placement okay? Just wondering.

Please see the PDF renderings of my room in the following attachment. Sorry I couldn’t provide pics or measurements. I’m traveling this week. So I did this quickly in Visio.

[BlazeMaster]

sorry to hear about your problems Eddy, I think I'm kinda going through the same thing with my SVS PB12plus/2. Like you said, I'm very happy with its overall performance, ALOT of punch for movies, but it just doesn't seem all that consistent compared to different parts of the room. I can get up from couch and walk around and notice spots in the room where I can totally feel the bass thumping my chest and other areas where it almost disapears. I just got some Auralex Studio Wedges to help tame the first order reflections and going to give their bass traps a try also. Hopefully the bass traps can help smooth out some of the peaks and bass buildups in the room.
BTW: I have their GRAMMA pad on the way and should be here tomorrow. It's very effective at isolating the sub from the ground, I'll let you know what I think of it. It's suppose to be a great bang for the buck tweak for bass.

[Aussie Geoff]

EAmin and Blazemaster,

The problems you are both having are very typical of subwoofer placement issues. Bottom line the sound waves for deep bass can be 20 to 40 ft long creating huge standing waves of reinforced and cancelled sound in many rooms. Resulting in (as you describe Blazemaster) bass sound pressure levels that vary markedly (often by up to 20 db) throughout the room.

The first (and best for most cases) way to address this is to move the subwoofer. Remarkably moving by 6 inches to a foot can make a mid difference sometimes, especially for corner placed subwoofers.

EAmin - looking at your room I would first try moving the ASW750 to the other side - that gets it away from the couch and tables on the left which will be interfering with the bass and could easily be the source of your problems. Once in the corner try a variety of options ranging from tightly in the corner to out by 6 inches a foot and 18 inches on one side and both sides...(e.g. touching one wall while well away from the other) Also you should compare this to having the sub more centred (ie way from the corner and somewhere between the two front speakers. I've usually been able to tame most bass problems well with changing the front placement.

There are also side options that work in some rooms (e.g. middle of the left or right side wall can totally change a rooms standing wave characteristics.)

I am not keen on the second sub at the back option. Usually the two subwoofers sound waves meet in the middle and reinforce and cancel each other out just making the problem worse!!

Geoff

[EAmin]

Guys,

Thanks a lot for the advice. I'm going to try moving it to the other side and see what happens. Just curious about where other people are putting their second subs. Any recommendations for me with my room configuration, and recommendations on if it should be a ASW700 or 750?

[junior77blue]

Lot of a variables with subwoofers.

But I like to keep them close to my main speakers, especially if your planning on using 2 subs for R/L channel operation. But I'm sure location along with LP crossover frequency will play a significant role.

[BlazeMaster]

I read on an article on the recent HomeTheaterMagazine on room acoustics. There's a section about standing waves and that had a quote from one of the guys from THX, Tomlinson or some name like that. He suggested the brute way of taming standing waves is to add a 2nd sub in the room. Having one in a corner and then put the 2nd one about half the length of the wall and adjust the movement slightly to your preference. The reason for this, in the article, was that to get the 2nd sub's response meshing with the first one.
Not that I'd get another PB12plus/2 (one is way more than enough for my room), but for those that are thinking about adding a 2nd one, this might be a good place to start with your 2nd sub.

[EAmin]

But when you add another sub, is it typically the same size or do you mix up the sizes? For example, with my scenario of having a 12" ASW750. Should I look to add another ASW750 or should I balance it out with a 10" ASW700? Just wondering.

[Aussie Geoff]

Eamin,

The second sub for standing waves is normally exactly the same size and spec as the main so that the blend in....

However in your regular shaped, not too large room you shouldn't need it - with time I am 95% confident tha you will find a locaton for your ASW750 that largely solves the problem - to the point where the second sub could make it worse due to extra cancellations...

On the weekend very carefully try the different locations I have suggested and see...

Geoff

[EAmin]

Thanks Geoff as always! I couldn't wait til the weekend, so we moved stuff around today. I moved my 703s closer together and further away from the back wall --- over 2 ½ ft away. It takes some getting used to in the looks department, but it helps tremendously with the imaging. Norah Jones voice sounds like it’s coming out of my HTM7 center when in fact I’m playing only two channel --- amazing difference with the mains . At any rate, doing this gave me some wiggle room with the sub, which is no longer against the wall and is now pointed diagonally towards the sweet spot. Still in the same corner, but away from the walls enough to lose the boomy sound. We switched the EQ from B to A on the ASW750, and re-calibrated the speakers including the sub. Still tweaking, but it’s made a big difference in sound.

Part of me misses the boomieness of the sub before especially in movies, but I’d rather have clean bass. Still playing though. Thanks!

[Aussie Geoff]

EAmin,

Excellent news... It is amazing isn't it the difference placement makes - and so many people feel that they need to buy new speakers / subwoofers etc when it is really often a placement issue... I've helped several friends with this...

Re the "missing the deep bass" that's where you can use your Rotel RSP-1098 Processors SUBWOOFER SETUP menu to try giving the sub (say) a 3 db boost JUST for Dolby Digital and DTS - that way you get double the physical bass pressure just for movies etc. That's what a lot of the posts mean by "I like to run by sub hot for movies"...

Still try the other sub positions (right side corner and also the middle side wall of the room) to see what you like best.

Lastly - don't forget - each time you move the sub you will need to check and recalibrate it - the sound pressure van vary quite a lot from location to location!

Geoff

[kiki]

Hi people, I have 705 and htm7, and now picking a sub to go with them, finally comedown to velodyne spl 1000 for AUD$1500, what do you guys think about this sub or what other subs do you prefer? thanksss

[Aussie Geoff]

Kiki,

You can get the B&W ASW 650 for about Aussie $1650 (disocunt) and this is a great sub and a good match for your speakers - worth a listen...

Or for some serious bass - try the Dali SWA-15 - 15 inches, 1000W - 118db and flat to 22 Hz.... Retails for $Aussie 2800 but you can get for just under $2000 - and has been subwoofer of the year under $3000...

Geoff

[kiki]

Kiki,

You can get the B&W ASW 650 for about Aussie $1650 (disocunt) and this is a great sub and a good match for your speakers - worth a listen...

Or for some serious bass - try the Dali SWA-15 - 15 inches, 1000W - 118db and flat to 22 Hz.... Retails for $Aussie 2800 but you can get for just under $2000 - and has been subwoofer of the year under $3000...

Geoff

asw650, audition b4, dont like it, not very powerful sub, no slam, doesnt go deep enought, i'll check out dali swa 15, if spent around AUD$2000, I can get B&W700 sub around that price, i think, :lol: how compare to dali? Velodyne, no go??

[BlazeMaster]

EAmin, if you're still not happy with the subs ability to dish out clean and low distortion bass, try this... http://www.sweetwater.com/store/detail/SubDude/
For my SVS PB12plus/2, I needed 2 of them to have the sub resting on it stablily, not sure what's the exact dimensions of the ASW750. It give more definitions of the bass and eliminated almost all the vibration that the MONSTER was causing all the ground. Very good tweak for the money, IMO. Try it out, if it doesn't work then return it.

[Azeke]

Blazemaster,

I actually have my Sub on a patio stone covered with a rug, works wonderfully and a bit cheaper to boot, total cost around $12.00 and a trip to Home Depot. It one of the best tweaks I've done for my sub.

Regards,

Azeke