Well, hopefully I'll have two subwoofers soon. I'm still a little hazy on exactly how to optimally place two subwoofers. The popular recommendation of mid-wall front and rear or mid-wall on the sides applies mainly to closed, rectangular rooms, correct? Right now I am in a room with openings into other rooms, and it works out that the subwoofer crawl indicated nearly mid-wall on one side as a good place, but I don't think the opposite wall worked too well. However, I'm curious if you even want to place the second subwoofer according to the subwoofer crawl for the center seat. Will the bass be more even throughout the entire listening area simply by virtue of having two subwoofers placed in different parts of the room? I guess I'm asking a complicated question that probably won't have a clear-cut answer.

The layout for the basement area I'll have my system in (eventually) will be an odd shape, so I'm just trying to get a feel for what the general advice is. Place them both according to the single subwoofer crawl? Place them both mid-wall on the sides, even in the non-ideal layout? Try them all and graph them all and leave you all alone? Why would I even give you that last one as an option?

Charles, I don't know what the right answer is for an odd shaped room. . .

I have two of my subs about a third of the way on two walls and the third is tucked away in the front right corner.


I should add, if I was going to take one away, it would be the front right one.

Is that also your weakest sub?

Yes, it's one of the 10" sealed subs.

Man, now I'm hungry for a sub sandwich. I know about proper placement of those.

Wait, I shouldn't threadjack my own threads.

You're just making it easier for the rest of us. . .

I'd recommend if you get a party sub, to place it on the dining room table.. or if you have a long counter.

Now I need a foot long Sweet Onion Chicken Teriyaki.

CV, I think I would use the subcrawl to position the first sub and then I would try to graph out various placements and from different seating positions for the second sub, to see where the best position is for flatest response.

Charles, if you have any way to do so, I'd recommend you set up the REW software so that you can use it in your room to find the best positions for the new subs. The sub crawl is a good start, but since you're generally just estimating bass response of a single frequency while doing this, it's hard to know whether a given location provides the smoothest response or just the loudest response at the frequency you happen to be using for the sub crawl.

My (unconventional?) advice would be to start with placing both subs where they are most conveniently-placed in the room. In theory, with two subs, placement is going to be less important than with just one since the idea behind two is that they work to attenuate the effects of room peaks and nulls.

Based on that, I'd start where you want them and run a frequency response (FR) curve using REW from your main listening position and measure the results. Then without moving the subs, experiment by changing the phase on one, then the other, then both subs, and determine which combination gives you the smoothest response at your main listening position. This should be your benchmark against which you test any other placement options. (i.e. since this is the most convenient placement for your room, to move the subs to other locations which would look awkward or be less ideal than where they are, another position would have to have FAR better FR to justify making that move and dealing with subs sitting in the middle of the room, weirdly placed on sidewalls, etc.)

Once you've done this much, experiment with a couple of other options. Try the middle of two opposite walls if your room allows, or try opposite corners of the room (my current setup).

If/when my 800 arrives, I'm planning on moving both subs to the front corners outside of the M80s. That will be the "ideal" setup from which I create my benchmark readings. This choice is mainly for looks & balance. i.e. I think it'll look extremely odd to have an M80 and an 800 on one side of the room and just an M80 on the other side of the screen.

If I can't achieve the results I want from there (and using the BFD equalizer), I'll try going back to opposite corners or some other combination that produces flatter response than the way I'd prefer them to be set up in the front corners.

Just resign yourself to the fact that it's going to take some time to get right, and try to have fun in the process (it shouldn't be hard to have fun with it!). We'll look forward to hearing/seeing your results as you experiment.

Jason

Hi CV,

I was skeptical about having two subs providing a better FR across the different seats in our HT room. That skepticism quickly disappeared when my second EP500 arrived. I placed both subs under the projector screen, on either side of the center channel and about the same distance from it as from the M80s (same look as in dllewel's room that is on the main Axiom page). I simply used the frequency sweep from the SMS-1 and it was immediately obvious that the peaks and troughs were much less pronounced compared to the situation with the single sub. The FR curve looks virtually flat with this placement in our rectangular attic room with insloping side walls. I just kept this arrangement rather than moving the subs to mid walls. I think this is also Jason's advise above; simply place them where they seem to be conveniently placed and start from there. In my situation, it worked out very well. Good luck.

I appreciate the feedback, guys. Mid-wall on the sides is actually very convenient. The side walls are where I have space to play with. I don't think I can actually fit one on the front or rear wall.

I'll have to see about REW. I don't have a laptop, but my computer is in the next room. Would it be possible to use it that way, going back and forth between rooms?

I'm not sure how much effort I want to go to in my current room, but it would be nice to get my feet wet for when I do move my system.

The computer in the other isn't a problem. I am doing the same thing, you just need long enough RCA cables to reach the receiver from your PC for the signals to be sent; if you want to use the signal generator in REW, which is the most convenient way with the PC in another room.

I have found my onboard sound card is very lacking in the lower frequencies as well as the higher ones, it drops off substantially below 70 and above 12khz. I have just bought this external card so I can use our laptop and take it along with me to help set up other Ht systems as well. I will let you know how it works out, hopefully later tonight.

That would be great. It looks like it could be a decent, affordable solution.

I'm not sure if I have two RCA cables that long or not. I know I have at least one.

You only need one then a Y splitter to feed the left and right as it is a mono signal any way.

Charles, since you have Dr. Toole's new book you'll probably get more good info from that, especially Chapter 13, "Delivering Good Bass in Small Rooms" from about pp.222-236, than we can offer. Yes, as he points out, the positioning of two or more subs at opposite mid-wall locations is most effective in rectangular rooms without large openings to other connecting areas. In other situations he emphasizes that taking measurements and then following with corrective electronic room equalization will give better total results than simply following basic placement suggestions automatically as a complete solution. So, those who have either separate room equalization equipment or built-in processing such as Audyssey MultEQ which equalizes subs should also experiment with that, using various sub locations.

You remembered that I have the book. Now if only I had remembered. I will definitely have to get some use out of it. I'll have to throw Audyssey back into the mix when I'm playing around with everything. Thanks, John.

Those things are freaky as hell. I hate those ads. Wait, I hate all ads. Praise be to TiVo!

I had the cable problem until I bought these. http://www.hsuresearch.com/products/uls15dualdrive.html

Wireless subs. They sound awesome. I only have 2 but you could add as many as you want.

I don't understand how Hsu measures the extension specs on their subs. Bass extension = 15 dB? What does that mean? It plays down to 15 dB... but how much volume is it giving up at that level? Where's the +/- rating?

If you look at their sub comparison page, you see that on one of their subs (the MBM-12), they do list the entire frequency response with a +/- rating... the rest list only the mysterious "extension" number. I know Hsu is a relatively well-regarded sub manufacturer, so this lack of information seems odd to me.

Jason

If you go to the ULS-15's product page, it says "15 Hz - 1 dB."

Ok, I was reading that wrong, still it's odd not to give a +/- rating for the whole range, unless they're not focused on linearity?

Yeah, it would be nice to have greater detail. Considering ULS stands for Ultra Linear Sealed and it "features a woofer with patented super linear motor," I'd think that would be a focus.

Maybe they should add the word "deluxe"?

They don't have to resort to such ultra grandstanding.

A long cable is usually not a problem, RG59 or 6 can be run for as long as you want, but, CV was referring to a RCA cable long enough to reach from one room to another to run REW software, without needing to buy another.

Peener, how would you compare the sound the of the ULS15 to other subs? Are they as strong or do they just have good extension while sacrificing a little output.

My wife has been hinting the PB13 is too big for our room, so I might be looking for another sub and the ULS-15 is on the short list.

Yeah, I'm really interested in feedback on the ULS15s. I love my Hsu VTF3 and would seriously consider adding another Hsu to my HT.

Yeah, even with the EP800s coming, I'd still probably go for another sub for the computer eventually. It's nice to see sealed subs with such low extension and respectable output surfacing. Who knows if I'll ever be able to justify the cost on something that isn't my main system. I'm certainly interested in the ULS-15's performance, though.

I am looking at the ULS-15 and the SB-12's. I believe the ULS has a huge advantage in the low end at 15hz, so it is the front runner at the momment, if I give in to my wife, although she now says she doesn't mind the PB13 enough for me to sell it off and have to look for another one. I know better.....

I had a VTF-3 MK3 until I blew it. With 2 ULS15s I feel that I am getting a stronger pressure than with a single MK3. There is no question that the extension is much better with the ULS15s but a single ULS15 is not as strong as a single MK3. But 2 ULS15s give me everything I could ask for, including the ability to put them wherever I chose. Replacement parts are on the way for the MK3 and I will be able to compare them side by side. The MK3 is the best sub I ever had by far. The ULS15s would be the second best but I give them higher marks for wireless as this is important in my setup.

Thanks Peener! I guess I might need to look at dual subs to replace the PB13, to keep the pressure up where I like it and with the ULS being wireless I can put the second one any where....hmmmmmmm, this could be fun. Yet another sub adventure, my wife is going to kill me.

Fortunately since it's wireless, it'll work from the doghouse... your likely new home when you suggest going through the sub selection saga again.

Jason