Axiom Home Page Forums General Discussion Technical Questions Graphs multiple subs multiple seats.

Randy. If you expected that three or more subs would give you a lab like flat FR curve equally at all the seats it ain't ever going to happen.

What adding subs does accomplish though is smoothing those nulls and peaks at each seat which "can" translate into better sound. I qualified it because better sound isn't just flat FR but also depends on proper time alignment with the speakers and each other sub. It takes time and patience to get it right. When you do, the reward is you can take the SMS out of the circuit and get yourself a better processor.

Lab like freq response was not my goal John, it was to help improve the peaks/nulls across each seat. The discussions by Dr Toole and Ian are telling people what can happen by adding 2 or 4 subs in a room, people don't have labs at home.

At this point I am not seeing that improvement in the peaks/nulls, at least with the SMS graph, maybe I need to try my REW again, or the Realtraps tones in 1hz increments. If you look at the graphs from say 50hz and above, there is not much change if any by adding the additional subs. In most cases it is much worse.

What can I say Randy...my experience a couple of years ago confirmed the conclusions of the Harman papers and Ian's current video. However it took me longer than you to tweak and adjust the subs. Also you do have a very large irregular room compared to mine which is always a factor. In any event, it may be worthwhile to invest time tweaking the subs where you had them for the graphs. Which sub(s) are connected to the SMS? Have you used the variable phase function in the SMS to further dial in phase? What about other crossover points? Also, small changes in sub postion often change the picture. considerably.

For those that have a 350v3 and an SPL meter, can you put the dial on 60dB selection and place your mic about an inch from the sub grill cover, I'm getting 60dB's with nothing playing.

This is the buzzing I'm hearing, maybe my ears are sensitive, not sure. Sounds like the buzz you hear from a transformer station.

Change the dial to 40Hz and maybe it will go away .

BTW, I didn't have this problem with the 350 when framer brought it over. Then again, when I wired my basement, I made sure that all my AV equipment was on a single 30 Amp circuit.

John, what I have been trying to do, is find the positions that give me the best response possible without introducing EQ, yet. My subs are all hooked to the Denon, and I'm using the SMS graph to see what happens in various situations.

Hypothetically, if I can find a decent arangement without EQ, then I would not need the SMS. Originally, I did have the 350s going through the SMS, and the 600 as an anchor (as you called it), the problem is that nothing I did with manual EQ seemed to changed the graph, and when it did, it was the opposite affect. I was just trying to reduce peaks, which is suppose to be easier.

When you say corner loading, are you saying in the corners, or stack them? I can't put them outside my 80's, since my corner bass traps are in the way. I've got them now just inside each 80, with the drivers the same distance from the front wall. It sure looks like a roller coaster ride.

What is strange is if I put all the subs out of phase, 180, the graph is better, and the 40hz hump is not as bad. I've got the 600 back along the back wall again, next to the walk out door. Maybe I'll try the side wall again to see what happens.

I'm just getting tired of moving these subs around.

The dials stop at 60 on the SPL meters, I even get the noise out of my 600. All my AV equipment is on the same 20amp circuit as well.

Randy, I can't quite remember what I read that prompted me to move my subs, but I tried mid-wall placement on three walls. Actually, it's more like 2/3 of the way on two walls and almost 1/2 on the other. My thinking is that if all subs are in identical placement along each wall then nothing is really being done to cancel out problem frequencies. Asymmetry seems to be best. Of course, I could be wrong.

I don't have any means to graph my room response, but I did do the SPL thing and I made a handwritten chart. My room is fairly flat in the lower frequencies. Maybe I just got lucky. Or my ears are that bad and the anomolies don't bother me. . .

I know Sean, I think part of my problem stem from that I don't have a rectangular room. I know I keep showing my room picture hoping someone will say, oh, just put your subs there.....

As you can see my theater area is pushed over into the left side corner, so central on my screen wall, is not central of the room. Also, there is a huge hallway next to the bar leading into the other side of the basement.

Maybe I should not be trusting what I'm seeing on the SMS graph?