Interesting sub calibration I did (1 Viewer)

[Patrick Nevin]

I did play with the sub a little bit tonight. I notice that it was about 1-2 dB higher while standing up. I do not have it in a corner and was wondering if that will help it or not. The SVS manual says go for a corner. I have been wanting to take my dvd shelf out of the corner and switch it with my sub.

 

[Brian_cyberbri]

Patrick,

A corner or near a corner (2-4' out along a wall from the corner) is a good place to start. But you have to know how flat or bumpy your response is to know if the location is "good" or not. If the sound is boomy, bloated, one-noted, you know there's something wrong.

I'm not surprised you hear a different level of bass when you stand up. You can walk around your room and hear the bass disappear in one spot and be very loud 1' to the side. This goes for height as well. You probably have varying response at the different positions on your couch as well.

You can run frequency sweeps on Avia and watch your SPL meter to see how far it goes up and down at your listening position. You can also download individual frequency tones, and either run them off a computer or burn them to a CD, and chart out your sub's response with a pre-made Excel sheet off the Internet.

If you do either one, you can try testing the sub in different locations in your room. It will help to have a camera tripod to mount your SPL meter to to keep the results consistent.

Another way to find a good location is to put the sub in your listening position and crawl around the floor listening for the smoothest (least boomy, one-noted) bass with music with repeated bass. This "crawl test" can help narrow down placement. You might find that the direct corner has a lot of gain below 30Hz and above 80Hz, but a big hole in the middle. But maybe two feet along the side wall out from the corner, the bass is pretty smooth.


Here is what my frequency response looks like:
http://gallery.avsforum.com/data/503/3-5gain.jpg
Not too bad for not having an EQ on it, no dips, just a few peaks.
If you want to see how I got to that level, read this:
http://www.avsforum.com/avs-vb/showthread.php?t=640646


HTH

 

[Patrick Nevin]

Brian,

I did put the sub in the corner last night but did not get the chance to plug it in and calibrate it. When you say 2-4 feet out from the corner along the wall do you mean to have the sub against the longer of the two walls? I am still going to do a frequency sweep hopefully this weekend and will let you know the results.

 

[Brian_cyberbri]

If your couch is facing Wall A, and Wall B is on the right side of you, instead of having it right in the corner where Wall A and Wall B meet, move it out of the corner along Wall B a few feet or so (with still 8-12" or so clearance behind the subwoofer).

But running tests will tell you what it sounds like and where it sounds the best.

 

[Patrick Nevin]

I checked for the room response and I have a bad peak at 90Hz. It starts going up in the 70Hz range. I know it is not the sub, but the 3 main speakers. Is there any way to tame the upper bass frequencies?

 

[Brian_cyberbri]

Set the crossover at 100Hz and re-measure.

 

[Patrick Nevin]

Ok I might have done one of the most unusual things to get my frequency responce flat. Jim form SVS told me to set the crossover to 100 Hz. My receiver did not have that. So I went on www.denon.com to check there lower end home theater receivers. I found the AVR-1506 which was selling for 329. So I checked the manual on line to see if I can set the crossover in that receiver. I was happy to find out that I could. My mind was set so Friday night I went to Ultimate Electronics and bought it. I brought it home and unplugged the old receiver and hooked up the 1506. I had some trouble but I figured that out quickly. I set it up the best I could with no on screen display and set the crossover at 100 Hz. I calibrated the speakers the best I could whcih is really close. The speakers are at 75 dB and the sub is at 72 dB becuse of the radio shack meter being incorrect. I think the peak is gone but I don't know yet because I have not re-measured yet and I hope to get to that this weekend. I am using this receiver as a temp until some Denon receivers with HDMI's are more affordable.

 

[Patrick Nevin]

Hey Guys,

I have a really great update. Since the last time I posted I was in contact with a tech at SVS and he has been a tremendous in helping me with this. He had me doing frequency sweeps the hard way to check different positions of the sub. I even did frequency charts for the 5 speakers to see where a 90 hz peak was coming form. He recommend me the RoomEQ wizard and to get an eq, so I bought a Berhinger Ultra Curve PRO DEQ2496. So I was eqing stuff that way for a while and something happened so I stopped using it. So then I deiced to use the AUTO EQ and RTA on the 2496. It took me a couple of tries to get the hang of it and as of this past weekend my frequency response is just about flat. I want to tweak it this weekend before I watch Spiderman 1 & 2. I also bought a Yamaha RX-V2700 which has an awesome auto eq for the mains. It even found the 90 hz peak my speakers were doing. I thought if that can find the 90 hz peak then it can eq the 3 main and 2 surround speakers and they sound great with the sub about flat. Sorry for the long post but I just wanted to share my excitement.

One quick question. After re-reading this thread, what i should set my sub spl level at when i calibrate it at when the rest of the speakers are calibrated at 75 dB. I am cill confused on that.