SPL meter usage: tips and tripods (DEFINITELY use one!) [Archive] - Audio & Video Forums

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Woochifer
01-26-2004, 12:59 PM
Like others on this board, I'm thoroughly convinced that if you have a multichannel home theater/audio setup, you absolutely NEED a SPL meter to properly set the levels. Tweaking by ear alone with five, six, or seven speakers plus a subwoofer just cannot cut it. Having the levels properly calibrated is crucial to having a surround soundtrack envelop the listener and create that illusion that you're immersed in a scene or soundfield.

As mentioned in the title, I tried mounting the SPL meter on a camera tripod over the weekend and boy does it ever work! This whole process came about because I raised my surround speakers by 8" a couple of weeks ago (they are now nearly 2' above ear level), and it didn't quite sound right with the old settings.

So, I got out the SPL meter and found that my old surround levels were off (too low and skewed to the left). I made the adjustments and the results were better, but the speakers now sounded like point sources (i.e. I could easily pick out where the sound originated) and not blended in with the front three speakers. I also adjusted the levels by ear, but nothing I tried fixed the problem.

I remembered that there were several older threads that discussed how the SPL meter readings could get distorted by holding the meter at the wrong angle, having the microphone too close to the body, etc. At this point, I decided to mount the SPL meter on a camera tripod and take the readings that way.

The tripod was adjusted so that the SPL meter was at ear level, and based on recommendations from others on this board, I angled it at 45 degrees facing towards the center speaker.

With the SPL meter positioned with a tripod, the readings were very different. Turned out that I still had to adjust to the sound getting skewed to the left, but that I also had to dial down the levels for both surround speakers. Using this setting, the integration between the main and surround speakers is excellent and the side/back soundfield fills in very nicely.

The SPL meter with the tripod also gave me a different level reading with the subwoofer, so I adjusted that and it works great.

I could not believe how different the readings were between just holding the SPL meter in my hand versus mounting it on a tripod. When the surrounds were mounted lower, for some reason, my SPL meter readings worked fine. But, after raising the surround speakers, holding that SPL meter by hand just didn't give me the right readings. Tweaking by ear didn't work very well either.

Tried the camera tripod as an experiment and was pretty shocked at how much that affected the accuracy of the readings. At $30 for a basic tripod, that's a pretty minimal investment for the return that you get.

poneal
01-26-2004, 03:38 PM
Hi Woochifer, I totally agree. I had a camera tripod back from my days of photogrphy and found it was an excellent piece of equipment to hold my radioshack SPL meter since it already had the screw hole on the back. I too found that the measurements changed slightly and the result was a better sound stage. Good post and recommendation. Paul.