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PostPosted: 24 Sep 2012, 21:03 
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Joined: 04 Jun 2008, 20:59
Posts: 4189
Location: Arizona, USA
Hi Everyone, I'm not sure where this Subject belongs, so I put it here. Moving furniture in a listening area causes changes in room nodes and stereo imaging from your speakers. How bad depends on more things than I have the desire to write about here. So when I removed some large speaker cabinets from my listening room and shifted some other furniture I messed up the sound stage significantly. My stereo uses Martin Logan Vista ESL speakers as the primary transducers. I expect that pretty much anyone who uses either ESLs or open back speakers can tell horror stories of trying to get them set up correctly. It can be an extreme challenge as they rely as much on reflected sound as direct radiation. BTW a slight digression - they are not for everyone as the sound is quite different. They tend to paint what I would call a musical mural in the room vs pin point accuracy common in many more conventional speakers. Anyhow, I wanted to pass along a process I used on mine with great success. It will probably work with any type of speaker system though. I set up a sound level meter (cheap RS one set on fast response "C" curve) at my listening position. I fed the output to one channel of my DSO (Velleman PC based). I used a pink noise signal as input to the stereo (drive both channels with same signal). Then on the DSO set it for spectrum analyzer mode with a bandwidth of 20KHZ. It actually turns out that only 10K was really needed. BTW, pretty much ignore anything below about 300HZ for this step. With a moderate signal level I moved the speakers back and forth, side to side, angled in and out and in this case tilt front and back a bit. It was easy to see what every action did to the spectrum. Frequency shifts, holes and peaks. By careful increments I came up with locations that gave the maximum flatness at the listening position. Put tape marks on the floor to indicate the positions. Next check at a lower range to be sure there are no really bad bumps in the low mid range or bass. There will always be some because of room dimensions. If one or more are really bad, try shifting the speakers - most likely forward and back to see if they improve enough to justify re-doing the first checks. The end result of the process in my case was a really superior sound stage and imaging. Without the PC DSO I would probably still be fiddling with it and actually not find the right locations. They were significantly different from what I was using and expected.

Good listening

Some of my DIY Tube Amplifier Projects:

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