Caibrating LSi HT system

Babulas

This weekend I used the Avia II DVD and SPL meter to calibrate my system (Configuration below). Using Avia's advanced test tones section I was able to calibrate the volume in all channels, including the sub, to have a similar db reading in the SPL.

However, when I run the other test tones between one of the speakers and the sub (Left Front and Sub, Center and Sub, Right Front and Sub, etc.....) something weird happens.

The db reading in the SPL stays pretty much the same when I run the test between:

- Left Front and Sub,
- Center and Sub, and
- Right Front and Sub.

But when I run the test between:

- Right Surround and Sub, and
- Left Surround and Sub

the db reading jumps by 6db. Why is this if previously the system was fairly well calibrated when I was running individual test tones on each channel?

My system:
A/V NAD T753
Fronts and Center: LSi9
Left Surround: Lsi9
Right Surround: Lsi7
Sub: Velodyne DEQ-12R
Crossover set up in the A/V Receiver at 80
Velodyne crossover set up to max.

lumpy

just a guess - are they at a different height than the mains

maximillian

Babulas wrote: »

Left Surround: Lsi9
Right Surround: Lsi7

Is this accurate? Are you using two different speakers for L-R surrounds. I haven't heard about someone doing this before. I don't know if AVR's would respond correctly with this type of mismatch.

Babulas

Lumpy- They just a bit higher than the mains. However, despite of this, I was able to balance the volume from each channel and a similar reading on the SPL when doing a test tone per channel. So I don't think this is the issue.

maximillian: I have a LSiC, but do not like the quality of the dialogue coming from it. That's why I decided to use a LSi9 as center. Interesting comment about how the receiver will respond. Didn't think about this and welcome comments. I guess I figured that since most of the audio comes from the Fronts and Center, that the difference in audio from the surrounds would be hard to notice. Maybe worth the price to overcome the issue with the LSiC.

Whadyasay

Sounds like a phase/wave issue. Depending on the shape of your room, different pairs/sets of speakers that are each calibrated evenly will cause wave buildups or phase cancellations at different parts of the room, in your case the listening position. The only way to really alleviate this is by room treatment/placement. EQ's can help, but even with something like the Audyssey, they only base things on individual speaker measurements, not so much things that go on between certain pairs of speakers and the room. Surrounds and sub can be tricky because they're usually facing eachother, meaning radiating in different directions than, say, a front and sub at the front of the room. If your sub were, say, in the back of the room, you might very well get the reverse results between a front speaker and the sub.

I wouldn't worry about it too much, since very rarely will a surround speaker and subwoofer be putting out the exact same material in normal use, as opposed to checking an identical pink noise signal or what have you from both at the same time. You might also want to check your wire-speaker-receiver connections to make sure you have everything in the right +/- polarity.

Babulas

Thanks you Whadyasay.

Wire-speaker-receiver connections are correct.

I agree with you that it is not a issue to worry about but definitely curious about it.