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Speaker placement and dB differences

So I’m pretty anal about speaker placement. I use tape measures, along with laser lights and levels to assure proper and equal placement from walls. I was using my new Omni mic and testing software to run some white noise frequency graphs vs db range to see where I stand.  After overlaying the R/L graphs I noticed that there is about a -1db difference in the right channel generally across the entire frequency range and about -5 dB at about 250 hz. 
Also my room is 12’ x 13’. 

I remeasured my speaker distance from the seating position wall and I noticed the left speaker was 96” from the front the chair and the right speaker was 98.5” from the chair. By my calcs that would only account for a .22 dB difference. Not enough to account for the 1 dB drop in the right speaker and certainly not the -5 dB at 250 hz.
Question is, is a 1 dB difference between two speakers normal. My speakers are Thiel CS 2.4’s and I’m using an older ARC tube amp - which can certainly account for 1db.

the bigger questIon is can a 2.5” difference in room placement cause a 5 dB difference at 250 hz?
last_lemming

Showing 2 responses by erik_squires

erik_squires
16,678 posts
 
Was too tired when I answered this. If you are using OmniMic, use the swept signal with gating/blended results.

This will help you see if the problem is consistently across all frequencies (which would imply an equipment issue) or if it's in the bass for instance, which would imply more room issues...or narrow across 1 driver's range.
erik_squires
16,678 posts
 
2.5" is too small to account for a 1 dB difference.

Swap the speaker cables and see if the effect remains.  If the effect changes, it's your equipment.

If it remains, measure your speakers at 3'
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