Axiom Home Page Forums General Discussion Home Theater VP150 Calibration Problems

I spent this evening calibrating my M2i/VP150 system and discovered a problem. If I calibrate from the center listening position (75db, C weighting, using the Rat Shack analog meter) when I move to the right and left seats of the couch the left and right speakers remain at 75db, but the center channel drops by 2db to 73db. This would suggest that those seated on either end of the couch will be hearing dialog at a lower level than the central listener. I thought the point of the VP150 layout was to eliminate these variations in a horizontally oriented center. Any ideas as to why this is happening? Could my VP150 be defective?

I don't think there's anythging wrong with the speaker. A drop of 2db is barely noticeable to the human ear. If the difference concerns you, I'd calibrate the VP150 to 76dB so that more of the couch gets 75dB.

Also, remember that every speaker interacts with the room. Do you have a coffee table between you and the center channel?

No coffee table. Clean shot between the speaker and the couch. When I play pink noise and move from the center to the left and right seats, I notice a definite change in the sound, which is why I decided to measure. Other centers I've had did not demonstrate any change in level within the seating area.

I reran the calibration, and the actual db variation is 4. It goes from 77db at the central, seated location, to 73db at the left locaton. Ian is on the case. I'll let you know how it turns out.

Ian emailed me to say this is not normal behavior. Fedex has just picked up the sub and I should know something next week. Hopefully, it's a minor fix, but I knew something was obviously wrong. In fact, I heard something rattling around inside the cabinet when I packaged it up. Maybe shipping damage?

Well, it at least sounds like another case of good customer service. That's a +.

-Nick

Fedex picked up the sub?
I thought it was the vp150 giving you problems.

Oops. I've got subs on the brain. It's the VP150 of course.

Just got an email from Ian. He says my VP150 is working as designed. Has anyone else measured (with the receiver's calibration tone using a Rat Shack meter) the VP150 moving the meter from the central position to the left and right? I have tried this with an NHT Evolution M5 and an Axiom M2i and measure at most a 1 db variation from the central position the left and right couch seats. With the VP150, the variation is 5 db using the same measuring procedure (the center seat reads 75db while the left and right are 70db). I was lead to believe that the novel center channel arrangement of the VP150 lead to a more uniform dispersion pattern. This has not been my experience. Could someone please try this and post your results? At this point, I think I'm going to send back the M2i's and get a credit on the VP150. I had originally intended to get a complete Axiom setup, but the center channel is very important and the VP150, with this type of off-axis performance is a non-starter for me.

What is your current setup? What do you have for mains? A single M2i performed better off-axis than the VP150 as a center channel?