Axiom Home Page Forums General Discussion Home Theater Avia LFE calibration: odd behavior

So the other day I had the house to myself and decided to play with the sub a little, and threw the Avia disc in, RS meter in hand.

With the test that alternates LF,S,C,S,RF,S,RS,S,LS,S, I noticed - and I'm sure that this behaviour is no different than what I'd tested before, but didn't really think about it then - that the C -> S test cycle yields mucho higher sub SPL than the other fronts do. Like about 10db higher. Went from 80db for LF -> S to just under 90 db for C -> S. I had to adjust the dial on the meter to the 90s.

Is this likely to be due to my crappy cheap AVR? The AVR was using the optical connection to the DVD player so any bass management setup in the DVD player shouldn't factor in. Avia quirk maybe?

Anyone experience anything similar? I'd appreciate any ideas about what might be causing this and what I should do about calibrating.

Sometimes I believe the Avia disc has odd behavior also, I try to always cross check calibration levels over a couple or more sources.

Thanks for confirming that it's not just me and/or my 20th century gear.

I'll see what else I have kicking around to test with.

The last time I krunched some numbers with the RealTraps test CD and manual charts, I just got depressed thinking that my room was worse than Mark's.

Same here, obviously it was terribly wrong so I trashed the graphing idea and spent the time blissfully listening to the system ... I've been quite happy every since.

One could drive themselves into the nuthouse trying to achieve the perfect graph, not my cup of tea. I just use the AVR's test tones and the Avia disc for the cross checking.

Oh, and my ears of course.

(haven't even graphed anything though I'm using a new receiver with Audyssey for the same reason).

Unless your amp is broken, I think the spike is room driven. I had to adjust mine, but damn, 10 db? If you room half pillow and half concrete? I have a few ridiculous spikes around my room, but they are frequency-centric. Is your spike a pink noise spike or a specific frequency?

No, like most everyone I've got room modes too (in particular an audible dip around 60Hz, don't even need charts for that one), but this isn't that.

This particular test on the disc - I'll have to post the specific chapter number later - is meant to, I believe, use the same frequency as it goes around the cycle.

Meter or no meter, it's really obvious. Left front -> sub, audible but not loud. Center -> sub, rattles plates upstairs. Right front -> sub, softer again.

Weird.

My receiver that has fewer features than an AM transistor radio powered by a 9V. FWIW, mine's black. Like red cars that go faster, black receivers always sound better.

EDIT: I wonder if in my experimentation I've left the fronts set to Large rather than Small...

Yup, that was it. I'd left the front setting to Large.

Nothing like exposing my own oversights to the group.

I still don't get why Avia's sub tones alternate back and forth with the other speakers, all the the other speakers.