Sub Calibration, Help Please

[tapeshc]

My equipment is

Denon AVR 3806
SVS PCi 16-46
Polk LSi15 Front
Polk LSiC
Polk LSiFx

Settings are
Receiver:
Speaker Set to Small
Crossover Freq. 80hz.
Connetion Sub Pre-Out => Subs LFE.

Subwoofer (sitting in a corner at the back of the room.
Crossover setting all the way up, but disabled.
Gain ¼.

RS Analog SPL Meter
AVIA calibration disk.

My understanding is, in a properly calibrated system. I should get same DB response from 200 hz. To 16 hz. Now even if I was getting a dropping response I understand. But what I am getting is all over the place, like going in & out.

SPL meter set to 70DB or 80DB, when I play tone that goes from 200hz to 20 hz., response is extreme left to extreme right and then back to left, back to right, never ever staying in same place or atleast in +-5db range or even +-10db range.

I tried all the settings on Receiver.

[McLoki]

Sounds like some quality time with a BFD (http://www.behringer.com/DSP1124P/index.cfm?lang=ENG) may be a big help for you. It made a big difference in the bass in my room. (still far from perfect, but much better than it was)

It is a 12 band (stereo even) parametric equalizer that works wonders to smooth out the bass in a a room. Caution though - it should only be used to smooth peaks - not boost nulls.

They are about $125 (I got mine used for about $80) and work great.

Michael

BTW - that is the long version of - your speakers are fine but your room is messing up your sound.

Edit - to learn more about what a BFD can do for you (and how to set one up) this is a good page for you. (http://www.hometheatershack.com/forums/bfdguide/)

[MADGSF]

You're right, in a perfect room the meter would not move no matter what the frequency until it reached it's cutoff point. What you are seeing is the effect of your room on your system and is normal for an untreated room. It will absorb some frequencies and reflect others which are seen as lows and high on your meter.

The best way to fix it is treating your room to try and get a flat response. I have not applied any in my room but I know you can spend a lot having it treated or try the DIY route. Here is a link that will get you started on the DIY route, there is also a room buildig section on avsforums.

http://www.polkaudio.com/forums/showthread.php?t=47212

[tapeshc]

Nice tips to start with !

Its good to hear that I am not alone, :) I thought I am doing something wrong or something is not working in the chain.

[appadv]

A good parametric EQ should help solve the problem. Room placement is also very important too.

[Eric Wong]

Are you using a straight tone or a warble tone? If its a straight tone those are good for testing electronics and finding buzzes and rattles but not so good for acoustics measurements. Also keep in mind most systems simply will not exhibit an extremely flat response.