SPL drop with sub... Please help

[snafu37]

So I just got my system all set up and I'm fine tuning the Sub right now. My system is as follows:

Yamaha rx-v1800
4 x Polk Audio Rti 6
1 x Polk Audio Csi 5
SVS PB12 Plus

I'm using Avia and an SPL meter from Radio Shack. During the frequency/spl test I'm seeing either:

A.) A significant drop in SPL from 65-50 Hz (as low as 64 db) or
B.) Two spikes in SPL from 100-75 and 40-20 Hz (90 db high)

Can anyone help solve this issue? It seems pretty linear all except that weird drop. Thanks for your input in advance!

 

[MDS]

If you have some leeway in positioning the sub, try moving it to a different position. Even a small change in position can affect the frequency response somewhat.

Try adjusting the phase control on the sub and checking your results at each setting until you find what works best.

 

[snafu37]

Phasing was the first thing that came to mind and didn't help much at all. I'll play with the position a little bit and see if that helps any. Thanks MDS, I'll let ya know how it turns out.

 

[snafu37]

Well the positioning moved the dip and somewhat cured it, but the position of it is not practical. Meaning it's right in the middle of the room. Is there any other cure for a dip in SPL?

 

[snafu37]

To add on to that last post, it's still hitting 60 db range while the rest of the dbs are in the mid 80's

 

[mtrycrafts]

To add on to that last post, it's still hitting 60 db range while the rest of the dbs are in the mid 80's

Subs are a tough speaker to level for FR response. The room has a huge effect on it.
Traps may help taming the higher levels then you can boost the overall output. Or, you may need to buy a Behringer EQ, called feedback destroyer. This helps tailor what to cut, how wide, and how much. Not easy process.

 

[Dolby CP-200]

I’ve read that the (Feedback Destroyer) is a good asset to add on.

Here’s a list in the “Google Products” section if you browse though this you might find the best overall price to fit you’re budget.
http://www.google.co.uk/products?hl=en&q=Feedback Destroyer&oe=UTF-8&um=1&ie=UTF-8&sa=N&tab=if

If you have “Return of the Jedi” (1983-1997-2004) on DVD try the scene where Luke and Vader have the last duel right towards the where Vader gets his hand chocked off the depth of slam really hits you then the slow depth of the score booms out on the timpani.

If that is in someway lacking then you need to make a little adjustment here and there also the surrounds are full spectrum and centre channel, so maybe a sine wave or full band pink noise with an RTA might make things a little speedy in get in done.

 

[bpape]

Try shifiting the mic position to find a practical seating position that allows a practical sub position to produce a smooth response. The BFD is also a good option after doing this to fix any stubborn issues.

Bryan