My first filter. Does it look OK ?

[IRobot]

I've been playing around with REW for a few weeks now but only picked up a BFD yesterday. After sorting out the BFD hum problem, I had a look at the excellent instructions in the FAQ and did my first filter with the following settings:-

Frequency: 25.7Hz
Bandwidth: 1/6 octave
Gain: -12dB

Below are two charts (mains + sub, crossover = 80Hz). The first is the original chart and the second has the filter applied:-





Does it look OK and shall I continue with three more filters at 48Hz, 72Hz and 88Hz ?

Thanks

Steve

[brucek]

First you should turn off the mains, so you can see what the subwoofer is contributing to the mix. After all, it's the only signal that you're actually filtering.

Then once the sub is equalized, add the mains and use the subs phase control to clean up the crossover area.

Filters, of course, will have diminishing effect as you get above the crossover frequency...

brucek

[IRobot]

Done it:-

Sub only (no filtering):-


Sub only with cuts at 26, 48, 72 and 88Hz.


Sub + Mains with phase slightly adjusted:-


I guess I can now reduce the cut at 48Hz and increase the cut at 72Hz ?

Is it a bad idea to increase the gain at the trough at 51Hz ?

Thanks

Steve

[brucek]

I guess I can now reduce the cut at 48Hz and increase the cut at 72Hz ?

Yeah, that's generally the idea, but only after you have played with the subs phase control until you have the best crossover area possible.

Is it a bad idea to increase the gain at the trough at 51Hz ?

Yeah, it's quite narrow anyway, and gain is not generally a good idea. Think about it for a second - you know it's the room (and not the sub) causing that dip - the dip is a result of the direct and reflected signal combining at that point of measurement - if you increase the level of the direct signal, you will increase the level of the opposing reflection - the result is the same thing - so don't bother.......

It's a pretty good response. I might increase the level of the sub amp a wee bit...

brucek