Does calibration really make a difference?

[htguy]

Progress. I got the REW signal generator working, and sending a signal to the sub. Doing a quick sweep, looks like I have a peak some place between 55 and 65. I will do the time consuming test later. My wife thought the test tones were annoying. After I showed her the REW program and the meter, she at least now thinks this is mildly interesting.

[htguy]

Here is the result of my first graph. I used a RS analog meter, and I downloaded the excel spreadsheet. The signals were from the REW generator, Sine Wave. No dither added to output. RMS level dB FS at the default -20.0. My sub is crossed at 80, so I stopped testing above 100. I started at 10. Looks like I could use some EQ, but does this graph look "right?" Are the RS correction factors in the excel spreadsheet the most current ones? Thanks in advance.

[brucek]

Are the RS correction factors in the excel spreadsheet the most current ones?

Yes, they match the downloadable .cal files (as long as you chose the one for your meter).

If you have a sub that you know will not reach down to 10Hz (given its specifications) then I would recommend not measuring that low. The problem is that noise can be interpreted as signal at those very, very low frequencies and with the compensation at 10hz which can be ~30dB with the old RS meter, it results in false readings. I would limit my bottom end measures to 16Hz.

Other than that, it looks like a legitimate graph of your response. You have a couple dips at 30Hz and 45Hz. You will have to attempt a few other positions to see if you can alleviate the problem - then decide if it makes sense to move the sub...

brucek

[htguy]

Thanks. So, because I have "dips" instead of "peaks," does this mean that I would not really benefit that much from an equalizer like the BFD? I read that EQ can not help much with a dip, but it can bring down the peaks. I do not have many options for the sub in my room. If moving the sub does not even out the curve, would it help to use the BFD to bring down the "peaks" at 36 and at 50? Would that allow me to better hear the entire range of frequencies from the sub?

[brucek]

So, because I have "dips" instead of "peaks," does this mean that I would not really benefit that much from an equalizer like the BFD?

You really need to do some placement tests with your sub to see if you can get a bit smoother response. Your response is going up and down through some dips and peaks, so you may be able to help it a lot with placement.

I read that EQ can not help much with a dip, but it can bring down the peaks.

If you have a dip caused by an out of phase reflection, and so throwing some gain at that frequency will also increase the out of phase signal that's causing the problem. In that case you could add gain forever and you won't get rid of the dip. Moving the position a little might help though.

would it help to use the BFD to bring down the "peaks" at 36 and at 50?

As long as you don't cut too much, and if you have the headroom to boost the sub back up, it would help.

brucek

[htguy]

I moved the sub a little, and that made virtually no difference. I only have two other places for the sub. One is in a corner, and the other is a few feet from that corner. Both graphs are attached. It seems like I have problems no matter where the sub goes. Would EQ fix one of these positions better than the others? Room treatments are not an option.
Thanks

[brucek]

The second plot is a bit better. Removing the peak at 36Hz would probably help out.

It would be a lot easier if you were to get REW working. Do you not have an old PC around?

brucek

[htguy]

I have been working on trying to fine someone who will let me borrow a PC for a while.
Thanks