BFD just got easier.

[sensibull]

OK, well, if you'll pardon one last question, that's where my confusion lies. In your setup, when the sweep reaches the crossover range and above, doesn't the tone then begin to come out of your other speakers as well, and doesn't this compromise the test? Or do you just disconnect them during the sweep?

[Mag_Neato]

Since you are primarily interested in sub equalization, you could run the sub without any sattelites.

I have my sub crossed at 80hz through the receiver. The subs crossover is set to it's 150hz max. setting to get it out of the way. I ran a series of test tones from 18 to 150hz with the main speakers unplugged.

Near the crossover point, 84hz, I had 85.5db. At 150hz I had 54.5db......down 31db.

This is a good way to evaluate the sub's in room response and see what needs attention, since the EQ'ing will affect the sub's response first.

A full system response can then be used to determine proper phase and crossover settings.

My sub drops like a rock below 30hz, so I'm thinking of a cut from 30 on up to bring the other frequencies down closer to the sub-30 response. I have enough gain on the sub volume to compensate and bring things back up.

[sensibull]

Thanks, Mag.. "with the main speakers unplugged" is the info I was looking for. Hadn't seen (or hadn't registered) that step in any of the bass eq threads. Common sense, I know, but (despite my rather arbitrary user name -- I just liked the pun) sometimes I seem to be in short supply of it...

[BradJudy]

No, I don't do it with the mains unplugged. That actually defeats the purpose. The purpose is to have the complete response be even, which might require some tweaking in the crossover range. Unless you do it with the mains connected, you won't know what the summed sound is like (you will also miss destructive interference if the phase is not configured correctly). I do all of these tests with my mains on for this reason.

[DavidD]

No, I don't do it with the mains unplugged. That actually defeats the purpose. The purpose is to have the complete response be even, which might require some tweaking in the crossover range. Unless you do it with the mains connected, you won't know what the summed sound is like (you will also miss destructive interference if the phase is not configured correctly). I do all of these tests with my mains on for this reason.

Glad to see you post this. It seems that generally people test with the sub only. Assuming your signal is being bass managed, the only way to get a true picture of the final response is to measure with the mains on. If you mesure only the sub, you can get peaks caused by the output contributions from the mains. The phase issue is also a very good point.

[bikeman]

What has worked best for me after much experimenting is to EQ the sub only and then run a test with the mains connected. I got my best results with the BFD this way. YMMV.

David

[Nicholas Mosher]

I just use my SPL meter, a pad of paper, and a pencil...

Oh, and I too run my tones with the main five channels on. Not doing so will hurt you in the 60-120Hz range as the sub's output (in my case) needs to be cut at a few points in this range where it's supported by the main channels.

[Mag_Neato]

When I asked for Dave F.'s advice, he suggested doing it first with sub only, than full system for phase & crossover tweaking.

[BradJudy]

Apparently this app defaults to a C-weighting correction which I did not see and which accounts for the exaggerated hump. I will try measuring again this weekend, but I expect fixing this should put the measurement in-line with my ETF one.

BTW: If you read the AVS thread, the author posts there. Apparently he used to work for TAG.

[Abhi]

No, I don't do it with the mains unplugged. That actually defeats the purpose. The purpose is to have the complete response be even, which might require some tweaking in the crossover range. Unless you do it with the mains connected, you won't know what the summed sound is like (you will also miss destructive interference if the phase is not configured correctly). I do all of these tests with my mains on for this reason.

BradJudy,
Since you are connecting ONLY the right channel input, How do you measure the response near crossover point?
Will these 2 cases yield different results?:
1. Use a splitter cable and feed both left and right channels of the AVR with the signal from the PC's right LINE out.
2. Connect the PC's LINE out (right) directly to the AVR's right and leave the left channel alone