My mains produce a bad cuffing noise when "trying" to playing a continues low frequency tone. This cuffing is pretty loud and interferes with my measured SPL. So I measure from 10Hz to 42.2Hz with the mains off. I then turn my mains amp on and continue the measurements. I know this is probably not the "best" way, but it sounds pretty darn good after setting it up this way!Actually, the way you did it is just fine. The main reason to play the mains and subs together is to get readings that include the crossover and phase-induced response irregularities. Phase irregularities can generally get corrected with equalization, so you want the readings to reflect them. Phase problems typically show up most predominantly an octave or so above and below the crossover point, so at 42Hz and below you were probably far enough “downstream” from the crossover point and phase effects.
Irrespective of that, it sounds like the mains are struggling to deliver frequencies below their range, which is peculiar. If the mains are set to “small,” as they should be for best sub performance, the signal to the mains should be down at least 24dB at 42Hz, and off the map by 10Hz. Either your speakers are set to large, or the crossover is not performing as it should, or you were playing your test tones at extremely high levels – a definite no-no.
Wayne A. Pflughaupt
Irrespective of that, it sounds like the mains are struggling to deliver frequencies below their range, which is peculiar. If the mains are set to “small,” as they should be for best sub performance, the signal to the mains should be down at least 24dB at 42Hz, and off the map by 10Hz. Either your speakers are set to large, or the crossover is not performing as it should, or you were playing your test tones at extremely high levels – a definite no-no.I set up my BFD in stereo mode using a red book audio CD. My receiver does not have a lot of bass management in pure audio stereo mode. With DD and DTS I have a lot more options (Large, Small, 40, 60, 80, 100 x-over points, sub=LFE, sub=LFE+L/R, etc.) My options in stereo mode are no sub, or sub x-over at 40 or 60 and that is it. I cannot adjust the main speaker size when the receiver is set to pure music stereo mode. My mains play full range in pure music stereo mode too. The cuffing is only present when playing a continuous tone at a given frequency way below the natural roll-off point of my mains. It is not audible at all with normal listening levels of actual music. And for HT use the x-over on the mains will have kicked in by then. I wish I had a DVD with DD 5.1 encoded 1/12 octave test tones on it from 10Hz to 100Hz.
Thanks for all the good info and the conformation on my steps used in setting up the BFD. I was winging it and those steps seemed the most logical. I have read your old post on the house curve, and you are correct, my original preset looked more like a house curve than flat.
My BFD has a buzz to it, most always there, and if a preset has any boost in it, the buzz is louder. Is that normal?From what I've read in the various FAQs, the buzz is caused by a ground loop due to the BFD's grounded plug. This sometimes happens because something in the house (e.g. phone, cable) is grounded somewhere *other than* the power ground.
I used the EFT software to measure the sub and help set up my filters. My sub is not in an optimal place in the room, but I have no other choice. I had to boost a huge dip at 20 hz, and flatten out peaks at approx. 32, 60 and 70 hz. I left frequencies higher than 100 alone for now as my crossover is set at 60hz. Took 7 filters, but with my 122L Tempest I'm 3db down at 20 and flat (+- under 1db) to about 95hz after EQ.