JohnA Posted September 21, 2009 Share Posted September 21, 2009 A lot of subwoofers or sub amps have a phase control knob. Why can't I do the same thing with the distance (delay) setting in my Upgraded ACT-3? For instance, I have my crossover frequency set at 100 Hz. (1130 ft/s)/100 Hz = 11.3 feet for wavelength. To get 90 degreesof delay. I could tell the Pre/Pro that the subs are 11.3/4 = 2.83 feet closer than they really are. Would that not work correctly? Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted September 21, 2009 Share Posted September 21, 2009 I've heard of people using the distance adjustment in lieu of phase and saying that it works fine. I've never tried it however as my subs are in the same plane as my mains. I would think that it would work though. Listen to some music and try some different distances and see how it sounds. Quote Link to comment Share on other sites More sharing options...
DrWho Posted September 22, 2009 Share Posted September 22, 2009 Would that not work correctly? It should work better... Quote Link to comment Share on other sites More sharing options...
JohnA Posted September 23, 2009 Author Share Posted September 23, 2009 In fact it DID work. I can hear the bass change as I change the distance setting. The fattest, roundest, loudest bass came near, but not excatly at the 1/4 wave length point. In fact, the 1/4 wavelength distance is 2'-10", my subs and mains are 12'-10" from my listening position and the most bass output came at a 10'-11" setting (an offset of 1'-11" of additional delay). More testing to come, but I'd say this was a cool trick. I can't readily explain it. I thought the subs needed a 90 degree delay because of the characteristics of horns vs. direct radiators. The less than 1/4 wavelength seems to explain why reversing the phase of the subs also worked, to some extent. Quote Link to comment Share on other sites More sharing options...
russ69 Posted September 23, 2009 Share Posted September 23, 2009 A 20 hertz wavelength in air is 56 feet (at sea level/air density). To fully adjust the phase for your listening position, it may be 1 degree thru 359 degrees. So anywhere from 1 to 55 feet to get a full wavelength at 20 hertz. I think I have that right, someone will correct me if I'm wrong. Thanx, Russ Quote Link to comment Share on other sites More sharing options...
JohnA Posted September 23, 2009 Author Share Posted September 23, 2009 I get 56.25 feet (1125/20). However the phase angle is unimportant except where there is an interfering source, like the crossover frequency between the woofer and subwoofer. I believe that's where I have a problem, especially since I changed the cabinets of my subs and placed my La Scalas on top. Quote Link to comment Share on other sites More sharing options...
DrWho Posted September 23, 2009 Share Posted September 23, 2009 One thing you might try is to invert the polarity of your mains (just flip the speaker wires) and then tweak the distance setting on the sub until you get as little bass as possible. Then, unflip the polarity of your mains and you should be back in phase. It's usually easier to hear a big hole than it is a flat response. Where did you end up on your distance settings? Quote Link to comment Share on other sites More sharing options...
JohnA Posted September 23, 2009 Author Share Posted September 23, 2009 One thing you might try is to invert the polarity of your mains (just flip the speaker wires) and then tweak the distance setting on the sub until you get as little bass as possible. Then, unflip the polarity of your mains and you should be back in phase. It's usually easier to hear a big hole than it is a flat response. Where did you end up on your distance settings? Mike, I ended up with the Subs in normal phase (+ to red generates forward come movement) and the distance was 11" short of 1/4 wavelength at 100 Hz. Quote Link to comment Share on other sites More sharing options...
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