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Post by roly on Jul 10, 2020 3:05:37 GMT -5
Bought a sub to help out my Adam A7s below 60Hz.
Couldn't afford an Adam sub so I took a chance and bought a Polk Audio "consumer" sub. It has a variable low pass filter that goes down to 60Hz and seems to be working nicely. My "go too" reference track is Ruby Baby....Donald Fagan's version. Cued up Ruby and brought in the sub until it sounded right, then compared it to what I was working on and promptly relaxed the 50Hz lift on the kik, bass, and floor tom. Couldn't find any specks for the sub on line but my ears suggest that it's a forth order crossover (no significant lump at the corner frequency).....so....fourth order means there are no phase issues but there is an inherent delay but at the frequencies I am dealing with, a millisecond or two will not whack things. That wouldn't be the case if I was crossing over at say 3K. Anyway....if I think there's more to report, I will update this post. cheers
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Post by Auf Kiltre on Jul 11, 2020 12:14:41 GMT -5
I thought maybe you stopped by Tim Horton's for a sammich.
Carry on...
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gdw3
Halfnote
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Posts: 80
Formerly Known As: Gordon
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Post by gdw3 on Jul 14, 2020 12:47:55 GMT -5
Sounds like you're doing the right thing by checking your reference track. Subs can be dangerous in the home studio for certain types of music. You can pull out too much bass, because it's so strong in your home mix.
I'm curious about the delay you mention. I don't know what "4th order crossover" means. If you're crossing over at 3k instead, like you say, isn't the delay still there? Just over a wider spectrum? Obviously, I'm not an expert. Please learn me!
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Post by roly on Jul 14, 2020 23:52:41 GMT -5
Rats Posted a long reply to gdw3's reply and added a link.....didn't work...., will try again tomorrow. cheers
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Post by roly on Jul 16, 2020 22:58:41 GMT -5
OK...here goes...Better state that I am a self taught person and could be wrong. First....phase = time, not polarity. A first order crossover (6 dB per octave) whacks the phase 90 degrees, second order (12 dB per octave) whacks the phase 180 degrees.....extrapolate, and at 24 dB per octave....you are back in phase, however....there is an inherent delay due to the time it takes for the filtering to happen. So.....even though the phase is correct, one must compensate for the inherent delay of the filters. As a for instance, at my house gig, I cross the horns over at 1.6K with a 24 dB per octave slope....I bet people are surprised at the low crossover point but in this case the horns can handle it. 250 watt two inch exit B&C horns. Next, there are two things to consider.....the inherent delay of the filters, and the physical alignment of the drivers. Horn assembles are typically longer than than conventional speakers, which means the information exiting the horns shows up later than the information exiting the mids. Solution....(only possible with a crossover with output delay), is to shoot a sine wave at the crossover point (in this case 1.6K) into the system. Mute the mids, and with a measurement mic....settle on a volume level.....let's say 80 dB. Next....mute the horns, open up the mids, and adjust the mid output until the mic says 80 dB. Next....take the mutes off the horns and mids, if things are correctly time aligned, there will be a 3 dB bump. That won't be the case until the mids are delayed correctly....delay the mids until you get a 3 dB bump. Easy way to determine if you have got things right is to flip the polarity of either driver......in a perfect world, there will be no sound....that doesn't happen due to room reflections, but there should still be a noticeable drop in level. I think, in a round about way, I have answered your question gdw3. cheers
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