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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: Ed Lohr on December 02, 2012, 01:54:40 PM
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I've been entertaining the idea of running my subs on an aux but not sure how I want to set the crossover point between the subs and the mains. Right now I run my SRX715s in passive mode and crossover the subs at 140Hz with a 24db LW slope and no overlap. I know some people don't like to have any overlap when crossing over between different bands but I'm thinking that if I run the SRXs as full range mains with a low cutoff around 60-70Hz, I would then want to set the low pass on the subs around 120-130Hz to get a little more low mid (chest thump) out of the system. Has anyone tried this?
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What are you using for subs?
I have my 715's high passed at 90 Hz with a LR 48 filter. My 718's are low passed at 88Hz with a LR 48 filter.
Overlapping filters can cause phasing issues.
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I've been entertaining the idea of running my subs on an aux but not sure how I want to set the crossover point between the subs and the mains. Right now I run my SRX715s in passive mode and crossover the subs at 140Hz with a 24db LW slope and no overlap. I know some people don't like to have any overlap when crossing over between different bands but I'm thinking that if I run the SRXs as full range mains with a low cutoff around 60-70Hz, I would then want to set the low pass on the subs around 120-130Hz to get a little more low mid (chest thump) out of the system. Has anyone tried this?
Club system setup yesterday. 2 single 18 Subs running 35-80...with sone wide parametric out of band EQ to smooth the top end out. Mackie HD1531 crossed at 90 and up. I am usually happier with no overlap and independent filters.
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I've been entertaining the idea of running my subs on an aux but not sure how I want to set the crossover point between the subs and the mains. Right now I run my SRX715s in passive mode and crossover the subs at 140Hz with a 24db LW slope and no overlap. I know some people don't like to have any overlap when crossing over between different bands but I'm thinking that if I run the SRXs as full range mains with a low cutoff around 60-70Hz, I would then want to set the low pass on the subs around 120-130Hz to get a little more low mid (chest thump) out of the system. Has anyone tried this?
The "best" sound you can get is from a single source, referred to as a point source. Once you introduce a second delivery of the sound from another source (speaker, strong reflection), the two sounds interact with both constructive and destructive interference. This is often expressed by the term "comb filtering".
In attempting to get more "thump" out of your system by having multiple drivers delivering sound within the same range, you are also going to experience the problems associated with multiple-source delivery interference.
Learn what comprises the "thump" you want and give it to your speakers to reproduce. If you simply need more volume, get louder speakers.
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I've been entertaining the idea of running my subs on an aux but not sure how I want to set the crossover point between the subs and the mains. Right now I run my SRX715s in passive mode and crossover the subs at 140Hz with a 24db LW slope and no overlap. I know some people don't like to have any overlap when crossing over between different bands but I'm thinking that if I run the SRXs as full range mains with a low cutoff around 60-70Hz, I would then want to set the low pass on the subs around 120-130Hz to get a little more low mid (chest thump) out of the system. Has anyone tried this?
If you drive the subs louder than the tops (fairly common) you'd be better off with UNDERLAPPED crossover points. The disproportionately LOUDER you run the subs, the higher the ACOUSTIC crossover becomes for them.
Not knowing anything else about your rig, I'd low pass the subs at ~90Hz and tops around 90-100Hz as a starting point.
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If you drive the subs louder than the tops (fairly common) you'd be better off with UNDERLAPPED crossover points. The disproportionately LOUDER you run the subs, the higher the ACOUSTIC crossover becomes for them.
Not knowing anything else about your rig, I'd low pass the subs at ~90Hz and tops around 9-100Hz as a starting point.
Good point. When I do shows where the bass needs to be 5db or hotter than the tops I adjust my sub LP to keep from crapping up 100-150Hz.
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Thanks for the input. I'll keep running it like I have been. Crossover at 130Hz 24bd slope and no overlap. Going to ditch the aux fed subs idea too and just continue to the use low cut filter on the channels that need it.
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Thanks for the input. I'll keep running it like I have been. Crossover at 130Hz 24bd slope and no overlap. Going to ditch the aux fed subs idea too and just continue to the use low cut filter on the channels that need it.
And the crossover will still be wrong. Look at Jonathan Betts post above. Those crossover points are correct for the 715. Low mid doesn't come from the sub, it comes from your 15" driver and if crossed correctly will knock you on your ass. Better yet go to the JBL web site and use their crossover points for the 715. You'll find them to be very close to Jonathans.
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And the crossover will still be wrong. Look at Jonathan Betts post above. Those crossover points are correct for the 715. Low mid doesn't come from the sub, it comes from your 15" driver and if crossed correctly will knock you on your ass. Better yet go to the JBL web site and use their crossover points for the 715. You'll find them to be very close to Jonathans.
Thanks I'll give that a try.
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I've been entertaining the idea of running my subs on an aux but not sure how I want to set the crossover point between the subs and the mains. Right now I run my SRX715s in passive mode and crossover the subs at 140Hz with a 24db LW slope and no overlap. I know some people don't like to have any overlap when crossing over between different bands but I'm thinking that if I run the SRXs as full range mains with a low cutoff around 60-70Hz, I would then want to set the low pass on the subs around 120-130Hz to get a little more low mid (chest thump) out of the system. Has anyone tried this?
140hz crossover, really? There's no thump up that high, only annoying mud. Personally, I'd run your subs up to around 70-75hz, and your tops down to 85-90hz, 24dB BW on both ends.
There's nothing wrong with overlapping crossover points either. If the mains have enough oomph to deliver down to 50-60hz, then use it! As long as you can phase align the whole thing, it actually works really well!
Evan
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140hz crossover, really? There's no thump up that high, only annoying mud. Personally, I'd run your subs up to around 70-75hz, and your tops down to 85-90hz, 24dB BW on both ends.
I agree. Running the crossover point up that high with a 24dB/oct. slope is unwarranted. With those tops, definitely under 100Hz. The subs will sound much better with a lower crossover point, less "boxy." My setup has the tops going down to 60Hz with the subs set at 50-55Hz since they're running considerably hotter than the tops.
As for switching away from "subs on an aux," I wouldn't recommend it.
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Also consider what kind of filter topology you use. Different filters affect phase and consequently group delay differently. Butterworth for exemple AFAIK has the most overshoot at the XO frequency and might even be perceived as ringing, especially at lower frequencies where periods become longer. Same goes for filter order, 48 dB/oct. slope results in 360 degrees phase shift at XO. In case of i.e. 100 Hz this equals 1 cycle or 10 ms of delay.
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Looking at JBL recommended crossover points.... tops should be at 90 Hz with 24db LR slope. Bottoms at 88 Hz with 24db BW slope. Can't do the Butterworth right now so it'll have to be LR. I'll see how it goes this weekend. Thanks for all the input!
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What processor are you using? I don't recall ever seeing a BW alignment used as a sub LP filter. BW filters are usually used as sub HPF's. Higher end processors like the DR 260, 4800 and Crown Itechs recommend using LR 48 db octave filters at the crossover point for the SRX line. On the other hand the DRPA recommends LR 24db octave filters.