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Sending low frequencies to sub and mids and highs to mains?

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  • Sending low frequencies to sub and mids and highs to mains?

    I spoke to a tech support person at QSC about the best way to route my Mimic Pro through my Behringer board and on to my new CP8 mains and single KSC 212C sub. He said I should separate the low frequencies at the board and send those to the sub and then the mids and highs along to the mains. After studying my board for a while I still have no idea how to accomplish this or if this is possible or even a good idea? It seems that if for example I separate my kick and floor tom and send those to the sub all the nuanced higher frequencies that make up those great sounds would be missing.

  • #2
    This isn’t handled by the console. Basically, you’re wanting a crossover that can dictate where frequency range gets separated between subs and mains. Talk with your FOH engineer about whether you really need one, or if just running full range makes any difference. Given the frequency responses of the cabs you listed, I’m not sure running a crossover around 118hz (sub’s max) is really going to make a huge difference. You’d just be cutting off a lot of the lower end in your mains. I get what you’re trying to do, but I’d borrow a crossover first to see if it really makes enough of an impact on the resulting sound. I don’t think it really will.
    Alan
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    • #3
      Yes do send a full range and don't attempt to separate instruments between the top and sub. I hear some people do this for easy mixing but I highly disagree with the practice.

      Why not just Mimic TRS L+R into console (if necessary) then TRS full range signal into KSC 212C and XLR pass-thru to each CP8.

      Engauge crossovers on the 212C and CP8 then you can easily flip between 80Hz or 100Hz on the fly / whatever sounds cleaner.
      ♦ Diamond Drums 4pc in Di-Noc carbon ♦ MegaDRUM + Roland UA-1010 / cymbals / KT-10 (x2) ♦ Tama / Gibraltar hardware ♦ JBL LSR3 Series 2.1 Monitoring
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      • #4
        Originally posted by Kabonfaiba View Post
        Yes do send a full range and don't attempt to separate instruments between the top and sub. I hear some people do this for easy mixing but I highly disagree with the practice.
        Not to mention, attempting to send a specific instrument (like a BD) to just the sub would cut off any detail above 118hz. It would be like rolling off the entire low-mid to high end. That would sound terrible.
        Alan
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        • #5
          Yes! Simplicity is just what I was hoping to hear. I was digging deeper into this and found the following for those who may be interested-

          https://www.qsc.com/resource-files/a...112_review.pdf

          It's a very detailed review of the PC8's paired with a KS112.

          It quickly went deep into technical jargon and graphs that are lost on me but a couple of key statements seemed to confirm what you guys are telling me-

          "When used with a subwoofer, an all-pass filter is activated in addition to the high-pass filter already active in full-range mode. The all-pass filter lowers the volume around 60 Hz by 12 dB. The advantage of this type of filtering is that an all-pass filter has less of an impact on the phase relationship than if we change the frequency of the high-pass filter."

          "Figures 1 and 2 show how the KS112 performs together with the CP8. They show the KS112 individually but also as part of a full-range set up. The loudspeakers perform well in the crossover area where the two units are added. The lower cutoff frequency is now around 40 Hz. Between 50 and 100 Hz we see an exaggerated but presumably intentional in- crease of 2-3 dB, and we assume this is designed to exploit the performance of the loudspeaker without putting it under too much low-frequency strain."

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          • #6
            I would simply set the crossover high because the CP8's are small and much less powerful than the sub. I set my Ksub and K12's at 100 hz crossover for my house concerts. Outdoors I sometimes move it to 80 hz. You might need to go as high as 120 hz on the CP8's but try 100 first.
            What they are trying to explain is the practice of running the sub on an aux send. You need an extra send to do this. Then you send only low frequency instruments to the sub but they also go to the 2 ways from the main send. This way you avoid sending things like vocal mics to the sub.
            Is your board only for the Mimic? If so I would ignore this advice about the aux send.

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            • #7
              That review was a good read cobaltdrive, thanks for posting it.

              I also read up on how cardioid speakers work today, so I could understand the 212C better. I love the idea! But I doubt I could even afford the non-cardioid KS 112. I'm pretty sure I'll be picking a bandpass sub at least for efficiency with smaller 12inch drivers as I think a 15 or 18inch sub would just kill me on the road.
              ♦ Diamond Drums 4pc in Di-Noc carbon ♦ MegaDRUM + Roland UA-1010 / cymbals / KT-10 (x2) ♦ Tama / Gibraltar hardware ♦ JBL LSR3 Series 2.1 Monitoring
              Community Drum Module Document
              PA Specifications (wip)

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              • #8
                I know what you mean, Kabonfaiba. I already exceeded my budget for the whole system with the 212C but it seems perfect for my applications and I have a very understanding wife!

                "I would simply set the crossover high because the CP8's are small and much less powerful than the sub. I set my Ksub and K12's at 100 hz crossover for my house concerts. Outdoors I sometimes move it to 80 hz. You might need to go as high as 120 hz on the CP8's but try 100 first."
                Peter, my board is dedicated to the Mimic so is your advice about setting the crossover based on using the aux send? If not, then I'm not sure how to experiment with the crossover settings.

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                • #9
                  FWIW, I agree with the 80/100hz crossover settings. I just mentioned 118hz to point out the sub's max. You'll like find 100hz is the sweet spot; allowing the kick punch and sub lows to blend nicely with the mains, while not muddying up too much of that low end. (too many amateur engineers don't pay attention to rolling off any low bass & gtrs possibly going through the PA... leading to muddying up the system) 80hz will probably be too low.
                  Alan
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                  • #10
                    Originally posted by cobaltdrive View Post
                    I know what you mean, Kabonfaiba. I already exceeded my budget for the whole system with the 212C but it seems perfect for my applications and I have a very understanding wife!

                    "I would simply set the crossover high because the CP8's are small and much less powerful than the sub. I set my Ksub and K12's at 100 hz crossover for my house concerts. Outdoors I sometimes move it to 80 hz. You might need to go as high as 120 hz on the CP8's but try 100 first."
                    Peter, my board is dedicated to the Mimic so is your advice about setting the crossover based on using the aux send? If not, then I'm not sure how to experiment with the crossover settings.
                    The crossover is on the back of the sub and CP8's. You will have to use default External Sub setting on the CP8's. This will remove lower frequencies from them which will sound cleaner and also allow them to be louder. You can try 80 or 100 hz crossover point on the sub. The CP8 manual does not say what the crossover point is. The K series has a selectable crossover point. In my living room,100 hz is much better sounding but in larger rooms sometimes 80 hz works better.

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                    • #11
                      Just to mention, the 'aux sub' technique does not necessarily mean just routing bass instruments to the subs, but rather using the aux send to feed bass instruments to a separate output. This is usually done in the absence of a crossover but requires having a master eq on the mixer to cut off the frequencies handled by the subwoofers. In some cases this technique can even be superior to using a crossover because the overlaping freq can be anywhere in the range of the eq.
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                      • #12
                        So I've spent a little time on my kit with the new CP8's and KS212C. Wow! With the Mimic Pro and Alan's Vex packs I cannot believe how incredible it all sounds. It's a quantum leap beyond everything else I've played before. My band mates are really impressed too.

                        But in the quest for the best sound there are always more roadblocks- I'm sending the signal to the 8's and 212 out of the Monitor Out on my Behringer board per their instructions so i can send the Main Outs to the FOH. The Mon Out is mono so I ran it into my Roland PM3 as a mono feed then from there out to the 212 on 2 channels. Worked great. It worked so well that I decided to nix the PM3 as unnecessary (and one less thing to lug to gigs) and sent the Monitor Out from the board directly to one channel on the 212. But only one of the cp8's now gets the signal. A splitter doesn't work either so now it appears I'll have to run the signal through the PM3 or find it's equivalent for the signal alone. I certainly don't need the PM3 speaker, just whatever is happening internally to change the signal from 1 line to 2.

                        Any ideas?

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                        • #13
                          Originally posted by cobaltdrive View Post
                          So I've spent a little time on my kit with the new CP8's and KS212C. Wow! With the Mimic Pro and Alan's Vex packs I cannot believe how incredible it all sounds. It's a quantum leap beyond everything else I've played before. My band mates are really impressed too.

                          But in the quest for the best sound there are always more roadblocks- I'm sending the signal to the 8's and 212 out of the Monitor Out on my Behringer board per their instructions so i can send the Main Outs to the FOH. The Mon Out is mono so I ran it into my Roland PM3 as a mono feed then from there out to the 212 on 2 channels. Worked great. It worked so well that I decided to nix the PM3 as unnecessary (and one less thing to lug to gigs) and sent the Monitor Out from the board directly to one channel on the 212. But only one of the cp8's now gets the signal. A splitter doesn't work either so now it appears I'll have to run the signal through the PM3 or find it's equivalent for the signal alone. I certainly don't need the PM3 speaker, just whatever is happening internally to change the signal from 1 line to 2.

                          Any ideas?
                          It's very simple. Take the monitor out to sub,sub out to CP8 and then mix out on the CP8 to the other CP8.
                          Did you set the crossover in the sub and CP8's? My K12 sub does not have a crossover setting and I just used my QSC mixer to cut it at 100 hz. The sound is alot better. My K12.2's are set at 100 hz.

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                          • #14
                            Of course! That seems so obvious once you say it, Peter. Just hooked it up and works great. But is it me or is there less bass now that I’m going from one input to the sub vs two? Only had a minute to check it out tonight so I may have been mistaken.

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                            • #15
                              Just turn up the sub if needed . It should be a cleaner signal now.

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