Aux Fed Subs problem QU16

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This topic contains 6 replies, has 4 voices, and was last updated by Profile photo of airickess airickess 4 years, 4 months ago.

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    Profile photo of Aaronious

    I switched to auxfed subs at me venue and loved it. Everything in the real world sounds excellent after SMAARTing the system.
    The problem I have was when someone asked for and audio out from the QU16 into their video camera. I gave the the 2Track outs and it’s always been fine when using the L&R out from the console. Since switch to auxfed subs, there’s zero or very little kick and bass in the recording. I was also recording multitracks for virtual sound check but it also played back with no low end. Please help as I really love to stick with the auxfed subs setup.

    Profile photo of Mike C
    Mike C

    If your processing your system with a crossover/DSP to where the main L R signal feed to the top boxes is ultimately high passed at say 100hz the signal leaving the mixer still has the full amount of low end in it up until it hits the system processor.
    The mixers aux out for the sub feed will have those channels full frequency content until
    that aux sub mix hits the processor and is low passed at maybe 85hz and high passed for the subwoofer around 35hz.

    In the above case the 2 track out or for that matter the main L R out should still have all the low end present.

    A couple questions……….
    -Are you using an external system processor to do the proper crossover filtering or are you trying to do it all with the output EQ’s in the mixer, if that’s that case that is why your board mix recordings sound thin.
    -Are you running the aux feeding the sub as post fade?

    Another thought……
    -If your running the subs really hot either at the amps, system processor, at the boards aux out or all of the above that could in turn could cause you to be running the overall channel levels of inputs that your sending to the subs lower than where you would on a straight L R full mix system.

    Profile photo of DoctorG

    If you’ll check the flow diagram, you’ll see that the two-track outputs follow the main LR outputs, so if the low frequency devices do not feel the LR bus, their signal will not appear in the two-track outputs.

    If the kick and bass are feeding the LR mix as well as the Aux outputs, you can bring up their level in the LR and back off a bit in the Aux sends.

    Does that seem to address your issue?

    Profile photo of Aaronious

    Thanks for the quick response guys. LR goes to 2 DXR15 tops, HPF at100Hz. LR output eq flat with SMAART from 100Hz up with a slight dip starting at 2Khz. Kick and bass at unity on channel fader. Mix 1 output to pair of CW CVA18 chained. Mix out eq with +9dB slope from 100 down to 40Hz again using Smaart, also used high shelf to cut everything from 1Khz as there’s no LPF on QU16. Kick and bass also at unity and post fade. Only using the variable knob on CVA to adjust X-over. I don’t adjust anything from Mix 1, only move sliders on Main mix to add or remove some low end. I can hear the low end on headphones as well (without any solos on channels). It’s just weird that I don’t get any bass in the recordings. Once again, did not removed any Low Frequencies with eq on Main outputs. Both LR and Mix 1 used limiter at +14.5db.

    Profile photo of Mike C
    Mike C

    A few things…

    – Setting the HPF on your DXR cabinets is good and sending them the LR mix is correct.
    – You want to set the LPF on the sub around 80hz to 100hz and feed the subs your mix 1 output.
    – Mix 1 needs to be post fade, post eq.
    – No need to do a high cut shelf on the mix 1 output eq, the crossover in the sub takes care of that.
    – Not sure I would be doing that much broadband EQ boost on the low end of mix 1.
    – Systems that are EQ truly flat will sound thin with most modern music.
    – When you say “only move sliders on Main mix to add or remove some low end” are you talking about the mix 1 master output level or the main mix LR master?
    – Adjusting the main LR master should not be changing the levels feeding the sub woofer.
    – You could set up another mix to send to your recording, take one of the stereo mixes, set it to post fade, post EQ, set all of the channels to the same level feeding the mix, in the IO set up route that mix to the Qu Drive. That way the recording will bypass any of the main mix output EQ.

    Profile photo of Aaronious

    Hi Mike C,

    Mix 1 is post fade and post eq.

    The high cut shelf on Mix 1 makes the low end a bit more tight to my ears, but your right….the variable low cut on the subs can take care of that.

    I never boost anything on Busses EQ, just cut. Adjusting the volume on the sub prior to any alignment and EQ gave me that 9dB boost on the low end. Only after getting enough volume from the sub then I started SMAARting the system. 9dB boost is just incase I need all that power as low end can be controlled on Main LR channel faders. Can’t remember a time I ever had kick and bass fader all the way up unity, usually around -3 to -5 on sliders.

    My system is only flat from 125Hz-2Khz with 9dB boost from 100hz downwards and a slight drop of 3dB/octave after 2Khz. Tried EQ the system to the exact frequency response curve of my SRH-840 but that didn’t turned out very well. LOL

    Moving channel faders on main mix will add or reduce low end as Mix 1 is set to post fade with channel and master faders at unity. Never touched anything on Mix 1 again after required instruments are assigned to it. Created DCA for LR and Mix 1 master so they can be adjusted together without screwing up the phase alignment.

    Adjusting the main LR master should not be changing the levels feeding the sub woofer but it will create phasing issues between subs and top.

    Profile photo of airickess

    Using the faders on the Main fader layer to adjust the low-end is the wrong way to do that. Anything you adjust on that layer will affect the signal to the Yamahas as well. Any adjustments to the volume shouldn’t be done with the Master fader anyway. It would be easier to set up a DCA for the band rather than the LR and Mix 1 master faders. That way you never have to touch the Master or mix faders – you’d just have to push the band DCA up or down.
    You should probably use SMAART to help match the level of your subwoofers to your tops, rather than just doing it by ear. That way you’ll end up with a more even frequency response to the entire system.
    You really shouldn’t need to have a +9db boost for the subs. If you feel you need it then you don’t have enough subwoofers for your gig. I really doubt that those Cerwin Vega subs can keep up with the Yamaha DXR15 tops.
    If don’t have a choice and must continue to use the CVA-118s then you should try to not use them as speaker stands for the tops. Instead, try to put them together at the front of the stage so they will couple. You will get a bit more SPL out of them (but not +9db worth).
    If you are in this business for the long-haul I suggest you sell the Cerwin Vega subs at some point and save up for some Yamaha subwoofers to match your tops. DSP in powered speakers has come a long way and matching speaker brands really helps bring the P.A. system together.

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