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Gain Structure / Limiter Setup

0x15e0x15e Posts: 4
edited December 2010 in 200 Series General Discussion
I just got a DR260 and am having a bit of a problem setting up the limiter.

My system right now is a pair of Yamaha S115Vs and a QSC GX5 amp.

Since there's no preset for the amp, I set up the system with the amp set to custom and did a gain structure / limiter setup as found in the \"start here\" section.

This ended up with me setting the gain in the DR to +7db. It also resulted in me clipping constantly (and activating the limiter) with program material that was really way too low to be clipping anything. Once I turned the gain back down, that stopped.

I'm pretty sure I messed up something fundamental but don't really know what it was. Can someone help me with this?

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    DraDra Posts: 3,777
    Welcome.
    It is hard to imagine that if you followed the detailed steps that you achieved the outcome you did. You said \"program material\". You used pink noise for the structure process correct?
    +7? at what stage? Input mixer? X-over gains?

    DRA
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    0x15e0x15e Posts: 4
    Yes, I used the 20 minute pink noise track linked by the guide. \"Program material\" in this case is electronic dance music. In case it matters, the mixer is a Rane Empath.

    When I ran the noise through the mixer, I set it to about 6db lower than the mixer's clipping point, which is how I thought the guide said it should be. Now that I'm looking at it again, I think that may have only applied to the PFL section (for the record, on my mixer, PFL and AFL levels matched -- if I set PFL to 6db under clipping, the mains were at 6db under as well).

    I'm pretty sure that +7 was on the input mixer but I could be wrong.
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    DraDra Posts: 3,777
    Speakers unplugged.
    Set the pink noise level:
    Apply PFL and achieve -0- on mixer.
    Disable PFL bring the channel to -0-.
    Bring master level to -0-.
    Adjust DR260 input master to gring meters to -0- (GUI is more \"fine tunable\").
    Adjust x-over gains to -0- (on meters, again GUI is possible).
    Now bring master level up to hitting a pretty solid red.
    DR260 input meters should be no higher than +18 (max).
    Output meters should be the same.
    Bring the amps up (by band, in your case only one) until the amp barely clips. Make a note where it is, then turn it back until it does not clip anymore. Make a note of it and go back to the clip point.
    Now work the limiter in, then go back to the lower setting on the amp.
    Virtually impossible to clip, now.

    DRA
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    0x15e0x15e Posts: 4
    Thanks, I'll go through it again following that list. I can definitely say that at no point in the setup last time did anything get to \"solid red\" so I at least did that part wrong.
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    NoizyNeighborzNoizyNeighborz Posts: 41
    Hey guys I wonder if I did this wrong as well.

    I set up the mixer for -0- on the channel PFL and the Fader, but when I set the master fader to -0- the mixer output meters don't match (much lower). I also could not get the mixer to clip. I had to adjust the input gain for the pink noise channel way above -0- in order to get the mixer to clip.

    I'm just wondering why if the Channel is showing -0-, on the Fader,PFL meter and channel Input meter, why do the output meters not show the same level?

    The Mixer is a Mackie 1640, EQ is flat and filters were off.

    That being said, I used these settings to do the rest of the gain structure and it seemed to work fine. Although, I'll never run any inputs at the gain the setup was done at... so I also wonder if all channels are at -0-, and I crank the master faders, will they bottom out way before I reach the max headroom of the system.

    1. Let me know if I did the right thing by cranking the input gain to achieve the clip signal.
    2. Is it OK for the 260's output clip meters to be flashing yellow? Mine do when the mix master is pushed above -0-. I assume they will be red when they actually clip.

    Thanks
    Wally
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    DraDra Posts: 3,777
    Try to think of it as 2 completely different processes.
    1) Setting the input (mic, guitar, etc) gain on the channel to unity.
    2) Setting the down-range gear to the board's max output.

    They are not really that related (although they are).

    We'll assume that you are using the actual input source (vocal, guitar DI, guitar mic, kick mic, keyboard DI, etc) at normal (for them) levels? Pink noise on CD for CD input?

    If you are burying the masters and do not have enough output (and not in the red), then check the meters and compare to the Driverack meters. They should be the same (IN and OUT). If they are, then you... aren't pushing the input faders enough (even passed -0-) or the input level (sources) are lower than sound check.

    Gadget, Dennis, you guys think of anything else?

    DRA

    PS - Guess I should have added that getting the master into the red, is \" whatever it takes\", but hopefully you'll never have to go there while playing.
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    DraDra Posts: 3,777
    Just to clarify. The unity setting of the mixer output (-0-) to the Driverack input (-0-) to the Driverack output (-0-) can be done without any channel being \"unified\". The \"solid in the red\" of the mixer's meters to the Driverack's inputs (+18 max) to the Driverack's outputs, the same.

    Input unity is for the channels ONLY and have nothing to do with anything else.

    DRA
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    GadgetGadget Posts: 4,915
    The main principal here is that if you consider the potential for noise, with the main faders there are 2... with channel faders there are ...12, 16, 24, 32, 56...etc if we aren't careful with each channel we inducing noise with each channel... so, we put the channel faders @ unity, -0- and use the input gain control to send to the master fader...Further, if you depress the PFL per channel you can use the main output meters (which have more segments in the display for greater accuracy... some mixers have a small meter on each channel strip, or like you an LED that kinda gives you an idea where your at.

    So, if you can't get the sufficient output to clip the meters.. as long as the PFL'ed level doesn't clip, you are ok, Now you may find that you have to push the master faders well above unity..-0- but this is a one time set it up and find out where the whole system clips deal...

    Other than that you seem to have the basics down...

    As for why the PFL and master meter don't show the same.. the different stages have different gain structures within themselves.. the individual channels usually don't have the gain potential of the output stage simply because internal gain structure must account for a broad range of input levels and impedance's and be able to represent them all well at the master stage...
    Gadget
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    NoizyNeighborzNoizyNeighborz Posts: 41
    Thanks again guys. Sometimes things explained in plain english are a big help. So, I did it correctly and now I understand why I had to raise the input channels gain (for the pink noise cd).

    I did the gain structure again after the speaker flattening, and now the limiters seem to have more headroom before they kick in.

    Next question:
    I adjusted my crossover gains so the Ouput Levels for the Mains and Subs = Input levels. The Subs crossover gain is above -0- and the highs are below -0-. I then did the gain structure again. Was adjusting these gains the right thing to do, or should I have left them both at -0-?

    Wally
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    DraDra Posts: 3,777
    It is kind of a vicious circle, but how balanced is the system? While playing a good full bodied CD, are the subs too loud, too soft, just right?
    Depending on your answer, turn down the loudest speaker. If your subs are loudest, considering you boosted the gain on the sub x-over, I'd reduce the gain there to balance. In the end, when the system is balanced, go back and (unplug the speakers) and make sure the amps are not clipping when the board is. If all is well, you are set. Pat yourself on the back and R&R.

    DRA
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    NoizyNeighborzNoizyNeighborz Posts: 41
    Thanks Dra,
    The system seems pretty balanced both from a listening point of view and by the meters. I think I'm ready for the gig on the weekend. It's out doors so I'll be able to crank things up and check for leaks :wink:
    Thanks again
    Wally
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    jzzenjzzen Posts: 2
    Hi.
    I'm a new 260 user.
    I do sound hire from time to time, and although amp volumes are set to an optimal position, dj's sometimes fiddle with it. Could i not set all amps to max and then adjust the gain at xover.
    Would this method sacrifice headroom?
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    GadgetGadget Posts: 4,915
    Best bet for DJ work is to slightly UNDER power the speakers (meaning if there is a 200-400-800 power rating give them NO MORE then 400 watts0, run em wide open and set a brick wall limiter on the 260...You will need to also do a gain structure as in the "Start here" thread...


    You can also then set up password protecton for your settings that a DJ can't monkey with...

    BTW this thread is more than a year old, instead of hijacking a thread please consider starting a new one... this way lurkers can also learn more..

    Thanks

    Gadget
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