Mkaing Gain/Compression video

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This topic contains 5 replies, has 4 voices, and was last updated by Profile photo of SpicerBob SpicerBob 1 month, 3 weeks ago.

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    Profile photo of SpicerBob

    I am about to create a training video for the team of PA operators at my church and these guys have very little understanding of the various processing stages and want to introduce them to the basics of PreAmp Gain and Compression. It will include the steps below.
    I would really appreciate any comments on this content:
    Could I, should I, make it simpler?
    Is it factually correct?
    Are there easier ways do this?
    Here is my ‘script’
    Press the PAFL key to ensure that this channel is the source to the PAFL metering. It also conveniently Selects that channel for processing.
    PreAmp gain and compression are inter-related. What you normally see on the PAFL meter is the Level AFTER it has been modified by the Compressor.
    Make sure the ‘Processing’ key is selected for the touch screen.
    If you are looking at this screen then tap the Compressor ‘block’ at the bottom of the strip for the required channel.
    If you see another processing screen showing details one of the other processing options for your required channel then tap the Compressor ‘block’ on that that screen.
    You should then see a screen like this. Check the channel here and that you are looking at the compressor here.
    On either side of the graph you see some thin meter strips.
    The one on the left shows the signal coming in to the compressor.
    On the right there are 2 meters. The first shows the amount of compression and the second the signal level as it leaves the compressor.
    Below the graph is a histrogram showing the amount of compression over the last 12 seconds.
    Set the input gain by adjusting the PreAmp Gain rotary until you see the input meter reach 0dB when that source is at its loudest.
    Using the Comp Thres rotary now adjust the threshold until the amount of compression on the histogram shows around 6 to 8dB at the loudest parts.
    When you are happy with the compression, note that the level on the PAFL meter will probably have dropped. To compensate for this tap the ‘Gain’ parameter on the touch screen and use the general purpose rotary to adjust until the PAFL meter is just hitting 0dB again.

    Profile photo of Tom

    The last sentence should add “at the loudest parts”.

    You should also add explanations how to get ratio and timing right,
    depending on the material.
    Especially timing is important to avoid pumping.
    Also the Lib button should be added, so they know how to load the compressor model they are familiar with.

    I think for the kind of users you are addressing, CQ’s auto channel wizards might be a better answer?

    Profile photo of SpicerBob

    Thanks Tom for taking time to read through my script. I should have explained that prior to setting gain and compression threshold my guys will have already loaded full channel libraries for each of the speakers and singers. (Subject of a previous video). So the basics of ratio and timings will already be set.

    But what are CQ’s auto channel wizards?

    Profile photo of Dave

    Hi Spicerbob,

    I may be a bit late replying, but I think it is really worth mentioning something that SO many churches get wrong, and that is gain staging.

    The info from Allen and Heath says:

    “A 0dB on an input meter means that the gain and/or trim has been set optimally.”

    And later:

    “So it is best to start with the optimum signal, keep it near this level throughout any processing and only attenuate it at the end of the signal path.”

    For me, the end of the signal path is the matrix at the end of the chain.

    That 0dB mentioned by Allen and Heath is equal to -18 on many other boards. So, levels should hover around the 0dB mark, and occasionally going into the yellow at the loudest peaks. Avoid going into the red.

    I have seen churches with levels of -40dB on the SQ boards, which is really low, and thresholds on the compressors have to be really low, including other processing not really working well.

    I just thought I would pass this along, hoping that it is included in your presentation.



    p.s. – if anyone wants to correct me on any of this, that is fine. I’m always up for more learning.

    Profile photo of Mike C
    Mike C

    I’m going to look at this another way.
    Since your sound team volunteers have very little understanding of the inner processor workings of running sound I would focus on the basics for them.

    As Dave said gain staging, if something changes on the stage they should be able to
    know how to trim the input channel.

    Have the processing set up with a window of operating range ahead of time.
    Have them focus on hitting the needed cues, what to listen for and focus on in building a halfway decent mix and maybe how to touch up channel eq….if needed.

    I feel having them focus on the basics and paying attention to what’s happening on the stage would be better than have them staring at menus on the mixer and possibly getting into something they shouldn’t while missing cues or changes on the stage.

    If anyone on the team wants to then take their operational skills to the next level great!

    Profile photo of SpicerBob

    Thanks to Dave and Mike C for their helpful comments.

    To hopefully cover both of their points I should confirm that, as Mike C says, most of the guys on my team have little knowledge the processing, but are now skilled in listening to the band and getting a fair balance for the main mix. This planned video is indeed aimed at those who want to take a step further. They are also used to setting up the gain but up to now this has just been the final stage ie after compression. This approach leaves a gain staging problem where if the gain is set to achieve 0dB after compression then it could well be peaking before compression. The filters and EQ should be ok as I have set up libraries for the vocalists and speakers (this is a church situation) and there should be little change in the gain up to that point (just trying to keep it simple). [I shall move on to the instruments in the band later.] Where I feel we need to concentrate our efforts is get the gain right before compression and then adjust to bring it back up to zero. So this video is to cover the relationship between the gain and compression and show a practical way for non-technical operators to achieve the most critical step in gain staging.

    Thanks again to those who have helped me get my thoughts in better order.


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