Parallel Path Wet/Dry question

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This topic contains 11 replies, has 6 voices, and was last updated by Profile photo of WaihekeSoundie WaihekeSoundie 6 months, 1 week ago.

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  • #95734
    Profile photo of Lighthouse Church
    Lighthouse Church
    Participant

    This may seem like a very amateur question, but can someone please explain the dry/wet level effects for parallel compression? I understand the concept of parallel compression and think it will benefit our live stream sound, but I am curious as to what effect it would have, for instance, if I set my dry to -20db and wet to 0db versus 0db dry and 0db wet. I am new to this and don’t really have an opportunity to practice different settings a whole lot with our live group. Thank you for your help and have a great day 🙂

    #95741
    Profile photo of KeithJ A&H
    KeithJ A&H
    Moderator

    @Lighthouse Church,

    Although parallel compression is built into each processing channel on the SQ, you can think of it in the same way as having two channels next to each other, each with a fader.
    One channel is the uncompressed ‘dry’ signal, with full dynamic range. The other channel is exactly the same signal, but has been affected by the compressor so it is ‘wet’.
    If you had dry at 0dB and wet at -inf it would be the same sound as if you hadn’t even switched the compressor in.
    With -inf dry and 0dB wet, it would be the same as if you had the compressor switched in and parallel path off.
    So having -20dB dry signal and 0dB wet just means you’ll hear less of the uncompressed version relative to the compressed version.
    What it will actually sound like will be completely dependent on the source material and compressor settings.

    The reason there are two controls instead of a single wet/dry balance is because we spoke with many engineers who were used to having to use sends and returns or duplicate channels to achieve parallel compression. Almost all of them said they either started with the dry signal and brought in the wet, or started with the wet signal and brought in the dry.

    Cheers,
    Keith.

    #95745
    Profile photo of volounteer
    volounteer
    Participant

    @KeithJ A&H

    So would that be like the ability to set the mix ratio for wet/dry that some folks wanted to know about when I mentioned plug ins that did NY compression aka parallel compression with a knob icon to pick the ratio?

    What is the best way to do it on a Qu? We have come up with a few ideas but are leaning to splitting a channel in with a Y cable then applying compression separately on those two and then mixing them together by sending both to the next destination.

    #95747
    Profile photo of KeithJ A&H
    KeithJ A&H
    Moderator

    @volounteer

    The term ‘ratio’ could be confusing when referring to compressor parameters which are not the compression ratio – what we’re talking about here is closer to a ‘balance’ or ‘mix’ of two things anyway, rather than a ratio where one value is dependent on, or compared to, the other.

    I think there may already be a discussion on ways to achieve this with Qu over in the Qu section of the community and it would be best to keep discussion on the two platforms separate – but yes, an analogue split would be the easiest way.

    Thanks,
    Keith.

    #95750
    Profile photo of Lighthouse Church
    Lighthouse Church
    Participant

    Thank you Keith for explaining that. So by your explanation, I’m going the right route if I’m trying to hear a more controlled, or “compressed” sound on that output. That’s what I’m looking for in the live stream….a more controlled sound.

    Thanks again!
    -Jamie

    #95751
    Profile photo of Mfk0815
    Mfk0815
    Participant

    @KeithJA&H
    There is only one disadvantage with this parallel path settings. If you decide to use another compressor model these parameters will always reset to the defaults. (Parallel path off and dry signal -inv). It would be better when these parameters will stay as they are.

    #95753
    Profile photo of volounteer
    volounteer
    Participant

    @lighthouse church

    that is what parallel compression does.
    it squashes down the loud stuff but also raises up the low talkers so you can hear them.

    too wide a DR is a problem many churches have with people who speak to the audience.

    as I understand NY compression aka parallel compression, you need to play around some
    with a real heavy compression onone and the other channel that is none to light compressionwise.

    then try different amounts of mixing them to get the result you want.
    That I presume would be by raising and lowering faders to favor one over the other.

    @KeithJ A&H

    Thanks for the comment.
    Yes something like a mixing ratio or similar to panning although that latter is also a bit misleading.
    But definitely not compression ratios except to pick the amount on each channel that works best for you before combining them together.

    #95760
    Profile photo of Hugh
    Hugh
    Participant

    Over the past 15 years, that I have been working with Digital processing, I have never found a clear reason to deploy parallel compression. Careful application of threshold, ratio & make up gain with a single compressor has been working well enough for me. Please explain any known advantage a parallel approach has over a well structured single compressor. Controlling dynamic range is not the same as dealing with layering reverb between wet/dry segment needs.
    Hugh

    #95762
    Profile photo of volounteer
    volounteer
    Participant

    @Hugh

    Tell us how to use a single compressor to fix the ultra wide DR of talkers who cant be heard when they are talking softly.

    We can use a regular compressor to fix the loud end.
    But how can you fix the low end without using the parallel compression?????

    Have you fixed this sort of problem with a single compressor?
    Tthen please tell us your settings that worked and how wide the original DR was.

    #95764
    Profile photo of Mfk0815
    Mfk0815
    Participant

    @Hugh
    I personallyuse parallel compression most for musical improvements. You can add more body and punch on drum tracks, kick, snare or toms. You can push the bass forward in the mix without adding to much volumn and you can enrich the lead vocal with more body and make more clear to hear.
    Most of the time i do it together with hard compression. Low threshold, high ratio, fast attack and slow release. Without the parallel path you will hear the compressor working that hard, but the direct, dry signal will add the required transient signal parts to make it sound far more better.
    You can use it on single channels to improve that signal or you can use it for a group compression. I use it on single drum channels and also on the drum group (two stage compression) for rock bands with significant drums and also on vocal or horn groups to glue them to a compact, tight sounding group.
    Give the parallel compression a chance and I am sure you will use it more and more.

    #95765
    Profile photo of KeithJ A&H
    KeithJ A&H
    Moderator

    Attached is quick visual of what @mfk0815 describes.
    This is just some rock drums mixed to stereo, then uses only the left channel to make it easier to see.

    The clean track was sent to 3 channels on the SQ which were then patched back out from post-comp direct outputs to record simultaneously.

    So the first track is ‘as is’ (i.e. ‘Dry’)
    Second is with some heavy compression applied (i.e. ‘Wet’)
    Third has identical compression settings, but uses the parallel path with dry = -3dB and wet = -3dB mix (roughly half-power on each for a better comparison).

    You can see that the parallel path version retains both the raised lower/quieter levels of the compressed track, plus the transients of the original.

    Cheers,
    Keith.

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    #97285
    Profile photo of WaihekeSoundie
    WaihekeSoundie
    Participant

    Thanks all for above.

    I just about get the general concept of Parallel compression I think..
    – When we sum two identical tracks that are in phase – all other things being equal, we get a gain increase from the sum (6db- I believe).
    – If I sum a heavily compressed version of the track with an uncompressed version I still get the summing of the uncompressed program but there is less to sum in the compressed louder parts.
    In effect what you end up with is an upwards expansion of the softer material..

    So the peak level is still defined by the peak of the uncompressed signal but the dynamic range is still reduced because everything else has come up to meet it
    So if I now set an acceptable level for those peaks they won’t seem disproportionality loud because everything else has been brought up closer to that peak now..(including spill of course)
    I think that’s the general idea.
    Please correct me if I have not got this right in my head.

    What I’m struggling to understand is what settings to use as a start point:

    -Wet vs Dry levels (-3db and -3db seem a good start?)

    Compressor
    – Threshold– so that you see what.. a > 6db gain reduction on the compressed channel?
    – Make up gain- 0db?
    – Attack ?
    – Release?
    – Ratio: 20:1..?
    – Peak or RMS?
    – Knee: Hard or Soft?

    I do appreciate that one size does not fit all but it’s a very new concept to me and any thoughts about how people use in practice would be greatly appreciated.
    What should I be listening for.. how do these parameters interact when we have the dry?
    Many thanks Thanks

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