Hissing Noise

This topic contains 5 replies, has 5 voices, and was last updated by Profile photo of CaptainF CaptainF 11 years ago.

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  • #22440
    Profile photo of Knoxford
    Knoxford
    Participant

    I have hissing. For temporary fix I can use the equaliser and cut 4k and 5k for the Rmain and Lmain. I don’t want that long term.

    I am thinking it may have to do with several gains being pushed too high. Am adding 2 more speakers for a total of 3 on R and 3 on L so I think I can pull the gains down.

    Is there a way to isolate this hiss?

    #26257
    Profile photo of mumu
    mumu
    Participant

    pad on and gain hard open (on input channels) could be it

    cheers
    dave

    allen&heath iLive-144 /idr 64 / idr 48 (i am convinced there is a yamaha conspiracy against the release of the dante )

    #26260
    Profile photo of Stix
    Stix
    Participant

    quote:


    Originally posted by Knoxford

    Is there a way to isolate this hiss?


    Start muting channels – if the hiss drops considerably on specific channels then check your gain and PAD settings on those channels. Only use the pad if you really do need it. You will get way better signal to noise ratio with the pad off and gain on a lower setting. If you still have a lot of hiss then check your input sources – if they are coming from electronic devices (such as another mixer/DJ deck/preamp etc then try to improve the signal to noise ratio at the source first – then look at EQ settings and possibly look at using noise gates on problem channels.
    If your PA system has plenty of headroom then try running your master outputs hotter (say around 0Vu unity) with your amp attenuators turned down to compensate. This will reduce any external speaker processor noise – by the amount you have attenuated the amps by. Don’t use gain where gain isn’t needed – If your channel faders on some channels are only ever at half – then drop the gain and bring the fader back up close to 0Vu. It’s all about signal to noise ratio’s. Let us know if this sorts out your problems.

    Cheers

    Richard Howey
    Audio Dynamite Ltd
    IDR48/IDR16/T112/R72

    #26420
    Profile photo of Knoxford
    Knoxford
    Participant

    Stix – thanks for the response. I only get to set the T112 and iDR48 once a week for 2 hours as we are a portable church right now looking for a property to build out.
    It seems that Pad is on by default. I did save the last show and can bring it up in Editor and Pad is on on the 2 offending channels as well as one non offending channel. Voc1 is on channel 30 and has hiss. Voc2 – channel 31 and no hiss. Voc3 – channel 32 and has hiss. The mics are all sm58’s and all the settings appear the same.

    On a separate issue, as you described in your last post, I am running the master outputs at about -20 so I am going to rebalance by bringing the gain and trim down on channels and push up the master outs to 0Vu.

    Back on the Voc1 and Voc2 hiss, I think I will go low tech for a fix and replace the mic cables?

    Thanks again,

    Knox

    #26429
    Profile photo of kentlowt
    kentlowt
    Participant

    As Richard eluded to it is all about your gain structure. Get that right and your hiss will pretty much dissapear unless it is coming from an external source. Might be helpfull to google up on gain structure as a refresher.

    112T/IDR48/IDR16

    #26477
    Profile photo of CaptainF
    CaptainF
    Participant

    I like this video about gain structure:
    http://www.youtube.com/watch?v=1hwT15SSwgU

    – CaptainF

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