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  • Burafao
    Posts: 48
    Joined: Aug 2nd, 2007, 02:35
    Compressor question
    Hi, i am not understanding an aspect of Logics compressor. If i select a preset like "Bass Hard Compressor" and i move the COMPRESSION THRESHOLD slider down the sound gets LOUDER, but if i select the "Bass Smooth Compressor" when the COMPRESSION RATIO slider is moved down, increasing GAIN REDUCTION the sound gets QUIETER. This is how it logically should to work to my mind. The graph corrosponds to the 2 above scenarios. How can more gain reduction increase the output volume? Thanks TOM
    Reply
  • Burafao
    Posts: 48
    Joined: Aug 2nd, 2007, 02:35
    Re: Compressor question
    Hi I hope my questioning is clear. The question in my first post is truly baffling to me, please help. Thanks tOM
    Reply
  • Burafao
    Posts: 48
    Joined: Aug 2nd, 2007, 02:35
    Re: Compressor question
    IN my original post i said [quote:20529] but if i select the "Bass Smooth Compressor" when the COMPRESSION RATIO slider is moved down, increasing GAIN REDUCTION the sound gets QUIETER. This is how it logically should to work to my mind. [/quote] I ment to say but if i select the "Bass Smooth Compressor" preset when the COMPRESSOR THRESHOLD slider is moved down, increasing GAIN REDUCTION the sound gets QUIETER. This is how it logically should to work to my mind. Thanks tOM
    Reply
  • Burafao
    Posts: 48
    Joined: Aug 2nd, 2007, 02:35
    Re: Compressor question
    I got the answer in another forum. Its cause "auto gain" is "on" in some presets. I still dont understand why auto gain makes the sound louder as the threshold is lowered though
    Reply
  • Cajypiu
    Posts: 400
    Joined: Oct 11th, 2006, 09:48
    Re: Compressor question
    Hi Tablatom, the auto gain feature makes up the gain that the compressor reduced it by. For example, you reduce the threshold and the gain reduction meter flashes that it is reducing the gain by 10db. The make up gain feature will then add 10db to achieve the same peak volume as before. However, by nature, compressing a sound increases it's density and as a result it's average volume. Human hearing is more sensitive to average volume than peak volume so we hear higher average volumes as a higher perceived volume. Therefore, when you compress a sound and make up the gain to the same level as it was beforehand, we perceive it to sound louder than before.
    Reply
  • Burafao
    Posts: 48
    Joined: Aug 2nd, 2007, 02:35
    Re: Compressor question
    Hi Yadj, I am aware of perception with sound but it doesnt apply here. First off the manual says this much on Autogain You can use the Auto Gain parameter to compensate for the reduction in gain produced by compression, referenced to either �12 dB or 0 dB. Auto Gain sets the level of gain (amplification) to a value of T�(T/R), where T = the Threshold and R = the Ratio. Thats it!!! This topic really needs more in the manual. Here is a link to a forum also talking about Logics compressor and Auto gain. http://www.logic-users-group.com/forums/showthread.php?t=969 I understand the concept of what auto gain is supposed to do ( keep the output of the compressor the same as the input). If i apply auto gain -12dB the track does stay roughly the same dB no matter the amount of gain reduction. But with 0dB the track gets louder with more gain reduction. Why? And what does it actually mean -12dB and 0dB. Because when i add the compressor to a track with -12dB and with the ratio and threshold set so no gain reduction occurs and then bypass the compressor, its not like there is a gain difference. Thanks Tom
    Reply
  • AbbeyRhodes
    Posts: 76
    Joined: Jan 15th, 2008, 08:19
    Re: Compressor question
    Actually what YADJ said is correct and what you are experiencing is directly related to perception of average sound level. When you switch autogain on, it will set the MAXIMUM input and output levels to be the same, but chances are your signal is not consistently at maximum level. Therefore if you are compressing with autogain on, you are increasing the gain of the soft sounds. With autogain off compression will be decreasing the volume of the loud sounds. Increasing the volume of the soft sounds will naturally increase the average volume level, making it seem louder. Your meters are only showing you the peak output, which will remain the same because the max input and output are the same with autogain on, therefore the peak value of the sound will remain the same.
    Reply
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