Academy Dashboard Forum Production Digital Recording A very basic question about recording levels (gain, peak, rms) Reply To: A very basic question about recording levels (gain, peak, rms)

Donald MacTavish


    Gain staging is critical to prevent overloading the channel or the mix bus.  Originally it was based upon the optimal levels for analogue gear to prevent undesirable distortion.  If you use any plugins that are modelled after analogue gear gain staging is even more critical.

    Here is some basic math to help you understand the topic:

    1.23 volts = +4 dBu ( referred to as reference level for balanced xlr signals ) = 0 dBVU (RMS) = -18dBFS  ( Digital )

    RMS means Root Mean Square and the math is RMS / 0.707 = peak value Zzzzzzz...

    Best way to understand this is to add a Meter plugin and set for RMS and PEAK.  Watch how they respond to the signal, peak will be higher.  RMS is an average over time as opposed to short term peaks.

    The goal of gain staging is to make sure that the signals are at ideal levels for mixing. As a *basic guide* you should be sending tracks to the mix with peaking between -12 and -18 dBFS so the mix bus does not become overloaded. If you have 2-4 tracks this is manageable but if you have 20 - 100 the solution is with sub-mix busses to maintain control and sanity.  If every track is peaking at -1 dBFS the sum on the bus will be in the red. ( History: Analogue mix desks were happiest with the faders around zero and the faders taper allowed finer adjustments +/- zero... nerd out!) )

    You want to monitor peaks since they are the highest level for the signal. In Logic the little box you mention is the peak for the track.

    To address your questions 1):

    1) Try to record all audio with peaks around -12 to - 18 dBFS ( no plugins impacting the signal ). This will give you lots of headroom to add plugins and manage gain staging. Use the preamp in your interface as well as instrument volume controls to set the signal.  The "fader" in Logic has no impact on the recording level.  As you add plugins watch the gain if if a plugin is adding lots of gain manage that with the different "gain" controls for the plugin. For software instruments the same is true and you often need to turn the "volume" control down a bit.

    2) I think I answered above.

    Lots of good tutorials on YT about gain staging that can help you understand the topic. Once learned it becomes second nature.  Avoid tutorials that push everything into the red and advise to make it "loud".  Personally I have found the more you learn and understand analogue techniques the better your digital outcomes.