Why do master meters show different from master input

Getting Stuff Done How do I .... ?
#1

Hi
I am puzzled that the meter in the master channel does not show the same behaviour as master input, when trim and fader set to 0.0 and no plugins:

master different meter
master different meter307×1012 37.2 KB

in this screenshot a drum beat is sent to a drum bus which then goes straight to the master bus, in its default state. the two meters behave differently, especially when the kik hits.
Why could this be? Is there some form of compression? always active on the master?
Many thanks

#2

Look at the Unit (small text bottom right): dBFS vs K14
image

For tracks, Ardour uses a digital-peak meter. It is handy when recording to make sure the recorded audio never clips.

For mixing a loudness (as perceived by humans) meter makes more sense. Ardour uses a K14 meter by default.

For details, please see The Ardour Manual - Metering in Ardour

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You can change meter types by right-clicking on them, and the default for new sessions in Preferences

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#3

Ah, Thanks Robin, that is really useful to know.

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#4

Robin is clearly insightful as usual. I looked at webpage " K-System Metering 101". The K-12, K-14, and K-20 meters are essentially loudness meters to help achieve volume consistency and control.

Decibels are a logarithmic function. I do not understand this statement from the webpage:

Both the peak and RMS meters in the K-System are linear rather than logarithmic.

An explanation of the math transform of the one or other type (I guess) would be nice to know if someone wants to share. Undoing the logarithmic nature of dBs to match human hearing does not make sense to me.

#5

I didn’t even know that webpage, and it is indeed rather confusing.

Both the peak and RMS meters in the K-System are linear rather than logarithmic. In a linear scale, each dB has the same width or height (depending on whether or not the scale is horizontal or vertical).

I expect this refers to meter deflection (and that article is somewhat confusing IMHO).

The IEC peak meter on the left in the screenshot below uses about 50% of the vertical height for the range down to -20. The resolution (distance between tick-marks) decreases further with level. It is very noticeable at the bottom of the scale -40… -50 takes about half as much space as -30 … -40.

The K-meter on the right does not have this deflection.

image

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PS. The article linked from the Ardour manual by Bob Katz himself is a much better source of information: Level Practices (Part 2) - Digido.com

1 Like
#6

Bob Katz has a great mind. I can’t give it proper attention any time soon, but wow. Knowledgeable people who can communicate without adding a barrage of ‘noise artifacts’ are rare, which is why you recommended it in the first place, @x42 .