H - Metering Flashcards
what are meters used for when tracking
to ensure input signals do not overload, and you maintain reasonable headroom
what are meters used for during mixing
provide a rough estimate of the loudness of each track, and offer a visual indication of activity when working with a large number of tracks
what are meters used for during the mastering stage
they are used to check compliance with upstream levels and loudness standards, as well as to optimise the dynamic range for a given medium
what are the two meter sub tobics
meter scale and meter ballistics
what is the meaning of meter scale
what signal level corresponds to what indication on the meters.
what is the meaning of meter ballistics
how does the meter respond to changes in level over time.
what does VU stand for
standard volume indicator, and it was designed to indicate volume and not intended to be a unit.
what is the VU meters scale and integration time
the scale reads from -20 to +3 VU
what is 0VU equivalent to
1.228 Volts RMS (+4dBu)
what is a VU meters integration time
the time it takes a VU meter to reach OVU from the bottom (-20VU) is 300 ms +/- 10 %.
the time taken to drop back down to 0VU is standardised as 300 ms
is a VU meter quick enough to respond to peaks
no,
what is a VU meters overshoot percentage
1 - 1.5 %
when calibrating analogue tape what would represent a nominal level to match the optimum level of the tape
0VU
how would you go about calibrating a mixing console
0VU corresponds to an electrical signal (+4dBu), which is calibrated with a sine wave at a level of 1.228 RMS.
what does PPM stand for
peak programme meter
what are the different variations of the PPM
DIN, BBC (UK), EBU UER, Nordic
what are the specifics of the BBC PPM scale
it has no decibel markings, and is labelled from mark 1 to mark 7.
Each mark represents a 4db change, except from 0 to 1 (6db) and 7 to 8 (2dB).
PPM 4 = 0dBu
Mark 5 = + 4dBu
what are the specifics of the BBC PPM integration time
attack time of 5 ms, according to a time constant of 1.7 ms.
some PPMs have a ‘fast option’ with an integration time of 0.1 ms.
fall back time is 1.5 seconds per 20db.
slow fall back time to avoid eye fatigue.
what are the details of the EBU PPM
it is a variant on the British PPM.
test mark = 0dBu.
calibrated differently but otherwise the same
what are the details of the DIN PPM
the 0dB marking is at the edge of the red area.
0dB on the scale corresponds to + 6 dBu, which is 1.55 volts RMS.
the scale ranges from -50 to +5
the test level is marked by a small dot at -9dB below full modulation (0dB)
what are the details of the nordic PPM
the scale ranges from -36dB to + 9dB
in 6 dB steps (apart from + 6 to + 9)
the edge of the red area lies at +6dB.
0dB is the test marking, and is equivalent to 0,775 volts RMS
how do the nordic and din PPMs compare
full modulation to the edge of the red area in both PPMS scales is attained with a voltage of 1.55 V RMS
what level are broadcast meters set to compared to studio/professional recording equipment
4dB louder
the signal reading 0dB on a vu meter is going to be roughly how much higher than on a digital meter
+ 14 dB
what are the details of a dorrough meters integration time
the peak accusation time is 10μs (microseconds) to full scale
the peak decay is 180ms from full scale to all LEDs off
0 dB = 4dBu
what do digital peak meters display
the absolute maximum signal of the raw samples in the PCM signal (for a given time)
what are digital peak meters calibrated to
0dBFS (decibels relative to full scale) or the maximum level that can be represented digitally in a given system
this value depends only on the target medium, DPMs operate on raw digital sample data which does not take inter sample peaks into account
what are digital true peak meters
it is a digital peak meter with additional pre processing , where the audio signal is up sampled (usually by a factor of 4) to take inter sample peaks into account
what is LUFS - EBU R 128
it is the EBU loudness reccomendation
what is target level is needed to comply with EBU 128
assure that the programme level of your content is normalised to a target level of -23.0 LUFS.
the permitted deviation from the target level should generally not exceed +/- 1.0 LU
what other things are needed to comply with EBU 128
the audio signal must be measured in its entirety, beginning to end without emphasis on specific elements such as voice, music or sound effects
the maximum permitted true peak level of a programme during production must not exceed -1 dBTP (dB true peak)
what new measuring units did the EBU R128 standard introduce
LU (loudness unit) and LUFS (loudness unit, referenced to full scale)
plus new measures of programme loudness, loudness range and maximum true peak level that must characterise an audio signal in broadcast
what is the EBU R128 specification for momentary loudness (M)
uses an RMS window of 400 milliseconds, therefore it shows quick fluctuations in loudness
what is the EBU R128 specification for short-term loudness (S)
works the same way, but uses a window of 3 seconds, therefore it provides more stable loudness measurments
what is the EBU R128 specification for integrated loudness (I)
shows overall loudness, hence it is affected by the whole track from beginning of the playback until you reset it by clicking on the value field
what is the EBU R128 specification for loudness range meter (LR)
shows the input loudness range. the loudness meter, LU, follows the ITU-R BS. 1770-1 and the EBU 3342 specifications, so LU (loudness units) represents -23dBFS
What do VU meters indicate?
What unit(s) of measurement do they use?
Are they fast or slow?
Slow, showing the RMS levels not the peak
uses the decibel scale but also has a second scale indicated in percentage of volume.
What does the LED light indicate on a VU meter?
it’s a peak light, that light up when a predetermined transient level is detected (usually about 6-12 dB above the actual instrument)
In a PPM (BBC) meter, what does each mark represent?
each of the markings (1-7) represent a 4 dB change
with the exception of 0-1 which is a 6dB change
and 7-8, which is a 2dB change
In a PPM (BBC) meter, which marking corresponds to 0dBu?
Mark 4
In a DIN meter, what is the value of the 0 dB marking in dBu and in Volts RMS?
+6 dBu which is 1.55 Volts RMS
In a DIN meter, where is the marking for the test level?
-9 dB
How many volts is the 0dB (test marking) on a Nordic PPM meter?
0.775 Volts RMS
How are DPMs calibrated?
to 0dBFS or the max level that can be represented digitally in a given system
What scale and unit of measurement do true-peak meters use?
dBTP (decibels relative to full scale, measured as a true-peak value instead of dBFS.
dBTP and dBFS are identical except that dBTP may be larger than zero (full-scale) to indicate peaks.
To comply with EBU R128, how loud should your normalised content be? What is the permitted deviation from the target level?
Target Level: -23.0 LUFS
permitted deviation shall generally not exceed ±1.0 LU
What do LU and LUFS stand for?
Which broadcasting body uses these as standard measuring units?
Loudness Unit
Loudness Unit, referenced to Full Scale
EBU R128 (European Broadcasting Union)
What is the EBU R 128?
The European Broadcasting Union guideline for loudness normalization and permitted maximum level of audio signals, most recently revised in 2014.
What are intersample peaks?
created as part of the digital to analogue conversion where the reconstruction of a sound wave exceeds 0dBFS to the true peak of the sound occurs between digital samples and thus gets “squared off”, creating distortion
What does PPM stand for?
Peak Program Meter
What meter is the most useful for the mastering process?
The Dorrough Loudness Meter
What does the Dorrough Loudness Meter display?
What is it’s response time like?
diplays both average and peak elvels in a single readout with a very fast response time to accurately reflect incoming transients
A “EBU Mode” meter offers which two scales, for the user to select?
EBU +9 scale and EBU +18 scale
What is the range of EBU +9 scale?
-18.0 LU to +9.0 LU (-41.0 LUFS to -14.0 LUFS)
What is the range of the EBU +18 scale?
-36.0 LU to +18.0 LU (-59.0 LUFS to -5.0 LUFS)
