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and 10 dB higher than the reference level. The usefulness of the VU meter comes from the fact that for most types of audio sources the system engineer can count on these peaks being within this range and can design the audio system with confidence. Good engineering practice is to always build in a little extra "headroom", as it is called, to cover the strange conditions where an audio signal might exceed normal peak levels or the equipment operator fails to adjust the levels correctly. Typically the levels considered when designing systems using a VU meter are:
359:
149:. 0 VU is often referred to as "0 dB". The meter was designed not to measure the signal, but to let users aim the signal level to a target level of 0 VU (sometimes labelled 100%), so it is not important that the device is non-linear and imprecise for low levels. In effect, the scale ranges from −20 VU to +3 VU, with −3 VU right in the middle (half the power of 0 VU). Purely electronic devices may emulate the response of the needle; they are VU-meters in as much as they respect the standard.
240:
313:
296:, however, it served its purpose as an indication a) of the overall level and dynamics of the signal and b) of the proximity to the maximum admitted level, to the operators of recording and broadcasting equipment. Maintenance staff could also use it as a measurement apparatus, to check for losses in transmissions and level alignment, provided that they used exclusively sine waves as test signals.
89:
20:
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When using a VU meter, the audio system is calibrated with a sine wave tone at a "reference level" for the system. At the reference level, the VU meter shows "0" for a sine-wave tone, but the engineer must know that, with music or speech, to always infer that peak levels are always between 6 dB
172:
measure peaks, but simply inferred them. A real VU meter has a very specific "ballistic characteristic". This means that it responds to changing audio signals at a very precise speed, rising from no signal to 99% of "0 VU" when a 1 kHz sine wave tone is applied for 300 milliseconds.
229:
Note: The reference above is generally true now and was always true in the recording industry. However in some North
American broadcast installations up until late in the 20th century, the Reference level ("0VU") was +8dBm at large studio installations and some used 150 ohm impedance throughout the
354:
Academic research has shown that an SVI or VU meter behaves differently to the average value and RMS meters. The ballistics shown by this instrument, in response to signals with a large crest factor, position its readings halfway between both. For example, an increment of 3 dB in the crest
291:
of the part of the signal with more than approximately 0.4 V instantaneously because of the two copper-oxide rectifiers always in series, which transfer function curve has a knee around 0.2 V. Signals generally do not have a sinusoidal waveform by far, even if they all fall within the VU-meter
127:
meters. For this reason many audio practitioners prefer the VU meter to its alternatives, though the meter indication does not reflect some of the key features of the signal, most notably its peak level, which in many cases, must not pass a defined limit.
230:
studio.(CFRB Toronto and CFPL London Canada) This was yet another "standard" established in the early years of audio and the VU meter was altered by changing the series resistors to adjust its sensitivity. This had no effect on the ballistics.
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bandpass. The reading is the average of the voltage, and is not an indication of the power of the signal, which is proportional to the average of the square of the voltage, or the root-mean-square (RMS) value. As a conventional
775:
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Since a VU meter is a mechanical device, it can never reflect the instantaneous signal peaks of complex audio signals. The designers of the VU meter therefore took a different approach. They created a meter that did
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that the specification mentions only sinusoid waveforms. Given the electromechanical principle of the meter, the deviation of the needle is actually approximately proportional to the
259:, defined as the time it takes for the needle to reach 99% of the distance to 0 VU when the VU-meter is submitted to a signal that steps from 0 to a level that reads 0 VU, is 300 ms.
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281:. The reading should not depart from the reading at 1000 Hz by more than 0.2 dB from 35 Hz to 10 kHz or more than 0.5 dB between 25 Hz and 16 kHz.
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was standardized, in 2009 in the United States by the ATSC A/85, in 2010 in Europe by the EBU R-128, in 2011 in Japan by the TR-B32, and in 2010 in
Australia by the OP-59.
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The VU meter and its attenuator should present a 7,500-ohm impedance to the circuit it is applied to, measured with a sinusoid signal that sets the indicator to 0 dB.
222:“The reading of the volume indicator shall be 0 VU when it is connected to an AC voltage equal to 1.228 Volts RMS across a 600 ohm resistance (equal to +4 ) at 1000
205:
85:
Consumer audio equipment often features VU meters, both for utility purposes (e.g. in recording equipment) and for aesthetics (in playback devices).
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factor of an audio signal gives approximately a fall of −3 dB in a RMS meter, −6 dB in an average meter, and −4 dB in a VU meter.
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336:-filled, planar dual displays with up to 201 segments per stereo channel were popular among broadcasters as fast bar graph VU meters.
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The original designers of the VU meter were tasked with finding a way to measure complex audio signals with a simple technology.
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of 300 ms. This has the effect of averaging out peaks and troughs of short duration, and reflects the perceived
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then standardized it in 1942 (ANSI C16.5-1942) for use in telephone installation and radio broadcast stations.
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mounted within the meter case. The mass of the needle causes a relatively slow response, which in effect
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The
Bewildering Wilderness - "Navigating the complicated and frustrating world of audio standards"
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347:
BBC sound engineers would refer to the VU meter as the "Virtually
Useless" meter, preferring the
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753:
676:"On audio equipment, sound level meters are sometimes called VU meters. What does VU stand for?"
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The consumer audio industry often uses volume indicators that do not comply with any standard.
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The response of a VU meter (black line) compared to instantaneous input level (grey area) of a
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Clip level (6 dB above standard output level, "headroom" to allow for unusual conditions)
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Schmid, Hans (March 1977). "Audio
Program Level, The VU Meter, and The Peak Program Meter".
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Schmid, Hans (January 1976). "Audio, The
Stepchild of Television Broadcasting".
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The original VU meter is a passive electromechanical device, namely a 200 μA DC
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Source: the author worked on these systems and with the designers in the 1970s
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of the material more closely than the more modern and initially more expensive
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452:"Some Questions and Answers on the Standard Volume Indicator ("vu meter")"
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The VU-meter was originally developed in 1939 by the combined effort of
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Standard output level (10 dB above reference, typical peak levels);
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Reference level (typically +4 dBu, valid with tones only);
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Software to Design & Print Custom VU Meter Panels
434:"A New Standard Volume Indicator and Reference Level"
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The fall time is the same as the rise time, 300 ms.
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A New
Standard Volume Indicator and Reference Level
64:
A New
Standard Volume Indicator and Reference Level
739:Q What’s the difference between PPM and VU meters?
610:"What's the difference between PPM and VU meters?"
697:Method to Evaluate the Ballistics of Audio Meters
47:) is a device displaying a representation of the
713:AES Pro Audio Reference definition for VU meter
215:
785:Electrical and electronic measuring equipment
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626:Plasma Panel Displays - Dual Linear Bar Graph
58:The original design was proposed in the 1940
8:
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762:
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277:The level specification is meant at 1000
196:The behaviour of VU meters is defined in
637:, Columbus, Nebraska, USA. November 2000
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450:McKnight, John. G. (Jay) (2006-07-27).
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362:Another miniature magnetoelectric meter
749:VU Meter dBu & dBv Reference Chart
16:Audio signal level measurement device
7:
678:. Guardian News and Media Ltd. 2011
14:
537:IEEE Transactions on Broadcasting
109:full-wave copper-oxide rectifier
23:An analog VU meter with peak LED
720:by Chinn, Gannett & Morris
131:0 VU is equal to +4
115:or smooths the signal, with a
1:
80:Acoustical Society of America
981:Arbitrary waveform generator
884:Transformer ratio arm bridge
608:Robjohns, Hugh (July 2013).
1027:Sound production technology
152:In the broadcast industry,
76:Bell Telephone Laboratories
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266:must be within 1 to 1.5%.
66:, written by experts from
986:Digital pattern generator
879:Time-to-digital converter
874:Time-domain reflectometer
459:Audio Engineering Society
41:standard volume indicator
597:Average Voltage Tutorial
192:Standard characteristics
545:10.1109/TBC.1977.266233
473:"VU Meters Information"
316:Neon bar graph VU meter
1006:Video-signal generator
363:
317:
252:
251:and time is in seconds
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24:
1032:Measuring instruments
834:Microwave power meter
361:
315:
242:
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22:
859:Peak programme meter
539:. BC-23 (1): 22–26.
413:Peak programme meter
332:. In the 1970s–80s,
388:Loudness monitoring
154:loudness monitoring
991:Function generator
729:Audio Level Meters
699:– Victor M. Acuña.
661:2015-04-02 at the
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340:Other level meters
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273:Frequency response
253:
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25:
1014:
1013:
950:Spectrum analyzer
889:Transistor tester
819:Frequency counter
814:Electricity meter
804:Capacitance meter
612:. Sound on Sound.
566:volume unit or VU
324:and broadcasters
224:cycles per second
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1001:Signal generator
955:Waveform monitor
935:Network analyzer
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202:British Standard
135:, or 1.228
95:VU meter graphic
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996:Sweep generator
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945:Signal analyzer
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809:Distortionmeter
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477:Engineering 360
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398:Noise pollution
373:Audio equipment
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930:Logic analyzer
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734:VU Meter Video
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707:External links
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665:– Mike Rivers.
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522:10.5594/J07600
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247:. Level is in
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93:Surround audio
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656:Meter Madness
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510:SMPTE Journal
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432:Chinn, H. A.
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403:Nominal level
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940:Oscilloscope
925:Bus analyzer
908:
824:Galvanometer
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680:. Retrieved
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639:. Retrieved
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480:. Retrieved
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378:Crest factor
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200:C16.5-1942,
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55:equipment.
49:signal level
44:
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36:
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28:
26:
960:Vectorscope
894:Tube tester
864:Psophometer
844:Megohmmeter
635:Vishay Dale
218:VU defined:
107:fed from a
29:volume unit
1021:Categories
974:Generation
965:Videoscope
854:Peak meter
839:Multimeter
482:2017-03-23
419:References
408:Peak meter
294:VU reading
208:60268-17.
113:integrates
101:d'Arsonval
904:Voltmeter
899:Wattmeter
829:LCR meter
578:Re: -dBm?
322:Bell Labs
300:Impedance
264:overshoot
257:rise time
245:drum beat
235:Rise time
117:rise time
103:movement
918:Analysis
909:VU meter
849:Ohmmeter
792:Metering
682:8 August
659:Archived
553:40700960
496:VU Meter
367:See also
121:loudness
869:Q meter
799:Ammeter
641:8 March
516:: 6–9.
383:Decibel
308:History
289:average
105:ammeter
62:paper,
551:
78:. The
74:, and
631:(PDF)
549:S2CID
455:(PDF)
437:(PDF)
137:volts
53:audio
37:meter
684:2019
643:2014
334:neon
328:and
285:Note
262:The
255:The
198:ANSI
160:Lead
147:load
541:doi
518:doi
349:PPM
330:NBC
326:CBS
226:.”
206:IEC
170:not
144:ohm
140:RMS
133:dBu
125:PPM
72:NBC
68:CBS
60:IRE
51:in
45:SVI
39:or
1023::
633:.
547:.
514:85
512:.
475:.
457:.
351:.
279:Hz
249:dB
70:,
35:)
33:VU
27:A
777:e
770:t
763:v
686:.
645:.
628:"
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461:.
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43:(
31:(
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
