A quick glance at the specifications reveal both dBu and dBV are used. Its specifications are also representative of many mixers. Mixer SpecificationsĪ common mixer used in churches and schools is the Yamaha MG series. Hence most users switch in the 10dB attenuator on the Rode Videomic. When a sensitive or high output microphone (eg Rode Videomic) is used, it is useful to reduce the output on the microphone so as not to overload the camera input. This is about the level from a normal microphone so all will be good when a microphone is plugged in. Knowing the reference is 1 volt, and that 50dB is a ratio of 316 (see table) we can calculate the mic input is expecting 3.16 millivolts (1 divided by 316). The specifications also say “Mic input: mic sensitivity -50dB (0dB=1volt)”. So when we plug the line out from the camera into the line in of a recorder or TV, the levels match and all sounds good. This is good because this matches the standard consumer line level found in VCRs and TVs. The popular Panasonic GS500 (similar to most cameras) states that the audio output level (line) is -10dBV (316mV). The same level is used for line in on digital recorders, TVs, VCRs and cameras with line in.īelow is a table summarizing the different voltages and the relevant dBu and dBV for common line levels. That is why the tape out of a mixer is often -10dBV. The “standard” line level in consumer electronics is normally -10dBV, which is 316 millivolts or 0.316 volts. Before we look at some real world examples, we need to appreciate that 1 volt is a high level for line levels, and not commonly seen in consumer electronics. That is, if you are looking at two cameras or recorders or mixers and comparing the microphone input sensitivity, make sure both specifications are dBV, or both are dBu or dBm. 0dBm refers to 0dB also being 0.775 volts, but the power formula for decibel calculations needs to used, meaning 1dBm is close to 2dBu.ĭon’t get too bogged down in all this, just make sure you compare apples with apples.The secret is to pay close attention to the letter after dB. There are several conventional line levels that can normally be used if no other information is stated. A good specification table for a camera, amplifier, mixer or recorder will always say what voltage level they are using as 0dB. This is the $64,000 question, because there are various levels that are referred to as line level. That is, the nominal level that comes from a mixer, keyboard, camera, or DVD player etc. So what is this level? In most situations with audio, 0dB will refer to Line Level. When the measured level is neither above or below the reference level, then the difference in level is obviously zero, hence our reference level is called 0dB. It is the level that is being referred to. In simple terms, 0dB is the reference level. The stereo out of a mixer might be +4dB, meaning it is 4dB above 0dB. The line out of a mixer or DVD player might be -10dB, meaning it is 10dB lower than 0dB. The mic input on a camera or mixer might say -50dB, that would mean it is 50 dB lower than 0dB. Unless it is spelled out, that reference something is normally 0dB. A decibel reading on its own is meaningless if it isn’t referenced to something. In the first article we saw that a decibel is not a fixed unit, rather, it is a ratio between two levels.
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