A definitive explanation: Voltage Units VU, decibels dB, dBV, dBu - How to measure your guitar rig!
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- Опубликовано: 25 авг 2024
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What do we use dB and VU in music and what do they mean?? How do I calibrate my VU meter pedals against a Soundboard reference?
The decibel is a RELATIVE unit of measure. 0 dB or 10 dB by itself does not have a meaning. Something can be 10 dB louder or 5 dB quieter than something, but it's not an ABSOLUTE scale.
0 VU = 1.228 VRMS, 1 kHz sinewave.
0 dBV = 1.000 VRMS, 1 kHz sinewave.
0 dBu = 0.775 VRMS, 1 kHz sinewave.
And there are more!
0 dBFS = dB Full-Scale = the maximum the unit can put out because a digital -to-analog converter maxed out.
0 dBc = 0 dB relative to a carrier signal.
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Great content. Really appreciate the calculations and laying it all out.
such a great video
It would be a lot easier to just create a computer program to do the following:
1. Measure the actual VU of the output device (e.g. guitar)
2. Convert the VU measurement to whatever standard power units that you want to see
3. Set or calc & display whatever offset that fits your power meter's power level range.
Nice presentation though. Well done!
Yes, switching between VU, dBV, dBu would be easy, but not changing the "range" by 20dB. You'll find that you need more than 10 bits of analog to digital conversion -- You need something like 16 bits or even more. I couldn't find any tiny microcontrollers for $1 with native 16-bit ADCs that have only like 8 pins -- You either have to go to a high-performance "computer" for something like $8-20 each with maybe 48 pins (90% of them would be unused. It's overkill), or you need an external 16-bit ADC for significant extra cost. I spent days looking and considering alternatives. But if you know of something, let me know!
VU actually means volume unit, not voltage unit. This is important because you said dBu and dBV don’t matter if you are using VUs, but in reality they matter very much since VU is associated with what you hear and dBu and dBV is what you are amplifying or otherwise modifying. But great video otherwise. All the math was good to see.
Thanks for pointing that out. Of course dBu and dBV "matter" -- it's just no one (okay maybe a few %) seems to use those. They are just arbitrary variants of each other.