Calibrate VU meter in Reaper

Calibrate VU meter in Reaper

After watching the mastering tutorial Feaker suggested, I did a little pseudo master on one of my old tracks. I was trying to get to about -10 dB or so on the JS VU meter included in Reaper using a soft clipping limiter. The meter is showing levels that are quite different from the meter on the mix bus. Is it possible to get the two meters close, or which one should I be trusting as I crusade into the loudness war? The VU meter is the last plug in the fox chain, and is reading changes to the limiter, but it’s off by a good amount from the mix buss meter.

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Hey Bob, I’m going on memory but I think a good rule of thumb may be that that 0dB VU = -18dBFS (full scale, digital). I believe the reason is that a VU meter is measuring RMS to a degree, not peak. So you probably want a Peak meter too. You may find that VU (translating the values to -18 lower on dBFS) is a similar range to RMS and to LUFS or other loudness quantifiers - just my loose analogy.

You may be able to calibrate a VU meter the way you want, though the Reaper JS plugin might not have that. (?) Good post, it reminds me to work with VU meters some more. I got so used to digital I don’t pay much attention to them unless they’re built into a plugin interface.


Thanks for your input, Stan. The VU meter has the sweeping needle, but it also has a digital RMS readout, along with a digital peak readout.
The readout on the mix buss is just a vertical display in dB with a peak hold. When I’m seeing a fairly steady -8dB on the mix buss, with peaks at about -4dB, I’m getting -12 and -7 on the VU meter.
If I push it a touch harder it goes south fast. The difference in loudness and eq is substantial with the FX chain bypassed, and I would generally trust what I’m hearing over either of the meters, but it would be great to verify it numerically, if that makes any sense.
I could probably take a track Andrew has done for me as a reference point on the VU and just shoot for that.


So it’s the “JS: VU Meter (Summed)” you’re using? Have you tried playing with the Response and Release settings? I don’t know if that would help, but it’s the only type of calibration on that one I can see.

As I understand it, meters vary a lot in how they read out and respond. Even the standard digital meters from one DAW to another, even in loudness meters that are supposed to be measuring the same standard. It’s probably better to pick one that works for you and stick with that. If you cross-check, just make sure you’re not getting “overs” and other indicators of problems. Two different meters may never correlate, unless there is considerable effort (and parameters) put into calibration.

It may be confusing trying to combine a moving VU needle, a digital RMS readout, and a digital Peak readout … plus trying to correlate that with another meter. The VU meter (needle) is supposed to measure “energy”, and may be more responsive to low end material and energy.


I found I liked it better if I set Response to 300ms, which might be more similar to a traditional VU meter setting, and set Release to 1.5. The Release setting isn’t ‘ms’, I don’t know what the numbers mean, but it seems to work opposite in terms of slow/fast. Anyway, with those settings I was hitting about -12 RMS and -0.5 max Peak on the material I referenced - the VU meter digital readouts and my Reaper master meter correlated pretty close - and the VU needle was hitting just about -1 max and went no lower than about -6 during quieter moments.

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