Logic Pro 9 Gain staging, VUMT, and meter reading

Beatlefreek

Logician
Hi all,

I have a problem with setting up my gain staging and getting levels where they should be. The situation described below was being monitored in Pre-Fader mode.

Here's what I did:

1. In first position on a test channel's plug-in section, I inserted Logic 9's Test Oscillator, selected "sine wave", and set the gain at -18db. I then sent that sine wave into a Klanghelm VUMT, which is calibrated at -18db. With the VUMT Trim set at 0.0, the sine wave comes in and the VUMT VU meter reads a steady 0db, which is what the reading should be. On the channel strip meter it reads -18db. So far, so good.

2. When I have a recorded instrument track coming in, it first hits a VUMT (with its Trim at 0.0) and the VU needle responds. The instrument (in this case, a kick), however, is only reading at about -5.0db on the VUMT VU meter. Yet, the channel strip meter reads upwards of +2.5 to +3.5, depending on the dynamics. If I bring down the VUMT Trim so that the channel strip is reading at around -18db (where it should be), the VUMT winds up being set so low that it can't possibly be working optimally. "Working optimally" should have the VUMT VU needle hovering -0db. If I then increase the Trim on the VUMT to bring the VU needle up to 0, the channel strip's meter is then way into the red, often pinned a +6.0.

My question is how do I get these meters to read where they should? It seems to me that the instrument needs to come down (actually reducing the waveform; it looks like it might be a rather hot signal), but I don't know where to find its current gain value, let alone how to adjust it. In the end, some adjustment needs to be made so that the VUMT VU is hovering around 0db and the channel strip's meter is hovering around -18db.

Tell me what I'm doing wrong and how I can get this thing right.

Thanks in advance.
 

Beatlefreek

Logician
Update:

I found the instrument Gain control in the Inspector. Ta da! I hold & drag the cursor over the Gain value and I can change that gain value, which I did. I see it goes from -30db to +30db. But I still have the same problem.

If I adjust the gain on the instrument in the Inspector, so the VUMT VU is where it should be (hovering around 0db, the "sweet spot"), the level on the channel strip is too high (well past -18db if not into to the red).

If I pay attention to getting the -18db on the channel strip right, the VUMT VU needle is barely moving.

Arggggh!
 
Upvote 0

Peter Ostry

Administrator
Staff member
I think these traditional VU emulations are not very suitable for a DAW and not at the stage where you are using it. If you want a good technical readout, an overview of fast and slow level changes and some optimization possibilities you may be happier with plugins like the Blue Cat DP Meter Pro. The image in the webpage looks huge but it shows everything, not the collapsed view for normal work.

Even the built-in Logic level meter with Peak and RMS provides better information than the analog style VU needles.
 
Upvote 0

Beatlefreek

Logician
I think these traditional VU emulations are not very suitable for a DAW and not at the stage where you are using it. If you want a good technical readout, an overview of fast and slow level changes and some optimization possibilities you may be happier with plugins like the Blue Cat DP Meter Pro. The image in the webpage looks huge but it shows everything, not the collapsed view for normal work.

Even the built-in Logic level meter with Peak and RMS provides better information than the analog style VU needles.

Thanks for your reply.

I can't see the problem being with the meter, since a sine wave @ -18db into the VUMT @ Unity holds a perfect 0.0db on the VUMT VU meter and -18.0db on the channel strip meter. So by any account, that is how it should be working. But replace that sine wave with an instrument (a sound file) set @ 0 gain with the VUMT still on Unity, and things are quite different.

Just to be clear, the drums (any given particular drum/sound file — kick, snare, hi-hat ) that I'm working with are already set @ 0 gain by default without me adjusting anything. I can of course raise or lower the gain on the sound file to get the VU closer to 0 on the VUMT. Most of the different drums coming in (with the drum/sound file already set at 0 and the VUMT at Unity) register around -2.5 to -3.0, depending on the dynamics. So there would/should be (just from looking at the VUMT) sufficient enough room to increase the VUMT Trim so the needle gets closer to 0. But before even trying that, before touching anything, if I look to the channel strip meter, its already pushing into the yellow, way above the -18db.

So the problem seems to be not with what's going into the VUMT, but how the channel strip is reacting to the sound file coming through the VUMT to the channel. Why the channel is reacting differently to an instrument as opposed to a sine wave is what I can't figure out.
 
Upvote 0

Peter Ostry

Administrator
Staff member
Why the channel is reacting differently to an instrument as opposed to a sine wave is what I can't figure out.
The channel does not react differently. If you feed a kick drum signal which peaks at -18 dB, all peak meters and the channel level (which is also a peak meter) show -18 dB peak. Same with a sine wave at -18 dB.

For a sine wave, a VU-Meter shows the same value because it gets a steady signal. But with a pulsing signal like a kick drum, the VU-Meter readout becomes time-dependent. Standard integration time for VU is 300 ms. A kick drum hit is too short for that, the VU-Meter cannot measure it accurately and shows a lower level. If you raise the level until the VU-Meter shows 0 dB, you may be happy about the VU reading but your signal is far hotter. The VU-Meter simply shows a lower level because of the integration time.

Of course you can get used to VU but most level meters in DAWs are peak or RMS for good reasons. Peak responds immediately, RMS has usually an integration time of 600 ms. A combined Peak/RMS meter is the best you can get. For slow signals look at the RMS level and for fast signals look at the peak level. In between take both into account. Logic's level meter can be set to show Peak&RMS and there are a lot of other meters available on the market, freeware and payware.

If you love the VUMT and currently use the standard version, you may consider an upgrade to VUMT deluxe. In case of your drum recordings you can switch VUMT to the 'Nordic' type. This has an integration time of 5 ms and a slow fallback. Almost a peak meter. You cannot tweak the standard version for that, because it allows only 150 ms which is still too slow for single drums.
 
Upvote 0
There is no point in the digital domain with DAW and all that to use VU Meter (that were invented 80 years ago).

Most of the Plugin emulations have more of a sentimental value than an actual practical value. There is a reason why VU also stands for "virtually useless". The exception is if you are a seasoned engineer who grew up with those tools and know how to use them.
As Peter mentioned, use a Hybrid Meter (Peak +RMS) or better learn how to use the new Loudness Meters with True Peak (available in Logic Pro X). Whatever level meter you choose, you have to keep the two things in mind what a meter is used for:

1) Measure the Signal (technical aspect)
2) Interpret the perceived loudness (musical aspect)
 
Upvote 0
Top