VU meter question

davecg321

New member
hi all,

just a quick one. Ive tracked everything to average of about -12dbfs. However, I checked the first plugin (Waves CLA-2A) on the inserts of one of my tracks (vocals) and when I checked the input going into the compressor it's hitting around -12 to about -8 on the vu meter. I don't know much about VU meters but this doesn't equate to -12dbfs right....?

could someone please explain what going on ;/

dave
 
REAL, copper and iron VU meters have "ballistics" That is to say they take time to reach a value, overshoot it and take time to fall back.
In a 'proper' VU these things are tightly controlled. A software VU will have simulated ballistics but how much it over or under reads is in the lap of of the progging gods.

Dave.
 
You have to run calibration procedures to decipher accuracies. I wouldn't worry about digital too much as the level limitation exists, that didn't exist across hardware. Still, it doesn't hurt to have test files at different levels and wave forms to check things when doubt arises.

There may also be switches in software that change what any meter might be engineered to imitate - like RMS
 
For me, VU is fine if your used to 'em. It was easier before meters in some ways, because you had to "know", or, do the sound check. I've got a couple recorders without any level indicators and still shoot film without meters.

That mix culture that depends on metering is what it is : ) Might as well be heroin
 
my average level that I've tracked at is between -12 and -15 dbfs however the needle on the Waves CLA-2A is only hitting -12 on the VU meter. even if i add a whopping 48dbs with my pre gain trim pot it still doesnt reach 0 on the VU.

any idea whats going on?
 
There's a large element of truth in what ecc83 says about VU meters. They really are virtually useless.

Also as per ecc83, the problem with even the best VU meter is ballistics. The way the needle works simply can't keep up with short term peaks in the audio. You're fine if you're aligning a circuit to a continuous tone of known level but, for real life speech and music, you have to leave huge headroom to avoid clipping since you can't trust it to show you the peaks.

This is why, even in the analogue world, things had mainly moved to Peak Programme Meters even before digital reared its head.

It's interesting to note that the VU meter lasted longer in the USA than anywhere else. I made myself very unpopular back in the early/mid 1980s when, following numerous complaints about our New York facility, I had to pull rank and order them to install PPMs any place where audio was critical.
 
We have to assume here that you actually did flip the switch to assign that VU to show the input level, but you know sometimes the simplest things get missed. ;)
my average level that I've tracked at...
You are actually talking about "average level", not "average peak level"? I strongly suspect this to be the source of your confusion. If you're actually comparing the peak levels that your DAW is showing you to the averaged VU meters, those numbers sound about right.

...only hitting -12 on the VU meter. even if i add a whopping 48dbs with my pre gain trim pot it still doesnt reach 0 on the VU.
This freaked me out, because -12 + 48 is quite a bit more than 0! Then I actually looked at a picture of the plugin and I really don't think those knobs are labeled in db, but more like just perecent. I would expect unity gain to be somewhere around the middle, so maybe there's just no problem at all??? Is it significantly louder (to your ear) with that gain level than when the plug is bypassed?
 
my average level that I've tracked at is between -12 and -15 dbfs however the needle on the Waves CLA-2A is only hitting -12 on the VU meter. even if i add a whopping 48dbs with my pre gain trim pot it still doesnt reach 0 on the VU.

any idea whats going on?
If you are talking about the turning up the gain control on the plugin, you are just feeding the limiter more gain. The limiter is what is keeping the signal from getting very far.

Also, if you are looking at the VU meter on the CLA2A plugin, there is a switch in the upper right that changes what the meter is looking at. If you switch it to "input", you will see how much signal you are feeding it.
 
This freaked me out, because -12 + 48 is quite a bit more than 0! Then I actually looked at a picture of the plugin and I really don't think those knobs are labeled in db, but more like just perecent. I would expect unity gain to be somewhere around the middle, so maybe there's just no problem at all??? Is it significantly louder (to your ear) with that gain level than when the plug is bypassed?
The LA2A gain control isn't labeled in db. Unity gain tends to be around 9:00, but doesn't matter because the input gain acts as a threshold control. (it's fixed threshold and you have to adjust the gain to get your signal into the threshold)

If the OP has the meter set to GR, it will only be at 0db when there is no signal.

Any discussion of what real hardware VU meters do or don't do are a little pointless, since he is using a plugin emulation of CLA's personal LA2A, which may or may not be broken in some way. One of the 1176 plugins emulates his personal 1176 that he uses on vocals a lot. It is broken, but sounds awesome on vocals, so it isn't going to act like a normal 1176. I'm not sure if his LA2A is atypical, but it is a possibility.
 
Boobsy will have a much better handle on this than I but the development of the PPM was really more about quality than keeping transmitters on air AFAIK! There were and are plenty of automatic devices to do tha.
Tape machines were lined up for 3%thd* max and things got very unpleasant VERY quickly if levels exceeded that by much. The PPMs developer, the BBC was handling mainly 'classical' and dance band music, acoustic stuff that showed up distortion, especially so since the Beeb was one of the first developers of quality monitors!

The other problem with the VU meter was that any silly sod could make one. Just get an off-the-shelf 50mu amp movement, paint up a new dial, slap in a half wave Copper Oxide rectifier and Robert is your sister's kid. I well recall that the 'VU' meters on my first decent cassette recorder, a Yamaha weren't at all bad but when I built a peak LED device that lit at Dolby level that showed how crap they really were!

A PPM movement on the other hand is a very different beast and needs some pretty fancy 'tronics to drive it.

*Modern formulations and better heads and drive electronics means peeps can now probably line up to 1%thd? Still gets rough if you hit it too hard tho'but!

Dave.
 
I get the PPM thing, but we are still talking about a different game. AGC is another one of those other games, also. haha Ya, I got a 3-inch 3v VU from Radio Shack

Some of my recorders without metering were bought specifically to dirty-up the guitar MIC. Meters are pretty much immaterial

This Voice of Music, if I recall, is idler driven
3858214828_31208a1f98_o.jpg
 
Lol...if the function of your process is to "dirty up" the sound then all best are off.

My job was to keep the sound as clean as possible and have the Loudness meet specific ITU/EBU standards.
 
Boobsy will have a much better handle on this than I but the development of the PPM was really more about quality than keeping transmitters on air AFAIK! There were and are plenty of automatic devices to do tha.
Tape machines were lined up for 3%thd* max and things got very unpleasant VERY quickly if levels exceeded that by much. The PPMs developer, the BBC was handling mainly 'classical' and dance band music, acoustic stuff that showed up distortion, especially so since the Beeb was one of the first developers of quality monitors!

^^^^^'This. We had limiters on outgoing circuits and satellite uplinks, adjusted for the spec that was needed on each.

Most of the monitoring was purely to keep our audio signals as clean and consistent as possible. This included lots of incoming satellites and landlines every day, feeds from VT playback to studios and feeds from studios to record machines. Even within edit suites, (we had 16) audio levels were monitored on PPMs.
 
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