What's wrong with the calibration? You should be able to do a simple comparison with a trusted meter on steady tones. Maybe they are calibrated at +6dBu (the German broadcast standard of the time). Or is it the response to transients? Do you have other peak-meters you van compare with? Specs for PPM's have evolved over the years, particularly the attack time, which was originally 10ms, gradually shifted to 1ms, and now to zero (True-PPM). That makes a lot of difference in terms of what the eye perceives.Gold said:I have a set of light beam PPM meters in a Neumann SP66 mastering console. I had another set in previous MT66 which is almost the same as an SP66. I could never get them calibrated where I trusted them.
Calibrating at nominal level is the first step in the calibration process. However, adjustment of other parameters interact with it; it is often necessary to redo the initial level calibration, sometimes several times. It's a lengthy and tedious procedure.Gold said:I think the calibration problem was that if I adjusted 0% to minimum deflection and 100% to the red line then 0VU didn’t match up at +4 dBu.
I respect your opinion, but would you agree they are almost useless in a digital environment? I tend to look at them as decorative signal presence indicators.I like VU meters.
That makes sense IMO.I have an RTW plasma PPM that I like better. I’m going to use that in my main console instead of the mechanical PPM’s.
The meters are probably the most difficult in that endeavour.The light beam meters are built into the Neumann SP66. I want that restored to original condition.
abbey road d enfer said:Calibrating at nominal level is the first step in the calibration process. However, adjustment of other parameters interact with it; it is often necessary to redo the initial level calibration, sometimes several times. It's a lengthy and tedious procedure.
I respect your opinion, but would you agree they are almost useless in a digital environment? I tend to look at them as decorative signal presence indicators.
There are a few components in them that are prone to drifting; when they do, the log amp goes all over the place. Finding which is defective is sometimes uneasy. IIRC, they had to be sent back to the factory; even the french distributor was not properly equipped (competent?) to service them.Gold said:As I remember no matter what I did something didn’t seem right. It wasn’t subtle like being picky about integration time.
If you mean they are a rough indicator of how loud it will sound, I agree; that's their raison d'etre, but it's been demonstrated often enough that the perception of loudness is not a simple matter and that it takes a quite complex analysis to achieve proper measurement of perceived loudness.They are obviously useless for seeing overs but still just as useful for judging how the audio will hit a mechanical transducer like a speaker.
abbey road d enfer said:There are a few components in them that are prone to drifting; when they do, the log amp goes all over the place. Finding which is defective is sometimes uneasy. IIRC, they had to be sent back to the factory; even the french distributor was not properly equipped (competent?) to service them.
If you mean they are a rough indicator of how loud it will sound, I agree; that's their raison d'etre, but it's been demonstrated often enough that the perception of loudness is not a simple matter and that it takes a quite complex analysis to achieve proper measurement of perceived loudness.
If you mean that a VU-meter can give a useful indication of how a loudspeaker is stressed, that is far drom the reality; the mechanisms are very complex. A VU-meter may indicate roughly the electrical power delivered to the loudspeaker, that's about it.
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