Generic LED Vu meter/understanding them!

[iampoor1]

Does anyone know  of a generic LED Vu meter based on he lm3914/15/16 series of chips that is already set up for line level applications?  I know here are many, and the datasheet has quite a few, but Im confused. What is a "standard vu meter set up for? If a preamp has a maximum output of +22 is he vu meter calibrated to show 0db on a +22db output? Or is the headroom of a preamp seperate from the output? Or do most preamps have significantly more headroom than resolution on the vu meter, and the meter is displaying the actual output?

I know this is a really simple question, but Im missing something obvious!

 

[ruffrecords]

The standard for VU meters is the 0VU = +4dBu. In the distant past, some broadcasters have set it at +8dBu but these days the standard is +4dBu.

I understand you concern about peaks reaching +22dBu. The original VU standard was aimed at approximating how loud program material was not with measuring absolute levels. With a continuous sine wave, a +4dBu input will read +4dBu. However, because of the ballistics of the VU meter standard, typical short program  peaks will be under read by anything from 12 to 16dB so a +20dBu short peak might only read 0VU.

With semiconductors and LEDs being very fast, it is possible for a LED VU to read peaks rather than the rough average a true VU meter reads. However, a good LED VU will have circuit that emulates the the VU spec so it reads the same as a genuine VU meter.

Cheers

Ian