pink noise

[viaspiaggia]

being the studious duc-er that i am, i strive for proper calibration, and have searched the depths of this forum for info. at the place i used to be on staff, i used all the gathered info to calibrate my room. since there were no true analog meters, i even crawled around measuring electrical signal with a signal tester to find 0vu. i know that each speaker should be -20dbfs = 0vu = 85db (except the surrounds for theatrical!) on a good old radio shack spl meter set to c - slow, and i've pored over the links in dr. sound's masterful post on the subject.

these days you can find me at several different studios around town mixing independent feature films (among other things). most of these have no system for exact calibration of the rooms to any reproducable level, though most have an spl meter laying around that i can use. importantly, most of these studios have no analog VU meters - its ALL inside protools. so there is no quick way to find a true electrical 0vu.

so the nutshell of my question is, how can i know i am generating 0vu (=-20dbfs) pink noise when setting my level?

if i set up the digi signal generator and use its pink set to -20, that's not really 0vu, right? what about the 500-2.5k band limited blue sky files (that's i've downloaded)? can i assume that the -20dbfs listed on those files is an acoustic 0vu? if neither of these is true, what's a traveling mixer to trust? or is there really no way to do a 100% proper setup without a true electrical measurement or VU meter?

PLEASE point me to another resource if that's easiest, or slap me on the head if i missed this somewhere else in a discussion here online. but i don't think this particular little part of the equation has been covered here or in any literature i have found in my bookshelf or online.

thanks!

-adam-

[dr sound]

Adam,
If I were in your shoes, I'd make a properly calibrated sound file of band limited pink using a Dorrough Meter calibrated to - 20 = O. I don't have the Volt Meter exact measurement (I think it's 1.23 or close)and use a 1K -20 ="0" tone for the Volt/RMS Meter. That is +4 or "0". Calibrate your whole sysyem and bring your digital Volt/RMS Meter and your Dorrough Meters (at least 2, it will set you back around $450ea meter) and you have a calibrated set up. That way you'll be much closer to your goal of a properly calibrated and good sounding room.Hope this makes sense.
Good Luck and Keep Busy!

[TVPostSound]

Correct Marti

-20FS = OdBu @ +4 = 1.23 Volts on my Dorrough 280C

[dr sound]

Pat,
Call me tomorrow.

[viaspiaggia]

thanks dr. i didn't even consider carrying my own meters around - great idea!!!

a few quick follow ups:

- if i carried my own meters, i just need to briefly confirm upon arriving at a new studio that a -20dbfs 1k sine tone does in fact come to 0vu. then send my custom band limited pink out the system and adjust the speaker outputs based on that.

- is there really no quick way to do this otherwise short of bringing my own meters?

thanks as always dr.

-adam-

[trakbytes]

One other thing to note, is that the "pink" noise generator in Pro Tools is not even close to being accurate in regards to frequency response. If you have the Dolby Encoder plug in, it's pink noise is much better. Then again, if you have pinc noise from a test CD, you're probably better off still.

rcm

[CCash]

Right!! Don't use the Signal Generator's pink... you'll get very bad results. It rolls off the high end a lot. If you want an accurate pink noise file, email me and I'll send it to you. If you have Spectrafoo, it can generate proper pink and create a file. Just import the file into Pro Tools, send it out either a discrete output (NOT 1-2 out) or pan it hard left or right if sending out 1-2.

What you said about checking that a 1k tone = -20dBFS/0VU should work fine, then check the control room output to individual speakers w/ the pink.

[TVPostSound]

Download and burn these to a data CD, carry the CD along with a Radio Shack SPL meter and a set of Dorrough meters!!!
Blue Sky -20 tones

[TVPostSound]

Will do!!!

[dr sound]

Adam,
What I do is cary my own 5.1 Dorrough's, a Martinsound Multimax with it's own built in Pink generator and an HD4 and Control 24. I guess all I need is a room!