metering and reference

i57dwun4yb1pt8

still trying ot get my head round this ;

in mixing and monitoring terms as a way of thinking :

1/ if we play music approx 85 db - the fletcher munson evens out to approx flat - so we hear the full spectrum fairly flat .

2/ is this what we would term 0 db on the analog metering of a mixer ? ?

3/ i see alot of reccomendations that approx - 18dbfs = approx - 0db analog

there fore in the digi world in 24 bit - it best to aim for a -18dbfs average signal when tracking ?

is this a correct train of logic - or am I being mislead ?

how do I know my 0db on my daw is the same as everyone elses 0db - ie when it comes to supplying files to a mastering house ?

if maybe i measured a supplied - 18 dfsa pink noise at my mix spot and turned up the monitors until they registered 85 db slow c scale in volume ?

its a minefield !
i have all the books and have read the web - but everyone says differring things .

DamagedTrax

theres a few differant db scales relating to differant things but for your purposes:

db is a measurement between to differant sound levels. it makes no sense to say that something is 85db. 85db would be the differance between 1db and 86db

for actual louness you would measure in db SPL

i think...

PaulBrewer

http://www.cdc.gov/niosh/topics/noise/abouthlp/noisemeter_flash/soundmeter_flash.html

i57dwun4yb1pt8

thanks paul but im deaf already - no coming back now .

damaged - yeah I understand all the db science stuff
but there must be a way to tie all this together for the layish-man so to speak

madtheory

It's dB, not db, after Alex Bell.

I'd suggest that the reason you're confused is that you don't know what the reference levels are for each scale.

For example, in layman's terms, 0 dB SPL is a certain amount of energy of a certain size of "air" hitting your ear, and it's the quietest thing the average person can hear.

OdBFS is the point where the digital converter will flat top the input, causing nasty clipping distortion.

So dBSPL and dBFS are totally different. We only use dB so that we can fit a huge range of quantities on a small meter.

Lining up analogue and digital gets a little complicated. Put simply, +4dBu on your mic pre should be lined up with -18dBFS in your DAW, using pink noise. If I was to explain any deeper, it would get scientific. And anyway there are plenty of good sources on the web that will explain it better than I could here. Try the EBU tech docs.

PaulBrewer

madtheory wrote: »

It's dB, not db, after Alex Bell.

I'd suggest that the reason you're confused is that you don't know what the reference levels are for each scale.

For example, in layman's terms, 0 dB SPL is a certain amount of energy of a certain size of "air" hitting your ear, and it's the quietest thing the average person can hear.

OdBFS is the point where the digital converter will flat top the input, causing nasty clipping distortion.

So dBSPL and dBFS are totally different. We only use dB so that we can fit a huge range of quantities on a small meter.

Lining up analogue and digital gets a little complicated. Put simply, +4dBu on your mic pre should be lined up with -18dBFS in your DAW, using pink noise. If I was to explain any deeper, it would get scientific. And anyway there are plenty of good sources on the web that will explain it better than I could here. Try the EBU tech docs.

I think what Mad is saying is 'don't be worrying about that shyt and get on with it' ..... if he's not , I am ...

i57dwun4yb1pt8

ok,
dont worry about it and get on with it

<< last time i checked - this is what amateurs and the sloppy tend to do

ok back to the books then .

madtheory

DaDumTish wrote: »

ok,
dont worry about it and get on with it

<< last time i checked - this is what amateurs and the sloppy tend to do

ok back to the books then .

Yamaha Sound Reinforcement Handbook explains it really well.

danjokill

madtheory wrote: »

Yamaha Sound Reinforcement Handbook explains it really well.

I love this book ..... its my bedside novel!!

PaulBrewer

DaDumTish wrote: »

ok,
dont worry about it and get on with it

<< last time i checked - this is what amateurs and the sloppy tend to do

ok back to the books then .

That's what the big guys do !

Getting caught up in the minutia will only hinder - get the broad strokes right first, then deal with the details.

Or maybe you already have ?

i57dwun4yb1pt8

the big guys know what they are doing paul- thats how they got big

i feel proper calibration is not a detail- its abroad stroke of importance

madtheory

To be fair, the "big guys" usually have an electronics tech employed to do that stuff. Us mortals can't afford that, and have to use our brains to save money

i57dwun4yb1pt8

i always knew that physics degree would pay off some day .

actaully i just got the yammaha book *cough *

and its very interessting ...

dav nagle

DaDumTish wrote: »

i always knew that physics degree would pay off some day .

actaully i just got the yammaha book *cough *

and its very interessting ...

But is it as interesting as 'Road Wars' on Sky one? Now that is the real question.

danjokill

dav nagle wrote: »

But is it as interesting as 'Road Wars' on Sky one? Now that is the real question.

better :-)

PaulBrewer

DaDumTish wrote: »

the big guys know what they are doing paul- thats how they got big

i feel proper calibration is not a detail- its abroad stroke of importance

You know best Chief ....

i57dwun4yb1pt8

i love road wars ,
love seeing those hash addled techno knackbags with the huge exhausts getting nailed by the man

PaulBrewer

DaDumTish wrote: »

i love road wars ,
love seeing those hash addled techno knackbags with the huge exhausts getting nailed by the man

What's 'Road Wars' ? How does it relate to this thread?

iquinn

somewhat related....I've analog outboard set up as inserts in my DAW, I set them up so -14dbFS corresponds to 0 on the VU, which is what madtheory is saying about -18dbFS and +4dBu, but instead I'm using -14dbFS.

I just found -18dbFS was more prone to occasionally clipping my converters or overloading the analog stage.
Obviously you can control the gain in the DAW and send whatever level you want, but using -14 to calibrate seems to work better for me.

PaulBrewer

It depends on the gear doesn't it ? -20 is another O too.

iquinn

PaulBrewer wrote: »

It depends on the gear doesn't it ? -20 is another O too.

for sure. It's mostly just to match sides on a stereo piece of gear and to be on the safe side of overloading the analog stage....but of course you might want that sound.....and so on...

i57dwun4yb1pt8

dav nagle wrote: »

But is it as interesting as 'Road Wars' on Sky one? Now that is the real question.

there you go Paul

madtheory

Hi iquinn, it might be that on your gear OVU is not +4dBu. The standard varies. Hugh Robjohns explained it clearly to me here recently:
http://www.soundonsound.com/forum/showflat.php?Cat=&Number=804770&page=0&view=collapsed&sb=5&o=&fpart=1#804770

But I don't understand why -18dBFS gives you clipping while -14dBFS does not, given that -14dBFS is a higher level. Have I missed something?

iquinn

madtheory wrote: »

Hi iquinn, it might be that on your gear OVU is not +4dBu. The standard varies. Hugh Robjohns explained it clearly to me here recently:
http://www.soundonsound.com/forum/showflat.php?Cat=&Number=804770&page=0&view=collapsed&sb=5&o=&fpart=1#804770

But I don't understand why -18dBFS gives you clipping while -14dBFS does not, given that -14dBFS is a higher level. Have I missed something?

thanks Tomás.
yes I want to set a higher level going in.

But really it could be set at anything and tweaked, I just want some sort of reference for aligning channels.
-14dBFS in my situation works best for me.

I think brad blackwoods post near the bottom explains it better:
http://recforums.prosoundweb.com/index.php/mv/msg/19350/0/0/18871/

madtheory

I think I get it- it's your analogue gear that's clipping, not the ADC?

iquinn

correct.

(but also A-D would sometimes clip using -18dbfs, as some of my analog gear doesn't have output attenuation.)

i57dwun4yb1pt8

ok,

1/ i got the free PSP vintage VU meters plugin - very handy
2/ set up the meters to read 0vu as -14dbfs - lots of people reckon this is a good point to set it.

3/ used a -14dfs sign wave to check it all

then I used an spl meter to set the speakers using sine and pink noise for 82 db combined at mix spot .


seems alot better now .


thanks for the tips