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Old 03-02-2021, 03:35 AM   #6
bigjoe
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Quote:
Originally Posted by ashcat_lt View Post
I'm sorry, I do normally try to answer questions before I get all philosophical because I do know how frustrating that is. I'm kind of over "gain staging" questions, though. If it's too hot, it'll distort more than you want. If it's not hot enough, it won't distort enough. If you can't hear the difference, then it probably doesn't matter. If you want to be sure it doesn't distort, you should maybe consider using something else that you know won't.

Even (maybe especially?) in real analog, this is the way it actually works. Gain staging is about getting your signal as far out of the noise floor as possible without unwanted distortion, but frankly distortion is half the fun, so...

Turn the knobs til it sounds good.
That's absolutely on point.
Also people really get stuck on the "0VU = -18dbFS" and they get this in a messed up way, just because of the many misleading info and videos on the internet.
Fist of all VU and dbfs measure different things.
VU refers to "volume units" that are a measurement that involves electric signals measured over a period of time.
dBfs refers to the instantaneous value of a SAMPLE in a precise moment.
They are no comparable, they measures different things in different domains.
But they can relate to each other by making conventions.
VU has the 0 value as the "center" of the scale and indicate the preferred and most useful working level to achieve optimal Signal-To-Noise value while NOT pushing analog components into saturation.
Everithing Above is called "Headroom" and that's the amount of extra dynamic range over 0VU that an analog device can handle before a really bad distortion (over 0VU you begin to break into saturation usually, until becomes distortion).
For headroom and dynamic range measuring we use dBu, and 0dBu are referring to a VOLTAGE of 0.774V and since most PROFESSIONAL analog equipment are nuilt to have an optimal operating level at +4dBu (1.23V) we can say that 0VU is usually 1.23V

On the other hand, dBfs use a value of 0dB to define the MAXIMUM value a digital device can handle.
You have NO HEADROOM above 0dBfs vo it's impossible to assume that 0VU and 0dBfs can be related.

So why -18dB?
It's a "convention" (an European one made by EBU), american standard value for post is -20dbfs = 0VU (if i recall correctly)
But is not really a "rule" since there's a lot of analog devices with a lot more than 18dB of headroom (most provessional analog desks boast a 22 to 24 extra dBu of dynamic over 0dBu.

What's the conclusion?
Plugin developers for sure MUST define a certain headroom because they need to replicate the behaviour of the modeled device and because 0dBfs is a barrier that (ideally) no-one should cross (that's true for 24 and 16 bit, but that's another topic).
So they give them to you tuned following a "convention" (EBU -18dBfsRMS = 0VU) but most of the time they give you the opportunity to decide an headroom for yourself (VU and THD calibrations are there for that purpose).

It's important to understand that -18db (or any other headroom setting) should be an RMS measure, not a peak one.

Also, i own myself a copy of Focusrite Channel by Brainworks and, if you take a look to the settings, you can observe that it's default value is -10dB = 0VU...so it's tuned for louder signals.
Also the meters are (obviously) RMS, so they are slow and shows low values... you need to get used to them to read properly.

Sorry for the long post

EDIT: you can enter and alter the PPM and VU Scale by clicking the Brainworks Logo above the high shelf EQ
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