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The Alamo
 
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Default Console Channel levels vs stereo bus levels?

Hi All,

I was wondering on your approaches on stereo bus output levels (while
mixing) in order to keep those levels under control: here's the situation:

we send all tracks (separately) from PT HD to an SSL console. The stereo
mix is converted to digital with a HEDD192 and recorded in Sadie.
PT is referenced to 0VU = -18dB(FS). Most of the time, the tracks we get
(to mix) arrive at fairly hot levels (distortion guitarsliving in the -2 to
-4 dB range). So, already by sending out everything at 0 out to the SSL, the
console's meters tend to be pegged from the start.
Throw in a few dB's of compression where needed and we'll end up with a mix
that is WAY too hot (By the way, on the SSL's output 0 VU = -14dB). Not to
mention that it is also too hot for the HEDD (also calibrated for 0VU =
-14dB).
So what's to do?
1/ Lower the master fader on the console? possibly yes, but if the levels
are that hot, will the tracks not already be distorted prior to their
arrival at the quad bus? or at the quad bus input?

2/ Lower the output levels in PT so that the tracks hit the console at a
lower starting level? Is that a good way to start or would you rather
recalibrate PT so that for instance 0VU=-14dB (and thus reducing the
headroom by 4 dB??)

3/ Bring down the individual faders by x dB? Yes but this is not an option
when you're halfway a mix as it changes levels to sends, submaster inserts
etc...

4/ Recalibrate the HEDD? 0VU=-16dB is the most you can get (I believe) but
then that would still not solve the problem if the quad bus is overloading??


How do you folks deal with this? How's the headroom and calibration thing
affecting you?

Thanks & All The Best,

R.

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Gordon Rice
 
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hey there--

I've spent a fair amount of time doing exactly the same thing you are.
In my experience, setting the PT outputs to -18 nearly always results
in console overload at the input. -15 makes a bit more sense in
general; with older SSL's I've sometimes had to go all the way to 0VU=
-12dBFS to avoid having channels break up on me before I've even done
anything. This will also enable you to run more faders closer to
unity, where their resolution is greatest.

By the way, lowering those outputs doesn't reduce your headroom at the
console--at mix, it just avoids overload at the input. At the same
time, in my experience it's hard to get enough output from most analog
consoles to drive digital systems to 0dBFS without distortion when 0VU
is set to -18dBFS.

Hope this helps,

Gordon Rice

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Jeff Chestek
 
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In article ,
The Alamo wrote:

Hi All,

I was wondering on your approaches on stereo bus output levels (while
mixing) in order to keep those levels under control: here's the situation:

we send all tracks (separately) from PT HD to an SSL console. The stereo
mix is converted to digital with a HEDD192 and recorded in Sadie.
PT is referenced to 0VU = -18dB(FS). Most of the time, the tracks we get
(to mix) arrive at fairly hot levels (distortion guitarsliving in the -2 to
-4 dB range). So, already by sending out everything at 0 out to the SSL, the
console's meters tend to be pegged from the start.


The first thing you might want to do is re-calibrate the Protools output
so that -14 dBfs = 0 VU on the SSL. (BTW, also re-calibrate the inputs
to Protools to the same standard, so that the Protools system is unity
gain input to output!)

Throw in a few dB's of compression where needed and we'll end up with a mix
that is WAY too hot (By the way, on the SSL's output 0 VU = -14dB). Not to
mention that it is also too hot for the HEDD (also calibrated for 0VU =
-14dB).
So what's to do?
1/ Lower the master fader on the console? possibly yes, but if the levels
are that hot, will the tracks not already be distorted prior to their
arrival at the quad bus? or at the quad bus input?


You need to address your gain structure when mixing....If the input
channels aren't distorting (see below) then the quad bus needn't be
distorting in front of the quad fader.

It sounds as if your setting up your levels too hot at the early stages
of the mix, and "painting yourself into a corner" with the levels. Begin
the mix with the levels lower! Then when you start adding stuff, you've
got some headroom to work with.

But if you still find the quad bus too hot, use the VCA grouping to set
up group masters, and pull the overall level feeding the quad bus down
until it's comfortable, or use the "VCA trim" control to do the same.

Be aware that when you use the "VCA trim", any effects sends returning
to large faders need to be set to "I" (independent) to make sure that
the returns levels aren't being reduced at the same time the send levels
(from the post-fader sends) are also being reduced!


2/ Lower the output levels in PT so that the tracks hit the console at a
lower starting level? Is that a good way to start or would you rather
recalibrate PT so that for instance 0VU=-14dB (and thus reducing the
headroom by 4 dB??)


It's possible that you can overload the input channels on the SSL with
your current gain structure, but the SSL input stage should be good for
at least +24 dBu, several dB hotter than the Protools rig can deliver
with your current calibration. Of course adding compression, or boost EQ
will push you into clipping, so you should reduce the levels feeding the
channel, either by recalibrating Protools as above, or by trimming the
line inputs down (makes total recall a little more time-consuming), or
by lowering the faders in Protools (probably the easiest and most
expedient method, but some claim that Protools sounds worse when the
"faders" are not at unity gain...make your own tests and choose your
poison).



3/ Bring down the individual faders by x dB? Yes but this is not an option
when you're halfway a mix as it changes levels to sends, submaster inserts
etc...


Setting up and using VCA subgroups makes changing the individual faders
unnecesary, but you would need to adjust threshold levels on any
dynamics processors that are post-fader (quad bus compression, channels
"float"ed out to groups and compressed, etc...)

And, since sends are ALMOST always post-fader, they're not a problem
(unless you're doing dynamics from an effects send)....you WANT the send
levels to drop when you drop the level of the track.

Keep in mind that a mix is a changeable thing...there's nothing wrong
with just pulling all the faders down and re-building the mix again if
it's out of control....you've already set up the EQ and effects for each
track, so it shouldn't take more than a couple of minutes to just pull
up the faders again and establish a balance of the sounds you already
got! It's a VERY useful technique sometimes....it'll help you re-focus
the mix on what's important. (sorry if I've gone off on a little tangent
here!)

The point is, if the individual channels aren't clipping, than there are
several ways to keep from clipping the mix bus.


4/ Recalibrate the HEDD? 0VU=-16dB is the most you can get (I believe) but
then that would still not solve the problem if the quad bus is overloading??


You might want to do that too. Remember that the quad bus output is
capable of delivering more level without clipping than the HEDD is
likely to be able to accept. If you've got good levels at the HEDD when
the master fader is all the way up at unity, then it's very unlikely
you're distorting pre-fader (unless you've got some wacky stuff going on
in the quad insert). Mix to the level you need to see at the HEDD and
ignore (to a point) the meters on the console. At 0 VU = -16dBfs, you
will probably end up with the console meters pretty hot!


How do you folks deal with this? How's the headroom and calibration thing
affecting you?


The SSL rooms I work are calibrated to 0 VU = -16 dBfs (I'm considering
re-calibrating to -14), so quite often with tracks that are recorded in
all-digital rooms with levels approaching (and often crashing into!)
0dBfs, I usually end up pulling some of the "faders" in Protools down
5-8 dB if for no other reason than to keep the meters in the console
from banging all day long and annoying me! (I mix pretty quietly)

And I use subgroups and the VCA trim to get the final bus level where I
want it once I've got the mix together....experience helps me get close
to the ballpark but you always need to tweak up or down a little just
before printing the mix.

Jeff C.

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