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More Headroom?
Old 16th July 2005
  #1
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More Headroom?

Hey guys once again,

Just moving to OSX-Pro Tools 6.4.1 in Mix Plus. I've noticed a few other things other than OSX being slower than OS9.
When I pulled up one of my old sessions and it asked me if I wanted to use +12db or +6db. I was told that I should always pick +6db as +12db is really for Post people not for recording and mixing audio.
I also noticed that the overall level gets much lower when picking +12db. It seems lower on +6db as well but not as much.
Am I tripping or what?
I'm using a Mix plus with an 888/24 & PSX100 converter. Is there any advantage in using the 6.4.1cs3 other than the little extra shortcuts? Does this version have the more headroom mixer that suppose to be 48bit or is that just Pro Tools HD?

Thanx
M2E
Old 17th July 2005
  #2
Um... it wouldn't be, perchance, 6 dB and 12 dB lower, would it?

(Assuming here that the baseline is 0 dB, of course. I'm not a PT person, so I could be grasping at virtual straws here...)
Old 18th July 2005
  #3
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pro tools 6.4 allows for +12db faders, nothing huge, the only drawback comes if you want to run the session on an older version of pro tools that doesnt allow +12, any faders, including any automation will stop at +6db

pro tools runs a very different mix engine so the baseline isnt 0 as such. i dont know alot about mix systems but with HD there is a 48bit fixed point mix engine, the top 8 bits provide for extra headroom 24bits of actual audio and then the lower 16bits for an extreamly low noise floor and huge dynamic range, it may be possible there is some difference here that results in your different levels but it doesnt seem logical. the mix engine is run in the TDM hardware so the software shouldnt affect it.

have u posted on the DUC? its the best place for anything pro tools related

6.4 has more features, check the digi website fro details

are you sure you havnt just turned down the level on your monitors or a master fader
Old 18th July 2005
  #4
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Nope-Haven't moved anything, fader, master fader, nothin. It does seem like when you change a session from +6 to +12 that its 6db lower in volume.
Does anyone own a mix plus and a HD and can see if the stereo mix is different or is it the same? There does seem to be a sound dfference in osx then os9. I don''t know if my mind is playing tricks on me or what.

Thanx
M2E
Old 18th July 2005
  #5
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Digital has no headroom...you're dead when you hit overs. This is yet another reason why digital sound quality is so inferior when compared to great analogue.
Old 18th July 2005
  #6
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??? Whaat???

By recording at -20 dB FS, 20dB headroom is exactly what you have..
Old 18th July 2005
  #7
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Quote:
Originally Posted by theblue1
Um... it wouldn't be, perchance, 6 dB and 12 dB lower, would it?

(Assuming here that the baseline is 0 dB, of course. I'm not a PT person, so I could be grasping at virtual straws here...)
0dB is always the baseline - since dB is a ratio value.

..pedantic head

and yea!! - of course digital has headroom, otherwise everything would be a solid square wave.
Old 18th July 2005
  #8
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No, Digital has *NO* Headroom. Nadda. Zero. End of story. Period.

There's a huge thread on Digital's having "No Headroom" over on George Massenburg's Forum, go there and do a search, you'll learn that Digital has "Zero" Headroom and why people hate this fact.
Old 18th July 2005
  #9
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Quote:
Originally Posted by Johnny B
No, Digital has *NO* Headroom. Nadda. Zero. End of story. Period.

There's a huge thread on Digital's having "No Headroom" over on George Massenburg's Forum, go there and do a search, you'll learn that Digital has "Zero" Headroom and why people hate this fact.
A link would be easier. I dont seem to be able to find the discussion you're on about.

Old 18th July 2005
  #10
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Quote:
Originally Posted by mogWai
A link would be easier. I dont seem to be able to find the discussion you're on about.

Do a search for "Paul Frindel," he had a lot to say about Digital's "Zero" headroom.
Old 18th July 2005
  #11
well in logic you can drive channels into reds and they wont clip because the resolution is 32 bit i think. but if you run the master channel red then you will get clipping

analog gain stages behave differently - instead of performing linearly until zero and then clipping hard, you can overdrive them and the sound can still remain pleasant

there have been attempts to reproduce this digitally, with soft saturation algorithms but none of the ones ive heard sound like the real deal

tanh (hyperbolic tangent) waveshaping gets close to transistor overdrive
Old 18th July 2005
  #12
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Quote:
Originally Posted by Johnny B
No, Digital has *NO* Headroom. Nadda. Zero. End of story. Period.

.
Right defination or not, by recording at lower levels, you get great dynamic
range with digital. End of story. Period.

Even if you haven't got the 0 Fs ceiling in the analog domain, you certainly
hit a limit when all sound ****.
Old 18th July 2005
  #13
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Headroom. Hmmmm...
Old 19th July 2005
  #14
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Exclamation

Quote:
Originally Posted by max cooper
Headroom. Hmmmm...
LOL!
heh
Back on track, are you using v6.4.1cs3? I've heard that changing (toggling) the playback engine may resolve this problem. I maintain serveral systems and have not been plagued by this.
Old 19th July 2005
  #15
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Quote:
Originally Posted by mogWai
0dB is always the baseline
on the converter yes but not within protools, the master fader selects the relitive zero to go to the converter, the bus can be run way over 0 (i forget the exact value)
Quote:
and yea!! - of course digital has headroom, otherwise everything would be a solid square wave.
impossible for a converter to go above 0 therefor there is no headroom, winding the gain back essentially gives you headroom while tracking but the reference point is still zero you cant just say your reference point is -20 even if that is you peak
Old 19th July 2005
  #16
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Ah! Well that explains things a bit better. I don't use Pro Tools. Thanks for putting me straight
Old 19th July 2005
  #17
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Quote:
Originally Posted by aussie_techie
..impossible for a converter to go above 0 therefor there is no headroom, winding the gain back essentially gives you headroom while tracking but the reference point is still zero you cant just say your reference point is -20 even if that is you peak
Who says you can't?
I've delivered -12dB Fs ( my 0 dB VU at that point) mixes to ME's, and let them take it
from there. Just like an analog studio would..


ruudman
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