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PTHD/PTLE floating point thing?
Old 30th May 2006
  #1
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PTHD/PTLE floating point thing?

Could somebody explain in laymen's terms what exactly the difference between PTHD & PTLE is when bouncing to disc ITB on each respective system? I've been around both systems enough & I know about the obvious hardware and horsepower differences between the two but where does the 48 fixed/32 floating point factor come in to play...processing plugins?

I bounced to disc a couple of files exactly the same way in both PTHD & PTLE...panned hard, not as hard, straight up and the statistics between the two in each case were identical so the summing thing apparently is the same? or is it when plugins are used is when the differences will become apparent. I purposely didn't use plugs but I guess I'll try it with. Just askin.
Old 30th May 2006
  #2
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48 bits fixed point allows you to sum, without clipping, 128 tracks of phase aligned sinewaves peaking at +12dbFS. That should be enough headroom for anybody. The noise floor remains constant - waayy below human hearing.

32 bits floating point is basically never going to clip, although the further you abuse it, you lose some bit depth resolution. As the floating point moves, the noise floor changes too.

In practice, neither should present an audible problem, even when abused. If sensible tracking and mixing levels are maintained, I think it's a non-issue.
Old 30th May 2006
  #3
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Interesting. Hey thanks for that!
Old 30th May 2006
  #4
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mrbobb's Avatar
 

To hijack the thread real quick, would there be a benefit to starting my mix on LE, and finishing up and outputing on a HD system. Would just transfering my session over (plugins and all) result in more depth or clarity?


Thanks

Matt
Old 30th May 2006
  #5
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No - except the HD system likely would have superior D/A converters with a more stable clock, and better outboard and monitor speakers, so it would probably sound better immediately. But no audible improvement in your audio files as such.
Old 30th May 2006
  #6
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I've used both Pro Tools LE and Pro Tools HD, both were clocked to an Apogee converter and did the bounce. Sound quality wise pretty much the same.

However the Pro Tools HD tracks have plugin delay compensation which should make a difference.
Old 30th May 2006
  #7
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SORRY FOR HI-JACK OF THREAD

Quote:
Originally Posted by KiwiBurger
48 bits fixed point allows you to sum, without clipping, 128 tracks of phase aligned sinewaves peaking at +12dbFS. That should be enough headroom for anybody. The noise floor remains constant - waayy below human hearing.

32 bits floating point is basically never going to clip, although the further you abuse it, you lose some bit depth resolution. As the floating point moves, the noise floor changes too.

In practice, neither should present an audible problem, even when abused. If sensible tracking and mixing levels are maintained, I think it's a non-issue.
Right on man, thanks for sharing some good info. thumbsup

Quote:
Originally Posted by Kestral
However the Pro Tools HD tracks have plugin delay compensation which should make a difference.
Actually... it makes no difference because any good engineer will time-align any latent tracks to bring the final product, processing included, to a phase coherent state.

IMHO Automatic Delay Compensation is nice, but not essential... (well it saves time).

On the other hand, Delay Compensation due to processing and other buffers is essential in any mix (unless ur using comb filtering as an effect).

Kind Regards,
-SCott
Old 30th May 2006
  #8
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Thanks for the quick replies.

M
Old 30th May 2006
  #9
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Quote:
Originally Posted by Harley-OIART
Actually... it makes no difference because any good engineer will time-align any latent tracks to bring the final product, processing included, to a phase coherent state.
I don't know - there isn't always time for that kind of attention to details. I'm not saying that it shouldn't be done, but it's certainly overlooked more than it's dealt with. With Delay Comp. it's done for you. In any case, yes, it makes a difference when everything lines up horizontally.
Old 30th May 2006
  #10
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Quote:
Originally Posted by Kestral
However the Pro Tools HD tracks have plugin delay compensation which should make a difference.

so does my LE
Old 30th May 2006
  #11
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Quote:
Originally Posted by Kestral
I've used both Pro Tools LE and Pro Tools HD, both were clocked to an Apogee converter and did the bounce. Sound quality wise pretty much the same.

However the Pro Tools HD tracks have plugin delay compensation which should make a difference.
Manually compensating for 32-48 tracks of Pro Tools LE would drive me insane. Easier to just pick up a phone and call a friend with an HD system to do the bounce.
Old 30th May 2006
  #12
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Quote:
Originally Posted by Kiwiburger
No - except the HD system likely would have superior D/A converters with a more stable clock, and better outboard and monitor speakers, so it would probably sound better immediately. But no audible improvement in your audio files as such.


well...
you never know, I've seen some pretty impressive setups all based around an LE system
I know someone who has an oo2r with big ben, rosetta800, rosetta200, 12 channels of API pre, and 8 channels of misc. Neve clones.
monitoring through a pair of ADAM's.

my guess is there are plenty of less impressive HD systems out there.

my $.02

-jeff
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