Discuss Me!! HEAT vs Sample Rates - Get the most from your system.

[Mixmaster Nate]

Hi there,

so, I've bitten the bullet, paid the money, got the 'HEAT' on.... Now, I've playing with it aaaallllll day....!!

I have pulled up a 60 track session, it's good ol' rock n roll.

- 24 Bit / 96Khz. This uses 64 Voice/4 DSP Chips for the HD Engine.
- With HEAT active, the DSP Sharing uses 5 DSP Chips. (HEAT Pre or Post only effects voice count)
- With 'Short Delay Compensation' also enabled, this uses another 6 DSP Chips.
- That leaves approx 10 DSP Chips for TDM plugs, plus any additonal requirements.

Now, disable HEAT and that frees up those 5 DSP Chips - and this 'NO HEAT' config, along with my selective outboard has been mix heaven for a few years now. However, HEAT is becoming too good to stay out in the cold and keep it turned off, effectively knocking a big hole in my processing power.

As an experiment, I've loaded the same session (exactly the same tracks/plugs etc, less audio) as a 48Khz session, and I have DSP Chips to burn.

So - what if I was to record my projects at 96Khz (because it is way better sounding) - then export the files once edited, compiled, etc etc, ready to mix as new files with a sample rate of 48Khz/Tweak Head...do a save copy as with a new sample rate.

With the 96Khz session above open, I did it. Same song, same track count, same plugins, now 48Khz (still 24 bit of course)...

I have two HD systems, both PCIe, same Lynx Aurora A/D/A. I played one group of tracks on system# 1 at 96Khz, the other on system # 2 at 48Khz, swapping between the two playing simultaneously together (#2 locking to # 1 via SYNC I/O's) to see if I could 'spot the difference'. Monitoring via my C24 and Focal Monitors. I have a very well balanced and tuned Mix Room, so the environment I've conducted this experiment in has influenced my results little, and of course the same for each.

Except in the very end of reverb tails when solo'ed, I can't hear any discernible difference. What I can't tell is if the same source was recorded at 48Khz, and played at 48Khz would it sound the same...I will never know. But down converting from 96Khz to 48Khz appears in my ears to sound the same.

Now, I don't actually know what wizardry behind the scenes is happening inside my Mac when doing the down convert, nor do I know the exact science. I do get that there is re-sampling going on.

Here's what I'd like to open up to your thoughts;

- Has anyone else tried anything similar..??
- Can you tell a difference..??
- Is this a worthy way to get more from our Pro Tools systems now that HEAT is using up processing power in previously DSP heavy sessions..??
- What is happening to my re-sampled audio when I 'save a copy as' at a lower sample rate..??

I guess there are people who are going to say to me 'if you think it sounds good, do it' but I'd like to get a discussion going to hear peoples thoughts.

Thanks!



Mac Pro 2.8Ghz Quad-Core Intel Xeon 8GB Ram
OSx 10.6.4, Pro Tool 8.1, C24
HD PCIe Accel 3, Sync I/O, HEDD 192, Lynx Aurora 16+8
Focal Twin 6Es and Focal SM8 Sub
www.mixosmosis.com
www.bridgeroadpost.com

[formfunction]

Originally Posted by Mixmaster Nate

So - what if I was to record my projects at 96Khz (because it is way better sounding)

Sounds to me like you just debunked your own theory..... ff