24-bit dilemma

[CStern]

I am finally upgrading to 24-bit Pro Tools (PTIII->d24). I want to do this as cheaply as possible while yielding the best possible sonics. I have a d24 card with two old farms and a 882/20. I'd like the 888/24 but I haven't the funds. I was thinking of the following manuever to get the best possible sound with a limited budget:

Since I rarely record more than two tracks at once (I was happily using a 882 and a Symetrix 620 with PTIII) I plan to get an Apogee Rosetta and hook it up to the 24-bit S/PIDF on the 882/20. That way I am getting high quality 24-bit recordings from nice converters. Outside of the
two-track-at-once-limitation, I would have to find a way to hear these 24-bit tracks since the D/A converters on the 882/20 are only 20-bit.

My thoughts are:

1) I could get a cheap 24-bit a/d to handle this.

2) I could dither to 16 bits at the master fader and could therefore monitor at 16 bits from the 882/20.

3) An Apogee PSX-100 is out of the question financially.

My questions:

1) How cheaply can I get a 24-bit d/a converter?

2) Is option two a valid option?

3) Any other ideas?

[zavijah]

I'm not speaking from vast experience here, but if I may speculate .... It might be the case that you'd have to listen real carefully to actually hear the difference between output from the 882/20 and from a 24-bit DAC -- especially a cheap one. The signal path from the DAC to your monitors, the monitors themselves, the listening environment, etc, could change the sound and add noise, etc, making it hard to tell the difference. So long as your sources are high-quality 24-bit, you might be okay just monitoring with a less-than-stellar DAC. The 882/20 truncates 24-bit words to 20 bits, I believe, so you'd be monitoring at 20 bits, which is still better than 16.

The extra depth and fidelity in the Rosetta-recorded audio should serve you well inside the computer, as you mix and process the sound. This is what's important, anyway, if you'll ultimately be dithering down to 16-bits, right? (Though I couldn't blame you for wanting to experience the happiness that is 24-bit audio... it's a _huge_ improvement over 16 bits.)

Anyway, just a thought.

[CStern]

So if I have an 882/20 24-bit files will automatically truncate to 20 bits and sound through the 882/20?

[Eric.D]

No, you would have to dither down to 20bits..

Eric

[5down1up]

your sure eric ??? i never had a problem even playing back 24 bit files through a 882/16 bit .i mean of course the 888/24 sounds totally different.but theres no need to dither the files to play them on 882/16 or 20.the d/a converters dont basically care what they get.
for example , connect a DAT 16 bit to an interface and playback 24 bit files , no big deal ... my experience

[daniel_c]

I've been using a system with a 888/24 and 2 x 882/20. Anything recorded through the 882/20's shows up as 24 bit files in Pro Tools , and 24 bit files play back fine through them.

I don't know exactly what the 882/20 does to 24 bit files but I presume that there is already some form of dithering there (depending on the resolution of the session? 16 or 24 bit?)and not just a hard truncation of bits.

Digi?

[MMazurek]

The 20 bit INS of any interface record into a 24 bit session. (you're only using the 20 bits, but you mix in 24 bits)

When you MONITOR, you're hearing 20bits on the outs, but your audio is still 24 bit in the machine.

On MIXDOWN, you usually dither to 16 bits for CD's/DAT's.

[5down1up]

it just cuts off the missing 4 bits , thats not dithering its just depends on the d/a a/d converters. imagine you´ll run a dat on the digital i/os of an interface. how should the interface ( if clock is not connected - most dats are just running internal clock via spdif or asebu )know what bit deepth the dat is able to playback ??? its not a mathematic process its just physical cuttingof the d/a-c.

[Eric.D]

The whole point on dither is to mask
quantization noise from the reduction
of the bit depth, it`s not required,
just a recommendation...

(Sorry, didn`t read the question right.)

Eric

www.peaksound.com

[music]

Does anyone know if the Motu boxes will integrate w PT? 24 bits.

Keith