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sabletones

Joined: 07/03/11
Posts: 165
Loc: uk

ADAT out@24 bit. recording @16 bit. any issues? new

#955783 - 27/11/11 03:43 PM

Hi. I await Yamaha response but maybe it's a generic question?

I will output x8 mic channels via ADAT @ 24 bit/44.1 from Focusrite ISA828 to Yamaha AW2400 multi track recorder set to record at 16 bit/44.1. (X4 mic's will go direct into recorder) (I need the track count so cannot set recorder to 24 bit). Will my audio be compromised? Will the recorder simply see an audio stream regardless of the differing bit rates?

It's happening in 2 days so I am keen to sort it. thanks in advance.

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Hugh Robjohns
SOS Technical Editor

Joined: 25/07/03
Posts: 18368
Loc: Worcestershire

Re: ADAT out@24 bit. recording @16 bit. any issues? [Re: sabletones]
#955834 - 27/11/11 09:48 PM

Technically, the recorder will simply lop-off the bottom eight bits of audio data coming from the converters. In theory, that means the dithering is lost and will result in quantisation distortion products -- possibly audible as increasing distortion as reverb tails die away etc.

However, in a live recording situation the chances are that the ambient noise floor will be well above the nominal -96dBFS noise floor of the 16 bit recording tracks, and that elevated noise floor will essentially act as the dithering anyway.

So technically, it's a bad thing to do. Practically, you'll probably get away with it.

hugh

--------------------
Technical Editor, Sound On Sound

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sabletones

Joined: 07/03/11
Posts: 165
Loc: uk

Re: ADAT out@24 bit. recording @16 bit. any issues? new

[Re: sabletones]
#955990 - 28/11/11 06:27 PM

Note to self: a post in 'another place' (alt.pro.audio-live) mentioned finding nothing about changing bit depth in ISA828 manual. Jogged my memory....i installed a digital card into my unit and on the bit of paper that shows how to fit (it)...is a list of various user options. 24/20/16 bit depth can be chosen by moving a jumper. I lost the paper but focusrite promptly sent me a download. nothing wasted here though...i understand dithering more than i did before. so thank you.

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