I never do, as I am concerned that constant overwriting of the SD card while my MixPre is on standby will cause the card to fail prematurely. Am I wrong about this?
Hm, I never thought about card wear in this context.
I had simply assumed it just buffered to RAM and wrote the bits to the SD card when the user unpaused ......
Oh---that would be a cleverer way of implementing this, so long as they spec'd enough additional RAM for it (running out would make the machine freeze/brick until reset). You may be right---this would explain why the max pre-roll time decreases as you increase the sample rates. Strangely, one would think it would also depend hugely on the number of tracks/inputs you're recording. The write-speed would be OK assuming you can let the unit keep writing to the SD card for 2 secs after you hit the STOP button. Still, it makes me too nervous to try it unless I actually could monitor the RAM usage and make sure it was nowhere close to full.
Sony PCM-M10 flashes the card access light for a couple seconds after the STOP button is pressed.
I doubt 5 seconds of audio data would take very long to write to the card, but if it buffered the first section into RAM and was recording max tracks at max rate/depth, it might keep the RAM full the entire time?
Seems like that's an overly tight design, if that would be the case.
As for the amount of RAM, it's as much a matter of limiting the pre-roll time as it is providing enough RAM for that data.
Those two figures are very much dependent on one another, and easily calculated.
Another example: on a Behringer X32 audio console, when recording via thumb drive, the operator MUST wait until the light STOPS flashing after pressing STOP, or be forced to use data recovery techniques to get the audio!
Strangely, one would think it would also depend hugely on the number of tracks/inputs you're recording.
Not if the RAM is per track somehow