20 bit Alesis ADAT to 002

[BookSix]

Hey all!

Just wondering about using an Alesis ADAT as a A/D convert to go into a 002 via Litepipe. The problem is its a 20 bit machine, and when I hooked it up, any channel that doesn't have signal going into the ADAT machine produces pops on the way out (shows up on PT, peaks the channels). First of all, does this have anything to do with the bitrate mismatch, or is it another problem we have to work out (perhaps a setting on the ADAT) and second, are we going to be degrading our audio because it's 20 bit being converted to 24 bit on the fly in Pro Tools? Thanks for the help!

[martinsbouchard]

Why use the adat for a/d conversions...

Use your ears to know if the sound as changed 20/24bit.
In theory there should be no loss on your sound.

good luck

martin

[NannerPuddin']

Book,

I do it all the time. First, make sure the clock in the Hardware setup is set to external. Sounds like you have a clocking issue with the pops. Make sure you have a 24 bit session open. There is no problem going from 20 to 24 bits.

NP

[BookSix]

External? Why external, is there a clock signal sent through litepipe? Do I need to connect Litepipe both ways between the 002 and ADAT?

And Martin, we are using them as converters because we have them and we need more than 8 tracks in. So we go through them. Rather than sell them for a fraction of their original cost and then buy a seperate converter (which is exactly when we'd need to fire up the adats again)!!

As for the bitrate conversion, I ask because in some cases, it seems that converting a lower bitrate to 24 and then back down later to disc ends up a tiny bit worse than the original in the lower bitrate. But if people are doing it with success, I'm sure we will be successful too. Thanks

[16yearsjeff]

yes the clock has to come from the adat. set it to external and your pops will go away. also it may be best for you to open the new session in 48k because PT will automatically go to 48 when the adat in connected. that way when you unplug ypur playback will be the correct speed. good luck -jeff

[terraform]

i just had a session a couple weeks ago and did the same thing. sounded really good, i would say that the converters in the adat are way better than the 001's. the 20bit thing didn't seem to matter at all. i recorded at 44.1khz/24bit.

[BookSix]

Cool, I just went to the studio to check it out. External sync did the trick. But I don't think I am going to open my sessions in 48K. I set the Adat to 44.1 and will leave it connected for the clock. Thanks everyone!

[16yearsjeff]

right, i see. i have the old blackface adats they are only 48k (as far as i know) so when i opened in 44.1 and dumped in my tracks i had to leave the adats connected for the rest of thr session. glad its working out for you-jeff

[drunton]

On the blackface ADAT you just need to "clock it down". Just from memory, so details might be off - Slow down the playback, by holding the down arrow. When you hit a certain point (around -115, I think), the display will switch to 44.1 for a fraction of a second. That is where you want to stop and the blackface will now be running at 44.1kHz.

Enjoy!