All tracks with an HD24 can be used simutaneously except when recording @96k.Then its only 12.

The HD24 is a good choice. If you want the best quality AD and DA converters, get the HD24XR.

At 44.1/48KHz, you can record 2,4,8,16,24 channels at a time, provided they are all analog or all digital (optical ADAT). On replay, you get both analog and digital at the same time. The number of channels is halved at 88.2/96kHz. Note that the non-XR version of the HD24 will only record at the higher rates from ADAT, not from analog inputs.

If you want to back up your recordings, you have several ways to go:

1) Archiving HD24 hard drives, with or without the caddies

2) Use the built-in 10Mbps eithernet port via FTP to a PC. The transfer rates are roughly 1 track in real-time, so 60 minutes of 24-track recording would take you 24 hours to backup.

3) Get the Alesis Firewire data port. This is much faster than the ethernet. You end up with a series of files that each contain one track per song. You take the drive caddy out of the HD24 to do this, so the backup operation does not tie up the HD24 for other uses.

4) Replay the songs via ADAT into a computer (real-time).

If you are mixing down in your PC, I would strongly urge you not to use analog replay through your pre-amps, but to get an ADAT input card for your PC. That way, you keep the signals in the digital domain.

Gator, you're on the right track, and you're getting some good advice here. The stand-alone 24 track machines are a great way to capture things live, sometimes even right off the same board being used for FOH. You might want to run a CDr at the same time you're tracking, just in case of problems, or to have something as a reference in case of trouble.

As you're hearing, there's always a bit of a catch; in this case importing the files via ethernet (slowwwwww) or firewire (much faster). I have the Fostex LV2424 for one of my live rigs, and afterwards I transfer the projects out via ADAT optical, 8 tracks at a time to a standard windows HD. (This can be a lot of work if it's a long 24 track evening!) Sorry to say, the Fostex uses it's own file system, so the HDs' can't be used anywhere else.

The other way around it is to go to a MAC or Windows compatible HD system (I think maybe the Mackie HDR was?), so you can swap the drive out and get right to work at your home studio.

A third way is to use an A/D converter live and go right to a laptop (or portable PC/MAC) and use a Firewire HD. I also use a Mackie ONYX 1640 (with the firewire card), going right into the computer (Sony VAIO) and out to a Western Digital HD (via firewire). When the gig is over, I simply connect the portable FW HD to my studio system and I'm off and running immediately.

The time you save by going right to a Mac or Windows-readable HD may influence your decision; its a LOT less work in the long run. Perhaps a bit more $$ up front, but much less hassle after each gig. It's a tough call, but think about how long you'll be doing this, and what your time is worth.

And don't forget to join the Yahoo HD24 discussion group, where you'll be meeting over 1200 other HD24 owners who really know how to get the most out of this unit. http://groups.yahoo.com/group/hd24

Be sure to get a UPS and a Fireport with your HD24. The Fireport lets you easily move your tracks to your PC. The UPS prevents you from accidentally losing your tracks to a power failure. Hard disk recorders in general do NOT like to have their power interrupted.

thank you very much for your replies. :)

MOTU has a 24 channel FIREWIRE interface in their product line.
it's way more powerfull than the alesis stuff!!!..all u need is a Laptop

With the Alesis, as mentioned, you do need the fire port (is that what it's called?) because it uses its own propritery file format and needs to convert. I have been using the Mackie HDR since 1999 and I love it. The removable hard drives slide out of the recorder and slide right in the computer in BWF all time stamped and ready to go. For live recordings, I often record 24 tracks at once. I reciently just got another Mackie only this time I got the SDR. In the SDR it will accept hard drives as large as 2 terrabite for each drive. I would not recommend putting too many eggs in one basket. After a live session, I bring back to the studio and mix on the analog board, or on the computer using either Tracktion or Protools
I guess I am a die hard stand-alone recorder lover