I'm thinking of purchasing either the Alesis HD24 or the Mackie SDR24.
This will be for archiving and playback of previously obtained 4 ch
material. Might seem like overkill, but it would be a "bridge" to my
ultimate project and would protect the material, meanwhile. Thoughts,
comments, opinions, etc appreciated. Thanks in advance. Ivan

It does seem like overkill, but if you want to get into
that big of a system eventually either of those machines
will serve you well. I use the Tascam product MX2424.
I've never used either of the units you mentioned. I came
from ADAT's and 8track 1/2 inch (tascam 38) machines.
I archived most of my material when I got the 24 track
and it worked well for that. There's so much more dynamic
range that any 24 bit machine will do well. You may find that
you start to hear things you never heard before like
microphonics and motor noise from the tape machines etc..

Did you use any dolby/dbx encoding when recording? It's
possible to transfer to digital without decoding and then
using a digital decoder which will perform with less
noise and artifact than an electronic one.

Before you copy them, you'll want to be sure that your 4
track is tuned up. In some cases, if the machine wasn't
regularly alligned or biased for the tape then you may
even want to adjust it to match each tape for optimal
results..
Are there test tones of any kind on the tape? These can
help provide a reference.

You should let us know what type of 4 track and format
and you'll get better advice. It it's 1/2 inch then all
the above applies. If it's a cassette then it's not likely
that you striped it with test tones and the adjustments
are generally fewer but there are still some. If there
aren't test tones, you can either adjust via a cal tape
or if you have really good ears you can treak it till the
actual material sounds right.

There are some sonic advantages to fewer tracks. There's
another thread about that going on right now. It can be
surprising how good those old recordings sound. Some of
the stuff I did on those 38's really sound nice. The ADAT's
on the other hand.. well.... chuckle

g'luck,
Steve