configuring an old MIX plus system... calibration issues

[mertmo]

Hi everyone!

Don't come around here much, but I'm hoping someone here might have some
info for me.

I've recently put together an old MIX plus rig. A friend of mine had it running
years ago on an old macbook and a Magma chassis. I have rebuilt this rig into
my Dell Dimension 4550 desktop. Not the ultimate computer I realize, but
it's on the approved list and all the details check out.

Here's the parts in the rig:

Mix core
Mix farm
latest revision of PT TDM 6.4.1, downloaded from the website
(4) 888/24 interfaces
(1) USD universal slave driver
(1) 24 bit ADAT bridge
all the necessary cabling including the Y cables

I'm skipping the ADAT bridge for now, I am currently trying the configure
this system to use all 4 888/24's for a 32 I/O rig.

I have managed to get all this up and running so far! Pretty exciting as I'm
used to LE for the most part. I have an old Carvin MX-1688 console that I'm
tying into this rig for now. Bigger and better console to come later, but for
now the Carvin works fine and sounds crunchy and fun at least...

So: The I/O on all 4 interfaces works. Cool. The USD is working as the
master clock, although I can't find the "USD setup" window, but I don't need
it's fancy features yet, just want it as the master clock so I'm good there
for now.

My issues are with calibration. I have read through the official method,
using the "calibration mode" in the software etc. It makes my brain melt
a little bit. I chose, for now, to just work out my own ghetto method so
that the interfaces match up to my console and all is happy. I will
eventually learn the more official method, but ghetto is fine for me right
now. I don't have visiting engineers, just me and my MIX rig experiment.
All that really matters is that my rig is calibrated with itself.

So between using an external signal generator to calibrate the inputs for
my mic preamps, and using a signal generator plugin to calibrate the outputs
that go to the console, I have a method that has worked so far.

BUT: I have noticed that the output levels of the converters are not what
they should be. Meaning: All the internal jumpers are set for +4, but I am
actually getting a -10 output level I think. I used my 003 as a reference
point, playing 8 tracks of an identical session copy simultaneously as I was
playing the original session from the MIX rig. Same 8 tracks, side by side,
but the 003 version is *way* louder coming into the console than the MIX
rig version. I have to turn the software faders up about 10db past zero for
the levels to match what's coming out of the 003. And I have the 888/24's
levels calibrated up as high as they will go, via the little calibration screws.

I don't understand this at all. Also, to make things much weirder, the
following two things have happened:
1) the output levels of 4 channels of my second 888 keep changing on their own!
One day they match the others, then the next day they are blasting loud
(like they should be, being set to +4 internally etc.). They are going back
and forth on their own, and I now have to check the calibration and adjust
each time I power the rig up!

2) Today, I found the second Y cable, enabling me to try out the 4th 888.
came online no problem, but when I wired it to the console so I could listen
and verify, I noticed that both it AND the first 888's output levels were
suddenly loud, like they should be. Like the 003... Both 888's were driving
my console correctly all the sudden! I didn't even power the computer
down, just quit the software, added the new interface, restarted the software etc.

Then, powered the rig down, added the USD, powered back up and both
888 #1 and 888 #2 have changed again, now their output levels are both
back to being very quiet. I didn't touch anything, they changed by themselves!!

WOW, this makes my brain hurt. Why would my interfaces be all over the
place, intermittently changing their own output levels like that?

I couldn't find anything on the web where this was discussed, so I thought
I'd start a thread.

Super stoked about this rig in general, as I can most likely buy it from the
original owner for a song...

But man, this is a strange glitch that could be a dealbreaker if unsolved...

Anyone experience this before? Help!

[mertmo]

figured this out, it's a software glitch.

It has to do with the playback engine settings, whether or not they are set
to 32 voices per DSP or 64. Apparently some systems can behave strangely
in regards to both internal bussing and external analog levels.

I had it set to 64. Switched it to 32 and my levels were all louder, like they
should be. Switched it back to 64 and they stayed loud.

Don't know if I have to leave it one way or another in the long run, but at
least now I know what the source of the problem is...

[Filmusic]

thanks!