Digi 192 Problem
« on: November 19, 2011, 10:44:29 AM »
Yesterday I was testing gear at home and I noticed something when I went to calibrate FuzzMeasure. My Digi192 has terrible highend response.

So being the naturally curious person I am, I wondered does this change with the sample rate (assuming higher would be better of course) and behold it did change, unfortunately for the worse. As I go up in sample rates my 192 gets worse.  To me this rules out that there is an issue in my analog domain (ie patchbay and cables) since it is sample rate dependent.

To make sure it's not just a core audio thing I repeated the test (more crudely, using signal generator and PAZ-meter) and observed the exact same behavior inside Pro Tools.

Went to my other studio tonight and did the same test and it was flat from 20-20,000 like it's supposed to. The 192s between home and the studio are about the same age, I use HD|Native at home and HD3 at the studio.

I assume this is something malfunctioning in my 192, right?

Has anyone else experienced this?

I attached the sweeps showing the issue, the best one is 44.1 and the worst is 96.

(This is cross-posted from gearslutz, I figured I'd get more intelligent responses over here)

Re: Digi 192 Problem
« Reply #1 on: November 19, 2011, 12:28:48 PM »
Update: I forgot to be thorough and test the other channels of the 192. Channels 1-4 are actually perfect! 5-6 have the frequency deficiency and 7-8 are dead (have been dead ever since I bought the unit 2nd hand). Time to take it out of the rack and investigate further.


Re: Digi 192 Problem
« Reply #2 on: November 19, 2011, 04:42:19 PM »
Can you use a scope to trace the signal path with a tone through inputs 7 or 8? maybe go straight to the opamps and check input/output signal to see that they are functioning. If you dont have a scope as a start you could check voltages across the opamps +/- pins according to their datasheet pin conifg.
is it the same as the unit in this link? (photo in 2nd post) http://www.gearslutz.com/board/geekslutz-forum/455132-digi-192-i-o-help-request-lost-analog-1-2-input.html


Re: Digi 192 Problem
« Reply #3 on: November 23, 2011, 10:23:16 AM »
Good luck scoping anything out on that board. 

This is just a hunch, but have you tried jiggling the handle...

no but seriously, the calibration pots on the back of the unit, mess with those before you start going component to component.  An older blue face we had at the studio in the city had a similar issue, turns out the pots in the back (since they;re open to the air) got really crudded up.  Some cleaning, and everything was ok...  Might wanna check that out for the 2 dead channels as well... whoever owned it before you may have killed em by messing up the pots (pushing too hard with the screwdriver)
MEI Studio - Long Island, NY: http://www.meirecords.com

Re: Digi 192 Problem
« Reply #4 on: November 23, 2011, 01:32:09 PM »
Thanks for the hints guys. I'm planning on pulling it out and investigating it over the holiday, I'll report back.

Re: Digi 192 Problem
« Reply #5 on: November 23, 2011, 02:19:20 PM »
Have you tried different DigiLink cables? 

Matt Ward

Re: Digi 192 Problem
« Reply #6 on: December 12, 2011, 11:06:49 PM »
I've seen relays fail on the 192 analogue boards a few times which can lead to varying levels and difficulty lining the things up.  I doubt this has anything to do with your problem.  The fact that you have problems with pairs of channels suggests to me something in the digital domain or converter.  It may be teaching my grandmother to sock eggs but it's always worth re-seating  the boards and connectors in misbehaving 192s.

Matt Ward


Re: Digi 192 Problem
« Reply #7 on: December 13, 2011, 11:52:08 AM »
I have to play devils advocate. any 192 problems I have ever had, have always been related to the ad or da cards. If you blew a  something on those I or O channels the unit should not power up at all.  you would here the PSU switching over and over and not turning on at all. Those pots are sh*t and could easily be broken by an assistant who uses the wrong tool or turns it up  or down to far.
Every mic has a purpose it might be a door stop or a hammer, but every mic has a purpose.

Re: Digi 192 Problem
« Reply #8 on: December 16, 2011, 08:56:47 PM »
yeah, must have its origin in the digital / converter domain. The slope looks way too smooth to be caused by anything of the analog section. That's just my piece of the cake.


Re: Digi 192 Problem
« Reply #9 on: February 27, 2012, 02:57:43 PM »
Send the unit back to AVID.   I went through a tantrum on this forum over problems that were handled by Avid once I got hold of them which can be challenging.    It was $250 or so to repair and they also fixed other channels that were working by changing the small  caps on the other channels as well.   My though is a bad lot of SMD caps were the problems.   I had white noise and channels not working and burn parts on the A to D input card.

When you call Avid your in a Que to the phone.   The trick is to push a number choice that your are checking on a item already returned to them.  This gets you to a Tech that you can explain your problem to rather than go through there avoidance internet system.    (Did this in Oct 2010 hope it still works.)

Once I talked to a tech, I had an RA number and about a week and a half to get the unit back.   Its worked great ever since.     The Cards are quite delicate and also very hard to find any schematics for.   I had a friend that worked for Digi a few years ago and high up.   He didn't even have schematics for 192's.

I would do this sooner than latter with the Avid get rid of HD policy at the present.   Its just a matter of time before they make it impossible  to fix these thing. 

Good luck.   


Re: Digi 192 Problem
« Reply #10 on: March 05, 2012, 05:37:20 PM »
I have replaced tons of diodes on the AD cards.
Why does it happen? Because it happens - Roll the bones...

Greg Norman

Re: Digi 192 Problem
« Reply #11 on: April 27, 2012, 01:26:03 AM »
We had exactly the same problem on one input of our 192s.  Not having any time to mess with it, I just sent the A/D board to Ground Control in Florida in for repair (roughly $300).  I asked them to include some tech notes.  I'll see if they did.

Hey benlindell,
What program did you use to generate that response curve?  I am looking for a decent software package that will do this without breaking the bank.

Re: Digi 192 Problem
« Reply #12 on: April 30, 2012, 09:38:27 PM »
Hey benlindell,
What program did you use to generate that response curve?  I am looking for a decent software package that will do this without breaking the bank.
It's called fuzzmeasure, great app for measuring stuff. I did a little tutorial a while ago on it, http://blog.benlindell.com/?p=112