A M/L XLR input not working well

[MrMonkey]

Greetings!

Wondering if any of you have experienced this. My DM 4800 XLR port 22 recently developed an issue where the signal from the input into the board is very low. I get maybe 5-10% of the signal showing up on the meter and in the audio output. Have any of you experienced something similar and if so how did you resolve it?
I have done all the usual troubleshooting one would think to do here; swap cable, check mic/line switch and phantom power switch at the top of the channel, check trim pot, ensure routing is correct, and even tried creating a new project to be sure.
My next step is to open the board and check internal connections. If nothing obvious is seen next step is to test with a multimeter. I fear it may require a new input circuit board but hope not.
Thanks for any input (ha ha, get it - input ) or guidance anyone can provide.

 

[snafu]

Hey MrMonkey,

I'm afraid you already did very well "first aid" to the DM there. The only little hope at the moment I could think of:
a) do you use them as raw inputs ? (i.e. mono input straight into your DAW/Tape recorder...?)
b) or is this part of a stereo channel (so maybe linked with input 21?)
c) do you listen back input 21 directly (so, signal goes into your DM and is directly transfered to your stereo sum?)

if a) maybe try and look at the settings in your DAW/tape machine or whatever --> maybe there is a seperate trim, a fx you have inserted on (maybe) a template track (sometimes one forgets about those things on templates especially), a sepereate volume trim, volume automation not related to your DM

if b) look at the panning, maybe it's not all the way L/R and then linked, or all centered. Also check for any level discrepancies that may occour from instances in your DM library (should they be active for any of your stereo links)

if c) any discrepancy here would (IMHO) point the fastest and easiest way to a problem with the input circuit. Get a signal source, set it's input to input 12 and 22 (so they are not the same group of for in the phantom power group, route them to two different tracks in your DAW. The levels should be equal. Also check TCM (meter bridge if applicable).

best of luck to you,
snafu

 

[MrMonkey]

@snafu thanks for your reply and suggestions. I was using 21-22 as a stereo pair. I did check panning, unlink/relink, etc. I have localized the problem to the xlr specifically as when I plug an instrument into the line input for 22 and move the mic/line switch to line, I get good signal on the meter bridge and the actual audio.
Your suggestion of splitting the signal across another group on the board is a good one that I didn’t think of so will add that to my toolbox for sure. Thanks for that.

 

[snafu]

You're very welcome! Glad, it worked out so far.

I have localized the problem to the xlr specifically as when I plug an instrument into the line input [...]

Just to be sure: is there a microphone connected to 21/22 or is your instrument directly connected to these channels?

If you use a microfone, it depends on your mic - and also everything along the way into your DM (so for instance: do you use another mic pre before the DM? Or do you directly inject?)
If you want to send an instrument (e.g. a guitar) to that particular channel, the same principles apply: do you direct inject (which would call for a D.I. box) or is there some sort of pre-amp in between?

Something tells me you wanted to send line level into an input that is only for mic input level? But I might be wrong :-D

 

[MrMonkey]

I appreciate your diligence @snafu - thank you.
I have been using 22 of the 24 xlr inputs for various sw synths. I take the digital out from Logic Pro into a MOTU AVB network where I convert these channels to MADI, send the MADI for ch 1-24 into a Euphonix MA703 converter (MADI in—>xlr analog out), and into the DM 4800 via xlr snake from the Euphonix.
All the channels have been set properly regarding mic/line and phantom power. It was working fine for the last ~2 years.
My multimeter died so I am ordering a new one and will open the board and see what’s going on. Stay tuned…

 

[snafu]

Ah, I really hoped it wasn't a technical malfunction - sorry to hear that.
I would be very interested in your findings, and how you (eventualy I hope) fixed them.
Good luck, mate!

 

[mixerizer]

“To eBay PCB, or not to eBay PCB?
That is the question:
whether it is nooblier in the mind
to suffer the unlinks and fade-outs of outrageous mixdowns,
to arm tracks against a signal-to-noise of troubles,
or by un-phasing, blend them?”

I’m sure you have a smart friend who has appropriately questionable judgment, vision and motor skills to help you, or at least just shake their heads while you do the scary parts.

 

[MrMonkey]

Stereo, oh stereo; where for art thou stereo…
@mixerizer I am fortunate to have friends who are indeed questionable- and I wouldn’t trade that for anything.

 

[mixerizer]

Ah, but would they?

Something tells me you r gonna fix that mic preamp fairly soon, prob when sufficiently drunk - n you’ll be back to linking and unlinking and linking and unlinking and linking and unlinking soon enough.