• RobH
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Topic: Octamic XTC 0dbFS noise!

Hi,

I use my octamic XTC's as remote mic preamps and control them using the midi over madi software from my PC through a Madiface XT. I was using this set up yesterday to record a number of workshops and I suddenly got 0dBFS noise down one of the mic channels and nothing would stop it - unplugging the XLR, switching phantom on and off. The only thing that stops it is to switch off the Octamic and turn it back on again, and the noise is no longer on the channel. This then happened again when I was switching the phantom on one of the channels! Again, the only way to resolve it was to switch off the Octamic and turn it on again. Any thoughts?!

Robin

2 Reply by MC

  • MC
  • MC
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  • From: Germany/Thailand
  • Registered: 2007-04-06
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Re: Octamic XTC 0dbFS noise!

Maybe instead of phantom the gain got set to maximum?

Trying to reproduce this effect requires further details (signal flow, configuration, which channel excactly...).

Regards
Matthias Carstens
RME

MC's Website

  • RobH
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Re: Octamic XTC 0dbFS noise!

Hi MC,

So the setup was

-Windows 7 PC running Pyramix 9 native DAW --> USB 3 to Madiface XT --> MADI 50m fibre (from Madi port 1) --> 2x Octamic XTC's --> 16 x Condensor Microphones.

-XTC no 1 configured to send Mics 1-8 down Madi 1-8 and XTC no 2 configured to send Mics 1-8 down Madi 9-16.
-Midi Remote 1.70 used to control gains, +48v...etc.. of XTC's.
-Autoset gain was not enabled
-Delay Comp. on XTC's was set to Auto-ID
-Madiface XT masterclock and XTC's set to clock from MADI. It was all running at 48kHz. although Madi Frame set to 96k.
-Madiface XT SW version 33 and Octamic XTC's were running SW version 25/36

The problem occurred on channels 2 and 8 of XTC no 1. The first time it happened was when plugging a microphone in to channel 8 (+48v already on) and the XTC LCD channel meter would immediately read 0dB and just stay there and there would be this horrible very very heavily distorted signal that sounded like massive digital clipping. Switching +48v on and off, changing the gain to 0 and then winding it back up would not have any effect all. The only way to get rid of it was to switch off the XTC and turn it back on again. Channel 8 would then be fine again as long as I didn't plug and unplug the microphone.
The other thing that triggered it off was switching the phantom on for the channel once the microphone was plugged in.

I hope this is helpful,

Robin

4 Reply by MC

  • MC
  • MC
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Re: Octamic XTC 0dbFS noise!

In that case I would expect the mic preamp of that channel chip to be defective.

BTW:

> The first time it happened was when plugging a microphone in to channel 8 (+48v already on)

stand in corner with hat on... fryingpan

Regards
Matthias Carstens
RME

MC's Website

  • Ulrich
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  • Registered: 2008-05-31
  • Posts: 315

Re: Octamic XTC 0dbFS noise!

I managed to create 0dB noise output from certain channels of the XTC by messing around with sample rates (double, quad). Only power-cycling did help.

  • Registered: 2014-05-02
  • Posts: 3

Re: Octamic XTC 0dbFS noise!

I'm having this exact issue with my unit. The warrantly is already gone and noticed this bug way too late.

My setup is:
RME UFX -> MIDI -> RME XTC.

1. Add mic to XTC's mic input
2. Set phantom ON (this will make the meters go wild as they pop up and then slowly down)
3. Set gain somewhere over 25db.
4. Restart XTC
5. The XTC's meters will pop for this mic channel really early on (after phantom is initialized?). The signal clips in the meters. The signal starts overflowing in red and the signal keeps clipping in infinite loop. Only lowering the gain under 25db and resetting the power to XTC clears this error.

I think this problem could be bypassed with a simple software update, but I guess I need to keep fighting with the unit. I've also noticed some problems the first time I turned on the phantom powers in the unit when I got it.

Is there anything I could do?

  • mjfe87
  • mjfe87
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  • Registered: 2011-06-21
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Re: Octamic XTC 0dbFS noise!

Hello, does anyone know if this bug was fixed?

Eastwood Records
www.eastwoodrecords.co.uk

mjfe87's Website

  • Ulrich
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Re: Octamic XTC 0dbFS noise!

Haven't really cared about this since then, but there have been some firmware updates in the meantime, I would recommend to check these.