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Old 20th June 2020
Here for the gear

SSL MX Converter - Higher noise floor than expected

Hi all, I recently purchased an SSL MX16-4 to replace my aging MOTU HD192's and I noticed a noise floor difference right away that surprised me. Essentially, the noise floor on the MX is 20-30db hotter than the old MOTU.

The old setup consisted of two HD192's connected to my machine via the PCIe-424 card. In my DAW, any armed/open channel showed around -100dbFS when nothing was connected to the HD192 input.

I now have one MX16-4 connected over MADI to an RME HDSPe MADI card. With this setup an open/armed channel in my DAW shows anywhere from -95dbFS to -70dbFs in the worst case. Two of the channels even show low level activity (as much as -60dbFS at times) when nothing is connected to the inputs! I've confirmed this low level activity is white noise and crackling. I've tried every clocking configuration available and always get the same results. I do always get a solid clock sync according to the Hammerfall driver. I've also played with the level setting on the MX, it is currently at -24db which should give me the lowest noise floor.

Wondering if anyone else with experience using the SSL MX series and/or RME HDSPe MADI may be able to provide info on their noise floor so I could determine if there's an issue with my new setup.

This audio file is a recording of each channel in sequence, boosted so you can hear the noise the offending channels are making:
Attached Files

SSL_MX16-4.wav (3.81 MB, 46 views)