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TOPIC: C-DSP 8x12 ground loop

C-DSP 8x12 ground loop 1 month 1 week ago #45579

  • vwman01
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Hi guys, I have been using a Minidsp 2x4 between my AVR and 3 subwoofers with great success, however as they require 1.8VRMS for rated power, the MiniDSP 2x4 can only supply 1/4 of rated power.

I have a C-DSP 8x12 from my previous car system. I replaced the 2x4 with the 8x12 and added -10db attenuators to the RCA outputs as this unit outputs 6VRMS, however now I have a bad 50hz hum.

I have tried unplugging almost everything in different combinations, and even using a ground loop isolator on the RCA inputs to the C-DSP and the hum is still present. When I connect the Laptop, the input level is showing -39db so the hum is fairly loud.

If I connect the bare minimum (AVR with no HDMI’s connected, C-DSP and 1 subwoofer) the input level is still around -50db. If I swap back to the 2x4, the hum disappears and the system works perfectly.

In summary, the ONLY change I have made to the entire system is changing a 2x4 for a 8x12 (using same DC power supply) and this introduces a nasty 50hz hum. If anyone has any ideas, that would be greatly appreciated.
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C-DSP 8x12 ground loop 2 weeks 4 days ago #45821

  • PsyCLown
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Did you manage to find a solution to this issue of yours?
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C-DSP 8x12 ground loop 2 weeks 3 days ago #45891

  • vwman01
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No unfortunately not. I have just put the 2x4 back into the system as it does not suffer this issue. I am limited to -5db from reference before it clips but this is more than adequate 95% of the time
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C-DSP 8x12 ground loop 2 weeks 2 days ago #45895

  • PsyCLown
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If you have a 12v battery laying around, try powering it with that and see if it makes any difference?

The hum only appears when you use the analogue inputs? If so, have you tried using digital inputs?
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