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+--- Thread: Loud Electrical Hum from Sub Preout when units are in Standby! (/Thread-Loud-Electrical-Hum-from-Sub-Preout-when-units-are-in-Standby)
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Loud Electrical Hum from Sub Preout when units are in Standby! - SquiggFSM - 28-Jan-2018
Hi Folks
I’m getting loud electrical hum from the sub pre out while the unit’s are in standby mode, loud enough to trigger the sub to turn on, and stay on. When you turn the units on, the hum goes away. It’s the same for the master and the slave outputs. Anyone got any thoughts?
440 Pro Core Infinity
2.1.0 + 12.1.2
PowerSoundAudio S3000i Sub
Thanks in advance
RE: Loud Electrical Hum from Sub Preout when units are in Standby! - Pleyel - 07-Feb-2018
(28-Jan-2018, 16:03)SquiggFSM Wrote: Hi Folks
I’m getting loud electrical hum from the sub pre out while the unit’s are in standby mode, loud enough to trigger the sub to turn on, and stay on. When you turn the units on, the hum goes away. It’s the same for the master and the slave outputs. Anyone got any thoughts?
440 Pro Core Infinity
2.1.0 + 12.1.2
PowerSoundAudio S3000i Sub
Thanks in advance
Did you try making sure both the amp feeding the sub and the sub are powered from the same (earthed) power strip?
RE: Loud Electrical Hum from Sub Preout when units are in Standby! - SquiggFSM - 09-Feb-2018
(07-Feb-2018, 09:15)Pleyel Wrote: Did you try making sure both the amp feeding the sub and the sub are powered from the same (earthed) power strip?
No I haven't tried that, but I don't get the hum via the AV amp which is also connected to the power separately.
Should also note that the PowerSoundAudio Sub doesn't have an earth pin, so probably wouldn't make a difference anyway.
Devialet have suggested using the latest beta firmware to see if that fixes it, so I'm looking at that just now
RE: Loud Electrical Hum from Sub Preout when units are in Standby! - SquiggFSM - 09-Feb-2018
Well DOS 2.2.0 beta12 + 12.2.6 didn't fix anything, still got the same problem
RE: Loud Electrical Hum from Sub Preout when units are in Standby! - ogs - 09-Feb-2018
What happens if you unplug the cable at the amp end when you have hum? Does the hum go away?
RE: Loud Electrical Hum from Sub Preout when units are in Standby! - zdenes - 10-Feb-2018
I had exactly the same problem that you described. Devialet on - no hum from the subs, off - hum from the subs. Also, no ground pin on my subs.
To cut a long story short, I noticed that moving the interconnect going to the subs changed the volume of the hum from the subs. These are good quality $600 interconnects (Zcable Live5) I had used with a lot of different gear and never had such an issue. I'm quite certain that these interconnects are not shielded.
I changed them to coaxial interconnects from Canare (and since then Oyaide) and the hum is gone for good. The first interconnects definitely picked up the noise, I just don't know why that didn't happen when the Devialet was on. I have a strong feeling that it is the same problem in your case.
RE: Loud Electrical Hum from Sub Preout when units are in Standby! - ogs - 10-Feb-2018
If this is 'normal' hum, then it is because the cable (and hence the subwoofer input) is not grounded when the Devialet amp is off or in standby, i.e. the Devialet disconnects ground of the RCA rather than creating a short between signal and ground. If you disconnect the cable(s) and touch the signal pin without touching the sleeve of the plug you'll probably get a similar (not identical) hum in the subwoofer. As soon as you touch the metal on the sleeve hum will be much weaker or go away completely.
The other type of hum can , as zdenes says, be created by the cable itself. The input circuit of the subwoofer is then triggered into an unstable mode. This is actually not hum, but a sort of oscillation in the input circuitry where the cable acts as a kind of antenna - when it is unterminated at the amplifier end. A different cable can help here.
EDIT. keeping the ground connected and disconnect the signal pin in the amplifier could also work. Either way it is something Devialet needs to fix
Loud Electrical Hum from Sub Preout when units are in Standby! - Soniclife - 11-Feb-2018
Were you getting the hum before the CI upgrade?
RE: Loud Electrical Hum from Sub Preout when units are in Standby! - ogs - 11-Feb-2018
I think zdenes above is using the D800. He also describe hum in his post. So yes, the hum is probably there even before the Pro upgrade
RE: Loud Electrical Hum from Sub Preout when units are in Standby! - zdenes - 12-Feb-2018
(11-Feb-2018, 20:29)ogs Wrote: I think zdenes above is using the D800. He also describe hum in his post. So yes, the hum is probably there even before the Pro upgrade
That is correct. I have the D800.
BTW, I did not hear any hum with the first interconnect I used but after a few months, I thought I would use the Zcable that I had hanging around (not many analogue cables were needed after buying the Dev. in 2011).
I often change things in my system, so it took me a while to realise that it may be the interconnects to the sub causing this. They were.