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Post by bourneendboy on Jul 22, 2020 10:44:36 GMT
I have recently noticed an 'electrical sensation' when touching the front panel of my headphone amp and a hum when inserting the headphone jack (clears when fully inserted).
After discussion with the amp manufacturer and Googling I now know this is because both items are Class 11 double insulated and have no earth connection
I have done a bit of experimenting and found that connecting a cable to the ground of an unused RCA socket on the amp to a radiator pipe cures the issue. Also, unless I'm kidding myself, it sounds better, more natural.
I'm now wondering if this is the best way to ground/earth the system?
It's just a headphone amp and a R-Pi with Allo Boss. The culprit is definitely the Pi as there is no issue with the headphone amp when the Pi is unplugged.
I've read here about using a USB cable with from the Pi with just ground attached, is this any different to the RCA connection?
Thanks for any guidance chaps
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Post by MartinT on Jul 22, 2020 11:06:17 GMT
It won't be the Pi, rather it'll be its power supply. Many power supplies are made 'floating' so that you can arrange your own grounding.
Strictly speaking, you shouldn't ground a Class II device. It's meant to remain double-insulated.
However, there is no harm in grounding the Pi. You can try grounding to an RCA socket as you have done or, better still, use a grounding box with USB connection straight into the Pi's USB socket so that you're grounding the 'dirty' digital ground plane.
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Post by bourneendboy on Jul 22, 2020 11:13:51 GMT
It won't be the Pi, rather it'll be its power supply. Many power supplies are made 'floating' so that you can arrange your own grounding. Strictly speaking, you shouldn't ground a Class II device. It's meant to remain double-insulated. However, there is no harm in grounding the Pi. You can try grounding to an RCA socket as you have done or, better still, use a grounding box with USB connection straight into the Pi's USB socket so that you're grounding the 'dirty' digital ground plane. Thanks Martin. This is what the amp manufacturer said as well - you shouldn't really ground a Class 11 device. I'm using an iFi ipower PSU for the Pi. The RCA I have currently connected to is on the amp, if I use one of the USB sockets on the Pi instead, is it a case of using a standard USB cable, cutting off the unused connector and making use of the black ground wire? Can I then attach this to a radiator pipe? Is this any different to what I'm currently doing? |
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Post by MartinT on Jul 22, 2020 11:18:57 GMT
if I use one of the USB sockets on the Pi instead, is it a case of using a standard USB cable, cutting off the unused connector and making use of the black ground wire? Can I then attach this to a radiator pipe? Is this any different to what I'm currently doing? Yes, you can do that and it's probably a better arrangement as you're grounding the Pi's ground plane where the worst of the noise will be and you're leaving the amplifier alone. |
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Post by bourneendboy on Jul 22, 2020 11:40:21 GMT
if I use one of the USB sockets on the Pi instead, is it a case of using a standard USB cable, cutting off the unused connector and making use of the black ground wire? Can I then attach this to a radiator pipe? Is this any different to what I'm currently doing? Yes, you can do that and it's probably a better arrangement as you're grounding the Pi's ground plane where the worst of the noise will be and you're leaving the amplifier alone. Cheers Martin, I'll give that a go and report back. |
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Post by bourneendboy on Jul 22, 2020 19:28:15 GMT
I've swapped out the RCA earth lead for a USB earth lead connected to one of the USB sockets on the Pi. Absolutely silent with no hum or electrical sensation from the amp font panel.
Works perfectly!
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