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Post by ChrisB on Jan 12, 2016 8:27:30 GMT
The Pi that I use in the second system is battery powered and sits on top of the Yamaha receiver. If I leave the Pi switched on but switch the receiver to use the tuner section, I get horrendous interference which persists unaltered if I move the Pi away a bit.
It doesn't particularly matter in this system, as I'm not exactly focused on ultimate sound quality here, but this can't be a good state of affairs in principle and more particularly, when I use the one in the main system downstairs.
This surely is something that we should be addressing. Still looking for that high quality screened case but in the meantime is there anything that can be done cheaply and easily?
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Post by MartinT on Jan 12, 2016 8:35:44 GMT
Yes, a screened case would be ideal. Build it into a tin of some sort?
The Pi is a full-blown computer with a clock speed in the region of 1GHz and it's going to transmit all manner of nasties without shielding. A radio tuner is designed to receive, so it's going to be vulnerable to a Pi only a few metres away.
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Post by ChrisB on Jan 12, 2016 8:42:12 GMT
As I say, I'm not too bothered about the effect on the tuner - that's easily remedied. I just think that a device chucking all that crap out in close proximity to the main system can't be good.
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Post by MartinT on Jan 12, 2016 9:26:11 GMT
Agreed!
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Post by guy on Feb 9, 2016 20:44:48 GMT
would something like woven wire mesh stuck to inside surfaces of the acrylic box (then earthed to amplifier or similar work)? www.wires.co.uk/acatalog/cu_fabric.htmlrelatively cheap and retain nice lines of the acrylic box. |
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Post by MartinT on Feb 9, 2016 22:07:25 GMT
It could work if it forms a good earthed shield.
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Post by ChrisB on Feb 9, 2016 22:43:00 GMT
Is this intended to act as a Faraday Cage?
If so, I thought they were supposed not to be connected to Earth. Or am I wrong?
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Post by Stratmangler on Feb 9, 2016 23:01:51 GMT
Is this intended to act as a Faraday Cage? If so, I thought they were supposed not to be connected to Earth. Or am I wrong? Faraday cages can be grounded. They don't necessarily have to be, but they can be. en.wikipedia.org/wiki/Faraday_cage |
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Post by ChrisB on Feb 9, 2016 23:58:30 GMT
OK, thanks.
So.......does that make Martin's statement true, false or incomplete?
And does it mean that an ungrounded one would or wouldn't solve the problem.
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Post by Stratmangler on Feb 10, 2016 0:13:31 GMT
I would think that a properly shielded and grounded case would provide a quieter environment, especially with there being a RF receiver in close proximity.
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Post by ChrisB on Feb 10, 2016 0:18:36 GMT
OK, thanks. That tells me which you think might be better.
You little tinker you...
But would an ungrounded one do the job too (albeit to a lesser degree according to your way of thinking)?
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Post by Stratmangler on Feb 10, 2016 0:52:51 GMT
An ungrounded one could be tuned to attenuate certain frequency bands.
It would be effective at the tuned band, and ineffective at others.
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Post by MartinT on Feb 10, 2016 6:30:15 GMT
A Faraday cage works to protect things inside it from external influence, but I would have thought that earthing the case would be best.
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Post by zippy on Feb 10, 2016 8:21:05 GMT
Yes, a screened case would be ideal. Build it into a tin of some sort? The Pi is a full-blown computer with a clock speed in the region of 1GHz and it's going to transmit all manner of nasties without shielding. A radio tuner is designed to receive, so it's going to be vulnerable to a Pi only a few metres away. That's what I would do - find a metal case big enough for the Pi and put it in that - if you need ventilation then you'd probably need a wire mesh covered cut out. RS have cases that look good to me. A thought: Just because your receiver (which is obviously designed to pick up radio frequencies) picks up interference, doesn't of course mean that your hifi will too as it will presumably itself be shielded by its own case. |
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Post by MartinT on Feb 10, 2016 8:26:38 GMT
The idea is to cut down interference whether you can hear it obviously or not. Too much RFI can adversely affect the sound of your system even if you don't hear it as interference.
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Post by ChrisB on Feb 10, 2016 8:36:52 GMT
I've been looking for a reasonably priced metal case for the Pi and Digi+ for a over year now! The HiFiBerry case is supposed to be comeing on the market next month, though I have found this one from France. I don't like the big hole that you need to leave when you take the panel out to gain access to the Digi+ connectors. There are options for a power button and remote control and even a volume control, should you want one. |
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Post by ChrisB on Feb 10, 2016 8:48:45 GMT
Here's that rather smart looking Nuxii case  |
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Post by MartinT on Feb 10, 2016 8:55:27 GMT
That's nice, but plastic?
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Post by ChrisB on Feb 10, 2016 8:58:15 GMT
Apparently not....
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Post by MartinT on Feb 10, 2016 9:16:00 GMT
That's good at the price. I might wait until the HiFiBerry one and then choose.
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