Arcam Delta DAC buzzing on left channel

OMG I'm so stupid!
 

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OK, you see the 1kHz looks nice and clean. Now search for a point where you can make the distortion you hear visible. From there follow the signal path and you will find the point where the problem starts to appear... At least in theory 😉

Ah, in the video that's a 50Hz hum! You can verify here... Probably from the AC mains coming through the smoothers / regulators - so look at the local caps, the 3leg regulators, the PSU caps etc.

If you zoom out from your 1kHz scope setting you should be able to see the 50Hz frequency...
 
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Each channel displays the zoom level chosen. This can be different for each channel. The probes have a small switch at the grip, set that to the same setting. If you change settings while measuring the changes only affect the channel currently activated with the channel button. You also can reset your scope to factory settings... But why don't you take your time to watch a tutorial video for the Rigol? This will save you tons of time in the future 😎
 
Another 'gotcha' that sometimes catches novice 'scope users -- a probe must be 'calibrated' to be accurate. There's a trim cap, usually in the handle; use a plastic tool / screwdriver to adjust it to display a nice, flat-topped 1 kHz-or-so square wave. I didn't see one on your front panel, but all my (very) old analog 'scopes have a test hook on the front. Only takes a few seconds. Don't rely on any measurements unless you've done it. And it's a very likely explanation for differing measurements on different probes.

Also, I highly recommend using only x10 probes / settings. Much less interference / loading-on the circuit you're probing. Once you get used to it, it's no extra trouble. Modern 'scopes have plenty of low-noise front-end gain to still see what you need to usually.

Cheers

edit: Just took a peek at your earlier post -- looks like Cal hooks on the '1054s lower right corner.
 
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