Ultralite mk3 Buzzing and probable ground issue

[bartak101]

Hi there,

My Ultralite mk3 has recently developed a buzz that appears to emanate from the area around where the power adapter plugs in. I run off USB so require the 15v power supply. The adapter also runs hot.

This issues seems to also be effecting the audio path. The other night I was sending out from the sound card, into a DAV BG1u, via a Radial DI. There was obvious distortion/buzz that actually appeared to get quieter as I applied more gain on the preamp. This leads me to think this may be a grounding issue.

I'm in the UK. So almost all my gear is on three pronged adapters or IEC plugs. I have borrowed a PAT tester and will check all my outboard's grounds this weekend, but it seems pretty obvious to me that the Motu is the culprit owing to the audible noise coming out of its rear.

Has anyone had a similar issue? I've got a horrible feeling its the unit's transformer or related circuitry and will have to send it in for work. I read that that can take three weeks and I have a lot of work on at the moment.

Thanks for now.

[mikehalloran]

This has been reported before. You'll have to do a search to find it. I don't recall the outcome.