The No.1 Website for Pro Audio
Noise Floor Question - EMF Noise Grounding Problem?
Old 6 days ago
Gear Nut
camadair's Avatar

Noise Floor Question - EMF Noise Grounding Problem?

I recently moved studios and am getting what sounds like electromagnetic interference in my main chain.
The chain here is FLEA 47 > Mic Tie Panel > Patch Bay > Patched to BAE 1073 > Patched to Purple MC77 > Patched to Apogee Symphony

What is this noise!?

The noise goes away when unplugging everything in the chain individually in reverse e.g. starting with the apogee input and ending at the last connection which is the mic end of the mic cable for which the noise returns. This makes me think that its the 47 itself but Im not sure. Is the tube dying? The noise goes away when other (dynamic) mics are swapped. The noise also lessens when the rack holding all the outboard is moved away from the wall.

I also get the same interference noise when something is not grounded properly e.g. plugging unbalanced gear into the patch bay without a DI.

Patch bay is grounded to the rack. I tried moving power supplies away from the rack but that wasnt the problem either.

Its driving me nuts. Help!
Attached Files

2019_11_06_EMF NOISE=.wav (11.83 MB, 114 views)

Last edited by camadair; 5 days ago at 11:43 AM..
Old 5 days ago
Gear Nut
camadair's Avatar

these were helpful but im not sure where to start. might get an ebtech hum x.

I plugged a Tascam 414 in in another room and it has the same exact rfi noise in the hp mon with nothing plugged in aside from power and headphones. It is ungrounded. This is leading me to think its the ****ty power in this 1920's building. The GFCI outlet in the bathroom doesnt seem to carry the RFI for some reason.

The squeal and chirping is at 2kHz, 4kHz, 8kHz, 10kHz, 15kHz, 18kHz. Apparently the owner has a solar inverter in the basement and a cannabis grow room in the dispensary on the first floor (LED lights) which are both known to cause dirty electricity.

If its dirty electricity what are my options?
Attached Files

Last edited by camadair; 4 days ago at 12:29 PM..
Old 4 days ago
Gear Nut
camadair's Avatar

Old 4 days ago
Lives for gear
BrentA's Avatar

If it’s coming through the electrical then a Tripp Lite isolation transformer should help. If it’s coming through the air then all you can do is build a Faraday cage.
Old 4 days ago
Gear Nut
camadair's Avatar

Ok, after some research I ordered a Ebtech Hum X, an Ebtech Hum Eliminator for the output of an unbalanced outboard tube preamp connected to the patch bay, and a radial jdi for the output of an re-201 that was also picking up the noise the worst. I also might change the unbalanced cables with balanced cables connecting these and add trs connectors on the patch bay side if it still doesnt cease. None of these are the source of the noise but this seems to be the 'correct' way to connect them.

These were helpful:

Originally Posted by BrentA View Post
If it’s coming through the electrical then a Tripp Lite isolation transformer should help.
I was looking at Tripp Lite IS250. I was also looking at Ground Isolated Outlets, Furman AR-1215, P-1800 AR, and PF R. Any thoughts on these? Im unclear on if a ground isolated outlet is effective without running a new ground to the breaker, how much wattage I need for a Tripp Lite and on what the Furmans actually do as far as "conditioning".
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.

Slide to join now Processing…
Thread Tools
Search this Thread
Search this Thread:

Advanced Search
Forum Jump
Forum Jump