The No.1 Website for Pro Audio
 Search This Thread  Search This Forum  Search Reviews  Search Gear Database  Search Gear for sale  Search Gearslutz Go Advanced
ATC 20ASL MKII hearing FM radio from the tweeter
Old 23rd December 2017
  #1
Here for the gear
 

ATC 20ASL MKII hearing FM radio from the tweeter

Ok, this one surprise me...

I though I was hallucinating sound. Upon close inspection to see where it's coming from, it's FM radio coming from one of my speaker tweeter. I don't even know how is that even possible. I unplugged the XLR cable, still there! Seems like ATC have integrated a 1 channel radio station in one of my speaker.

I just realized that I don't even have a radio anymore in my home, so I can't check which channel is it, but if I keep listening I might catch it. I'm in Montreal and it's a French channel.

I'm not trying to screw up ATC reputation or anything, but I'm starting to think that they don't put much to isolate their amps from interference (electrical or even radio station). I also have issue where the transfo in the amp hum if there is voltage variation (like when the laser printer is warming up) or before I had to replace the transfo on my router, as he was causing amp to hum non stop.

I already checked the ground is good. I'm thinking of getting an isolation transformer to fix all those issue.

Any thought?
Old 23rd December 2017
  #2
Lives for gear
 

You should never have laser printers, refrigerators, or any motors on the same circuit as audio. Also many backup UPS will void the warranty if you plug one of those in too.

RF interference with speakers is nothing new. It tends to be very location dependent. If you unplugged the speaker xlr and still pick it up, try moving the speaker and plugging it into a different outlet in a different room/circuit (this is just to trace the problem.) Also try getting simple snap-on ferrite core beads to snap around the power cable to help shield the cable from injecting RF.

How did you check the ground?
Old 23rd December 2017
  #3
Lives for gear
 

Are you sure it's FM? AM leakage is much more common. The most frequent cause is a cable with an unsoldered ground connection, making the entire length of wire act as an antenna. Swap out the various cables feeding that speaker and see if this ends your unscheduled listening party.
Good luck!
Old 23rd December 2017
  #4
Here for the gear
 

Yes, it is FM, it's those pop music channel..

I have a cable with those ferrite on it, I just tried, still doing it. The other speaker is not doing it, so I guess the cable is making some sort of antenna where it's located.

As for the other thing on the same circuit, as for now I don't have any choice, that's why I was considering getting a isolation transformer, probably cheaper then adding and other electric outlet as I'm pretty far from the electric box. I also checked all the plug around, it's all on the same circuit.

What do people use in professional studio to protect their equipment?

To test the ground I use a Garder Bender GFI-3501, I get the 2 oranges light. If I put a ground lift, I get 1 light only.

Edit: I decided to listen to find out which station while comparing with radio online. I found it! It's CKOI 96,9 FM.
Old 23rd December 2017
  #5
Lives for gear
 

Quote:
Originally Posted by amphibulus View Post

What do people use in professional studio to protect their equipment?

To test the ground I use a Garder Bender GFI-3501, I get the 2 oranges light. If I put a ground lift, I get 1 light only.

Edit: I decided to listen to find out which station while comparing with radio online. I found it! It's CKOI 96,9 FM.
Try swapping left and right speakers and see what happens.

Those testers can tell you if there's a ground but they can't tell you if it is a good ground. An electrician could or if you had wiring diagrams (where the ground actually goes.) You have to trace the line.

I can't speak for all professional studios, but the ones I work in are built ground up with a proper wiring scheme and circuits split up. As for protection -- we use battery UPS systems which can do voltage regulation (some have online UPS systems.) However, online UPS have to go in machine rooms because of the sound of the cooling fans always running and heat.
But no isolation transformers.
Old 24th December 2017
  #6
Gear Nut
 

Almost certain you have a board with a borderline component or solder point causing it to act as a diode, making a slope detector fm demodulator.

Send it in to ATC...
Old 24th December 2017
  #7
Here for the gear
 

Quote:
Originally Posted by rasher View Post
Almost certain you have a board with a borderline component or solder point causing it to act as a diode, making a slope detector fm demodulator.

Send it in to ATC...
Easy to say, but from Canada the shipping cost would be expensive for the distributor here... (hopefully it's them who will cover that, as they are brand new). Those ATC speaker are full of surprise. But yeah FM station in a speaker it doesn't smell good. That exact speaker arrived with few scratch on the cabinet out of the box, if I send it back I will ask them to fix that at the same time. Kind of not what you are expecting on speaker of that price.
Old 24th December 2017
  #8
Lives for gear
 

FM in a speaker is a first for me. Just goes to show you're never too old to see something new.
On the positive side, ATC is noted for excellent customer service. So, if these are new, I'd be very surprised if they didn't cover you on this.
Old 24th December 2017
  #9
Lives for gear
 

I don't understand why powering UPS should void a warranty AS LONG AS a serious UPS is used, i.e. an true online double conversion model with "sine wave output" (not a perfect sinus of course as it's still generated by PWM but at least not some so-called "quasi sinus").

A good UPS is not cheap, I'd say not below around CHF/EUR/USD 1500 w/o local VAT and without higher capacity batteries for a reliable small single phase model. Make sure to understand ratings correctly, especially as most electronic devices are non-linear loads. Typically a small UPS will cost more than the computer it powers.
I've designed power distribution systems and commissioned larger 3-phase online UPS and we hadn't much issues, higher-end units are very reliable though ambient temperature for the batteries is very important.

Cheap low-end UPS are worse than no UPS and devices are more likely to end damaged due to the UPS than due to power quality issues.

BTW Equipotential bonding can be important when it comes to EMI/RFI issues. If not done carefully there can be several grounds at different potentials with all sorts of compensations currents.
Old 26th December 2017
  #10
Lives for gear
 

or, chill have them send you a "loaner" or just have them send a freeone under warranty
Old 26th December 2017
  #11
Lives for gear
 

Quote:
Originally Posted by amphibulus View Post
Ok, this one surprise me...

I though I was hallucinating sound. Upon close inspection to see where it's coming from, it's FM radio coming from one of my speaker tweeter. I don't even know how is that even possible. I unplugged the XLR cable, still there! Seems like ATC have integrated a 1 channel radio station in one of my speaker.

I just realized that I don't even have a radio anymore in my home, so I can't check which channel is it, but if I keep listening I might catch it. I'm in Montreal and it's a French channel.

I'm not trying to screw up ATC reputation or anything, but I'm starting to think that they don't put much to isolate their amps from interference (electrical or even radio station). I also have issue where the transfo in the amp hum if there is voltage variation (like when the laser printer is warming up) or before I had to replace the transfo on my router, as he was causing amp to hum non stop.

I already checked the ground is good. I'm thinking of getting an isolation transformer to fix all those issue.

Any thought?
Can I clarify: no cables plugged in, no input, you hear radio on one speaker? If you adjust the sensitivity on the rear, no cables plugged in, does the radio apparent level change?

In all my years with ATC (17), I have not experienced this before. Not to say it couldn't happen, RF is a difficult beast, especially in high RF areas.

Brad
Old 27th December 2017
  #12
Here for the gear
 

Quote:
Originally Posted by DannyMac View Post
or, chill have them send you a "loaner" or just have them send a freeone under warranty
Hehe, I like your approach.

Thanks all, I will do a few more test and I will contact my dealer after and see from there how we proceed.
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 Reverb.com 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