You are here

Buzzing mic conundrum

All about the tools and techniques involved in capturing sound, in the studio or on location.

Re: Buzzing mic conundrum

Postby Mike Stranks » Tue Dec 19, 2017 10:47 am

Well, the scheduled recording on Friday didn't happen (long and complicated story involving 'politics' in which I got caught in the crossfire. :( )

But the 'other users too' news from Rode causes a modicum of concern. Later today/tomorrow I'll set up some tests with various long cables and report back...
Mike Stranks
Jedi Poster
Posts: 7674
Joined: Fri Jan 03, 2003 1:00 am

Re: Buzzing mic conundrum

Postby Hugh Robjohns » Tue Dec 19, 2017 11:49 am

snipedog wrote:I have now been in touch with Rode, and they have today replied suggested that other users may have had a similar problem with these mics, and invited us to return them for testing / replacement?

Interesting... I'm glad you followed that suggestion! ;-)

H
User avatar
Hugh Robjohns
Moderator
Posts: 29090
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Re: Buzzing mic conundrum

Postby Mike Stranks » Tue Dec 19, 2017 4:14 pm

I've done some tests this afternoon, using both my M5s as follows:

Cheap 25m Pulse multicore unwound about 15 m. Tested both mics on various lines of the multicore.

30m single mic cable with both shells 'floating'. Again 15m uncoiled.

2 x 10m cables connected together. One 'decent'; one cheapish.

Connected to a cheapish analogue Behringer mixer and then to a QSC Touchmix 8. Both devices have an IEC (incorrectly called 'kettle-lead') connector with an earth pin.

All connections were balanced. Cables were deliberately routed within 1m of a wifi router.



In all cases there was nary a hint of buzz or hum. I had the gain and the headphones up to much higher settings than I would use in real-life.

Looking back through the thread I'm a little concerned that for the OP even with the NT3 and NT5 there was still some extraneous noise present. I've owned both of those in the past and used them many times in all sorts of environments and using all sorts of cables and gear. I never recall any problems which couldn't immediately be identified as a cable 'gone bad'.
Mike Stranks
Jedi Poster
Posts: 7674
Joined: Fri Jan 03, 2003 1:00 am

Re: Buzzing mic conundrum

Postby Hugh Robjohns » Tue Dec 19, 2017 4:59 pm

I share your interest, Mike. Unless I've missed it, I don't think we've had a report yet of whether the buzz was improved with a solid earth provided to the interface... and I think we need that before jumping to conclusions.
User avatar
Hugh Robjohns
Moderator
Posts: 29090
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Re: Buzzing mic conundrum

Postby snipedog » Wed Dec 20, 2017 2:05 am

Hello ,
Thanks again for your comments. Just to clarify the point about buzz when testing with the NT3s and NT5s. The buzz, )which I think I referred to as "at an acceptable level") , with those two mics, was only audible at very high monitoring levels, far higher than in normal use. I haven't had an opportunity to check the earthing via USB issue yet as the studio has been very busy over the last week and access has not been possible. However, over that week we have put the M5s away and continued to use the snake and the interface with a range of other mics, (LDCs, dynamics and ribbons with a Fethead) without encountering any hum problems. I hope to run some more tests once things get a little less busy ! S
snipedog
Poster
Posts: 25
Joined: Tue Jun 04, 2002 12:00 am
Location: Newcastle-upon-Tyne

Re: Buzzing mic conundrum

Postby mat_171 » Sun Dec 09, 2018 5:59 am

Hi. I’m having the same issue with a pair of M5. Did you resolve this ground issue with the M5?
Thanks.
mat_171
Posts: 2
Joined: Sun Dec 09, 2018 5:56 am

Re: Buzzing mic conundrum

Postby snipedog » Sun Dec 09, 2018 3:25 pm

Hello Mat_171,
The M5's were eventually returned to Rode at their suggestion. However Rode sent them back with the problem reduced but not eliminated. We have since been replaced them with a pair of Rode NT5's as we gained the impression there is a fault in the design of the M5s. The coating on the outside of the mics might possibly be interfering with the earthing somehow, but we were not able to confirm this. S
snipedog
Poster
Posts: 25
Joined: Tue Jun 04, 2002 12:00 am
Location: Newcastle-upon-Tyne

Re: Buzzing mic conundrum

Postby Wonks » Sun Dec 09, 2018 3:40 pm

Thanks for the feedback. A shame they couldn't cure the problem completely, but you've ended up with better mics.

I'd probably suspect that coating as well, though a simple multimeter test should have shown up any high resistance.
User avatar
Wonks
Jedi Poster
Posts: 10889
Joined: Thu May 29, 2003 12:00 am
Location: Reading, UK
Correcting mistakes on the internet since 1853

Re: Buzzing mic conundrum

Postby Hugh Robjohns » Sun Dec 09, 2018 3:56 pm

I can't see how any coating on the outside of the mic would be a problem. But if the paint treatment got on the inside it could prevent an effective bond with the XLR pin1.

And I have come across other Rode's mics with various internal grounding issues.

H
User avatar
Hugh Robjohns
Moderator
Posts: 29090
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Re: Buzzing mic conundrum

Postby Wonks » Sun Dec 09, 2018 4:09 pm

The coating normally covers the screw thread holding the capsule on, which can reduce or prevent the capsule casing being grounded. And mic case ground bonding often seems to be down to the screw holding the XLR in place, which also relies on any coating on the body to be conductive.

If there was some conductive component of the coating that didn't get added to the mix before it was applied (or in too small a quantity to be effective), then it may be why just some M5 mics are problematic rather than all of them.
User avatar
Wonks
Jedi Poster
Posts: 10889
Joined: Thu May 29, 2003 12:00 am
Location: Reading, UK
Correcting mistakes on the internet since 1853

Re: Buzzing mic conundrum

Postby mat_171 » Mon Dec 10, 2018 5:55 pm

Thanks for all responses.

I've tested the same setup in a friend's house, (supposedly well grounded) when I first notice the 50hz hum. I've check all inputs at the interface (presonus 44VSL), different cables and laptop running on batteries. This setup consist of 2xM5, a SM57 and a Audiotechnica AT2035, only the rode pair has the noticiable hum. Later I checked at my house (not so well grounded) and the hum is gone. The only thing is when I touch the rode mics whith my fingers, there is a static noise (hum plus harmonics, but way softer than the original hum problem).

I think I'm going to return them and buy something else.

Sorry about my English and grammar.

Greatings from Argentina.
mat_171
Posts: 2
Joined: Sun Dec 09, 2018 5:56 am

Previous