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Gear / Technical Help => Microphones & Setup => Topic started by: ChrisV on April 17, 2004, 02:43:42 AM

Title: Mic problem (loud humming)
Post by: ChrisV on April 17, 2004, 02:43:42 AM
So I am testing out my mics here at home.   I just got the cables recently so this is my first time actually trying them out.   And as I turn the levels up there is a very loud audible hum or buzzing that is coming from one of the mics....so loud that even in dead silence it is showing up on the meters big time on one side but nothing on the other.    So I tried to narrow down the problem by swapping the mic caps with the bodies and when I did that it switched sides.   So I've determined it is something wrong with one of the caps.    I am thinking I may need to get these serviced unless someone else can figure out a solution to the problem.   The mics in question are the Superlux SMK-H8K (if that matters).

If anyone has any ideas of what could be causing it please chime in.  Thanks!
Title: Re:Mic problem (loud humming)
Post by: F.O.Bean on April 17, 2004, 03:53:01 AM
has to be the damn caps, try switching the xlr's too, that was a common problem on my 480's till i tightened a screw on the body
Title: Re:Mic problem (loud humming)
Post by: BCostigan on April 17, 2004, 07:19:47 AM
Sounds like it may be some kind of grounding issue....though I'm not sure how the cap could be mis grounded?

Title: Re:Mic problem (loud humming)
Post by: Swampy on April 17, 2004, 09:05:51 AM
Ya, thats what cables will do if they have somthing out of wack...
Title: Re:Mic problem (loud humming)
Post by: ChrisV on April 17, 2004, 02:06:15 PM
I tried tightening it on as much as possible but it didn't help....thanks for the suggestion though.

I am pretty sure it isn't the cables because I switched them up and it switched sides.  Unless it is both of the cables conflicting with only one of the caps in the exact same way.  But I am positive it isn't the cables because I tried plugging the mics directly into the UA-5 and same problem.

I just made a massive discovery though...when I touched the mic it stopped the hum/buzz completely.    So all I need to do is hold the mic the entire time I am recording ;p

So perhaps it is a grounding issue then?
Title: Re:Mic problem (loud humming)
Post by: blu666z on April 17, 2004, 02:45:17 PM
Hey Chris.  Don't know much about those mics.  Are the caps removable?  If so, could it be a problem with the caps connecting tightly?

-Kevin
Title: Re:Mic problem (loud humming)
Post by: johnw on April 17, 2004, 03:30:07 PM
I was thinking that electret capsules only had a + and - wire, and that the ground is added in the body stage. but I could be wrong. If it stops when you touch the mic it sounds like a ground problem. Just to be sure, you have the High Z set to low, you have switched cables and the hum stays with the same mic, you plugged the mic bodies directly into the UA5 (no cable) and the hum stays with the same mic. If you have the mics plugged directly into the UA5 and switch only the capsules, the hum moves to the other channel? If all this is true, then it does sound like a grounding issue in that capsule. When I got mine, the capsules were really hard to unscrew, so I didn't bother trying to hard. I believe yours were from the same place, and were a new pair. Is it possible that when you unscrewed or rescrewed the capsule, some of the threading broke off, or the capsule is not threading on correctly? If possible could you take a picture of the capsule off the body?
Title: Re:Mic problem (loud humming)
Post by: ChrisV on April 17, 2004, 05:04:36 PM
Yep, the caps are removable...it is how I isolated it to a problem being with those.  Have switched everything around every possible way and the one cap is the common denominator.

They unscrewed fairly easy and screw back on so that they are very snug.  Examined both pieces' threads and they both appear exactly the same and in tact.   I'll see if I can take a few pics to post with them off anyways.
Title: Re:Mic problem (loud humming)
Post by: johnw on April 17, 2004, 05:15:54 PM
I guess what I'd probably do is call up the seller (Earthshaking music right?) and tell them you got a bum pair. They seemed like pretty decent folks, and I bet they'd replace them no problems. If they won't or you don't want the hastle, you could try grounding the cap to your mic stand. I'm thinking just  strip the ends off a 6" piece of wire and tape one end to the cap and the other to a metal part of the stand. Not entirely sure this would work, but I bet you'll probably go with option #1 anyway. Hope this works out for you. Go Lux!
Title: Re:Mic problem (loud humming)
Post by: rustle on April 18, 2004, 09:33:54 PM
I guess what I'd probably do is call up the seller (Earthshaking music right?) and tell them you got a bum pair. They seemed like pretty decent folks, and I bet they'd replace them no problems. If they won't or you don't want the hastle, you could try grounding the cap to your mic stand. I'm thinking just  strip the ends off a 6" piece of wire and tape one end to the cap and the other to a metal part of the stand. Not entirely sure this would work, but I bet you'll probably go with option #1 anyway. Hope this works out for you. Go Lux!

 Chris,
   Go with option #1 ;).

 Outside, Option #2 would turn your stand into a Lightning Rod :o

peace,
 Russell
Title: Re:Mic problem (loud humming)
Post by: utahtaper on April 18, 2004, 10:34:53 PM
has to be the damn caps, try switching the xlr's too, that was a common problem on my 480's till i tightened a screw on the body

I had this same problem with my 480's. It totally sounds like a grounding issue. Especially when you mention that it goes away when the mic is touched.
Title: Re:Mic problem (loud humming)
Post by: ChrisV on April 19, 2004, 01:18:03 AM
Thanks for the input guys...I am going to contact Earthshaking tomorrow.
Title: Re:Mic problem (loud humming)
Post by: F.O.Bean on April 19, 2004, 06:49:16 AM
has to be the damn caps, try switching the xlr's too, that was a common problem on my 480's till i tightened a screw on the body

I had this same problem with my 480's. It totally sounds like a grounding issue. Especially when you mention that it goes away when the mic is touched.

utah, when you had that problem, did you tighten the screw on the bodies???

i had a similar problem and did that and BAM, problem solved
Title: Re:Mic problem (loud humming)
Post by: utahtaper on April 20, 2004, 01:28:09 AM
Hey Bean,
Yea totally, the one screw on the body down by the XLR connector. Tightened it and golden.  ;)
Title: Re:Mic problem (loud humming)
Post by: ChrisV on April 21, 2004, 03:21:30 AM
Just an update....got in contact with Dave @ Earthshaking Music and arranged to have me send them direct to the manufactor(Avlex) and they should either repair or replace my busted mic(s).   Sent them off yesterday and hopefully I can get the things back in time for next week.
Title: Re:Mic problem (loud humming)
Post by: johnw on April 21, 2004, 08:49:24 AM
Sounds good. If you get to talk to anyone at Avlex, try and find out if there is a dealer that sells the capsules only. Or if Avlex is willing to sell capsules direct. Good luck!
Title: Re:Mic problem (loud humming)
Post by: ChrisV on April 23, 2004, 09:33:03 PM
I sent them off Fedex saver on Monday @ 5 PM and they got there 10 AM(central time) on Wednesday....not bad at all.  So I gave them a call today just to check on the status and found out they replaced them completely under the warranty with a completely new matched pair and sent them off to me UPS yesterday!   So I should be getting them Tuesday/Wednesday of next week and in plenty of time for my upcoming concerts.   Definately great service there from the manufacturer(Avlex), 1 day turnaround with a brand new set of mics :)

Damn, I forgot to ask about the seperate capsules though...I guess I forgot in all the excitement ;p

You could try giving their line a call to ask, it is toll free which is nice.  Listed on their site here:
http://www.avlex.com/contact.html

Title: Re:Mic problem (loud humming)
Post by: johnw on April 23, 2004, 11:03:33 PM
I'll give them a try on Monday. I've been checking around trying to find other distributors and these seem to be pretty rare mics! Only a few people carry the large diaphragm ones and it looks like even fewer have the CMK-H8K. I tried to look up the factory to see if they make other similar mics whose capsules might work - not much there. Glad this worked out for you though. +T
Title: Re:Mic problem (loud humming)
Post by: johnw on April 27, 2004, 11:39:16 AM
I called Avlex and asked if other capsules are available. I was told that they are not, and there are no plans to ever make them available, but they may sometime in the future. I told them that I know the factory also makes microphones for other brands and was wondering if there are other brand capsules that might work. The tech guy said that no other capsules will even physically fit on the bodies. The capsules have a pin that pushes against a spring loaded contact on the body. Both are about 3mm in diameter and are centered inside the 20mm diameter case. I doubt this design or the threading is unique, but who knows. I have pictures if anyonw is interested. Too bad.
Title: Re:Mic problem (loud humming)
Post by: ChrisV on April 27, 2004, 10:32:55 PM
Wow, got them today from UPS and I got a brand new entire kit.   Did a quick test on them and no hum/buzz on either of them...yay!  :clapping:

Gonna test the mics in depth more later tonight.
Title: Re:Mic problem (loud humming)
Post by: blu666z on April 28, 2004, 12:39:55 AM
Right on Chris..can't wait to see your new rig this weekend.

-Kevin
Title: Re:Mic problem (loud humming)
Post by: johnw on April 28, 2004, 07:09:23 AM
Congrats! + T