Topic: Strange rumble with my MKE40's. Could someone take a listen please?

[TheJez]

Hello all,

Wow, I've been an amature taper since the late 1980's, and only just very recently I discovered this amazing forum overhere! I've been reading up and I am very impressed with the 'tribal knowledge' present in the forum. That's why I'd like to ask you for some help.

Back in 1989, I inherited a pair of Sennheiser MKE40's and a Sony WMD-6C. That's when my stealth taping career started. Over time, I upgraded to a Sony TCD-D7 and PCM-D100, and now I am about to buy an Edirol R09-HR. So recording gear has never been an issue. However, my MKE40's have been giving me some trouble. At first, they worked flawlessly, but after a few years, one of the mikes started generating a weird noise every now and then. It's hard to describe, but it sounds as if someone is moving a cloth over the mike or blowing into it. This noise appeared rarely first (once or twice per gig), but over time it appeared more often, and finally it was there on and off during the entire recording. It happens both at indoors and outdoors gigs, so I guess wind is not the issue. Also it happens during loud parts and quite parts, so it is not some overload.

When then my second mike started acting likewise, and when my budget finally allowed it, I got a new set of mikes (Coresound Stealth Cardiods) and all problems were gone.

However, I still have my MKE40's laying around, and I am still very curious what this weird noise is. I hope some of you can take a listen, and maybe recognize the noise or even come up with a solution. (I still like the sound of my MKE40's over the CSC for 'not so loud' gigs.)

I have attached a short part of one of my recordings (about 37 seconds in 443kb mono mp3)

It is most obvious right after the song ends (during the clapping), but it is there on and off during this clip. The frequency of the 'rumble' is <200Hz.

I have been taking good care of the mics, like replacing the batteries often enough, so I am pritty clueless. Could it be the capacitor in the battery box acting up or something?
Any suggestions or ideas are very kindly appreciated!

Thanks,
TheJez

[digifish_music]

Sounds a lot like wind noise to me...were there fans or aircon? Are you using foam shields? Are you using suspensions?

digifish

[TheJez]

Hi digifish,

Thanks for your reply. I know, it sounds a lot like wind, but it isn't. This noise appears consequently through all recordings, either indoors or outdoors, at gigs or at home, at first very occasionally on just one mike, but later more frequently and now almost constantly. Also at first with one mike, but later also on the other one. It seems to me that something has been degrading over the years, but I'd like to know what it is and if it's repairable. That's why I was thinking of maybe leaking capacitors in the battery unit of the mikes, or problems with the capsules themselves.

Thanks!

TheJez

[digifish_music]

Hi digifish,

Thanks for your reply. I know, it sounds a lot like wind, but it isn't. This noise appears consequently through all recordings, either indoors or outdoors, at gigs or at home, at first very occasionally on just one mike, but later more frequently and now almost constantly. Also at first with one mike, but later also on the other one. It seems to me that something has been degrading over the years, but I'd like to know what it is and if it's repairable. That's why I was thinking of maybe leaking capacitors in the battery unit of the mikes, or problems with the capsules themselves.

Thanks!

TheJez

In that case are you shure it's not your mic preamp? Phantom power playing up?

Regards Scott

[TheJez]

Hi Scot,

I'm not sure about much, but I am sure about one thing: It is not my pre-amp, because I don't use any  .
I usually go straight to line in, or very occasionally to the mic-in (for low-volume recordings). Because the strange noise occurs on the WMD-6C, the TCD-D7 and the D100, and through line-in and mic-in, I think I can also rule out the recorders and their amps. So the source is either the mics themselves, or the 'battery box' in the leads to the mics. That 'box' consists of a tiny box with a 1.5V battery (a small one, as can also be found in watches and pocket calculators), a switch, a capacitor and a resistor.

I was kind of hoping somebody would recognize the noise and say: "Sure, that's the ...".
I think it's either the power supply (the tiny 1.5V box) or the capsule. I guess the only way to find out is to build my own battery box, hook it up and see if this solves the issue. If not, than I might as well throw the mics away (with pain in my heart  ...)

Thanks for listening and thinking along!

TheJez

[digifish_music]

Hi Scot,

Thanks for listening and thinking along!

TheJez

No problem,

your problem here is that it sounds exactly like wind noise or mechanical knocking on the mic 

However some issue with the power supply to the mics would be a good first place to look.

Don't throw your mics away before you have tested them on another rig tho...still could be something in the recorder.

digifish

[Church-Audio]

Hi Scot,

I'm not sure about much, but I am sure about one thing: It is not my pre-amp, because I don't use any  .
I usually go straight to line in, or very occasionally to the mic-in (for low-volume recordings). Because the strange noise occurs on the WMD-6C, the TCD-D7 and the D100, and through line-in and mic-in, I think I can also rule out the recorders and their amps. So the source is either the mics themselves, or the 'battery box' in the leads to the mics. That 'box' consists of a tiny box with a 1.5V battery (a small one, as can also be found in watches and pocket calculators), a switch, a capacitor and a resistor.

I was kind of hoping somebody would recognize the noise and say: "Sure, that's the ...".
I think it's either the power supply (the tiny 1.5V box) or the capsule. I guess the only way to find out is to build my own battery box, hook it up and see if this solves the issue. If not, than I might as well throw the mics away (with pain in my heart  ...)

Thanks for listening and thinking along!

TheJez

It sounds like the capsules need to be looked at I can repair these if your interested. I cant guarantee results until I look at them. They might just need to be disassembled and cleaned ( the capsule )