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[John L Nobile]

Getting a loud hiss on a couple of ULXD bodypacks that goes away when the antenna touches the performers skin. Only seems to affect 2 of 5 mics and they go quiet when the grab the antenna. Is that a bad antenna or do they take too many iron pills?

[Milt Hathaway]

That's odd. I've never heard a bit of noise out of mine ever, in even the worst situations. Are they all on the latest (and matching) firmware? Have you tried retuning?

[John L Nobile]

I've tried retuning. Numerous times. I was going to check the firmware next. It's kind of weird.

[Scott Helmke]

Tried using different mics on those packs?

[John L Nobile]

Tried using different mics on those packs?

I haven't. I don't think that it's a mic noise problem. It's a steady hiss that goes away when the antenna touches their body. I've moved my paddles around and retuned the 2 packs a few times. I'll try swapping antennas with packs that don't make noise next.

[Robert Lofgren]

Could it be rf-noise entering the analog preamp in tbe mic? When touching the antenna you divert some of the rf so it may not induce noise into the analog circuit.

[John L Nobile]

Could it be rf-noise entering the analog preamp in tbe mic? When touching the antenna you divert some of the rf so it may not induce noise into the analog circuit.

Interesting thought. I'm using Crown CM311's and never had that problem after many years of use.

I'm going to update the firmware today. 3 quad units.

[Jerome Malsack]

are you also using the same crown mics on the same body packs ?  take one that does not make noise and move to one that has hissssss. 

[John L Nobile]

Could it be rf-noise entering the analog preamp in tbe mic? When touching the antenna you divert some of the rf so it may not induce noise into the analog circuit.

I finished my firmware updates. 12 mics and I gotta say it feels weird updating the transmitters using IR, but it worked. Still gotta do the guitar and bass.

Noise was still there so I played with a few units (Crown CM311) and found that the noise was induced when the inline preamp (I think that's what it is) was near or touching the body pack. As I've been using these mics for years I'm going to assume that it's another QC problem since AKG bought them. I'm going to have to find another mic. 8 of them and so far I've yet to find anything that works as well as the Crown. 

Now that I think about it, could be the wiring in the TA4F connector. I'll have to check that tonight.

[Jens Palm Bacher]

I finished my firmware updates. 12 mics and I gotta say it feels weird updating the transmitters using IR, but it worked. Still gotta do the guitar and bass.

Noise was still there so I played with a few units (Crown CM311) and found that the noise was induced when the inline preamp (I think that's what it is) was near or touching the body pack. As I've been using these mics for years I'm going to assume that it's another QC problem since AKG bought them. I'm going to have to find another mic. 8 of them and so far I've yet to find anything that works as well as the Crown. 

Now that I think about it, could be the wiring in the TA4F connector. I'll have to check that tonight.

http://shure.custhelp.com/app/answers/detail/a_id/4903/~/ulxd1-bodypack-transmitter-and-crown-headset-mic---i-hear-noise

[John L Nobile]

http://shure.custhelp.com/app/answers/detail/a_id/4903/~/ulxd1-bodypack-transmitter-and-crown-headset-mic---i-hear-noise

Thanks for that link. It's from 3 years ago when I was using U4D systems with no problems. I have been having noise since I got the ulxd's but I thought I had things working by moving antennas and changing frequency. But the noise always came back.
Problem solved. I should have googled it a year ago. Guess I'll have to find new headsets.

[Keith Broughton]

Thanks for that link. It's from 3 years ago when I was using U4D systems with no problems. I have been having noise since I got the ulxd's but I thought I had things working by moving antennas and changing frequency. But the noise always came back.
Problem solved. I should have googled it a year ago. Guess I'll have to find new headsets.

How close do the antennas have to be to the mic cable to induce noise?
could you orient the pack belt clips so they hang upside down and run the mic cable directly up and away from the pack?

[John L Nobile]

How close do the antennas have to be to the mic cable to induce noise?
could you orient the pack belt clips so they hang upside down and run the mic cable directly up and away from the pack?

It seems to be when the inline preamp is near any part of the pack. And it's maybe a foot away from the jack.

I called AKG today and left a message. I emailed them a while back to complain about the build quality but never got a reply so I'm not expecting an answer.

[John L Nobile]

I called AKG again today and they returned my call. Third time a charm. I explained the issue which he had never heard about and sent him the link that Jens posted. (thanks so much for that Jens)
He's going to talk to his engineers about this and also about the build quality that has gone downhill since they bought Crown.
I hope to see them address and fix these issues but in the meantime I'm going to check out other mics. We have probably averaged 3 new mics a year for almost 20 years. At first we'd go through one or 2 a year but I've ordered 6 this year and last and I'm down to one spare.
I still love the sound of them though.

[Tim McCulloch]

I called AKG again today and they returned my call. Third time a charm. I explained the issue which he had never heard about and sent him the link that Jens posted. (thanks so much for that Jens)
He's going to talk to his engineers about this and also about the build quality that has gone downhill since they bought Crown.
I hope to see them address and fix these issues but in the meantime I'm going to check out other mics. We have probably averaged 3 new mics a year for almost 20 years. At first we'd go through one or 2 a year but I've ordered 6 this year and last and I'm down to one spare.
I still love the sound of them though.

AKG is a Harman brand, so is Crown.  It's not that AKG "bought" the CM series but that Harman decided microphone business belonged under the umbrella of AKG, as microphones are their primary product.  I think the corporate-speak is "realignment".

Man, I wish Sidney Harman was still alive and running the company...

[John L Nobile]

Here's the reply I got from AKG


 

It was stated in the answer – only a CM 311 redesign would solve this problem.

I dont think that this will happen, so maybe it helps to shield the EQ module with self glueing chopper band ( or any similar …).

To all of you merry christmas and I am back in the office 12.1.2016.


What is a "self gluing chopper band"? 

[Henry Cohen]

What is a "self gluing chopper band"?

Copper foil tape

[John L Nobile]

Copper foil tape

Thanks so much for that. I suppose "chopper" was a typo. I'll give it a try. I did try aluminum foil with no affect. Never thought of copper.

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