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Author Topic: Neumann SM69fet popping noise  (Read 644 times)

Jogging

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Neumann SM69fet popping noise
« on: June 02, 2024, 04:23:41 AM »

Hi there. Have an original SM69 with an CU 48 K power supply. Any chance there are some schematics floating around?
The mic pop noises in some settings. Many thanks in advance.
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Kai

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Re: Neumann CU 48 K Schematics
« Reply #1 on: June 02, 2024, 12:23:27 PM »

If the pop noise appears in one channel only, the problem likely is inside the mic.
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klaus

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Re: Neumann CU 48 K Schematics
« Reply #2 on: June 02, 2024, 05:41:07 PM »

Please upload a sound sample of the popping.
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Klaus Heyne
German Masterworks®
www.GermanMasterworks.com

Jogging

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Re: Neumann SM69fet popping noise
« Reply #3 on: June 10, 2024, 06:20:24 AM »

Hi Klaus. I've uploaded some noise samples. Maybe popping is the wrong description. 2 files. Each for the individual system. I also realised that the individual gain seems to differ depending on the polar pattern setting. Sometimes System I seems louder, sometimes System II. It's difficult te reproduce the noise to begin with. Seems random. Hope that makes sense.

Here's a link
https://www.dropbox.com/scl/fo/lk8jhi6qxjcr6ikp1say7/AKt8ghMy9KVzwIc4Utnkjvc?rlkey=n00gdksyywcoaen5n55alx4dh&dl=0
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klaus

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Re: Neumann SM69fet popping noise
« Reply #4 on: June 10, 2024, 12:00:10 PM »

The fact that both systems (which have completely separate capsule and processor systems) have a similar noise profile leads me to believe that this is an issue outside of the mic.

I also do not exclude cell interference as cause of the noise, which would point to the XLR audio cables and their ground/shield terminations (do a search on my recommendations for proper ground/shield).
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Klaus Heyne
German Masterworks®
www.GermanMasterworks.com

Jogging

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Re: Neumann SM69fet popping noise
« Reply #5 on: June 11, 2024, 03:13:36 AM »

But it’s not both systems. System I has no noise. There are two files in it. Only one has the noise on it. They only seem to have different gain structures. Depending on the polar pattern issue. Would you still consider it a PSU issue?
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klaus

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Re: Neumann SM69fet popping noise
« Reply #6 on: June 11, 2024, 01:26:54 PM »

You named your dropbox download containing the two sound files "System 1" and "System 2", just like Neumann refers to the two systems.

What am I not getting here?
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Klaus Heyne
German Masterworks®
www.GermanMasterworks.com

afterlifestudios

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Re: Neumann SM69fet popping noise
« Reply #7 on: June 12, 2024, 12:14:30 AM »

Both of your files certainly do have the noise in them.  System 2 noise is louder.  So, I'm with Klaus...   Could be something external getting in with improper shielding / termination in your sm69 setup...
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Jogging

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Re: Neumann SM69fet popping noise
« Reply #8 on: June 12, 2024, 01:53:44 PM »

Cool. One of them has a just a much louder noise response. So I was just not sure if I haven’t made a mistake exporting. But I guess you’re both have a valid point to begin with. Many thanks for that! Honestly greatly appreciated.
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