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Author Topic: Neumann U67 - C17 and C10 capacitors values and voltages  (Read 1011 times)

Kai

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Re: Neumann U67 - C17 and C10 capacitors values and voltages
« Reply #15 on: August 08, 2022, 05:02:56 PM »

I respectfully disagree: reducing gain at/before the FET gate does not remove any amplifier self-noise past the FET stage. At equal gain settings between padded and unpadded U87, the mic's signal-to-noise ratio is audibly reduced, around 6dB if not more.

Perform the test yourself and listen.
That’s exactly what I meant:
The -10 dB pad reduces S/N ratio by only about 6 dB for a given SPL, not 10 dB like initially assumed.
This even means the absolute self noise goes down ca. 4 dB and the dynamic range up by the same amount, but only for very loud sources close to 127 dB SPL peak.

The pad is meant to be used with these loud sources, like a closed mic’ed trumpet, tympani etc. e.g., to avoid internal overload in the mic.
I used a bunch of them on jazz drums with great results (pure luxury), without pad the toms sounded distorted, great with pad.

Unpadded the U 87 can stand just 117 dB SPL, that’s not enough for quite a number of instruments.

Using the pad in a spoken word production e.g., would be a stupidity of course.


BTW:
U 87 can put out 0.39 V only.
If your mic pre can be dialed down to 28 dB gain or lower, U 87 typically can’t overload it, assumed it has internal max. voltage of 10 V.
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RadarDoug2

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Re: Neumann U67 - C17 and C10 capacitors values and voltages
« Reply #16 on: August 09, 2022, 05:12:56 PM »

Neumann are not dummies. The pad is a tool, put there to use when sources are loud. The signal to noise of the amplifier does not significantly change.
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klaus

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Re: Neumann U67 - C17 and C10 capacitors values and voltages
« Reply #17 on: August 09, 2022, 05:56:01 PM »

We are going around and around on this.
Everyone had a chance to opine, and I am closing this thread.
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Klaus Heyne
German Masterworks®
www.GermanMasterworks.com
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