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Author Topic: Mi.C power supply  (Read 1417 times)

nappy

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Mi.C power supply
« on: December 24, 2023, 10:11:22 PM »

this power supply was presented to me as one that can power an m49
it looks identical to an n52 except for having "Mi.C" etched into its face
no Nr serial, no neumann logo
can anyone id this thing?     -m

mike napolitano - no affiliation
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Kai

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Re: Mi.C power supply
« Reply #1 on: December 26, 2023, 07:46:19 AM »

Mi. C probably is an individualized engraving.
Units with Mi. A and Mi. B likely have existed too.

The engraving does not characterize a certain model.

If you post pictures of the internals and the back someone could identify what it is.


Additionally, a measurement of the output voltages is mandatory anyway before plugging a valuable mic into the thing.

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nappy

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Re: Mi.C power supply
« Reply #2 on: December 26, 2023, 09:22:04 AM »

thanx Kai
howz this?
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nappy

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Re: Mi.C power supply
« Reply #3 on: December 26, 2023, 09:22:46 AM »

howz this? pt2
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Kai

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Re: Mi.C power supply
« Reply #4 on: December 26, 2023, 03:12:04 PM »

thanx Kai
howz this?
Its a tube mic power supply of unknown origin, from 1966.

Might work for an AC701k powered tube mic like the M49.

Heater voltage has electronic stabilization and can be trimmed with the black wire-wound resistor.
Anode voltage has a zener stabilization to 150 V and some resistor arrangement that might bring it down to the 120 V needed.


The following, if youre familiar with handling high, possibly deadly voltages:
Else: keep your hands off, find an expert, you only live once.


I suggest to connect dummy loads and check the voltages:

Anode voltage 120 V +/- 5% into dummy 235 kOhm.
Heater voltage 3.95 V + 0.00 /-0.05 V into dummy 40 Ohm.
Control voltage 0-120 V adjustable from the front, into dummy 2 MOhm.

No AC (hum) voltage should be measurable, or something is broken.

Once the supply is found working, you can calibrate the heater voltage for your microphone.
The heater voltage has to be measured at the mic side, including the cable voltage drop.
Anode voltage isnt mission critical.
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nappy

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Re: Mi.C power supply
« Reply #5 on: December 26, 2023, 03:22:53 PM »

..and again, thnx!
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