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Re: A hum while on charge

Subject: Re: A hum while on charge
From: Klas Strandberg <>
Date: Sun, 09 Mar 2003 14:24:14 +0100
Someone wrote:

">It's not the cable between the Telinga and Portadisc. I've replaced that 
>cable and am using a 5 pin XLR connector and Canare star quad cable. So, 
>it's all balanced cabling as far as the Telinga handle." 

--------

Hm... Just to make sure:

There are two inputs in a balanced mic amplifier. Pin 2 is one input and pin
3 the other. When recording, both inputs must "see" the same impedance. 

The output of a PRO5W handle is 200 Ohms. If the signal lead is connected to
pin 2 (hot / signal) the other lead (cold / no signal) must be connected to
ground - at the PC board, inside the handle - with a 10 mfd condensor and
200 Ohms resistor.

Then, a induced hum in the cable going to pin 2 will be cancelled by the
same induced hum in the cable going to pin 3, as the two amplifiers are
working out of phase with one another. 

Klas.


Telinga Microphones, Botarbo,
S-748 96 Tobo, Sweden.
Phone & fax int + 295 310 01
email: 
       



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