Thread
:
exceeding heater to cathode voltage
View Single Post
#
4
Chris Hornbeck
Posts: n/a
On 15 Apr 2005 12:44:00 -0700,
wrote:
i'm actually modifying an existing mic pre, and one thing they did that
i don't understand is they return each side of the AC heater supply to
ground with a 1k resistor. what is this done for?
Hum reduction. Make a voltage divider (pulling about 1mA)
to make a 75 volt reference. Bypass with a capacitor and
move the heater ground reference up there.
Piece of cake.
Chris Hornbeck
6x9=42 April 29
Reply With Quote