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Old 4th August 2011, 12:43 AM   #1
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Default Microphone modification help

Would someone please direct me to the components for this modification?
I don't understand all of the locations and the type of components described.
I have removed C9 and C10, I have replaced the tube.
Thanks in advance.


1. Remove C9 and C10 to remove the 25Khz peak resonance in the high end.

2. Change the caps in the signal path: Polystyrene input and 1uF polypropylene output (C8)

3. Change the tube to a 6072 or a very good 12AT7

4. Add a tiny EQ cap like that found in the ELA m251 design, to the output of the 1st stage. I like 200pF myself.
Optional:

5. Change the cathode bypass cap from 100uF to 22uF to reduce low frequency rumble and distortion.

6. Change the cathode bias resistor to 1.8K to increase plate current in both tubes and improve biasing on the 2nd stage.
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Old 4th August 2011, 02:01 AM   #2
SY is offline SY  United States
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Schematic, please?
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Old 4th August 2011, 02:52 AM   #3
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I thought I attached. Thanks
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Old 4th August 2011, 06:20 AM   #4
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Unreadable, use *.png instead.
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Old 4th August 2011, 12:36 PM   #5
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OK
Thanks
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