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Old 19th January 2007, 06:21 PM   #1
hotscot is offline hotscot  Scotland
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Default LM3875 Volume pot

A value of 10K is often suggested but I could only find a 100K value.

Safe to use?

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Old 19th January 2007, 10:02 PM   #2
impsick is offline impsick  United States
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Old 20th January 2007, 09:30 PM   #3
AndrewT is offline AndrewT  Scotland
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Default Passive Attenuator

Hi Hotscot,
How have you assembled your chipamp?
inverting, non-inverting, DC block on NFB, DC block on input, Zin, NFB resistor values,

All the above will affect the DC output offset and they interact with what source impedance/resistance the amplifier input sees.

If you want to use a passive attenuator then Zin>=5times the attenuator resistance.

attenuator resistance >=5times the source resistance.

5times is the minimum, but 10times is better.

A disadvantage of using high attenuator resistance is loss of treble from the amplifier. Careful selection of component values can avoid many of the problems.
regards Andrew T.
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