[mboxler]

Hi

When I built my Class D Audio amp (SDS), I replaced the 10K pot with one 2.2K resistor at the point where pins 2 and 3 of the pot attached to the board.  Seemed to work...all done.  Since then, I've been learning more about electronic circuits.  I'd say I've gone from knowing nothing to knowing very little.   

One thing now bothers me.  The 10K pot is a variable voltage divider.  At full volume, 0 ohm resistance to input stage, 10K ohm to ground.  Turn the knob...the 10K is divided between the input stage and ground. 

Is it true that the 10K pot is included in the 47K input impedance of the amp, regardless of it's setting?  Should I have wired a 7.8K resistor between pins 1 and 2 on the board to obtain the full 10K resistance?

Thanks for another lesson.

Mike

[Davey]

If the 10k pot is upstream of your amps input your source now see's an 8.24k minimum load.  (10k in parallel with 47k at max volume.)  Shouldn't be a problem in most cases.

I'm not sure about your SDS 2.2k ohm implementation.  Would need to see the schematic to see where the pot/resistor fits into the topology.

Cheers,

Dave.

[Folsom]

If the 10k pot is upstream of your amps input your source now see's an 8.24k minimum load.  (10k in parallel with 47k at max volume.)  Shouldn't be a problem in most cases.

I'm not sure about your SDS 2.2k ohm implementation.  Would need to see the schematic to see where the pot/resistor fits into the topology.

Cheers,

Dave.

Right, if you are voltage dividing you'll never completely do away with resistance.

Try two of these, you can easily adjust them in the 1khz-10khz range to see what sounds best 

[mboxler]

If the 10k pot is upstream of your amps input your source now see's an 8.24k minimum load.  (10k in parallel with 47k at max volume.)  Shouldn't be a problem in most cases.

I'm not sure about your SDS 2.2k ohm implementation.  Would need to see the schematic to see where the pot/resistor fits into the topology.

Cheers,

Dave.

Thanks, Dave

The inputs are on the right side of the picture.  The gain pot is appears to be after the inputs and before the input stage of the amp (the picture isn't too clear, but there are three pins next to each input).  I placed the resistor between pins 2 and 3, leaving pin 1 open.  Had the 10K pot been used, and the resistance between pins 2 and 3 been 2.2 K, the resistance between pins 1 and 2 would have been 7.8 K (?).

My question is this...is the full 10K resistance of the pot included in the 47K input impedance of the amp.  Should I have wired a 7.8k resistor between pins 1 and 2?