Bypassing a volume pot

[whitelabrat]

If an amp specifies the use of a 100k volume pot, what is the proper way to bypass it so as to be free of volume control?

I ask because I have a Alpha pot in my headphone amp that is driving me nuts. The vol control on the audio source is fine by itself.

 

[kacernator]

Replace the pot with 100k resistor. Connect it where went the wiper out and then connect it to ground. Usualy 100k will be connected from grid, before any grid stopper, to ground.

 

[leadbelly]

Do you have a schematic? The answer may be that you don't need to add any resistor or that a bigger value resistor might be a better choice.

 

[whitelabrat]

I've got a couple things in mind, but for the sake of argument let's analyze this one:

An externally hosted image should be here but it was not working when we last tested it.

 

[leadbelly]

For that example there's no need to replace it with anything.

 

[bayermar]

Hi Labrat,

If you are unsure, the safest way would be to parallel R1 (1M) with a 100k resistor and feed the signal directly to the connection where originally the wiper went (junction of 100k, 1M and 100R resistors).
This way your amp still has ~100k input impedance.

If I understand the basics right, leaving the input open (without the 100k resistor) would increase your input impedance (mostly determined by R1=1M). In most cases that might not be a problem but I am always scared of picking up RF if the input impedance is too high.

My 1 1/2 cents worth...

Martin

 

[whitelabrat]

All good advice. Thanks!