Pull Down resistors for anti-pop ...

[Melanhead]

I just noticed this but while going through schematics/layouts ( my own, and others here ) I've noticed a trend of putting an anti-pop pull down resistor on the input but not the output.

I recently read a few articles at RG's website where he mentions using them on the outer leg of the Input AND Output of the DC blocking caps.

Have we become lazy and just put 'em on the input, or is it more a case of try putting one on the input and if the pop goes away then don't bother with the output ?

Comments ?

[George Giblet]

They should go on both.

> don't bother with the output

I don't think people are lazy, just don't know they should use it (the same reason that some people don't put them on the inputs!!).

[Mihkel]

There's usually a volume pot on the output that does that.

[Melanhead]

There's usually a volume pot on the output that does that.

hmmmm never thought of that ... So what you're saying is that as long as there is some kinda resistance on the ouput leg of the Out  blocking cap then that's sufficient ?

THAT would explain a lot

[R.G.]

hmmmm never thought of that ... So what you're saying is that as long as there is some kinda resistance on the ouput leg of the Out  blocking cap then that's sufficient ?

Resistors is resistors.

You need a DC resistance to ground on the outside of BOTH the input and output to avoid generating pops when switching single supply effects. Any resistance which is smaller than 1/100 of the DC resistance of the input or output CAPACITOR's leakage resistance will do nicely. Generally the capacitors have resistances that are much bigger than 1M ohm. Of course, smaller resistor values work too.

An output volume control of 1M or less with its cold side grounded fits the bill.

[Melanhead]

Great! ... I just learned something! ...


Wish I had the theory backround to figure this out on my own though