470k bypass resistor for EQ capacitors

[ed rees]

What is the purpose of 470k capacitors in parallel with capacitors in a passive EQ? Most seem to be on the large value caps, but there is one .25uf with the resistor and another in a different band without it.

What makes the distinction between placing one or not placing one across a capacitor? Thank you.

 

[ruffrecords]

I have not heard of this technique before. Can you point to a schematic the demonstrates it?

Cheers

Ian

 

[warpie]

I'm not familiar with such topology either.
Maybe you mean 4.7M in parallel with the caps, in order to avoid 'clicks' if the switch is BBM?
Although 1M is a more common value for this purpose, I think some circuits (including Neve?) use 4.7M .

 

[joaquins]

If the network is a much lower Z than 470K it won't harm... but I used between a cap to the next instead of parallel with each cap, you get 1 resistor less and, I guess, less losses.

JS

 

[ruffrecords]

If click prevention is what you are after then 4.7Meg resistors across switch contacts, rather than across capacitors, will do the trick.

Cheers

Ian

 

[warpie]

I've seen circuits where the resistor is across the cap rather than across the switch contacts so I thought it wouldn't make any difference.
Possibly is easier across the caps if you use panel mount switches.

 

[ruffrecords]

I've seen circuits where the resistor is across the cap rather than across the switch contacts so I thought it wouldn't make any difference.
Possibly is easier across the caps if you use panel mount switches.

Can you give a link to an example?

Cheers

Ian

 

[warpie]

Can you give a link to an example?

Yes sure, I guess it depends on the circuit. Here, effectively it's the same thing.

But it's still no clear to me what the OP's question is.

 

[ed rees]

That's essentially what I'm asking about, Warpie. Is this resistor-across-capacitor sufficient to allow use of a non-shorting switch and not experience audible popping? It'd be nice not to have to use custom order switches with a 2 month lead time...

Thank you!

 

[gyraf]

Switching inductors will always give you some degree of popping (inductors dod't take lightly having current cut off instantly) no matter what type of switch you use.

But it will be reduced by using shorting switches and those cap leak resistors.

Jakob E.