What type of Capacitor

[marvin]

I was advised to install a 10 uF shunt capacitor across switch contacts to prevent a "pop" when opening the pro audio line level output circuit between mixer and amp. What type capacitor should I use? Is non-polarized OK?

Thanks,
Marvin

[Æ]

I was advised to install a 10 uF shunt capacitor across switch contacts to prevent a "pop" when opening the pro audio line level output circuit between mixer and amp. What type capacitor should I use? Is non-polarized OK?

Thanks,
Marvin

Use a film capacitor. All film capacitors are non-polarized. Film capacitors usually have higher voltage ratings than electrolytic capacitors too. But if you are unable to fit a larger sized film capacitor then use a smaller sized electrolytic.
Not being familiar with the circuit, I would definitely recommend a non polarized electrolytic over a standard electrolytic.
I am familiar with using a capacitor across switch contacts to minimize "pop" but I'm wondering why such a large value was recommended. 10uf seems kind of big to me.

[marvin]

Use a film capacitor. All film capacitors are non-polarized. Film capacitors usually have higher voltage ratings than electrolytic capacitors too. But if you are unable to fit a larger sized film capacitor then use a smaller sized electrolytic.
Not being familiar with the circuit, I would definitely recommend a non polarized electrolytic over a standard electrolytic.
I am familiar with using a capacitor across switch contacts to minimize "pop" but I'm wondering why such a large value was recommended. 10uf seems kind of big to me.

Thanks for the prompt reply, AE.
My installer just mentioned the 10 uF off the cuff when I asked him what size to use. What size would you suggest?

[Æ]

Thanks for the prompt reply, AE.
My installer just mentioned the 10 uF off the cuff when I asked him what size to use. What size would you suggest?

Can you actually hear the "pop?' I would start out with smaller sizes and listen for the afore mentioned pop, then move up to larger values until the "pop" disappeared. Since I have drawers full of parts, it would be easy for me to do.

But if his recommendation has already been used successfully by other people then by all means follow his recommendation.

I have several times heard a "pop" coming through the system from the on/off power switch. In those cases I will use something along the order of .1 uf. And it will be a high voltage ceramic disc capacitor not film or electrolytic.

[marvin]

Can you actually hear the "pop?' I would start out with smaller sizes and listen for the afore mentioned pop, then move up to larger values until the "pop" disappeared. Since I have drawers full of parts, it would be easy for me to do.

But if his recommendation has already been used successfully by other people then by all means follow his recommendation.

I have several times heard a "pop" coming through the system from the on/off power switch. In those cases I will use something along the order of .1 uf. And it will be a high voltage ceramic disc capacitor not film or electrolytic.

FYI, AE, these circuits are balanced XLR or TRS connections.

Our present switches are just SPST toggle switches. Lately, when turning one of the switches off (open), the speaker produces a very audible ground loop type hum. Our solution is to use SPDT switches which will open the + (number 2) signal lead from the source while the double throw function shorts the signal + to the signal - in the cable going to the amp rack. We have tested this with jumpers, and it works. When I questioned whether it would produce a pop, he suggested adding the cap for insurance. It does not produce a pop now, but we are only opening the + signal wire, not shorting it to the -.

The output of the Mackie mixer is 28dBu, so I would expect any of the Polyester film caps in the PE catalog should fit the bill. They are all rated at 100V or more. I am expecting to place a PE order soon, so thought I would just order a few caps in case I need them. I will try some .1 http://www.parts-express.com/pe/show...TOKEN=70730423 and some .5--they want a minimum quantity of 10. I will have spares, but they are inexpensive.