Electrolitc caps are more prone to leaky DC? Than poliester?

[Kleber AG]

Does electrolitc caps are more prone to leaky when used to coupling DC than poliester caps???

I'm trying to make a silicon-rangemaster booster pop-free, with a pull-down resistor after the out-cap but it still pops... even with a 100K resistor...

Thanks
Kleber AG

[leonhendrix]

most pulldown resistor are above 1meg ussally 2m2 or 4m7

leon

[jimmy]

use a bigger resistor like 1M or 2M2

edit: leon you totally beat me. guess i shouldnt let myself get so sidetracked...

good luck
Jim

[Kleber AG]

Sorry, let me explain better, first I had a 1M pull-down, but because of the pop I lowered to 100K just to see the difference and the pop is lower with 100K but is still there...

So I'm wondering:
"Does electrolitc caps are more prone to leaky when used to coupling DC than poliester caps???"
But it would be too dificult to change the electrolitic I have there to a polyester cap just to hear the difference... :?

Anyone had experiences with poping "electrolitic X polyester" caps???

Thanks
Kleber AG

[R.G.]

"Does electrolitc caps are more prone to leaky when used to coupling DC than poliester caps???"
But it would be too dificult to change the electrolitic I have there to a polyester cap just to hear the difference...

Yes, electrolytic caps leak more than polyester caps.

Electrolytic capacitors are a special case of materials used to do one special function to get miniaturization. They are leakier than all plastic film caps and have a limited lifetime because the electrochemical process that forms the insulating film inside them eventually reverses and they leak more and eventually die.

There is no slow wearout mechanism for plastic film caps like polyester, polypropylene, mylar, teflon, polystyrene, polycarbonate, etc. They have unlimited life if not overstressed. They also leak orders of magnitude less than electrolytics.

Electrolytics would never be used if anything else could be made that small and that cheaply. So electros fill the niche.

[Kleber AG]

Thanks RG,
So electrolytic caps may not be a good idea for input or output blocking DC caps???

I know the pulldown resistor is suposed to take care of that leaked DC from that caps, but in this circuit (rangemaster style) it looks to not be enough...

Yeah, I've read the "Why does my stompbox pop when I hit bypass?" article at Geofex, I may read that once again...

Thanks so much!
Kleber AG

[stm]

Some facts to consider:

1) Electrolytics do leak
2) Electrolytics do suffer aging (especially on power supplies)
3) Electrolytics do introduce audio distortion when used as bypass caps
4) If possible, use tantalum instead of electrolytic, since they have lower leakage and slightly less distortion
5) In audio decoupling applications, electrolytic capacitor polarity IS relevant.  For instance, if you have a transistor as an emitter follower, the decoupling capacitor going out the emitter should have the + terminal on its side. The - side of the electrolytic is the output and is usually connected to ground via some resistor.  If this cap is connected backwards, it is for sure that it will always be reversed-polarized -- not good.  The above is true in the context of single supply voltage, like in most guitar FX.

* I suggest you check if polarity of your electrolytic is OK. *

Good luck.

[Kleber AG]

* I suggest you check if polarity of your electrolytic is OK. *

Yes it's a rangemaster style of booster and the electrolitic output cap is with the "+" side at the transistor's colector...

I guess I'll have to change to polyester and use 1M pull-down resistor...
Right?  

Kleber AG

[R.G.]

Yes it's a rangemaster style of booster and the electrolitic output cap is with the "+" side at the transistor's colector...

If you used a PNP transistor and a positive ground, then the output capacitor is indeed backwards. I suggest that you use a voltmeter and measure whether the collector that the cap connects to is more positive or more negative than audio ground.

[Kleber AG]

Nope, it's NPN.

 After all, I changed the electrolitic out cap (that was well polarized) to a polyester cap and bingo!!!

No more audible pop...

Thanks everyone!
Kleber AG