Bleeder Cap Question

lpd · 19th October 2007, 07:02 PM

I recently built a volume pot with shunt resistor in a box. I then tried ot add a bleeder cap (200pf) and 75 ohm resistor to ground as suggested in a thread here. I found it removed some of the overall transparency. What would the purpose of adding a cap/resistor to input to ground other than rolling off the top frequencies?

Thanks,

richie00boy · 19th October 2007, 07:11 PM

Got a link to the thread you mean? Seems a barmy idea if it's as you describe. Can't see what it could be bleeding either, other than the high frequencies down the drain.

sharpi31 · 19th October 2007, 08:08 PM

The 200pf cap and resistor will drain RF interference on the signal wire to ground.

Personally I'd do this at power amp chip input pin but this will depend on whether you have built your own amp :-)

lpd · 19th October 2007, 09:14 PM

I tried it both with a 100K Alps pot, 10 shunt resistor, and 200pf/75 ohm resistor on the input to ground. Personally I find the bleeder doesn't just take the rf out, but it seems to bleed out some of the top end. Maybe I'm mistaking the rf noise as top end frequency.

19th October 2007, 07:02 PM	#1
lpd diyAudio Member Join Date: Nov 2003 Location: BC	Bleeder Cap Question I recently built a volume pot with shunt resistor in a box. I then tried ot add a bleeder cap (200pf) and 75 ohm resistor to ground as suggested in a thread here. I found it removed some of the overall transparency. What would the purpose of adding a cap/resistor to input to ground other than rolling off the top frequencies? Thanks,

19th October 2007, 07:11 PM	#2
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Got a link to the thread you mean? Seems a barmy idea if it's as you describe. Can't see what it could be bleeding either, other than the high frequencies down the drain. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

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19th October 2007, 08:08 PM	#3
sharpi31 diyAudio Member Join Date: Oct 2005	The 200pf cap and resistor will drain RF interference on the signal wire to ground. Personally I'd do this at power amp chip input pin but this will depend on whether you have built your own amp :-)

19th October 2007, 09:14 PM	#4
lpd diyAudio Member Join Date: Nov 2003 Location: BC	I tried it both with a 100K Alps pot, 10 shunt resistor, and 200pf/75 ohm resistor on the input to ground. Personally I find the bleeder doesn't just take the rf out, but it seems to bleed out some of the top end. Maybe I'm mistaking the rf noise as top end frequency.

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