Active Filter Capacitor Voltage Rating

substrate · 21st April 2011, 02:11 AM

Hi,

I'm building an active crossover right now and would like to use Vishay MKP filter capacitors, with a 5mm lead spacing. Digikey has some in stock, though they are rated for 25VAC / 63VDC. Is this AC voltage rating too low in anyone's opinion? I was hoping to get caps rated for 63VAC.

part no. BFC241644703

Alternatively, does anyone have any recommendations for MKP's with a 5mm spacing?

Thanks

stratus46 · 21st April 2011, 03:46 AM

25 Volts AC _across_ the cap in a crossover? I wouldn't expect even 5 V AC in normal operation. Look more if you feel the need but I'd use them without hesitation. You know that 25 Volt is almost 9 Volts RMS. A few power amps here don't get to 25 V p-p at the output much less the input.

G²

substrate · 24th April 2011, 03:36 AM

Okay thanks for the response.

The reason for the question was because Rod Eliot from ESP indicated that filter caps should be rated for 63V. I just wasn't sure if that was the DC or AC rating.

I understand that the voltage levels will be very low (based on the gain of your input buffer, which is usually unity) but thought, perhaps, that people prefer using caps with a higher voltage rating because they sounded better.

sofaspud · 24th April 2011, 07:22 AM

I don't know about sounding better, and don't really want to go there. I may be wrong but I tend to think what you read from Mr. Elliot was within a certain context, eg a 5V supply and a 40V supply both need 63WVDC capacitors??
My rule of thumb (I say "my" but probably picked it up somewhere) is to add ~50% to whatever voltage I'm working with. More than that won't hurt and I second stratus46; I'd use those MKPs without hesitation.

infinia · 24th April 2011, 09:24 AM

25 Vac = 63 Vp-p they are the same specs ie dielectric strength rating

most active solutions involve op-amps with +/- 15 supplies, which is about 30V pp max. so you already have 2 to 1 safety margin when using 63Vdc caps.

21st April 2011, 02:11 AM	#1
substrate diyAudio Member Join Date: May 2003 Location: Winnipeg, MB, Canada	Active Filter Capacitor Voltage Rating Hi, I'm building an active crossover right now and would like to use Vishay MKP filter capacitors, with a 5mm lead spacing. Digikey has some in stock, though they are rated for 25VAC / 63VDC. Is this AC voltage rating too low in anyone's opinion? I was hoping to get caps rated for 63VAC. part no. BFC241644703 Alternatively, does anyone have any recommendations for MKP's with a 5mm spacing? Thanks

24th April 2011, 07:22 AM	#4
sofaspud diyAudio Member Join Date: Nov 2005 Location: San Antonio TX	I don't know about sounding better, and don't really want to go there. I may be wrong but I tend to think what you read from Mr. Elliot was within a certain context, eg a 5V supply and a 40V supply both need 63WVDC capacitors?? My rule of thumb (I say "my" but probably picked it up somewhere) is to add ~50% to whatever voltage I'm working with. More than that won't hurt and I second stratus46; I'd use those MKPs without hesitation. __________________ It is error only, and not truth, that shrinks from enquiry. - Thomas Paine

24th April 2011, 09:24 AM	#5
infinia diyAudio Member Join Date: May 2005 Location: Californication	25 Vac = 63 Vp-p they are the same specs ie dielectric strength rating most active solutions involve op-amps with +/- 15 supplies, which is about 30V pp max. so you already have 2 to 1 safety margin when using 63Vdc caps. __________________ like four million tons of hydrogen exploding on the sun like the whisper of the termites building castles in the dust

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Capacitor Voltage Rating Question	Trout	Tubes / Valves	11	5th June 2009 06:49 PM
Capacitor voltage rating in dots?	olev	Parts	9	9th July 2007 07:41 AM
Capacitor Voltage Rating	diyman	Solid State	2	21st December 2004 02:49 PM
Capacitor Voltage Rating	Super_BQ	Parts	14	22nd September 2001 03:50 AM


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

21st April 2011, 03:46 AM	#2
stratus46 diyAudio Member Join Date: Nov 2009 Location: Los Angeles	25 Volts AC _across_ the cap in a crossover? I wouldn't expect even 5 V AC in normal operation. Look more if you feel the need but I'd use them without hesitation. You know that 25 Volt is almost 9 Volts RMS. A few power amps here don't get to 25 V p-p at the output much less the input. G²

24th April 2011, 03:36 AM	#3
substrate diyAudio Member Join Date: May 2003 Location: Winnipeg, MB, Canada	Okay thanks for the response. The reason for the question was because Rod Eliot from ESP indicated that filter caps should be rated for 63V. I just wasn't sure if that was the DC or AC rating. I understand that the voltage levels will be very low (based on the gain of your input buffer, which is usually unity) but thought, perhaps, that people prefer using caps with a higher voltage rating because they sounded better.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read