small value caps in AC lines

Hap · « **on:** 10 Dec 2007, 07:13 am »

Am new to this board, and would appreciate any feedback on this issue.
I have several component power cables that have small value capacitors; three 0.1uf 250v polypropylene NP caps connected in a triangle series between the three plug side terminals, but never on the component end, or IEC socket end.
Am pretty sure this is to suppress some of the high frequency from passing through the system mains, but please correct me if I am wrong.
Are there any other values that are used for different components; amps, preamps, ESL speakers or turntable CD source.
Cheers All.

Occam · « **Reply #1 on:** 10 Dec 2007, 08:14 pm »

Hap,

Welcome to AC. Those caps are a parallel, delta, capacitor filter. One cap is connected as an X cap across the line, from hot to neutral. And the other 2 are configured as Y caps from hot to ground and neutral to ground. The X caps function is basically to shunt noise from the hot to neutral prior to it entering your equipment. The Y caps which shunt noise to ground from both lines, and are limited in value because of leakage issues and a tendancy to trip ground fault breakers. Folks tend not to use Y caps of greater the .1uf, if that.

X caps are a whole nuther matter. Many recommend paralleling multiple caps which provides benefits over using a single cap of the same total capacitance. One vendor makes such with 4,8, 16 capacitors which are, around 2+, 4+, and 8+? uf of capacitance each in total. Another vendor, Gilbert Yeung, of Blue Circle Audio makes his BC6000 ac cross the line capacitive filter, consisting of 157

paralleled capacitors, functioning as a single (albeit wicked) X cap.

I'll give the standard caveats..... use only capacitors rated for those functions, X2 caps for ac cross the line use, and Y2 caps for caps that shunt to ground. Mains power is very dangerous if not treated with the proper knowledge (and fear).

richidoo · « **Reply #2 on:** 10 Dec 2007, 08:17 pm »

Paul, you never cease to amaze with your broad knowledge.

Do most high end power cords have caps? I never knew...
Thanks
Rich

tanchiro58 · « **Reply #3 on:** 10 Dec 2007, 09:10 pm »

Quote

I'll give the standard caveats..... use only capacitors rated for those functions, X2 caps for ac cross the line use, and Y2 caps for caps that shunt to ground. Mains power is very dangerous if not treated with the proper knowledge (and fear).

Occam,

What kind of caps and what values would you suggest to do in AC line? How about in the DC line like the output caps would have the same effects like AC? Thanks.

Regards,
Tan

Occam · « **Reply #4 on:** 13 Dec 2007, 01:01 am »

Rich,

As far as I know, most high end powerords do not contain capacitors, as such. Some cords, like those from the late Bob Crump, have many pairs of twisted conductors carrying the hot and neutral, which actually make a very high quality 'across the line', X type cap. I have heard of some cords that actually contain caps, but don't know the specifics.

Thanks for the complement, I think.

Sadly, its the unintended result of a misunderstanding on my part. 35+ years ago when I was just a wee sprat, I was waxing poetic about capacitors in a experimental physics lab, (specifically about capacitive voltage multipliers aka Cockcroft-Walton circuits) and an exasperated Senior commented - "Golly Paul, such musings will make you a great babe magnet!"
Sadly, it was only years later that I realized he was being facetious.

Tan,

For across the line, for hot to neutral, you should use a X2 rated cap (Y2 caps are also fine, and within codes for this use). I've personally not gone above 3uf in total for this use, but given what Blue Circle, Alan Maher, etc... is doing with their products, I guess you could go substantially higher. You should bypass your main cap, with one 1/5 - 1/10 of the prior value, and then bypass that with.... so that if you started with a 1uf cap, you could bypass (wire in parallel) a 0.1uf cap, and a 0.001uf cap.

Dunno why, but different caps, and their combinations can sound quite different subjectively, even though their action is quite a bit upstream of the actual audio. Among the better manufacturers of X2 and Y2 caps are Vishay, Epcos, Wima, Mallory and Evox/Rifa. Nor is the standard 'polypropylene is better than..." necessarily true as Vishay and Mallory make very good mylar caps for this use, and Wima and Rifa make excellent metalized paper caps.

As far as Y2 caps for ground to line/neutral use, I don't use them, nor do many audio power conditioner makers. Audience does in their 12 outlet Adept (a pair of 33nf) and Isotek uses multiple 4.7nf caps.

FWIW,
Paul

richidoo · « **Reply #5 on:** 13 Dec 2007, 02:22 am »

Quote from: Occam on 13 Dec 2007, 01:01 am

Thanks for the complement, I think.

Sincere as can be!

Thanks
Rich

zacster · « **Reply #6 on:** 17 Dec 2007, 09:34 pm »

http://www.justradios.com/safetytips.html

This is a pretty good discussion of safety caps as it applies to radios. It applies equally well to other audio gear.

kyrill · « **Reply #7 on:** 18 Dec 2007, 03:23 pm »

GOOD read zacster

however more and more highend (?) line conditioners manufacturers use Audio film caps ( metallised film Auricaps for instance) as X ( or Y?) caps Maybe it is hearable..