|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
209.78.23.141
I purchased some of the Audioprism Quietlines and am quite pleased with the results, but would now like to go further.
I am writing with a quick question about the hot to neutral cap tweak mentioned on the Magnan website that is said should be installed as close as possible to the IEC input of the CD player. Is it possible to simply open the CD player and solder a 50uF cap from the “black” prong of the input IEC to the “white” prong of the IEC on the inside of the CD player and thereby achieve the desired filtering without building a fancy plug adaptor? Is this the so-called "Auricap tweak"?
If not, could someone explain in detail how to build the needed adaptor? Do I simply need to wire a female IEC plug to a male IEC plug using a black, white, and green wire, and in the middle run a cap across the black and white lines? Also, Magnan mentions that to avoid shock one can use a 10kOhm ½ watt resistor. To wire this, would I just run the 50uF cap and the resistor in parallel across the black and white wires?
Also, to make these filters, do I need to use some special kind of cap that can handle AC line voltage? Magnan says metallized polypropylene...
Thanks so much for your help.
Chris
Follow Ups:
Are you sure it is 50uF? It will be really big if it is 50uF at 250VAC
Magnan's website tweak section says 50uF, but when I e-mailed Magnan they said it should be 5-10uF with a 0.47uF bypass and a 0.1uF bypass.
Sorry about that; this still seems much bigger than what other on this forum have discussed, and very big for an X1-rated cap...
Chris
ChrisA single .47uf and .01uf bypass if the min amount for this filter project. You can fine tune the filter by increasing the number of bypass caps. When I make the filter I use the older 40uf model using two 20uf caps. I use two bypasses to support the main caps. The additional bypass caps open up the mids and top end detail.
Good luck finding 10uf x-caps....so if you decide to use polypropelene metallized caps make sure you keep the voltage at around 600v for safety and only use caps that have been tested. I have seen a lot of caps at 600v heat up and smoke after a few days...so be careful.
Look for R-C and Al Sekela as the author here and in cables. Al's posted numerous times about how to do this. You want to do it correctly, as there's always some danger with AC.I made several versions of these from Al's designs. They work well OUTSIDE the box. Could you do inside? I suppose so, but the intervening jack assembly them has an impact.
You can make these as simple parallel line filters and they're cumulative and don't have to be on your PC itself, you know. A cheap 2 prong plug and a cap and a resistor in series is what does it, properly constructed and properly covered to prevent shock.
YOu must use AC rated caps, though. X or X2 or Y. Read Al's posts on this first and make sure you understand or ask more questions.
Thanks for the help. I have another question, however. Why does Al recommend having the resitor in series with the caps while Magnan says the resistor should be in parallel to dissipate the charge from the caps when unplugged? Sorry if this is ignorant, but it seems to be an important difference and I don't know enough about AC power to understand the difference of opinion
Also, can one use normal resistors, or is there some special type people like for this application? I known Al recommends PRP resitors for the speaker R-C filters, but for AC I don't know... Thanks
Chris
The QuietLines approach is to use a resistor in series with a capacitor. The purpose of the resistor is to dissipate the energy in RF noise on the AC line, and the purpose of the capacitor is to keep substantial 60 Hz power out of the resistor.The AC line acts like a transmission line with approximately 120 ohms characteristic impedance. If you terminate such a line with a low impedance, which is what the Magnan tweak does, RF noise will be reflected from the filter and go somewhere else to cause trouble. If you terminate it with a 120-ohm resistor, then the noise will stop at the resistor, but you will dissipate a lot of 60 Hz power in the resistor (120 watts). By using a series capacitor of the correct size (say, one microfarad or less for half-watt resistor), the RF noise will be dissipated but the 60 Hz power will be kept to a quarter of a watt or less.
A very large capacitor may retain a powerful jolt if it is disconnected from the AC line at just the right instant. This is why Magnan recommends a shunt resistor to dissipate any remaining charge. The stored charge in a small cap will be small and IMO you do not need a shunt resistor. It will not hurt to have one, however.
The capacitors must be X- or Y-rated to avoid a fire hazard. Even with an X-rated cap, however, you can get a short-circuit failure. This would cause the resistor to burn out. A non-flame-proof resistor will burst into a flame about the size of a kitchen match, so provide a suitable fire-proof housing if you do not use a flame-proof resistor.
Hi Al
Thanks for the very helpful info. So a good starting point to make a filter for the input to my CD player could be [a 1uF cap perhaps bypassed with a 0.1uF cap placed in series with a 1/2 watt 120ohm fireproof resistor] between the hot and neutral line? Does it matter which line is attached to the resistor and which to the capacitor? I seem to remember for your recommended speaker R-C filters there was a directionality, but I don't remember which way they went.
Thanks again
Chris
Also, you might want to use some smaller caps as well, with a separate resistor for each. You can get Y-rated caps at very small values, and these are safer than X-rated types.
You'll have to ping Al for the theory. Not my department!I use the flameproof resistors you can buy pretty much anywhere. It's a safety issue.
This post is made possible by the generous support of people like you and our sponsors: