power cord with filter?

[Cowanrg]

i just got a couple new subs and was going to put some upgraded power cords on them. i already have a few different brands on my system, and i work for an audio shop, so i can get a couple good ones cheap, but i want something different...

after seeing thomasw's balanced power project, i was thinking about doing a power cord with built in RF/EMI filter, and the cap across the hot and nuetral wires. it would sit in a little metal box that would be inline with the cable.

i already have all the wire and connectors, im just wondering about adding the box. would it be something to try?

[ThomasW]

If the components themselves don't already have these types of filters inside the chassis, then there maybe benefit from a power cord add-on.

The cost is certainly minimal, so sure I say go for it and see what happens. I may try it myself ....

[Cowanrg]

cool.

yeah, the equipment doesnt have the filters...

the extra cost would be like $11 for the filter (might as well do the 10A version), and then the box, which i can get a nice little one locally for a few dollars. why not? it would look great.

btw, i sent you an email.

[Cowanrg]

here are some updates of my power cord progress. its going to be a really great looking cord for under $40 each.

the RFI/EMI filters are from allelectronics.com and were only $2 each, and are 10 amp. but, i had to modify them as seen in the pictures. i just cut out the little hood with my bandsaw, and will solder directly to the pins. the box was also from allelectronics.com and was a whopping $3. it will hold the filter and a cap, and possibly a MOV or something, not sure yet. might have a fuse in there, who knows, it has screws, so it wont be sealed forever, i can always add stuff later.

[brucek]

Found this item today while lookin' around. Looks like someone else had the same idea...

http://www.arraysolutions.com/Products/nqnaclinefilter.htm

[ThomasW]

Funny ........ :wink:

$99 for a 7 amp cord in the world of tweak cords that's pretty cheap.



Nice of them to provide instructions for the DIYer in the audience.

Optimum shielding to provide minimum line cord radiation by using a three-wire power-line cord having a combination of braid and foil shielding.
Four 250 VAC .01 uF capacitors and one .047 uF 250 VAC capacitor 50/60-Hz class Y polyester-film types are used. These capacitors are Roederstein Series F1710 radio interference suppressor caps, and they are rated for across-the-line and line bypass applications.
Two Panasonic Class X-Y metallized-film interference suppressor capacitors are also used for input and output across-the- line filtering. This capacitors are type ECQ-UF, .01 uF/250 VAC, rated for across-the-line service.
Four 55 uH powdered-iron toroidal inductors (two per line) are used for optimum power-line differential-mode filtering and are conservatively rated for a line current of seven amperes.
The braid and foil shields and third-wire ground are maintained via the filter's aluminum case from the IEC female receptacle to the NEMA three-prong male AC plug.
The 115-VAC leakage current measured through a 1,500 ohm resistor from the filter case to ground is less than 1.4 milli-ampere.
The voltage drop between the filter input and output at a load current of seven amperes is about 1 volt which is less than a 1% drop in the 115-VAC input line voltage.
A three-prong female-to-two-prong-male adapter "cheater" is included if you need to break the shield ground at your 115 VAC power receptacle to eliminate a ground loop via the shield.
The cover is secured to the aluminum case with four 4-40 machine screws into four 4-40 captive nuts that are press fit into the case body. This eliminates the possibility of stripping of the threads if sheet metal screws had been used

[Cowanrg]

interesting. its ugly, mine will look a lot better, but still kinda cool.

if i get the plugs from Thomas today, i will be almost done! although im having a hard time finding the right grommets and/or strain reliefs for the box.

[brucek]

Nice of them to provide instructions for the DIYer in the audience

I thought that too - they've given you everything but the schematic itself.....

having a hard time finding the right grommets and/or strain reliefs for the box

Radio Shack sells assorted bags of these rubber grommets that once inserted in the correct size hole you only need to put a tie-wrap on the inside of the box to secure for strain....

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=64-3025

brucek

[brucek]

Or, another interesting one is the GATEKEEPER X1, where they'll let you buy the guts without all the stuff around it.....

http://www.welbornelabs.com/ac.htm

X1 Filter Assembly
You may also purchase the X1 filter assembly separately. If you prefer not to use external ac line filters, the X1 can be built into your existing preamplifier or amplifier.
The complete filter assembly including the filter, capacitor, surge suppression, terminal strip and hookup wire for $65.00

[Cowanrg]

looks like a couple of MOV's, a eurostyle terminal strip, a couple of ferrite beads, and a poly cap. about $15 worth of parts. im not seeing what the filter is, unless its just the ferrite beads around the wire.

[ThomasW]

Welborne Labs is about 10 minutes away from my house .....

They're using ferrite cores as the 'filters'. But for ferrites to be truly effective, the wire needs to do at least one full 360 degree loop through the core, and more loops are better.

The 4 cores used in the ArraySolutions filter are the 'best' way to do this.

[Cowanrg]

I'm almost done with one cable, minus the connectors of course.

its turning out pretty decent. its a very heavy cord, considering i used 10/3. with the box and all it will definately be a substantial cord.

i found some really overkill strain reliefs up in longmont. they use a nut to tighten over a tube that conrtacts as its tightened. its big, but works much better. i also had to get slightly bigger enclosures.

there isnt much room left in side the enclosure once all the junk is in there though. its pretty tight, and very hard to work inside.

[Cowanrg]

ive updated my site with pictures now. check it out (of course under DIY power cord).

http://www.cowanrg.mesanetworks.net/projects/

[ThomasW]

Looks professional :wink:

[Cowanrg]

thanks. that was the intention

[Ten 99]

I agree.

I got to pokin' around your website. Looks good. Did you do the work on those Aleph 2 aluminum cases? Those are friggin' nice! Tedious looking work, and great attention to detail.

I know they aren't all complete and assembled, but it makes me want to revisit your website when they are! I bookmarked it.

[Cowanrg]

thanks!

i try and update my site at least once a week, but closer to once every two weeks.

everything on that site is my work (or outsourced), but its all exclusively my projects. there isn't anyone else's stuff on there. the aleph2's were hand drawn and done with a CNC machine with 1.5" T6061 aluminum stock. once i get done with the aleph3's, i will start working more on the text for the aleph2. its actually been a year and a half in the making. most of it is planning and sourcing of components.

i appreciate your comments! ive been working on many of these things for years, so its nice to see something happen with it all. in a week or so my aleph3's will both be running and i can move on the the next project (which will be the preamp).

[Doug Fraser]

Where did you get the case that houses the filter components for your power cord filter?

It looks good.

Doug

[ThomasW]

http://www.allelectronics.com/cgi-bin/category.cgi?category=145&type=store

[aud19]

Damn! 8O :P You should sell those power cables!

Jason