Custom Right Angle Double Shielded IEC Power Cord

So you may notice from the abundance of power cords on DIYAudioBlog that I enjoy making them ;) I find that they're both cost effective and higher quality compared to many audiophile-marketed power cords. Also, if you're bitten by the DIY bug, you tend to enjoy building everything you can on your own. In this post, I'll be assembling a relatively short 3 foot right angle double-shielded IEC power cord. This will be my first double shielded power cord, making use of both a tinned copper mesh braid and a full coverage EMI / RFI blocking 3M aluminum tape shield.

What's unusual is many of the handmade audiophile power cables don't use a shield at all; it's typical to see a cable with three 10 gauge conductors in a spiral within a big thick PVC jacket, but no shielding when it could be easily incorporated. Because these power cords are huge and make use of big conductors, they have a ton of capacitance, which offers EMI / RFI a great opportunity to rear its ugly head. Companies like PS Audio offer shields on their cords; their pricier models offering as many as four shields. It's hard to say if adding shield after shield is beneficial having never tested past 2, perhaps it can be the subject of a future post.

This cord will making use of a right-angle hospital-grade Marinco 3 prong plug. This is achieved by purchasing the typical Marinco 8215 plug (~$9) and the Wattgate WG15RA (~$15) right-angle adapter piece and combining the two. The right-angle adapter can be oriented in eight different positions depending on what angle you'd like the wire leaving the outlet.

The Wattgate WG15RA

The cable starts like the other power cables I've built. I trimmed three 10 gauge SPC in Teflon conductors and twisted them together in a spiral by hand.

Spiral of three 10 gauge SPC in Teflon conductors

These conductors are then wrapped in PTFE (Teflon) tape. Rather than using the thin 1/2" plumbers tape that I've used in the past, I opted to source some thicker 1" PTFE tape to trim down the time on the wrapping process, as the cable gets wrapped a total of four times, it can take a while.

Initial two layers of 1" PTFE Tape

Once the teflon is wrapped around the three conductors, a layer of 3M EMI / RFI blocking 3M aluminum tape is wrapped around the cable. This is a full coverage shield, none of the cable underneath is visible once wrapped, and there is a decent amount of overlap.

3M EMI / RFI blocking tape layer (first shield)

After the foil shield is laid down, the tinned copper braid mesh is run over top of it, then a buss wire is wrapped around the shield and soldered at the source side. This acts as a drain wire and connects the shield conductivity to the ground at the power source.  

Tinned copper mesh shield layer (second shield)

Now, the two final layers of PTFE tape are wrapped around the cable. 

Final two layers of 1" PTFE tape

Then comes a layer of attractive nylon multifilament copper sleeving to cover up the bland looking PTFE tape, followed by black heatshrink at each end. The Marinco 3 prong connectors are screwed on each side, with enough force to keep them in place but not enough to strip the screws within. Here's a photo of the finished product:

The finished two shield 10 gauge power cable

Power and beauty in one! ;)

The Fine Print:

The above steps detailing the creation of a power cord are for entertainment purposes only, and not to be performed under any circumstances. Please remember that attempting to use homemade power cords can be dangerous to you and/or your surroundings. The owner of this blog and all associated parties can not / will not be held responsible if you attempt the process posted below and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and DIY power cables can be a fire hazard. Please keep this in mind.

Custom C7 Power Cable

If you're familiar with a standard IEC inlet, it has three separate connectors for hot, neutral and ground and is on nearly all audio equipment worth its salt, with a few exceptions of course. But we just can't be lucky enough that all equipment has an IEC three prong power inlet, can we?

Furutech gold IEC power inlet

Older equipment and certain newer universal disc players, among other things, have a C7 inlet. A C7 inlet does away with the safety ground connector, and is unpolarized, meaning that the hot and neutral is interchangeable as the cord can be aligned either way on the inlet. There are certain C7 connectors that are polarized which have a square end on one side and a circle on the other to ensure the hot and neutral go through the appropriate route.

Polarized C7 power cord

In my case, I'm currently building a Dynaco ST35 kit which combines the circuit ground with the chassis ground. When this is the case, there is a good chance for hum if attaching a preamp and amp on the same breaker if the circuit ground of each is attached to the safety ground of the power cords. Many of the forums I've visited recommend not attaching the chassis ground to the safety ground on the power connector to prevent hum on Dynacos. Please note that safety ground is called safety for a reason, if it's not connected and the circuit shorts to the chassis, it can be very unsafe.

I'm using a Shurter C7 inlet for my ST35, and it would be blasphemous for me to connect an ordinary C7 power cord to my tricked out new Dynaco ;)

Schurter C7 Power Inlet

So, what are the options for aftermarket C7 cables? PS Audio produces the 12 gauge Jewel power cord which is offered in a C7 configuration and runs ~$70-80 on the street, then there is the Audioquest NRG-1 power cord, which has a similar street price and comes in 16 gauge. Both are larger than the typical 18 gauge unshielded C7 power cord that comes with most equipment and are of course much more attractive.

In the interest of DIY, I chose to build my own. There are sparse few choices for a cable-end plug. Furutech offers a very attractive one, but at $45 as of this writing for a C7 plug is a little rich for my blood ;) It's also a little large for my purposes.

Furutech C7 power plug

Luckily, a builder in Japan offers a low cost C7 connector with solder connections that accept anything up to 16 gauge. These are floating around on that auction site if one searches for "C7 solder".

The power cord starts off a little differently than my other power cords. Rather than twist 10 gauge wires together in a spiral, I chose to use 16 gauge wire and braid it in a tri-braid configuration.

A bundle of 16 gauge silver plated copper in Teflon

Tribraided conductors

Then came the Teflon tape insulation, which covers the braided cable twice over.

Initial Teflon wrapping

A shield is then added over the top, which is connected to the source side ground via a soldered bus wire to create a floating shield.

Wrapped with a tinned copper mesh shield

The next step is two additional layers of Teflon are added to the top, over the braided mesh shielding.

Teflon wrapped 16 gauge power cord

Finally, the decorative techflex sleeving is added to the top, in this case both Chrome XC and black PET sleeving was employed to give a low-level shimmer. The low-cost Marinco 5266 is screwed down on one end and the C7 connector is soldered to the other. A piece of heatshrink is used as a strain relief, and in this case, the joint was bent at 90 degrees while the heatshrink was still hot for ample clearance behind the amp.

High quality DIY C7 power cord

Reverse shot detailing Techflex covering

The Fine Print:

The above steps detailing the creation of a power cord are for entertainment purposes only, and not to be performed under any circumstances. Please remember that attempting to use homemade power cords can be dangerous to you and/or your surroundings. The owner of this blog and all associated parties can not / will not be held responsible if you attempt the process posted below and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and DIY power cables can be a fire hazard. Please keep this in mind.

Custom Audiophile Power Strip

Audiophiles can be very finicky about their power source. There are countless products available for music listeners to replace their receptacles, power cords, line conditioning and even the faceplate with audio-branded merchandise. Companies like PS Audio, Furutech, Oyaide, Wattgate, Neotech and Onix (just to name a few) all have extensive power-related products made specifically for audio enthusiasts. There are other companies that offer well-made products for a variety of consumers and are still very worthwhile for the discerning audio listener who isn't interested in paying the high prices of audio-niche gear. These companies include Marinco Industrial Group, Hubbell and Schurter.

In this post, I'll be putting together a custom audiophile power strip from a variety of low-cost but high quality components. Please note that this post is for entertainment purposes only, attempting to replicate anything shown here has the potential to be a fire or electrical hazard. I've selected a Hubbell 20A 4-Plex Box in a nice dark-brown color to mount to a generic 2 gang steel box to be the base of this "audiophile" power strip. Some other parts I'll be using are 5 rolls of Teflon tape, a Marinco 8215 hospital-spec 3 prong plug, a run of military-spec 10 gauge silver-plated copper in Teflon wire, some tinned copper braided shielding, a small amount of bus wire and some sleeving and heatshrink.

Oddly enough, it's not too often that you find silver-plated copper or Teflon in power products marketed to audiophiles. PS Audio had a very substantial power cord called the Premier SC that was released in 2006 with silver in it, but it was quickly discontinued (possibly due to people not biting on the $999 SRP). Also, many audio power cords come with cheap high-loss poly vinyl chloride (PVC) dielectric, as one moves up the line, the quality of the copper gets better, but the dielectric remains the same. Nordost actually pays quite a bit of attention to the quality of their dielectric, but it's not terribly common with other companies; you're lucky if they even tell you in the specifications. One would think if these companies agree that the difference in power cords is audible, and I hope they would considering how much some of them cost, that they would consider the quality of the dielectric a little bit more.

This cord starts off nearly identically to my Right Angle Power Cord, so I won't be covering those initial steps in this post. There is basically the twisting of the geometry of the three 10 gauge wires, wrapping with several layers of Teflon, covering with a full-coverage braided copper shield, soldering a bus wire to it, then wrapping with several more layers of Teflon. It's a very time-consuming process, but nice to do while listening to some music. Below you will see the power cord after all these steps are complete.

Powercoated 2 gang box, Hubbell 4 Plex outlet and Marinco plug.

Once all these parts are ready, it's nice to dress the cable with some techflex. I chose to use one layer of red and two layers of black on top to give it a dark brown look and match with the other parts to some extent.

Cable dressed with three layers of heatshrink

Once the dressing process was complete and heatshrink was applied, it was time to attach the Marinco 8215 plug. The silver plated wire was stripped and the bus wire that's conductively attached to the shield is wrapped around the bottom of the ground wire and soldered in place. This allows the braided shield to act as a floating shield (it's not connected at the other end) and protect from EMI / RFI.  

Bus wire soldered to ground conductor

The Marinco plug is installed completely by screwdriver. Pressure allows the contacts to work without soldering. I personally prefer soldering, but soldering terminals are fairly uncommon with these DIY type electrical plugs. If these conductors were pure copper, I would tin them with solder before installing them in the plug to prevent oxidation. The strain relief system is tightened with screwdriver and the plug is ready for use. Before the Hubbell 4 Plex sockets are installed, a small strain relief collar is installed on the two gang box and I used some epoxy to hold it in place, fed the cable through it, installed a clamp and added additional epoxy around the clamp to ensure this cable wasn't going anywhere. The wires were then stripped and screwed down to the corresponding screws on the Hubbell 4 Plex.

Hubbell 4 Plex installed

I was going to use some vinyl dye on the blue collar, but I kinda like it as an unusual accent, it's about the same color blue as the Zynsonix heatshrink. Now that these conductors were fastened on, the 4 plex outlets needed to be screwed down and the unit tested.

Outlet testing device approved

Hardware stores have a very handy outlet tester that gives you a three LED readout to let you know if everything is wired correctly. The two LEDs above indicate that the outlet is in working order. Below is the finished unit ready to feed a hungry amp ;)

The Fine Print:

The above steps detailing the creation of a power cord are for entertainment purposes only, and not to be performed under any circumstances. Please remember that attempting to use homemade power cords can be dangerous to you and/or your surroundings. The owner of this blog and all associated parties can not / will not be held responsible if you attempt the process posted above and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and DIY power cables can be a fire hazard. Please keep this in mind.