The Zero-va Interconnect a DIY project

Tips or a thread for balanced cables

thnx, Tony

Thanks for this great thread. I just got a pair of active monitors, that have to be connected with interconnects, so I will definitely build these cables!

In light of the discussion on using cotton rope as a core material (re. true dielectric constant) I would now recommend using 1/4" polypropylene rope. I used a larger diameter polypropylene rope for the Zero-va speaker cable design. I think cotton works well enough but clearly based on the new facts polypropylene should work better.

If I ever have to add more cables to my set-up I will try it.

ROVA

Hi Mumbles,

If you are suggesting using another wire, other than CAT 5e Plenum cable wire, that is already straight then that sounds like a good idea. Of course it would have to be reasonably good quality copper and would also have to have FEP insulatiion.

I chose the wire from the CAT 5e Plenum because it was cheap enough and easily available.

ROVA

Rova
You described having to untwist and straighten the cat5 wire to get the teflon coated strands to work with, prior to assembly.
I was thinking that straight wire might sound better due to it's smoother surface area rather than untwisting the cat5.

Well you have to look at your source. The site that you linked to, which is the one that is commonly refered to, is a mfg. the makes instruments to measure bulk solids. For cotton that would be in its raw form which has much more air per volume then cotton that has been turned into textiles (that site I refered to) or rope, hence the low DC number.

Cotton is great at reducing mechanical vibration but its DC and the fact that it is hydrophilic are not positive attributes for this application.

Interesting Chris....!

Who can you trust? I'm sure the same caveat would apply to many different materials. According to the site you linked cotton should be terrible for audio cables. Yet, several high end cables do use cotton.

All I can say is that my cables work very, very well for me. I suspect that the core material is not so important when the copper itself has the FEP coating, and the other side of the "sandwhich" is Teflon tape.

Live and learn.

ROVA

your DC for cotton in the form you are using it in is wrong. 1.3 - 1.4 is for raw, unprocessed cotton, not rope. Try this site: http://www.swicofil.com/products/001cotton.html#Properties

that more accurately reflects where the rope is at DC wise.

Good Luck!

Chris Kline
Tel Wire

Hi Mumbles,

Do you mean wire from another source other than CAT 5e Plenum, or do you mean don't wind the wire in a helix pattern?

For the interconnect I thought smaller and minimal material was better. For other projects, like the speaker cables, I used a larger core and many more strands of wire.

ROVA

Thank you for this great instructional diy thread!
Always wanted to know how it was done, may even give it a try myself.
Couple of questions tho, wouldn't it be worthwile using untwisted wire for a cleaner, more contiguous surface area and less work?
What about using larger diameter chord for larger helix like shunyata's design?

Follow up.

For those of you who wonder just how much CAT 5e to get or how much Teflon tape to get, I can now help you a little bit more. I just took apart the first proto-types and measured the materials used. Since the first proto-type used 1/4" polypropylene tubing rather than 1/4" cotton cord the values will be a little off. I've rounded up and added a little extra to allow for trimming as well.

Anyway for each inch of interconnect you want to make (cable only not including connectors) you will need 1.22 inches of CAT 5e plenum cable and 2.87 inches of Teflon tape. That is for a single cable, so for a pair you need twice is much.

As an example, if you are making 1m interconnects you would need 41 inches of cotton cord (allowing an inch at each end for trimming) 41 inches of jacketing (again allowing for trimming) 48 inches of CAT 5e Plenum cable (giving you a minimum of 6 strands of wire that will be a little longer than 48 inches when straightened) and 112" of Teflon tape. Of course twice that for a pair of 1m interconnects.

By the way of comparison to other reference cables, the only higher price cable I have is the Atlas Quadstar with the Eichmann Bullet Plugs. UHF Magazine sells them here in Canada for $95.95 as a kit or $169.95 assembled. They reviewed the cables and they compared well with their own reference cables (not as good mind you but favorably). Well, I have tried the Atlas Quadstar cables, wired as semi-balanced and unbalanced, and I was never totally satisfied with the results (to me the high end was never really there). The DIY cables I just made are a least one order of magnitude better than the Atlas Quadstars in my opinion

For anyone who has problems finding the cotton rope.

You can also try looking for cotton piping at fabric and drapery supply stores. Cotton piping comes in several diameters. Some are woven into cords, some are just tubes of wool held in by a slim polyester web.

Here is a link to see what they look like:

http://www.textiletrimmings.com/Commerce.Web/productList.aspx?catID=323

ROVA

Part 3 the construction.

Okay here we go….deep breath….and ready….begin.

Start with the cotton cord; this will be the core of the cable. Twist one end and add a small strip of packing tape to keep the end together and small.
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Cut a small piece of heat shrink tubing about ½ inch long and slide it over the cord.
You are going to use 6 of the strands of wire from the CAT 5e cable and wrap them around the core in a helical pattern, three winding clockwise and three winding counter clockwise.

Three of the wires will be the positive wires that go to the positive (center) pin of the RCA connector and three will be the ground wires that go to the outside of the RCA connector. You should group these wires using the color code. I chose to make all the wires containing white the positive wires. So I used white, white with an orange stripe and white with a green stripe, as positive wires. (Your colors may vary!) The three solid colored wires were used for the negative wires. So again in my case I used the orange, green and brown wires for the negatives.

You need to feed the wires under the heat shrink and up past the end of the core. You need to leave enough wire beyond the core to attach the RCA plug. You need to add all six wires spacing them more or less evenly around the outside of the core. Not only that but you need to alternate positive and negative wires as you go around the core. For example, if you use a positive wire at 0 degrees you would place a negative wire at 60 degrees, a positive wire at 120 degrees, a negative wire at 180 degrees, a positive wire at 240 degrees, and the final negative wire at 300 degrees.

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Why 6 wires? Or in other words why 3 wires for each polarity? Well mainly it is a guess. Remember I needed to balance the minimization of conduction material with the resistance. My first proto-type used only two wires per polarity wound around a polypropylene tube core. I thought the bass was a little lacking on this proto-type so I added a third wire on the next level. This sounded good so I stopped adding wires.

Next slide the heat shrink up to the end of the core being careful to keep the wires spaced evenly around the core. Shrink the heat shrink into place to lock the wires in position.

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Next you need to clamp the end of this cable into a vise (or something similar) to support one end. In order to make sure the wires won’t pull out of the heat shrink while you wrap them; fold the wires over before you clamp them into the vise.

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Clamp the wire in the vise.
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Next you need to support the other end of the core far enough away to allow the interconnect to be wrapped. You can do this in any number of ways. I just put together something temporary.

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Next you need to mark the core at 2 inch intervals with a marker or something similar. Mark every 2 inches until you have reached the length you want the final interconnect to be.

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Why 2 inches, because it seemed to give the wire wraps a reasonable pitch. Again it is just a guess that seems to work out well.

Next you need to separate the three positive wires from the three negative wires. I kind of hooked the negative wires back out of the way.

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Now you begin the wrapping of the wires. I usually start with the positive wire that is closest to the top of the bundle as it is clamped in the vise. Begin to wind this wire around the core (clockwise or counter clockwise doesn’t matter at this point). You need to wind it one revolution each two inches so you end up crossing the mark you made on the core. Continue to wrap this wire around the core until you reach the final mark for your interconnect. Wrap one more turn around the core in roughly the correct position (this isn’t critical). Try to hit the mark on every revolution.

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Now take the next positive wire and begin wrapping it around the core in the same direction. You want to keep this wire spaced a little above or a little below the first wire (above or below will depend on which of the remaining positive wires you choose). Try to place the wire 1/3 of the way between the turns of the first wire. This is not critical so it is OK to “eyeball” it. Just make it reasonably close to 1/3 spacing.

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Wrap the final positive wire in the same direction, hitting the space between the last two wires so that each is spaced about 1/3 of the distance from each other.

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Next you are going to wrap the negative wires. Again pick a negative wire near the top of the bundle. However this time you will wrap it in the opposite direction to the positive wires. So if you wrapped your positive wires clockwise you need to wrap the negative wires counter clockwise. If you wrapped your positive wire counter clockwise then you need to wrap the negative wires clockwise. Again for the first negative wire try to hit the marks spaced every 2 inches.

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Like you did for the positive wires add the final two negative wires, winding in the same direction as the first negative wire, keeping them spaced roughly 1/3, 1/3, 1/3.

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You now have completed the wiring.

Why this pattern? Again this is a compromise trying to find the best configuration to reduce both the inductance and the capacitance. If you twist the wires tightly together they have a very small loop circuit and therefore the inductance is low. However, the wires will be right beside each other and this will make the capacitance high. On the other hand, if you run the wires widely separated, but parallel, your capacitance will be very low but your circuit loop is big and open and hence the inductance will be high. Braiding the wires tightens the loops again and therefore lowers the inductance. However, just like with twisting the wire, much of the time the positive and negative wires are close to each other and parallel to each other. This increases the capacitance again. With this helix wound pattern the positive and negative wires spend very little time in contact with each other so the capacitance is low. Although the circuit loops are a bit open they do still bend and twist back and forth over each other. This allows the magnetic fields of the wires to interact and the inductance is lower than if the wire ran parallel. As I said a compromise, but a pretty good compromise.

Next you need to cover the wiring with a layer of Teflon tape. This provides an outer layer of insulation as well as helps hold all the wires in place.

Begin by wrapping a couple of turns around the end that is in the clamp (I use a small strip of packing tape to anchor the Teflon tape to the cable). After you have anchored the Teflon tape with a couple of straight turns begin to use overlapping turns and make your way down the cable.

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As you wrap you need to keep a little tension, or pressure, on the tape. You want the tape to deform around the wire slightly. Keep wrapping until you come to the final mark at the end of your desired interconnect length. Finish with two straight wraps at that point and then cut the tape off. You can use a small strip of packing tape again to hold down the end of the Teflon tape.
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Clip the wires off leaving some extra length to finish the end of the cable.

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You can now cut the core but do so a little way from the end of the taped area. You will need to add the heat shrink tubing before trimming the core to its final length. After cutting the core use a small strip of packing tape to point the end of the core like you did at the other end.

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Now slide a second ½ inch piece of heat shrink over the wires and core. Shrink it into place locking the wires in place.

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Now you can trim off the core flush with the end of the heat shrink.

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You have now completed the cable itself.

Next you need to cut your outer jacket to length. (I cut mine so it would almost reach the end of the heat shrink tube but not quite.) You also need to cut a couple of pieces of larger heat shrink that will be used to lock the jacket in place.

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Place the jacket over the cable. Feed the heat shrink tube over each end of the cable and jacket. Line up one end of the jacket about half way on the cable’s heat shrink tube.

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Now slide the outside heat shrink right up to be flush with the cable heat shrink.

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Shrink this in place.

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Stretch out the jacket until the other end is about half way on the cable’s heat shrink tube. As you did with the first end, slide the outer heat shrink flush to the inner heat shrink end (while making sure the jacket doesn’t slide back). Shrink it in place and you have finished the cable itself.

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Now you need to put the RCA connectors on.
Trim the wire on both ends to the appropriate length for the type of connector you are using. For the Eichmann bullet plugs I used that would be approximately ½ inches in length.
At this time you can strip the insulation off of each wire. You can also sort the wires into two groups. Place all the positive wires together and then place all the negative wires together.

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Now twist the ends of the positive wires together. Twist the ends of the negative wires together.

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Tin the ends of the wires (I guess with silver solder we should call that silvering?). Align the wires ready to solder to the plug and then trim the ends to length.

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Solder on the plug.

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Making sure you have put the shell of the plug over the cable first!

Complete the assembly of the plug and tighten the set screws on the shell. Voila, you are now done.

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You are ready to enjoy.

Burn In: You may need to give your new cables a few hours of burn in to get the sound you want. With my first proto-type I didn’t like the bass at first but after a few hours (maybe 10 to 12 hours) the bass was getting better; as was the overall sound. With my second (and final) design I immediately had good bass. The interconnect sounded very good from the get go. Perhaps it has improved a little bit with time but it is hard to tell. Regardless, you might want to give the cable a few hours of running before you do your critical listening.

Potential problems: This interconnect has no outside shield. In high noise areas you may have problems because of this. I don’t, and I imagine most of you will not have any problems, but you need to be aware that this is not a shielded cable design. I would not recommend adding shielding braids around this design as it will capacitive couple to both the positive and negative wires destroying some of the improvements obtained. The double helix winding pattern will provide a degree of noise rejection as noise induced on the positive lead will also be induced on the negative lead tending to cancel each other out. (One person who copied this design did use it for a phono cable and it worked well for him.)

Possible improvement: Some of you will notice I didn’t take all my design goals to extremes. Some of you would naturally ask couldn’t I have used silver wire. Yes, that would be a good idea. However that would conflict with the low cost and easy availability goals I set. If you want to improve the design by all means use silver wire. Using silver wire you might be able to go to only two positive and two negative wires rather than three of each. Also you would want to go to silver Eichmann bullets rather than the copper ones I used.

I hope I have made this clear enough for you to duplicate what I’ve done. If you do I think you’ll be happy with the results.

I would love to hear from any of you DIYers who make a pair of interconnects based on this design. I would love to hear how they worked for you. It would also be great to know how these interconnects compare to other commercial high-end products.

Anyway, have fun DIYing.

ROVA

Part 2 – The materials.

OK, to work.

The conductors for the interconnect come from CAT 5e Plenum cable. You will need somewhat longer CAT 5e cable than twice the length of your desired interconnects. Why CAT 5e plenum? CAT 5 cable uses OFC. Of course it likely is only 4N vs. 5N or 6N that most audiophile cables use but…..at what cost? It is important to use the plenum version of CAT 5e to get the required Teflon (FEP) insulation. Even so, check the supplier’s specification for the cable via the internet. Not every CAT 5e uses FEP. In my case I got my cable from the local Home Depot and it had 3 pairs using FEP and the other pair was Polyolefin. The wire is 24 AWG solid copper, so this is keeping with my desire to minimize the conduction path material. I also find that the solid conductor does very well for higher frequencies.

The core for the interconnect uses ¼ inch diameter cotton cord. (Make sure it is 100% cotton.) Why cotton? Look it up on a dielectric constant chart http://www.asiinstr.com/technical/Dielectric%20Constants.htm#Section%20C and you will see that cotton has a value of 1.3-1.4. This is even lower than Teflon at 2.0. Get more of this cord than you think you need, this will allow you to use the extra to help in the building of the cable. Note, do not cut the cord to length yet, leave it full length for now.

You will need some Teflon tape to wrap the cable. You can use the standard plumbers tape available at your hardware store. I could only get ½ inch width and that was fine. If you can get ¾ or 1 inch wide even better as it makes the wrapping process quicker.

You will need an outside jacket for the finished cable. I used what I had on hand. If you can get cotton shoe laces with the wider, tubular, lacing you could use that. Again, cotton should give excellent results due to the low dielectric constant. Since there is a coating of Teflon tape over the cable before the jacket goes on the jacket material is not so critical. Of course if you have a low dielectric constant materials available then use them!

You will need some short pieces of heat shrink to fix the jacket in place on the cable. You also need a couple of short pieces of heat shrink to lock the wires to the core at the start of the wire wrapping process (this will become clearer during the building instructions).

In keeping with the goal of using the minimal amount of material in the conduction path I used Eichmann bullet plugs. I do recommend them as they work well for me, but you can use whatever your favorite RCAs are. Although the bullet plugs worked well for me I did use some cheap “Source (Circuit City)” RCAs in an earlier proto-type. This proto-type required some extra burn in to get good results and I’m sure the cheaper plugs did degrade the results a little. The Eichmann plugs were the only item that wasn’t easily available and had to be ordered. This was also the only really expensive parts used, but from what I heard they were worth it.

Solder…I happened to have some silver solder so I used it. I would recommend silver solder but I don’t think this will make or break the project.

Packing tape….I use tiny strips of packing tape to hold the wires in place before getting the heat shrink in place. Why packing tape? Because the standard packing tape has a plastic base that is also a low dielectric constant material.

That’s it; nothing more exotic.

Except for bullet plugs you should be able to pick up the materials just about anywhere.

Wire preparation:

To make this interconnect you will need to separate the CAT 5e wires into individual strands.

First, strip the outer jacket off of one end. A short length of 3 – 4 inches is all that is required. You need to be able to get to the rip core (string in between the wires). Make a small slit in the jacket insulation on the end of the cable you just stripped. (This gives the rip cord a starting point to cut through the jacket.) Firmly grasp the rip cord in one hand a rip it down through the jacket of CAT 5e cable from one end to the other.

Now you can remove the jacket from the CAT 5e cable. You will now have four pairs of wires. Each pair will be twisted together. Identify which pairs have the appropriate insulation (FEP), these are the wires we will be using.

The easiest way to identify the FEP coated wires is to look up the manufacturer’s information on their web site. If that doesn’t work, or isn’t available, then here is a trick you can use.

Teflon insulation has a higher melting temperature than the Polyolefin so just touch a soldering iron briefly to the insulation. With Teflon a brief touch does not really melt the insulation and the soldering tip can easily slide up and down the insulation (provided you don't use too high a temperature or leave it in one place too long). With the Polyolefin when the tip touched the insulation it melts the insulation and sinks into the insulation.

Now you have to untwist the wires (we need individual strands). I suppose there must be some quick way of doing this but…I didn’t use it. I just clamped one end of a pair of wires in a vice, stretched out the wire and then began untwisting. It takes a bit of time but it’s not too bad.

Now you need to straighten the waves out of the strands. The easiest way to do this is to clamp one end of the wire in a vise. Take the other end in your hand and walk out until the wire is straight and suspended in the air between you and the vice. First, firmly but gently apply pressure to the wire (pull); not too hard but you should feel the wire stretch just a little bit. Now quickly ease the pressure off the wire (let it slacken a little) and then snap it tight again. Do this two or three times and you should have a straight wire. To ensure it was straight I went back to the end clamped in the vice and grabbed with wire with a cloth rag. I then walked back to the other end of the wire dragging the wire through the cloth in my hand. This pressure helps straighten any last waves in the insulation. You can now roll up the wire on reels or what ever you have to wrap it on until you can use it,

You are now ready to start making your interconnects.

ROVA