Wednesday, June 16, 2010

Creating Custom Cables for Field Recording

One of the lessons I have learned in my career is that good gear is hard to find. Great purchases always require a decent amount of research and even then you may not always find what you are looking for, especially in the specialized world of sound effects recording. For example, I was recently in the market for a 2-channel cable for my stereo MKH-30/MKH-60 combo rig. As there were no commercially available solutions that I was particularly fond of, I decided to build a cable from scratch with the exact materials I would like to see in a quality stereo mic cable.

My goal in this tutorial is to show the basics in custom cable construction, not specifically give instruction in soldering. For specifics in the art of soldering check out YouTube and enter a search criteria such as "How to Solder," where I was easily able to find approximately 5600 videos on the subject.

The first requirement in making good customs cables is good tools. Below you will see a picture of the basic tools I use when creating cables: Soldering Gun, Wire Strippers, Multi-Meter, Gator Clip Stand, and of course a small torch for heat shrink. (My favorite tool!)

Next we need the actual supplies for the cable itself. It is very important to buy quality components when building cables. For this build I am using Mogami W2739 4-core cable with Neutrik Black and Gold XLR's. One of the goals of this build was to create a stereo cable that was ultra light for field recording but also possessed enough quality to stand the rigors of the field. The W2739 cable is close to 1/4 the size of a standard mic cable, but is still rigid enough for field use. I am also using .125", .1875" and .25" shrink tubing to protect all exposed wire strands in the cable.

A close up of the shrink tube I am using. The clear shrink tube is for the ground lead, while the black is for the W2739. I will explain the use for both.

To start, clip the end of your cable so that you have a nice clean pice of wire to begin with.

This particular cable (W2739) has 4 conductors and a shield.

The shield will be used as the ground for the cable. Carefully take the shield strands and wind them into one single strand as shown below.

Next, take the 4 individual conductors and group them into 2-pairs. The grouping of the pairs does not matter as long as they are consistent throughout the project. I grouped the colored strands into one pair and the shaded strands into another.

It is now time to install the shrink tube on the exposed ground lead. This will prevent the possibility of any shorts in the future. I am also taking the time to apply solder to the tips of the leads to prevent any unraveling of the strands during the installation.

Soldering irons come in many shapes and price points. I use this $50 Weller workstation and have literally completed hundreds of projects with it. It also collapses nicely to fit into my toolbox. I have the iron set to approximately 80% power for this project.

After the cable is prepped, slide the back of the XLR connector onto the cable as well as the piece of shrink tube for the cable itself.

Now I will add a little solder to the XLR connector itself. I like to prep as much as I can before I actually solder the cable to the connector as it provides for a much cleaner joint.

One mistake I often see is people make when making cables is fill the cups of the XLR connector with solder. Try to use enough solder to get the job done; not so much as to fill the cups and make de-soldering a nightmare, but enough solder so that the cable does not fail due to cracked joints caused by rough handling.

Neutrik conveniently labels their connector terminals with numbers to make sure you get the cable in the right place every time. Just remember what XLR stands for when soldering XLR cables: X=1 for Ground, L=2 for Live, R=3 for Return. Below I have attached the ground to terminal 1. I will attach the colored wires to Terminal 2 (L=Live) and the Shades to Terminal 3. (R=Return)

Here is what the finished soldering job looks like. Clean and polished, with enough solder to retain a good, stable connection but not so much that if I needed to remove the cable from the terminal it would be an issue to de-solder. The only issue with the picture below is that the place where the cable sleeve ends has exposed shield material, which I will now cover with the shrink tube we slid onto the cable before soldering began.

With the cable sealed up with multiple layers of shrink tube we are now in business for a long lasting, hard-working cable that will stand up to years of field recording abuse.

To finish this end of the XLR simply slide the protective plastic sleeve and cover on and screw it together with the back piece you installed earlier. If you forgot to install the back before you soldered the cable, you will now have to de-solder the cable, install the back piece, and re-solder the cable back together again.

Since I need a stereo cable, I am repeating the steps I performed above to solder an XLR to a second cable and will use several pieces of shrink tube to link the two cables together. There is tubing available for purchase that can cover the entire cable, but in turn creates a more rigid cable than I want for field applications.

Difficult to see but here is the entire 15' cable linked together with multiple 1.5" pieces of shrink tube.

Now that I have the cables linked together, I will solder on the opposing connectors to the cable and create a finished product. A pic of the completed cable.

I like to check all of my new cables with a continuity tester before I go into the field.

If you have never used a Multi-Meter before I recommend checking one out. The meter I use checks everything from resistance to amperage to voltage. The setting you see below is used for checking continuity, which is simply a test to make sure path 1 connects to path 1, not path 2, or path 3, and so on...

Simply insert one end of the test node into the female XLR. Then test the matching terminal on the male side of the cable. A terminal with continuity will make the Multi-Meter beep or output some sort of signal. (Depending on your make and model) For example, Ground to Ground should have continuity, not Ground to Live. Also take the time to check for shorted connections. If pin 1 has continuity with pin 2 for example, you have a short and need to evaluate your cable before proceeding.

I always label my cables. In this case I am labeling them LT and RT.

I do not have time to worry about which cable is which while in the field. Always label your multi-channel cables!

And there you have it! A good looking and very flexible cable for field recording.

Here is a look at one of the other options in 2-channel cables. My cable is much lighter and way more flexible then this Mogami 2-pair AES/Analog cable.

Another comparison view of the cables.

For the last touch I always like to add a Bongo Tie to keep the cable neat while in storage.

Let me know of any feedback you may have and happy soldering!

Nick Meade
Audio Enthusiast


lostlab said...

Great overview of the process, major points for the detailed pictures.

"heat shrink. (My favorite tool!)"

-I love the way it makes everything just look nice.

Steady on,

guy smiley said...

brilliant. thanks

Great Crage said...

Your style of presentation is very impressive. The meaningful contribution of your mind reflects on those people who are looking for new ideas and informations regarding custom cable for field recording. I would like to tweet on it and keep spying at every moment you blogging.

Custom Cables

Vinod said...
This comment has been removed by the author.
Arnoud said...

Hi Nick,

thanks for the great walkthrough on creating this cable. I noticed that you use a rode blimp for your MKH30/60 setup. I also own this setup and was thinking about buying a Rycote stereo blimp... Do you think a Rycote will offer better wind protection or is the Rode also really good?
I don't know if you are able to compare, but i would sure like to hear your experiences with the rode blimp.

Your blog is added to my list :)


Arnoud Traa

Sound designer
The Netherlands