Rolling Your Own Instrument Cables

Discussion in 'Pickups & Electronics [BG]' started by MglMatador, Sep 7, 2010.


  1. MglMatador

    MglMatador

    May 5, 2010
    I thought I would throw together a short pictorial about what I do to make high quality cables for guitar and bass. Please feel free to add anything you do if you make your own as well!

    First, here's what you need:

    1) soldering iron with a wide and flat tip in the 35W+ range
    2) solder - I like 63/37 tin-lead eutectic solder from Kester
    3) cable - I use Canare GS-6 for this but I also like the stuff that ProEL (in Italy) is selling
    4) heat-shrink tubing of 3/8" diameter (pre-shrunk)
    5) 1/4" connectors - Switchcraft 280 is the industry standard for longevity and ruggedness (you can practically drive over these with cars!)
    6) Something to cut wires - preferably a cutter meant for stripping coax cable (the blue handled tool in the first picture)

    Here's all the pieces laid out for all to see:

    IMG_7134.jpg

    Start by seeing how much outer insulation needs to be stripped: you can lay the cable inside of the plug until it is about 1/16" from contacting the center plug conductor. Here's what that looks like:

    IMG_7135.jpg

    Then you strip the outer insulation, leaving enough to make sure that the portion of the cable under the cable crimps still has insulation (you don't want the crimps to be contacting the shield as this weakens the cable and provides a flex point where it can later break).

    Here's a pic of a stripped cable of the correct length (you can leave more insulation if you want, but you want as much of the braided shield available for soldering as you can get):

    IMG_7136.jpg

    You next need to unbraid the shield using a small screwdriver or sharp pencil. Once it is all unbraided you can twist it into a solid wire:

    IMG_7137.jpg

    Now comes a critical step: Canare cable has an extra electrostatic shield that is there to help reduce noises in the cable as it is bent (which is in turn caused by changes in the cable's capacitance). It's important to cut off this shield near the point where it comes into proximity with the center conductor, as it's fairly easy to make a weak short through this plastic to your center signal wire. This will cause a ~100k ohm short that won't be picked up by a cable tester, but it will wreck havoc with the loading on your pickups!

    In any case, carefully strip this outer shield back to the point where your braided shield is twisted. Here's what that looks like (it's very thin, so a light touch with a razor blade does the trick). You want to make sure you only go through this shield and not through the center insulation:

    IMG_7138.jpg

    Next strip the center insulation back from the tip about 1/8" or so:

    IMG_7139.jpg

    Next, carefully bend the center conductor post down about 20 degrees so that the center conductor has a fairly straight shot to make it through the mounting hole in the post. You can then push the center conductor through the hole and align the braid wire to be touching along the bottom of the plug. After this is done, you can crimp the barrel connectors down onto the outer insulation. This is what it looks like if it's done correctly (notice there are no whiskers of the center conductor reaching down and touching the shield braid...if there are, correct it now otherwise your new cable will be shorted):

    IMG_7140.jpg

    The mechanical ruggedness of this plug comes from the crimps: you should not be able to pull the wire from the plug at this point (it should feel solid). I would wiggle the cable and see if the cable moves in the crimp, and if it does do you should crimp a little harder...otherwise the shield braid and center conductor will become mechanical connections and the plug won't last! You want a solid mechanical connection at the crimp, but you don't want the cable crushed either!

    The plug is ready for soldering. Heat up your iron, and clean the tip until it's bright and shiny. Tin the tip with a little solder, then hold the iron under the center conductor. You can then apply the solder to the top of the center pin, and the solder should flow down the wires making up the center conductor and through the hole to the bottom side where the iron is heating.

    Do not put the tip of the iron on the top of the plug and apply solder to the top-side of the connection. It's asking for cold solder joints that will often break after you've assembled the plug (and by Murphy's Law probably during a gig). Here's what it should look like after soldering (notice how shiny it looks and how it's flowed down the center conductor and up the center pin):

    IMG_7141.jpg

    Next comes the braided shield. Same rules here: hold the iron under the plug, and apply the solder directly to the braid. It will start flowing along the bottom of the plug. Feed in enough solder so that the entire braid is soaked and shiny:

    IMG_7142.jpg

    Leave the plug to cool for 5 minutes, as it will be very hot after this step, and if it's hot it will completely botch up the next part of this, which is....

    ...the heat shrink tubing. Some don't apply this, but I've found it's great strain-relief for the cable. Cut about three inches of tubing, and run it along and over the enter center assembly of the plug:

    IMG_7144.jpg

    Shrink the tubing with a hot air gun, or if you're careful with a lighter. Here's what that looks like:

    IMG_7145.jpg

    Be sure to heat all of the tubing, because it must be shrunk down tight around the crimps to add the strain relief (you can clearly see the imprint of the crimps in the tubing in the picture above which means it's shrunk tight).

    Next you can thread the plastic shell carrier onto the other end of the cable and down over the plug. This carrier prevents the cable from coming into contact with the brass outer shell, which gives yet another layer of protection for the plugs from points of strain:

    IMG_7146.jpg

    Now you can thread on the outer plug casing, and one end of the cable is complete!

    IMG_7147.jpg

    The other end is done in the same fashion, however let me bold this part:

    BE SURE TO place the other outer casing, THEN the other plastic shell carrier, THEN the other piece of heat shrink tubing on the cable before starting the other side!!!! If you skip this step in haste, you'll be cutting off a brand new plug and starting over as there's no way to get these on after the other side plug is installed.

    I test new cables by plugging them in and playing them: if everything went ok you won't hear anything other than your bass. If the sound is extremely dark and muffled then you probably forgot to cut off the electrostatic shield and you have a high-impedance short from center conductor to sleeve: an ohm-meter will confirm this as it should read 'infinite' when set on a 200k ohm scale (between tip and sleeve). If it reads down near zero ohms then you have a direct short from center conductor to sleeve, which means the center conductor was probably touching on one end. If you follow this closely and everything looks the same as above you probably won't have any problems.

    The main variation to this procedure is to use a right-angle plug on one end (Switchcraft 226 if memory serves), which is used mainly on Jazz-basses with the output jack on a metal control plate.

    Feel free to comment or post your recipes!
     
  2. maxiegrant

    maxiegrant Bassist in Transition

    Nov 26, 2007
    Sellersburg, IN
    Beautiful. How much per foot do you suppose it costs you to do this?
     
  3. That depends entirely on the cable you buy.

    Different brands and qualities have a different cost per foot, as do different connectors. (Gold plated versus standard, for example.)
     
  4. maxiegrant

    maxiegrant Bassist in Transition

    Nov 26, 2007
    Sellersburg, IN
    Well, I'm trying to decide if it's a better deal than buying higher-end cables at the store. I would have to practice doing this because I'm an idiot when it comes to solder.
     
  5. Handyman

    Handyman

    Sep 4, 2007
    Austin, TX
  6. MglMatador

    MglMatador

    May 5, 2010
    The cable can be had for somewhere in the $0.50 to $1 per foot area: less if you buy more at once. The Switchcraft plugs are generally in the $2 to $3 range if you shop carefully.

    You should expect to pay about $15 for a 10 foot cable (for materials) if you are buying in small quantities (and you already have the tools). It's not significantly cheaper than stuff you find at Guitar Center (although it can be if you buy enough of it at once), however the quality of what you can make far exceeds that you can find in stores without paying a lot more.

    I last ordered GS-6 in a 50ft sections and I think it came out to $0.50 a foot shipped. I think the plugs were about $1.50 if you buy 100 at a time, so I can make a 10 foot cable for less than $10 (again, minus the tools).

    I have a dozen of these cables that I made back in 2004 that are still going strong, and my patch cables made with this method have been unplugged and replugged probably a thousand times. One would be hard pressed to match the quality of these cables without spending in the $25 to $30 range (for a 10 footer).
     
  7. FunkMetalBass

    FunkMetalBass

    Aug 5, 2005
    Phoenix, Arizona 85029
    Endorsing Artist: J.C. Basses
    I read a thread about this once where it was recommended to use a mic cable for the extra shielding it provided or the extra ground wire...or something of the like. Anyone care to chime in on this? IIRC, it still only came out to ~$1 per foot of the cable at Parts-Express.
     
  8. Instrument cable has only a single conductor and a shield.

    Mic cable, OTOH, transmits a balanced signal, and thus has extra conductors that would be unused.

    Does anyone know what the parasitic capacitance per-foot is like with mic cables compared to instrument cables?
    I'm too lazy to google.:hyper:
     
  9. FunkMetalBass

    FunkMetalBass

    Aug 5, 2005
    Phoenix, Arizona 85029
    Endorsing Artist: J.C. Basses
    Yes, I know that. I'm specifically referring to how it would be soldered up. I believe the idea was that you use the other inner wire for a single-directional ground, but I post far too often for me to try to dig that thread up.

    And stop being lazy. It's very un-Tesla of you.
     
  10. Wouldn't that increase the capacitance to some degree?

    Bah! I just spent 3 hours googling information about nursing pigeons to health.
     
  11. FunkMetalBass

    FunkMetalBass

    Aug 5, 2005
    Phoenix, Arizona 85029
    Endorsing Artist: J.C. Basses
    I delve in the realm of theoretical & particle physics. Applied electronics is your area. You tell me. :p

    Yes, I can see how that would take precedence to instrument cables.
     
  12. GERMS EVERYWHERE! OH GOD! PEARL EARRINGS!:bag:

    Alright, here is what's going on inside these cables:

    On a single conductor instrument cable, the single conductor's entire circumference is surrounded by the insulator, (dielectric material) whose entire circumference is surrounded by the shield. On a balanced cable, the capacitance should be lower, as only part of the insulating material around each conductor contacts the shield, therefore, the physical area of the dielectric between the conductor and shield is smaller. The parasitic capacitance of a balanced cable being used as an unbalanced cable should be lower than that of a regular unbalanced instrument cable for this reason.

    The parasitic capacitance of the balanced cable will increase if you use the second conductor as a ground, because then the insulation between the first and second conductors acts as a dielectric. However, the capacitance will still be lower than an unbalanced cable because the area of the dielectric material is still smaller, whether or not the second conductor is grounded. Also, the inner conductors are circles, not plates, so the area of the space where they actually physically touch is small. The increase in capacitance with the second conductor grounded should be very slight.:hyper:
     
  13. FunkMetalBass

    FunkMetalBass

    Aug 5, 2005
    Phoenix, Arizona 85029
    Endorsing Artist: J.C. Basses
    Germs?! Where?! I can't see them! Maybe they travel via gravitons from the 11th dimension.

    So then what do you do with the extra conductor? Nothing? It just serves to bleed off the parasitic capacitance and is more effective at reducing a cable's capacitance if it isn't directly connected to any part of the circuit?
     
  14. Honestly, I would just ground it.
     
  15. Handyman

    Handyman

    Sep 4, 2007
    Austin, TX
    I read something about that, but I don't see the point, really. If you compare the specs of the Canare L-2T2S microphone cable to Canare GS-6 instrument cable, the mic cable will get you a slightly higher cap/foot AND a higher resistance per foot. If you hook up both conductors in parallel, you'll just get a very capacitive cable.

    I'd just stick with good instrument cable. Its good at what it was designed to do, and should be a lot easier to hook up to 1/4" jacks.

    Specs for Canare GS-6 and L-2T2S:
    http://www.canare.com/ProductItemDisplay.aspx?productItemID=57
    http://www.canare.com/ProductItemDisplay.aspx?productItemID=61
     
  16. conqr

    conqr

    Feb 16, 2009
    +1

    Guess I really should put some effort into learning proper methodology, but I still just avoid it whenever possible :rollno: Why the heck cant we just use stripped wire and a screw instead? :D

    Great job by the OP though, that cable looks perfecto.
     
  17. SGD Lutherie

    SGD Lutherie Inactive Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    I raised a baby pigeon once. I had to teach it to fly too. :D

    That was before the interwebs, so I had to buy a book. :eek:
     
  18. SGD Lutherie

    SGD Lutherie Inactive Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    A balanced mic has (+), (-), and ground. Basses don't. I think the two conductors are generally twisted too. You can wire them up hot and ground, but I think I'd do two hots and the shield.

    Why not just get some cable that has foil and the braid?
     
  19. SGD Lutherie

    SGD Lutherie Inactive Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products

    Shouldn't you tin your leads first? Also when you solder, you do want to heat the wires first before you flow solder on them. It wasn't clear the way you wrote it.

    I like to go an extra step and put a small piece of shrink tubing over the hot connection.

    Nice tutorial though.
     
  20. MglMatador

    MglMatador

    May 5, 2010
    That's a good point. It's hard to take pictures of the soldering process, but let me give it a try so that the steps are clear.

    Pre-tinning makes the wire hard to route where it needs to go: so long as the wire is heated to a point where the flux can flash to gas it will bond properly. A drop of liquid flux on the braid goes a long way in help this as it's a sizable surface area to cover. If the iron has enough wattage this shouldn't be an issue however.

    Let me take some in-process pics to show the exact soldering sequence I use and I'll post them.
     
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