Wednesday, October 15, 2008

DIY Audio Cables

Cables are probably the most important parts of any rig. If you have crappy cables, you have to worry about poor signal, unreliable operation, and signal coloration. Quality cables are essential. However you don't have to spend a fortune to have excellent quality cables. Sure every cable manufacturer claims to be the best. A lot of them are also outrageously priced. Many will argue that the super expensive ones sound better here and there. Maybe true, but most people won't be able to tell and 99% of your audience won't care. This will focus on music specific cables. It will not provde in depth explantions, but just the results of what I have found. It will also talk about connectors and construction tips.

The Bottom Line

In general here are the most important things to know about what makes a good cable:
  1. Low Resistance - This is the signal strength. Of course length will have an effect. Applies more to speaker cables. Even crappy cables for instrument/line-signal cables will be good enough.
  2. Low Capacitance - The more capacitance (between conductor and shield), the more highs you will loose. This might be a good thing for some. But for most of us, this is the defining factor between good cables and crappy ones. Lower is better here. Doesn't apply as much to speaker cables.
  3. Good Shielding - Better shielding = better noise rejection. Only really applies to instrument/line-level cables. You don't need shielding for speaker cables unless in extreme conditions. Foil provides best and 100% shielding but will break easily (ie. only use for permanent installation). Braid or spiral are good, Braid often considered better/more durable, but is less flexible. It comes down to the Percent Shielded. If not published, it is probably a foil shield or pretty low.
  4. Physically Rugged - Assuming mobile use, you want rugged cables. If they are stationary (ie. permanent installation, racks, etc.) this isn't as important. But in my opinion it never hurts. Unless you are cabling hundreds of feet for a studio/venue, the price difference is minimal.

    Also consider construction. Ie. good strain relief, good solder joints, good connectors.

  5. The Right Cable for Job - This may seem obvious, but you would be amazed at how often I run into this. Just because the connector works, doesn't mean it is the right cable. In music you typically run into the following:
    • Instrument Cable (Unbalanced) - Connector type is typically 1/4" Tip-Ring (TR) connectors. Used for guitar/bass/etc. Also sometimes used to connect keyboards, processors, etc. where balanced connections are not available. Often you can use one of these in place of a balanced connection but with possibly more noise introduced.

      Can be smaller guage (18Ga - 26Ga). Shielding (ie. above 80%) and capacitance (blow 60pf/ft) are extremely important.

      This also applies to RCA cables used to hook up stereo equipment and cheaper mixers.

    • Microphone Cable (Balanced) - Now I am not referring to the cheap Radio Shack Karaoke type microphones. I mean professional grade microphones with detachable XLR cables. Balancing is using an inverted signal on a different wire and twisted with the original signal. This helps boost and keep noise out. Then when the two are joined (inverted, inverted again back to normal), the noise is cancelled out.

      Typically these use XLR connectors. However sometimes you will see Stereo 1/4" Tip-Ring-Sleeve (TRS) connectors. Typically used with mixers, processors, and other line-level devices. Also used almost exclusively with professional quality microphones.

      Look for good construction mostly. Good shielding is important as well. Capacitance doesn't matter as much, but still important. With this you can see that balancing whenever possible is really the way to go.

    • Speaker Cables - Often 1/4" TS connectors. Also often Neutrik Speakon's for higher powered applications. No shielding necessary and discouraged. Go for low resistance and physical ruggedness. Zip cord is fine. Look for 12-18Ga wire. Larger guage, lower resistance. Anything bigger than 12Ga is really difficult to work with and your construction will suffer. 14Ga-16Ga is good just about any application. Check your amp manuals and cable specs for more information. But in general you can use power-cable pretty much.

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