There’s a few options and issues here but first up I’ll show you what I think is the best method that will work for the vast majority of users.   The same principles also apply to computers, CD, and DVD players.

Method 1 – 3.5mm stereo jack to 6.5mm mono jack  “Y” cable in 2 mixer channels 

Plug the 6.5mm plugs into 2 of the “Line In” sockets of the mixer.

Benefits:

• -Most mixers have better features on the mic/line channels such as more bands of equalization and routing options.
• -Works where the PA speakers are set up in stereo
• -Almost all mixers have mono “Line In” sockets

Disadvantages

• -Ties up 2 channels of your mixer

Method 2 – 3.5mm stereo jack to 6.5mm mono jack  “Y” cable in 1 stereo mixer channel

Most modern mixers have a few channels that are specifically designed for stereo devices such as iPods, CD players or computers. You can use the same cable to plug into one of thse sockets

This uses the same cable as above

Benefits:

• -Works where the PA speakers are set up in stereo
• -Only ties up 1 channel of the mixer

Disadvantages

• -Equalisation and routing options may be more limited than a regular channel
• -Not all mixers have stereo sockets

Method 3 – 3.5mm stereo jack to 6.5mm mono jack cable in 1 mixer channel

This is the least preferred method.   It may work but there are two problems.   Firstly, this type of cable effectively shorts out the amplifier outputs on your iPod and allows current to flow from the left channel back into iPod’s right channel and vice versa.  It’s theoretically possible to damage the iPod’s output.   The second issue is that combining the two signals may cause distortion.

There is a work around to avoid the problems above.  If a resistor of  say 10k is inserted on each signal line this will prevent current flowing back into the iPod. These resistors can be soldered into the shell of the plug.

For more information see the Rane technical note about their “Unbalanced Summing Box”  here: http://www.rane.com/note109.html

Benefits:

• -Only ties up 1 channel of the mixer.
• -Most mixers have better features on the mic/line channels such as more bands of equalization and routing options.
• -Almost all mixers have mono “Line In” sockets.

Disadvantages:

• -Some risk of damage to iPod unless backflow currents are prevented.
• -Possible distortion and low signal.
• -Doesn’t allow stereo even if the PA allows it.

WARNING – Connecting Your  iPod to a Microphone Socket

Never connect your iPod the 3 pin XLR sockets of a mixer that has “Phantom Power”.   This would include most mixers. Phantom power is a 48 volt signal that the mixer can  send down the microphone lines to power devices such as condenser microphones  and  DI boxes.   The iPod is not designed to handle such high signals.  The only exception is when using a DI box (see below).

Balanced Mixer Inputs

Most mixers will have “Balanced” line inputs.  This is where a 3 conductor cable is  used which includes a shield and  a + and – signal line.   The purpose of this is to reduce possible interference from radio signals &  hum caused by AC power sources.  With methods 1 and 3 we are effectively connecting the shield  and the – signal together making it an “Unbalanced” cable.   Over a short distance this is not a problem as we are unlikely to pick up much radio interference or  AC hum.

Connecting an iPod Over a Long Distance

The above methods are fine for short distances.   If however, you need to send your iPod signal over a long distance, for example from the stage to the mixer at the back of the venue, then things need to be done a bit differently.   In this case you’ll need a “direct injection” or “DI” box.  The purpose of a DI box is to convert an “unbalanced” signal such as from an iPod into a “balanced” signal.   A balanced signal is better able to reject radio interference and  AC hum caused by electrical appliances. DI boxes can be either “Active” (requiring batteries or Phantom Power) or “Passive” (no power required).

Armed with the above knowledge you’ll be ready to connect your iPod up correctly to your PA & get great sound!

Lee Wright.