Have you ever used a regular "Y cable" for combining two audio outputs together, or for summing the Left and Right channels from a single stereo output to mono?

For example:
• You only had one channel input available on your mixer and needed to connect a balanced, line-level stereo source to it.
• You needed to sum the left and right stereo outputs of a mixer to connect to a single amplifier for a mono PA system.
• You needed to sum a stereo signal to mono for connecting it to a single subwoofer.
• You needed to connect the stereo outputs of a mixer, interface, or studio monitor volume controller to a single active monitor ("grot box") such as an Auratone, Avantone Mix Cube, Behritone, etc., to test your mix for mono compatibility.

If you're like me, you've probably done this, but what you may not know is this: a Y-cable used to SPLIT a signal into two outputs is being used properly. A Y-cable used to MIX or COMBINE two signals into one input is being abused, and may even damage your equipment!

Here's the rule: outputs are low impedance, and must only be connected to high impedance inputs. You should never tie two line-level audio outputs directly together. If you do, each output tries to back-feed into the other, and drive the very low impedance of the other output, forcing both outputs into current-limit. At best, this can cause signal loss, audible distortion (popping and clicking sounds), and weird phasing effects. At worst, it can actually damage your equipment over time!

From the research I've done, there aren't any other off-the-shelf boxes or cables on the market that do what this one does. It's a widely-known problem, but no one has addressed it until now. There are a few "mic combiners", but those aren't designed for use with line-level signals, so the resistor values are too low. There are also some regular Y cables that *claim* to do it, but none of them do it properly. Those cables simply short the wires together inside the connectors, but do not utilize any resistors.

Please note--this cable is for balanced, line-level signals. If you need an unbalanced stereo-to-mono summing cable for connecting the outputs of a CD player, laptop, iPod, iPad, Android tablet, phone, or other unbalanced device into a single 1/4" TS input channel on an audio mixer or other unbalanced input, I can also build a cable for you that does just that. Contact me for details.

For further reading on this subject, just Google search "Why Not Wye", which will lead you to an article on the Rane pro audio website that explains the problem and its solution in more detail.

Contact me with any questions.