Simple X Audio Switch (Double-Y)

I’ve had a small problem over a year: I have two headphone amplifiers, a transistor-based O2 headphone amp, and a tube-based Little Dot MKII. I also have two sets of headsets. Because switching the cables all the time is somewhat tedious, I haven’t really used the other amp and headphone set.

There are several Y switches that you can buy, but most seemed either expensive or mostly tailored towards electric guitar enthusiasts. And I would still need to combine two Y switches to toggle between the two amps and headphones. As the construction is really simple, I decided to solder my own. Here’s a short tutorial on how to make one yourself. You’ll need:

  1. 4 audio connectors (I chose 3.5mm over RCA), two to each end
  2. 2 switches with at least 3 connectors (left, right, ground) – I chose two 4 way switches
  3. A box where you can drill holes for the connectors and switches
  4. Small length of wire, some solder and soldering iron

1. The Schematic

Audio X switch schematic

The design of the switch is extremely simple. In both ends, three wires come from each of the two connectors to a switch, and the switches are connected to each other. I chose not to combine any ground lines to avoid ground loops. You need also to select a switch which breaks the connection on one side before connecting the other so the amplifiers will not feed into each other.

2. Soldering the wires

Despite the simple construction, there is a lot of soldering involved. Each of the four connectors will have ground plus left and right channels, and all have the switch on the other end. That makes 24 solder points (4x3x2), and there’s six more between the switches for a total of 30 points. The 3.5mm connectors had small “L” and “R” markings to tell which channel is left and which is right. I used different colors of wires for each type to avoid mixing L, R and ground.

solder
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A bit of audio tinkering

I’ve been quite busy the last two weekends, first on a weekend holiday trip to Tallinn, Estonia, and then playing in the Helsinki Casual go tournament which successfully took most of my time last weekend. This has somewhat delayed my continuation to the composite video decoder project.

However, I haven’t been resting on my laurels completely even electronics-wise. My trip to Tallinn had one good by-product, namely new Audiotechnica ATH-M50 headphones. They are a marked improvement over my previous HD-500 Sennheisers, and got me inspired to getting a headphone amp, a tube-based Little Dot mkIII to be more exact. The 32 ohm ATHs don’t necessarily need an amp, but now I’ll at least be prepared if I ever end up getting something like HD-650s.

While researching for a proper USB DAC I came across an amazing audio blog by NwAvGuy. Compared to a lot of “audiophile” coverage he seems to have a solid engineering perspective to audio issues, and he has put an amazing effort to long articles that deal with many issues that surround headphone amp gear.

In addition to great scientific info, NwAvGuy has also designed a USB DAC called ODAC, which I ordered from Head’n’Hifi (they conveniently ship inside EU so no customs). And while I was at it, I couldn’t resist getting a DIY version of NwAvGuy’s O2 headphone amplifier. Read on for my experiences on building it and pitting it against the Little Dot mkIII tube amp.
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