Monday, March 2, 2015


I have been building some really good guitar FX lately but I'll blog those later maybe, especially the Klon research I've been doing is of interest.  But this fun and rewarding little project just came off the bench:

I was looking at the Hosa and Coleman line selectors but they were dissatisfying for a few reasons: price, build quality, form factor.  So I decided to knock together one of my own.

I got a single deck 4P3T rotary switch from eBay, from China, and it's pretty nice.  This is the most essential part of the project.  With the knob attached, it shifts very smoothly from one position to the next, no clunky or harsh feel.  So far the switch is feels reliable, and it's noiseless.

Basically the 4 poles of the switch are attached to a common pair of TRS jacks (yellow wire, Left Tip, blue wire Left Ring, orange wire Right Tip, grey wire Right Ring) and all the grounds are through the chassis.  Rotating the switch sends the balanced TRS pair to A, B, or C pairs of 1/4" TRS jacks.  You can use this 3-in to 1-out, or vice versa 3-outs from 1-in.  Right now I'm using it as an input selector.  DAC #1, DAC #2, and Mackie Mixer is #3 routed through the switch into my speaker setup.  It would work equally well for switching powered monitor pairs, or what have you.

The spacing in the enclousure was a bit tight with these open frame jacks, it would have probably been best to use all enclosed black type ones, or to measure and lay it out better before drilling.  I was just emptying out my parts bin and I used every stereo jack I had left.  With a modicum of organization and care, the wiring was fairly straightforward, and I did a lot of double checking as I went along.  This is not a difficult project.

You might want to use a plastic jack with no ground connection to isolate all the grounds.  But I am not getting any ground loop noise with my setup.  I figure I'll lift grounds inside the cable plugs if that ever comes up.  I was pleasantly surprised that I don't have to yet.  Quiet like the mouse.

A very useful little project that can be used for any number of common studio audio routing tasks.  Indispensable!  Neato!  Gee Whiz! And check out that cool vintage knob!

No comments:

Post a Comment