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18: Technical Stuff 

Being an electronics engineer by hobby and former career, naturally I take a great interest in the technical presentation of music for ballroom dancing – particularly at KCT events!  As things stand, I use a Windows PC to store and play MP3 rips of CDs that I own personally, which feeds a mixer unit to control the level and mix in a microphone, and then output to a pair of PA ’speakers (meaning each ’speaker includes its own power amplifier).

I find I don’t get a good impression of the volume level when DJing from behind the ’speakers, so I like to have the ’speakers at one end of the hall and me at the other.  That menas sending the stereo audio signal from the mixer to the ’speakers a considerable distance, and it’s not just a case of having a long wire because of that being prone to hiss, hum, radio break-through (and any other kind of interference you can think of).  A radio link could avoid a trailing cable, but is again prone to radio interference, and a wireless digital link (such as Wi-Fi) was found too unreliable.

To that end, I designed and built my own set of adapters which “inject” the audio into a long line at the DJ/mixer end, and then recover the signal at the ’speaker end, using a standard Ethernet Cat5+RJ45 cable to connect the two.  I put this into service in March 2020 (in fact, the last dance before Covid lock-down).

Some of my lock-down time has been spent considering modifications to my PA ’speakers, to make them a better fit for the range of applications I might have rather than accept their off-the-shelf functionality.  That meant analysing their internal circuit to draw a circuit diagram and deduce their performance.

In aid of this, I was fortunate that Practical Electronics magazine happened to publish details of a commercial electronics design package (the sort of thing I might have used in my professional career) now available for free.  In case anyone is interested, you will find details here: Micro-Cap Users Forum.