Audio Band-Aid

Sometimes in the field, one has to improvise. Lately the Peanut Whistle blogger has found himself seeing this in practice. Our latest venture at the new radio station involves a funny contraption that reminds this blog of a Rube Goldberg Machine.

We were called to fix the audio from the control room computer. It runs a version of Adobe Audition that is used to record satellite shows for later broadcast. The audio into and out of the machine was distorted—badly. Prior to the Memorial Day holiday, it was imperative that we get the audio fixed. Toolkit in hand, the hunt began for the gremlin that invaded the board, once again.

The console is an ancient, but serviceable,  mono 10-channel rotary pot LPB Signature III that has extra inputs on select channels. For whatever reason, previous engineers had placed conflicting sources on the same pot. For example, the Enco DAD presenter feed was on the same switch as the satellite feed. That was corrected.

First thing, the Adobe Audition computer, an E-machines brand, was rerouted so we could eliminate possible crosstalk. That was not the problem. The wire pulled away from the source and it was discovered that the computer tower had been placed on the floor! A great location for board ops to kick it. The audio was coming from the soundcard port on the back of the tower (arguably, not an ideal pro connection.) The speaker port had been damaged inside, as well as the odd jack and assorted adapters. A 1/8” to 1/4” stereo phone plug adapter into a 1/4” phone to stereo RCA phono plug, then into a stereo to mono y-adapter and finally an RCA cord to the board. No wonder the jack had been damaged; all the length and weight not only had bent the 1/8” plug, the jack on the sound card had been virtually hollowed out. (See the photos below)

In the example above, we recreated the adapter “pigtail” with a mono phone adapter, otherwise, it is the same as the studio’s.

The repair session took place afterhours and Radio Shack was closed. Bummer, so we frantically rummaged through the parts attic and found a new mini-plug in a plastic bin full of random electrical stuff. This was lucky, to say the least.

After recreating the improvised circuit, the connection had to be replaced to the front of the computer where an extra speaker terminal was placed (more good luck.)

Levels had to be tweaked in Windows. The line in jack, although noisy due to electrical and RF interference, was okay, required electronic adjustments as well. Oddly enough, the connection from the board was a straight wire, terminating in a mini-plug (1/8”). A return trip is guaranteed. The repair is only a Band-Aid. Next we will relocate the E-machine higher and provide a USB interface with pro XLR and RCA connections for a noise free balanced circuit.

Stay tuned.