Studying for final exams this week

My apologies to the regular readers here. I have been busy studying, working, and managing family life.  The good news is my last final exam is this afternoon.  Even better news, the next semester is starting on May 22nd, during which I will be taking English 227, which is a Technical Writing course.  It is my hope that you all will be benefiting from my labor.

Electronic death

Good audio clip below of the WIYY’s (Rock 98, Baltimore) console melting down during the morning show.  These things happen from time to time. I often found, when it happened at one the stations I was working for, nobody would know anything about it. Nope. Just stopped working. What? No, I don’t know anything about the coffee dripping out of the bottom of the console.

Rock 98, (WIYY) Baltimore, coffee spilled into console courtesy of the Baltimore Sun.

If that link doesn’t work, try this one (7MB .mp3 file).

Pictures and stuff at their facebook page.

Off the air for twenty minutes during morning drive.  I wonder what kind of console it was?  From the pictures on facebook, it looks like Wheatstone stuff.  Ouch! That’s going to leave a mark.

I tried to enforce a no eating no drinking in the studio rule.  Most of the time I was successful, however, there were various incidents over the years.  The worst was the morning show spilling “distilled water” in the console, but not saying anything about it.  Months later, the air monitor stopped muting when the main mic was turned on. Nearly caused the guy who did the spilling to loose his hearing.  Karma.

At another station, someone spilled soda on all the remote mic on/off/cough switches for the guest positions.  That prompted an early morning phone call, which the morning show producer yelled at me and told me I must be at the station in five minutes (I lived about 25 minutes away at the time).  Ha!  I took my sweet time getting there.  The soda cooked all the +5VDC regulators on the guest microphone modules, thus, for the next several days, all the morning show DJ’s had to share one microphone.

Old time radio guys will tell you, do not mess with the engineer.

EAS text to speech permitted, not required

The FCC reverses it’s former position on EAS text to speech, permitting stations to begin using it today (May 7, 2012).  The FCC’s main issue with Text To Speech (TTS) was that it may  not render the text accurately enough to be understood, especially in emergencies.  This can lead to confusing messages and defeat the purpose of EAS altogether.

I have played around with some text to speech software and indeed it can mangle words, mispronounce punctuation as a part of the sentence structure, mumble, etc.  Further, as I have said before, listening to some robo voice is very impersonal.  But, I suppose that is the point, isn’t it; some big government agency computers generating messages that no one person is really responsible for.  Bureaucratic paradise.

Summing to Mono

It is surprising to me how many times I have seen this done incorrectly in the field. Summing a stereo source, whether it is balanced or unbalanced is not simply twisting a couple of wires together.  This will effectively reduce the impedance of the outputs by one half. With newer, active balanced outputs, this may cause damage to the output amplifiers.

The parallel resistance formula is thus:

Therefore a 600 ohm stereo output tied together would look like:

Rt = 1/(1/600+1/600) or 300 ohms.

It also creates an impedance mismatch with the next piece of gear, which will effect the common mode noise rejection of the circuit.

The best way to sum is through a resistive network.  That way stereo separation is maintained, the impedance of the output circuits is maintained and the output amplifier will not current cycle.  That looks like this:

resistive summing network
resistive summing network

Pretty easy to fabricate in the field.  It is good to do things the right way, it sounds better on the air too.