The Voltair

I have put off writing anything about this for several reasons. First of all, there is a lot of secrecy surrounding the use of the Voltair magic machine. No one will admit to it, however, I have had several off the record conversations with various engineers.  All of this is hush-hush, unofficially off the record and on the QT, so no names, call letters or cities of license can be disclosed.

The general gist of these conversations is this; the Voltair seems to be increasing ratings in some cases and but not others.  It is sometimes too early to tell whether the increased ratings are a one time anomaly or something more permanent.  In one case, an AC station saw 30% increase in numbers, while a certain talk station saw next to nothing.  Results are mixed.

In the credit where credit is due department; the Telos Marketing campaign is has been effective.  Again, from a variety of different sources; Program Directors, Market Managers and Sales Managers are “beside themselves,” or “giddy”  when the UPS truck delivers the Voltair to the front door.  In one case, requiring that “I (the market engineer) drop everything” to get it installed as quickly as possible and “acting like it is God’s gift to radio.”  It looks like all those trade publication ads are paying off, $15,000 at a time.

Voltair PPM encoder enhancing device, in the wild
Voltair PPM encoder enhancing device, in the wild

One interesting thing about the Voltair, you can program simulated listening environments such as sporting events, restaurants, kitchens, vehicles, etc.  This allows the user to see how their program material is being decoded by a PPM survey device in those types of environments.  For example, if you are a sports station, having your program material decode well at sporting events or restaurants and bars might be important.

Of course, we have all seen the confidence display:

Voltair PPM encoder enhancer "confidence display"
Voltair PPM encoder enhancer “confidence display”

So, what does this mean?  Perhaps there is an inherent flaw in the Nielsen PPM encoding technology?  In the past, PPM has been blamed for the demise of the Smooth Jazz format.  I always had the notion that Smooth Jazz was responsible for the demise of the Smooth Jazz format.  However, if PPM is indeed causing certain program material to disappear from the airwaves, then it would be a case of the tail wagging the dog.  If PPM requires that station owner’s purchase a $15,000 in order to get credit for their TSL and cume, then there is a pretty big problem with the technical aspects of the system.

Of course, there are others that say there is no “Voltair effect.”  The Voltair machine is simply a fancy and expensive gizmo that looks good but does not really do anything.

Nielson Audio is having a Webinar on July 21 to address some of the questions regarding the Voltair and PPM encoding for subscribers only.  It will be interesting to see what the outcome is.

Orban Optimod 8000

A piece of vintage gear from the late 1970’s, the Optimod 8000 was and still is a good sounding box.  I have often thought that these processors would make an excellent internet audio processor using the test jacks on the back of the unit.  The audio on these jacks is unbalanced and has 75 µS pre emphasis.   It would be easy enough to make a de-emphasis network and create balanced audio with a 10K:600 ohm transformer.  Some experimentation may be required with the transformer primary impedance value.  Orban notes that not less then 1 MΩ impedance should be connected to the test jacks.  For the internet station looking to copy the “FM radio” sound, this unit would do the job nicely.

The 75 µS  de-emphasis network would look something like this:

75 microsecond de-emphasis network, unbalanced to balaneced audio conversion
75 microsecond de-emphasis network, unbalanced to balanced audio conversion

In this case, the values for the de-emphasis network are fairly critical, therefore 1% or better tolerances for the resistors and capacitors is required.

Even better, an LPFM or some other radio station on a budget could acquire one of these for relatively little on eBay or somewhere else.  With a little TLC, most of these units can be rebuilt and put back into service.  I would recommend that some type of limiter be used in front of it, such as a Texar Audio Prism or CRL SEP-800.

Some classical music stations prefer these units.  I have noticed that they have a nice,  mellow, open sound.  Not at all fatiguing and yet still offer a nice easy 10 dB gain reduction.  There is also a modification that can slow down the release time on the gain reduction.  More gain reduction, AKA compression, can be had with something else in front of the unit.

The best part about these units, there is no rebooting, no processor lock ups, software glitches or any of that non-sense.  Additionally, a quick look at the front of the unit shows very few user controls, making it almost impossible to screw up and sound bad. They are well built and so long as the electrolytic capacitors are changed out, fairly bullet proof.  Other processors, not so much.

Optimod 8000A under test
Optimod 8000A under test

This is an Optimod 8000A that I decided to put through its paces.

Really, how much more do you need?  I recorded this on the camera microphone using a replica table radio, seen near the end of the video on the right hand side of the frame.

I used the Technics SL-1200 MKII turntable through an ATI P100 turntable preamp into the Optimod.  The Optimod is feeding a BE FX-30 exciter running 15 watts into a dummy load.   The Optimod is running about 5-7 dB gain reduction, which is enough in my mind.  The BE FX-30 is still just about the best sounding analog exciter every made.

Rechipped Optimod 8000A, TL071 opamp
Rechipped Optimod 8000A, TL071 opamp

This unit has been re-capped and re-chipped at one point.  The re-chipping follows the Orban recommendation; the 4558 and 1556 opamps are replaced by TL071CP and TL072CP respectively, and the uA 709 and 301A opamps are left in the unit.  A good thing to remember, the uA709 and 301A opamps can be replaced by TLO71cP opamps in the event of failure.  The Texas Instruments TL0 series opamps are very good and readily available.

Optmod 8000A input and limiter board
Optmod 8000A input and limiter board

Overall, this unit is in good condition, however, like many such units, it is missing its brown “Optimod” cover, which goes over the input/output controls.

Manual is available at the Orban ftp site: ftp.orban.com.

Occupy(ied) Bandwidth

Or rather occupied bandwidth.  During a recent Alternative Inspection of an FM station, there was some question as to the accuracy of the modulation monitor.  Truth be told, a modulation monitor is no longer required at a radio station, so long as the station ensures that they comply with relevant FCC regulations for their service.  Many modulation monitors continue on, however, as air monitor receivers.

That is all well and good, however,  many modulation monitors are notoriously inaccurate and tend to the overly sensitive side of the equation.  If used when setting the modulation levels, this can lead to under modulation, which, as we all know leads to disaster, destruction and bad ratings….  Because the volume knob on every radio in the entire metro, Total Survey Area (TSA), or even the whole country has been broken off and listeners are unable to compensate for the low audio levels from an under modulated FM transmitter.

But anyway.

FCC 73.1560 gives the maximum FM deviation as +/- 75 KHz from the carrier, with some allowance for SCA injection levels, up to +/- 78 KHz.  This is the definition of 100 percent modulation of an FM carrier.  Thus the entire occupied bandwidth is 150 KHz, leaving a guard band of 50 KHz between signals. That is, unless IBOC is employed, then the guard band is -100 KHz which is good science no matter how one looks at it.  On a spectrum analyzer, it looks something like this:

Occupied bandwidth of analog FM broadcast transmitter
Occupied bandwidth of analog FM broadcast transmitter

This shows that the 5 second average occupied bandwidth of 90 percent of the transmitted energy is within 153 KHz, which is slightly high but within the margin of error of the measurement device.  The vertical lines represent the -10 dB signal level as referenced to the carrier.  Thus this station is in compliance with FCC rules regarding modulation in spite of the face that the analog modulation monitor shows it being 10-20 percent over.   Had it actually been 110 percent, the occupied bandwidth would have been 165 KHz and 120 percent would have read 180 KHz.

Thus, before buying the latest squash-o-matic FM processor and setting it for full tilt boogy, a good engineer may want to check the occupied bandwidth with something other than the old analog FM modulation monitor in the rack.