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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 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.

They do it a little differently in Europe

Old world and all that.  I am of the impression that the European broadcast engineers are a more studied lot.  There process involves much more deliberation, thoughtful analysis and planing than ours does.  For example, when it comes to station loudness, most programmers and many engineers (myself not included) to the more is better.  It is thus that we get the Omina 11 and other audio squashers.

The EBU technical group takes a different approach:

EBU R128 (ed: Loudness Recommendation) is the result of two years of intense work by the audio experts in the EBU PLOUD Group

Aside from the above mentioned EBU R128, there are four technical papers dealing with implementation, meters, distribution and so on.  The body of work is a recommendation not a requirement.  I can’t imagine voluntary implementation of something like this in the US.  Even so, there are advantages to having a single acceptable level of programming audio.  It is interesting reading.

Sound Cards for Broadcast Use

Computer audio sound cards are the norm at nearly all radio stations. I often wonder, am I using the best audio quality sound card?  There are some trade offs on the quality vs. cost curve.  At the expensive end of the curve, one can spend a lot of money for an excellent sound card.  The question is, is it worth it?  The laws of diminishing returns states: No.  High quality reproduction audio can be obtained for a reasonable price.  The one possible exception to that rule would be production studios, especially where music mix downs occur.

I would establish the basic requirement for a professional sound card is balanced audio in and out, either analog, digital or preferably, both.  Almost all sound cards work on PCI buss architecture, some are available with PCMCIA (laptop) or USB.  For permanent installations, an internal PCI buss card is preferred.

Keeping an apples:apples comparison, this comparison it limited to PCI buss, stereo input/output, analog and digital balanced audio units for general use.  Manufactures of these cards often have other units with a higher number of input/output combinations if that is desired.   There are several cards to choose from:

The first and preferred general all around sound card that I use is the Digigram VX222HR series.   This is a mid price range PCI card, running about $525.00 per copy.

Digigram VX222HR professional sound card

Digigram VX222HR professional sound card

These are the cards preferred by BE Audiovault, ENCO and others. I have found them to be easy to install with copious documentation and driver downloads available on line.  The VX series cards are available in 2, 4, 8, or 12 input/output configurations.  The HR suffix stands for “High Resolution,” which indicates 192 KHz sample rate.  This card is capable of generating baseband composite audio, including RDS and subcarriers, with a program like Breakaway Broadcast.

Quick Specs:

  • 2/2 balanced analog and digital AES/EBU I/Os
  • Comprehensive set of drivers: driver for the Digigram SDK, as well as low-latency WDM DirectSound, ASIO, and Wave drivers
  • 32-bit/66 MHz PCI Master mode, PCI and PCI-X compatible interface
  • 24-bit/192 kHz converters
  • LTC input and inter-board Sync
  • Windows 2003 server, 2008 server, Seven, Eight, Vista, XP (32 and 64 bit), ALSA (Linux)
  • Hardware SRC on AES input and separate AES sync input (available on special request)

Next is the Lynx L22-PCI.  This card comes with a rudimentary 16 channel mixer program.  I have found them to be durable and slightly more flexible than the Digigram cards.  They run about $670.00 each.  Again, capable of 192 KHz sample rate on the analog input/outputs.  Like Digigram, Lynx has several other sound cards with multiple input/outputs which are appropriate for broadcast applications.

Lynx L22-PCI professional sound card

Lynx L22-PCI professional sound card

Specifications:

  • 200kHz sample rate / 100kHz analog bandwidth (Supported with all drivers)
  • Two 24-bit balanced analog inputs and outputs
  • +4dBu or -10dBV line levels selectable per channel pair
  • 24-bit AES3 or S/PDIF I/O with full status and subcode support
  • Sample rate conversion on digital input
  • Non-audio digital I/O support for Dolby Digital® and HDCD
  • 32-channel / 32-bit digital mixer with 16 sub outputs
  • Multiple dither algorithms per channel
  • Word, 256 Word, 13.5MHz or 27MHz clock sync
  • Extremely low-jitter tunable sample clock generator
  • Dedicated clock frequency diagnostic hardware
  • Multiple-board audio data routing and sync
  • Two LStream™ ports support 8 additional I/O channels each
  • Compatible with LStream modules for ADAT and AES/EBU standards
  • Zero-wait state, 16-channel, scatter-gather DMA engine
  • Windows 2000/XP/XPx64/Seven/Eight/Vista/Vistax64: MME, ASIO 2.0, WDM, DirectSound, Direct Kernel Streaming and GSIF
  • Macintosh OSX: CoreAudio (10.4)
  • Linux, FreeBSD: OSS
  • RoHS Compliant
  • Optional LStream Expansion Module LS-ADAT: provides sixteen-channel 24-bit ADAT optical I/O (Internal)
  • Optional LStream Expansion Module LS-AES: provides eight-channel 24-bit/96kHz AES/EBU or S/PDIF digital I/O (Internal)

Audio Science makes several different sound cards, which are used in BSI and others in automation systems.  These cards run about $675 each.

Audio Science ASI 5020 professional sound card

Audio Science ASI 5020 professional sound card

Specifications:

  • 6 stereo streams of playback into 2 stereo outputs
  • 4 stereo streams of record from 2 stereo inputs
  • PCM format with sample rates to 192kHz
  • Balanced stereo analog I/O with levels to +24dBu
  • 24bit ADC and DAC with 110dB DNR and 0.0015% THD+N
  • SoundGuard™ transient voltage suppression on all I/O
  • Short length PCI format (6.6 inches/168mm)
  • Up to 4 cards in one system
  • Windows 2000, XP and Linux software drivers available.

There are several other cards and card manufactures which do not use balanced audio.  These cards can be used with caution, but it is not recommended in high RF environments like transmitter sites or studios located at transmitter sites.  Appropriate measures for converting audio from balanced to unbalanced must be observed.

Further, there are many ethersound systems coming into the product pipeline which convert audio directly to TCP/IP for routing over an ethernet 802.x based network.  These systems are coming down in price and are being looked at more favorably by broadcast groups.  This is the future of broadcast audio.

AM can’t wait (can it?)

Click on picture for original memo (.pdf)

I was digging through some old manuals at the shop today and I found this June 1987 memo from Orban to AM stations titled “AM radio CAN sound almost like FM.”

The main purpose of the memo was to get AM radio stations to implement the NRSC standard for pre-emphasis and high frequency roll off to improve the sound of AM broadcasts on ordinary radios.

I am not sure why the receiver manufactures never designed an IF filter that would be compatible with NRSC, it seems like a fairly simple design.  Instead, what we have is “digital” AM radio (IBOC) which does not work well, creates many more problems with interference that of pre NRSC broadcasting.

If one were to look at the entirety of AM broadcasting history, one would find some striking parallels with what is happening with IBOC today on both AM and FM.

To start, the NAB began petitioning the FCC to allow more AM broadcasting stations, even as it was known that these stations would create interference with existing stations, especially at night.  Still, the NAB persisted and the FCC relented and through the fifties, sixties, seventies, and eighties many more class II and III stations were established on what used to be clear channels (classes I and IA).

Once the AM band was chock full of stuff, they began going to work on the FM band with 80-90 drop ins.

You see, for the NAB, more radio stations means more dues money, greater lobbying power because of the larger size of the industry.   Then came deregulation of ownership limits.  By this time, Big Group Radio was calling the shots and they wanted more.  This led to the great consolidation rush of the late 1990’s from which the radio industry is still reeling.  The consolidation rush led to highly overpriced radio stations being leveraged to the absolute maximum, leading to the recent bankruptcies.

Finally, the NAB’s great push toward adopting IBOC digital radio in the early years of the 00’s.  IBOC was supposed to save the day, greatly improving quality of both AM and FM and bring radio into the 21st century.  Except that the promised technical advances never materialized.  IBOC remains a great expensive boondoggle and I am beginning to think that perhaps we should stop listening to the NAB.

The memo itself is a fascinating thing, which were one could substitute AM with RADIO and come to some of the very same conclusions today regarding analog and IBOC digital radio.  For example, this paragraph on AM stereo:

AM stereo was thought to be an answer (to improve AM), but AM stereo was embraced with the false assumption that having ‘stereo’ automatically meant having ‘high fidelity’.  While AM stereo did provide somewhat better fidelity, it was not comprehensively engineered to get the best fidelity from AM.  It was hoped that the gimmick of having two channels would be enough to save AM.

AM stereo could have been an improvement, had it been properly implemented.  Unfortunately, the underlying problem of bad sounding receivers was never addressed.  About which, the same memo notes:

Receiver manufactures did what they could to reduce listener complaints – – they narrowed the bandwidth (thereby reducing audio fidelity) until the complaints about interference stopped.  Listeners clearly indicated, through their buying habits, a clear preference for lower fidelity over continuous irritating static, buzzes, whistles, and “monkey chatter’ from adjacent stations.  People accepted this situation for a long time – – until the simultaneous advent of improved receiver technology and the FCC’s anti-simulcasting rules created the FM boom of the late 1970’s. (ed note: I remember listening to FM because there were fewer commercials, not better sounding audio)

Then the memo goes on to stress the importance of implementing NRSC standard for AM broadcasting that included the sharp frequency roll off at 10 kHz, noting that receiver manufactures would design “fine new receivers” that would take full advantage of the new standard, but only if broadcasters first showed good faith by widely and promptly implementing it.

As I recall, NRSC-1 was adopted as rule of law by the FCC in 1989, about two years after this memo was written.  One could reasonably expect that receiver manufactures then started producing radios that took advantage of the NRSC pre-emphasis curve with IF filters that did not cut off audio frequencies above 3.5 kHz, but rather rolled them off in a gentle slope until about 7 kHz, more aggressively after that until 10 kHz, where they cut off.

Except they didn’t.

Instead, twenty years later, AM radios universally sound bad, with audio bandwidth of about 3 kHz or so.

I believe that AM receivers could be made with three IF bandwidths, automatically selected based on signal strength.  Within the 5 mv contour, full (10 kHz) audio can be reproduced using a high frequency roll off described above.  In the 1 – 5 mv contour, a 6 kHz bandwidth and less than 1 mv a 3 kHz bandwidth.  The automatic selection could be defeated with a “wide/narrow” IF bandwidth selection switch like the GE superradios have.  Of course, if one where listening to stations transmitting AM IBOC, the “narrow” setting would be the best.

Half of me thinks that the ship has already sailed on AM broadcasting.  The stations on the air will continue to decline until they are no longer able to broadcast due to expensive repairs or replacement, at which time they will be turned off.  The other half thinks that AM radio, as evidenced by the huge public response to WEOK and WALL broadcasting the true oldies channel, can be revived.  With the impending inevitable FM IBOC power increases, translator shoe ins, LPFM, etc; the FM band may become worse than the AM band.  At which point the public will have to decide whether free radio is important to them, or 3G/4G services will become the new method of broadcasting.

Axiom


A pessimist sees the glass as half empty. An optimist sees the glass as half full. The engineer sees the glass as twice the size it needs to be.

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
~1st amendment to the United States Constitution

Any society that would give up a little liberty to gain a little security will deserve neither and lose both.
~Benjamin Franklin

The individual has always had to struggle to keep from being overwhelmed by the tribe. To be your own man is hard business. If you try it, you will be lonely often, and sometimes frightened. But no price is too high to pay for the privilege of owning yourself.
~Rudyard Kipling

Everyone has the right to freedom of opinion and expression; this right includes the freedom to hold opinions without interference and to seek, receive and impart information and ideas through any media and regardless of frontiers
~Universal Declaration Of Human Rights, Article 19

...radio was discovered, and not invented, and that these frequencies and principles were always in existence long before man was aware of them. Therefore, no one owns them. They are there as free as sunlight, which is a higher frequency form of the same energy.
~Alan Weiner

Free counters!