11
Working with Engineering
Being Involved in How Your Station Sounds
The frequently adverse relationship between programming and sales is legendary and often overstated. However, there is another relationship involving the program director (PD) that sometimes borders on being frustrating, and it need not be. That’s the PD’s relationship with the chief engineer.
Frequently, the PD feels that the station doesn’t sound as good as it could. This is a legitimate programming concern because although the programming is considered to be the content of the broadcasts, the way the station sounds can definitely affect listeners’ reaction to the station. However, the chief engineer (CE) is frequently suspicious of the PD’s motives in wanting to change the sound of the station and fears that the PD wants to “junk up” the sound. The result, all too often, is mutual suspicion, with the CE stalling—nodding agreement but making no changes—secure in the knowledge that the PD doesn’t know how to achieve the sound that he or she is after. As I said, the relationship need not be this way.
Actually, the PD and the CE have many common goals; unlike others in the station management, their primary interest is in how the station is perceived by listeners. This should bring them together, without each fearing that the other is encroaching on his or her territory. Most CEs are a lot more concerned with the sound of the station than the content, and PDs are mainly concerned with the content; they simply want the technical sound that the station transmits to be competitive if not superior to that of other stations in the market.
Once the CE is satisfied that you want to make him or her a partner in getting the sound of the station right, rather than trampling on his or her judgment about how the station should process its audio, then the relationship generally becomes quite productive. I’ve only encountered one CE in my many years in the business who felt threatened by a programmer taking an interest in this—and he needn’t have. I still have no idea how to build or fix the equipment. I need the help of a superior engineer.
You may have heard the saying, “You don’t have to be a watchmaker to want to learn how to use a watch.” The chief engineer is the watchmaker; the program director is the user. It is legitimate and natural for the CE to work with the PD to achieve the sound the programmer wants, as long as it is consistent with good engineering practice.
There was a time when programmers wanted heavy audio limiting and compression for loudness and to impart “energy” to the broadcast, whereas the CEs quite rightly preferred not to ruin the quality of the audio with “pumping” and distortion. Nowadays, though, the tendency is for both parties to want the station to sound “clean” but competitive, which should lead to a natural partnership.
The use of heavy limiting and compression adds distortion to the signal. This can, under some circumstances, sound exciting, but it nearly always increases listening fatigue in members of the audience—particularly older ones—leading to shorter average listening spans. Furthermore, the rise of compact discs (CDs) and digital sound has been slowly educating consumers to recognize and want clean, undistorted, high-fidelity sound. This, in turn, has led to new generations of audio-processing gear that strives to reduce dynamic range and properly level all programming while still sounding as if there were no processing at all.
The Evolution of Modern Audio Processing
Let’s pause a moment and tip our hat to the father of modern audio processing, George M. Frese of East Wenatchee, Washington, whose studies of broadcast audio in the fifties and sixties led to his remarkable, hand-built Frese Audio Pilot. Though still little known in the business, Frese invented a computerlike device that introduced nearly every innovation in modern audio processing, including controlling enormously wide dynamic range instantaneously and inaudibly, with the speed of gain change controlled by program content; “gating” so that background noise didn’t get pulled up in moments of silence; asymmetrical peak switching; soft, wave-shaped “peak clipping” for maximum program density; and equalization—in other words, audio processing with an “unprocessed” sound.
The Frese Audio Pilot also incorporated one thing that is still unique to this historic device: output-monitored audio processing via a return line from the transmitter. This enabled the unit to be set to deliver exactly the desired modulation parameters and provide exactly the type and percentage of modulation desired. It controlled the two peaks of the wave separately, based on feedback from the actual transmitted wave.
Frese’s invention was a true “audio computer,” and it inspired a generation of equipment designers, including one whom I’m pleased to know personally, Donn Werrbach. His Aphex audio-processing devices mimic many of the Audio Pilot functions, though they use different and novel techniques to achieve them. Because Frese didn’t patent any of his inventions, he receives no financial benefit from the audio-processing industry he inspired, but we can at least acknowledge his contribution.
Maximizing Audio Processing
If you’re going to work with your chief engineer to get the station sounding the way you want, you’ll have to understand the basics of how and why audio is “processed.” You may not realize it, but all radio receivers contain an automatic volume control (AVC) circuit, which maintains the same subjective volume level for all signals received, regardless of whether they are strong or weak. As a result, the subjective loudness of a station is a function of the programming presented and especially the way it is processed, rather than the strength of the received signal.
Thus audio processing is important to all stations, and audio compression is fundamental to such processing. If a transmission is to be easily heard at normal listening locations (especially cars), it must be “processed” to reduce (or “compress”) the dynamic range. Dynamic range is the ratio of the softest sounds to the loudest.
Alas for audio purists who deplore any processing at all, even a small drop in level of 6 dB (equal to the volume difference between 0 VU and −6VU on a standard control board VU meter) is enough to make a station inaudible for most listeners because people tend to listen to radio in noisy environments. To keep the audio peaks from dropping even that much during normal programming, the basic tools of the radio station are a compressor and a limiter, used one after another in that order. Let’s take a look at what they do and how they do it.
Superficially, both of these devices seem about the same. Each is a level-controlling amplifier. From a practical standpoint, though, they work quite differently. The compressor is designed to take whatever audio signal is being sent to the transmitter and adjust the level (volume) inaudibly so that the peaks of the audio are held within a fairly narrow range. Portable cassette recorders and CB radios are just two devices that usually have automatic gain control built in, which means that the input volume does not have to be manually set; it’s done automatically by a compressor.
However, the compressor does not act speedily enough to keep occasional instantaneous peaks from shooting quite a bit above the average level it sets. As a result, if the only thing you use to control the loudness of the audio going into the transmitter is a compressor, the average level of the broadcast will be kept a lot lower than you’d like to have it in order to avoid having those occasional peaks “overmodulate” the transmitter and cause distortion in the receiver.
To allow the average audio level to be about the same as the peak level, there must be a limiter following the compressor. This device does not affect sound below a certain level, or audio threshold, which is adjustable. However, when any element of sound—even a very quick peak—exceeds that threshold, it instantaneously turns down the level enough to keep that peak from getting any louder than the preset threshold level.
The limiter is usually set so that the average peak level from the compressor pushes slightly above the threshold, causing 2 or 3 dB (or VU) of continuous limiting and stopping all peaks from exceeding the preset level. This permits a higher average level of audio to be fed to the transmitter. If the compressor audio were to be driven harder (higher) into the “limiting,” the audio density would increase. This makes the station sound louder at the cost of reduced dynamic range, and with older equipment, it causes more distortion of the audio.
Modern audio processing often mimics Frese’s “soft clipper” concept by using an audio-clipping device to flatten off the top of the wave peaks; this can allow even higher audio density and “loudness” than the compressor-limiter combination can achieve, by bringing the average level even closer to the peak level. However, this often occurs at the cost of increased undesirable distortion, which the listener calls a fuzziness or “buzziness” in the sound. If the listener notices the audio processing’s effects, you can be sure you’re overdoing it.
In general, audio processing should be set for the maximum loudness and audio density short of where distortion and other artifacts start becoming even slightly noticeable. A high average modulation level not only keeps the station competitive with other stations when tuning across the dial, but it can actually maximize the coverage area of the station.
For AM (amplitude modulation) stations, what’s being used to encode the audio information on the signal is a variation of the amplitude, or strength (the power in watts), of the signal. For this reason, there is actually more power leaving the transmitter on the positive peaks, and high positive peaks (within FCC limits) can improve the signal-to-noise ratio of the signal in the fringe areas.
For FM (frequency modulation) stations, in which the frequency of the station (the actual dial position) is what is varying to convey the audio information to the receiver, the much higher frequency “smaller” radio wave bounces off mountains, buildings, and metal objects, causing multipath distortion. Dense modulation on FM stations can reduce this type of distortion in the receiver and can extend the usable signal into areas where reception is difficult.
Your chief engineer might have some difficulty accepting that denser modulation could actually accomplish this for FM stations, but side-by-side comparisons by professional engineers have shown that the improvement can be quite significant. In addition, dense modulation also improves the signal-to-noise ratio of FM signals. However, high modulation density will not have any useful effect in forthcoming digital broadcasting, in which audio processing will only be needed to keep the broadcast audible over ambient background noise where people listen.
To avoid confusion, I should add that in digital broadcasting, digital compression is totally unlike audio compression. Digital compression is the technique of making a digital bit stream broadcastable within a manageable bandwidth by eliminating the parts of the audio data that would not be audible for various reasons. This can cut the digital data by as much as 80 percent, preferably without loss of audio quality.
Returning to audio, though, modern audio processing includes more than simply controlling the volume, or level, of the broadcast. There are sophisticated techniques available to radio stations today to further modify the sound to make one station sound different from another and to improve audio clarity. The most common of these involves adjusting the tonal balance of the audio, or “equalizing” it.
Before you embark on your odyssey to achieve the best possible tonal balance, or equalization, of your signal, you must change the way you think about sound. Your concept of sound probably derives from the audio systems in your home or car, but this can mislead you when tailoring radio station audio.
You see, consumers can turn up the bass, adjust the midrange, tweak the treble, and get the sound exactly the way they want it with ease. It’s much harder doing this for a station because you are stuck with a firm limit to the overall maximum sound level you can transmit.
If you turn up the bass at home, the midrange and treble can and do stay as they were. This is not so in radio transmission. If you boost one section of the audio spectrum, other parts must drop because you are changing the audio energy balance throughout the whole acoustic band of frequencies, altering the relative levels of each part of the audio spectrum.
In broadcasting, where there is a maximum level that you are always trying to stay near, the compressor and limiter combination will keep pulling up the newly equalized audio to hold it at the same maximum level as before. This means that you are actually turning down some parts of the audio band when you want to make other parts more prominent. In practice, that’s a considerable difference. To bring up the midrange, you are in effect turning down the bass and treble. Likewise, to emphasize bass, you must reduce the midrange and treble, and so forth.
If this distinction is not yet clear, visualize it this way: Compare your radio signal to a full drinking glass, containing three layers of differently colored fluids, each of which stay separate and distinct. The blue layer on the bottom is bass, the yellow layer in the middle is midrange, and the red layer on the top is treble.
Now, beside it, imagine your home audio system as a very big drinking glass that you hardly ever fill up; these three fluids stay rather low in that glass at all times. So, when you want more bass at home, you just pour in more blue fluid, and there’s still plenty of room in the glass to accommodate the new, larger layer of blue fluid without removing any of the other two layers.
For broadcasting, we keep the three fluids right up at the top of the glass at all times to achieve the best competitive loudness and coverage. When we add more blue fluid, we have to take out some of the other two colors of fluid so there is less of those in the glass. You want more bass in your signal? You’re going to have to lose some midrange and treble. Do you really want to do that?
In fact, most PDs do seem to want more bass in their signal—and sometimes more treble to balance it out. This works against the goals of the station, though, because most consumer radios have weak bass. (“Aha,” says the PD. “That’s why I want more bass.”) The result, on these poor receivers, is that the radio can’t reproduce the strong bass at anywhere near full level (and, worse yet, distorts it on the average radio, making the station sound muddy). Because the extra treble you added to counter the heavy bass is being boosted at the expense of the midrange—the section of the spectrum that we hear best and that most radios reproduce best—the station sounds muddy, shrill, and actually lower in average volume than the competition.
However, if we enhance just the midrange frequencies that we hear best, the station may sound competitively louder, but it may also sound “nasal” and unbalanced. The goal is to achieve a distinctive sound balance that sounds good on a wide variety of receivers while remaining competitively “loud”—and this is really the test of a good chief engineer.
Multiband processing, a tool developed in the sixties and seventies to help accomplish this, is today a very common part of stations’ audio chain. A multiband processor is a compression device that first splits the audio spectrum into two, three, or more bands, in much the same way as tone controls do, and then compresses each band separately. In effect, it’s an automatic equalizer. It brings up the bass on sources with weak bass and likewise adjusts the midrange and treble to keep the audio balance consistent from source to source, regardless of what sort of audio the station is broadcasting at any given moment.
The multiband processor not only keeps the audio balance of the station consistent, but by careful adjustment of the output levels of each individual band, it can maintain a desired balance of the audio spectrum, as you, your general manager, and your chief engineer mutually decide is best after many listening experiments. (This listening must be done on typical radios—not on super sound systems.)
Other types of sophisticated audio devices may be added experimentally to the processing—including stereo expanders and harmonic-generating devices that can restore overtones eliminated in recording and broadcasting and thus make the music sound more “live.” It’s important to make sure that you actually hear a practical difference using one of these expensive gizmos in a side-by-side comparison in and out of the circuit. If you can’t hear it when listening intently in a direct A/B comparison, it probably has no useful effect upon your listeners at all and should be discarded.
One additional type of processing device that can be very helpful in tailoring a station’s sound is a fixed equalizer—but it must be used very carefully. There are two basic kinds of equalizer: the graphic and the parametric. A graphic equalizer, the kind usually sold to home and auto hi-fi buffs, has a series of vertical sliders, each representing one octave of sound or a fraction of an octave. There may be five, ten, twelve, twenty, or more bands of tone control available, stretching from the deepest bass to the highest treble.
This device is called a graphic equalizer because the setting of the individual sliders forms a sort of jagged horizontal line—a “graph” of the bass-to-treble tonal balance of the sound. Graphic equalizers are very helpful in a production room, allowing correction of the tonal balance of recorded commercials, which all too often are somewhat deficient in audio quality. It can also create special effects for staff-produced spots.
However, the multiband processor is designed to accomplish automatically what a graphic equalizer does manually so you usually won’t need one of these in your audio chain to the transmitter. What you might instead choose to use between the compressor and the limiter is a parametric equalizer, so named because you can set the parameters for the part of the audio spectrum to be adjusted. One parameter would be the center frequency of the audio band to be adjusted; another would be the width of the audio band you’ve chosen; and the third would be the degree of boost or reduction in that band.
Because any adjustment of the audio using a parametric equalizer will still be subject to the “full drinking glass” phenomenon mentioned earlier, meaning that you will reduce some audio frequencies when you boost others, any work done with this device should be kept relatively subtle. Here are a few things you can do with a parametric equalizer.
To enhance perceived clarity of the overall station sound, including the voice clarity of your announcers, set the audio band in the midrange—around 3,000 Hz. Set the bandwidth to “narrow,” and try setting a boost of perhaps 6 dB. Then tune the center frequency slowly between 2,000 Hz and 4,000 Hz while listening on a variety of radios. You should find a center frequency that gives the station an open and very up-front sound without creating a harshness or a nasal quality with voices. Adjust the degree of boost on that audio frequency for the best overall bass-to-treble balance.
If you have a couple more bands of audio to work with on your parametric equalizer, consider adding a 2- or 3-dB bass boost around 120 Hz—and then rolling off all bass below about 70 or 60 Hz. This can add more apparent “bottom” to your signal while reducing the total bass energy, thus avoiding the fuzzy, distorted bass and weak midrange effects of a real bass boost. (Your transmitter might like the result better, too.)
With your third band, you might try a gentle, gradual roll-off of highs above 10kHz (for FM only; AM is not permitted to exceed 10kHz in treble response anyway) to reduce the distortion effects of modern high-frequency FM processing. Such a treble roll-off won’t be necessary in digital audio broadcasting, but the other two adjustments described might be.
Concerning the rationale for a treble roll-off for FM, I should explain that there’s a wicked treble boost built into the FM transmission process, which is matched by an equal roll-off of treble response in all receivers. This was intended to reduce the perceived hiss and noise in the high frequencies when FM was perfected in the thirties by its inventor, Major Edwin Armstrong. However, today’s hot highs from compact discs create terrible transmission problems for FM stations because of that automatic treble boost. As a result, severe treble reduction and clipping is built into modern FM audio processors to permit high average modulation without overmodulating the highs. This causes distortion and graininess in FM stations’ treble range, and rolling off the treble fed to the transmitter can clean up the station’s sound by causing less severe audio processing.
Because with all of the adjustments I’ve discussed making with a parametric equalizer, you are enhancing narrow bands of frequencies, there is relatively little energy added to the overall processed sound of the station after the multiband processing (very little “fluid” added to the “drinking glass”), minimizing the problems of balancing each part of the audio spectrum against one another. However, make sure that you place any parametric equalizer after the multiband processor, so that the equalizer’s enhancements are not systematically reversed by the processor!
A Few Warnings
I’ve given you the basics of audio processing and adjusting the sound of your station to help match your vision of how the station should sound. However, I have a couple of important warnings.
First and foremost, you should work with your CE on such adjustments. In fact, let him or her do the actual adjustments. If you have succeeded in being accepted as the CE’s sidekick in polishing the station’s sound, you two can be a very effective team, but the equipment is the CE’s province, and he or she should supervise any adjustments.
On the other hand, if your CE would rather not have you giving input on the station’s sound and audio processing, discuss your objectives with the general manager and obtain his or her approval for your goals. If the general manager endorses what you want to do, you should be able to get it done. Promise to keep your hands off of the machinery and to limit your participation to providing comments and suggestions! I hope the preceding section will enable you to make effective ones.
The second warning concerns how we all hear what we expect to hear. We must not lose sight of how the station is perceived by its listeners. I have seen otherwise intelligent PDs get so involved in “tweaking” the station’s sound to match a sound in their head that they haven’t been able to step back two paces and hear how truly awful the overall effect has become. Listen on a variety of radios, and notice not only the details, but the overall effect of your station in the competitive picture.
I’ve warned you to keep your hands off the processing gear and let the CE do the adjusting (with your input, of course). Most CEs are very firm about this because they are personally responsible to the general manager, owner, and the Federal Communications Commission for the legal operation of the station and the maintenance of the equipment. If they find the processing set up differently from the way they had it, they feel as violated as you would if the chief engineer had gone into the control room and made some change in your music rotation or your liner cards without asking you!
Once you’ve demonstrated fully to your CE that you can be trusted, you may be able to get his or her approval to make minor adjustments on your own after you have had a chance to do a lot of listening to the station. If you do get that permission, that’s useful, but don’t abuse it. Leave the CE notes explaining just what you did so that he or she is always fully up-to-date on what you’ve done and why—and has the opportunity of sharing his or her input on it with you.
Quick Fixes That You Can Do
More and more, stations are using “contract engineers” as their chief engineers. These multiple-station, part-time engineers have been a staple in smaller markets for decades, but now they can be found in even large markets. They are under contract for scheduled weekly maintenance, plus emergency work when the station is off the air, regardless of the day or hour. If your CE is a contract engineer, you may not see him or her around very much.
Under such circumstances, I’ve had to learn quite a bit about doing emergency maintenance myself, although I’m still not able to diagnose or fix a circuit or electronic component. If something quits working when no engineer is at hand, either you will have to save the day or you will have a real problem on your hands. I’ve discovered that at least 90 percent of the time, what needs fixing is something that a program director can do.
For example, if there is a big hum in the audio, look to see whether a ground wire has come loose somewhere on that input. (If it has, the hum you hear is referred to as a “ground loop” hum.)
If a piece of equipment has stopped working, see if it’s still plugged into the electric socket. If it is, see if it has a fuse—usually inside a round black plastic cap sticking out of the back of the unit (that’s a fuse holder). Push in the black cap and twist it clockwise part of a turn until it releases, pull it out with the fuse in it, and see if the wire visible through the fuse’s glass tube appears to be intact. If not, the fuse needs to be replaced.
There is another way to check the fuse: If you have access to a volt-ohmmeter, switch the meter to “resistance” and check the meter by touching its two probe wires together. You should get a full-scale or “zero resistance” reading. Then check the fuse by touching the two probes against the opposite metal ends of the fuse. This should give you the same “zero resistance” reading; if it doesn’t, the fuse is bad. Volt-ohmmeters are very cheap at electronic-supply stores; you may want to buy yourself one. They’re handy to have for purposes like this.
If the fuse is bad, replace it. If it’s okay, put it back in its socket by pushing the fuse holder cap—with the fuse in it, as you found it—all the way back in, and turning it counterclockwise until it stops and locks down.
When a large bank of equipment is down, find the station’s power panel and see if any of the electric circuit breakers are blown (the switch would be part way between on and off). Flip any blown breaker switches to off then back to on. If it blows again immediately, something has shorted out on the circuit. Unplug everything you can on that circuit, reset the breaker, and if it stays reset, return to the affected area and start plugging things back in one at a time. At some point, you should blow the breaker again. Unplug the last device plugged in—that’s the shorted unit—and reset the breaker again. You should be able to plug everything else back in and reset the breaker. The shorted item will have to be removed for the engineer’s inspection. Leave a note with it describing the problem.
If a tape recorder, cassette machine, or cart machine starts to sound dull or weak or even stops reproducing sound at all, first try cleaning the heads—the metal blocks that the tape runs across as it plays. Isopropyl alcohol, with as high a percentage as possible (99 percent is best), scrubbed over these heads with a cotton swab, will clean off the dirt. If dirt is the problem, you’ll see it on the swab.
If audiotape starts playing back with no highs and a weird “flanging” acoustic effect, the head azimuth has become misadjusted; the tape head is no longer absolutely perpendicular to the path of the tape. There’s a screw adjustment beside the head itself, often sealed with a drop of fingernail polish, and in an emergency it can be adjusted carefully with a small screwdriver while you listen to the tape play back in mono through the cue system. Turn the screw until the highs become as clear and bright as possible. However, it’s best not to do this yourself until you contact the CE and get approval to try. The CE may want to do it personally; if not, the CE will want to know later what you did to fine-tune the azimuth adjustment.
Sound “cutting out” in headphones means that a wire has broken in the cable between the plug and the headphones or has come off in the plug. If you know how to solder and have access to a soldering iron and a roll of electronics-type solder, you can unscrew the plug cover and fix any broken wires inside. If a wire is broken in the cable between the headphones and the plug, you may be able to find the bad spot by carefully twisting the cable in sections, one narrow segment at a time, while listening. If you find the bad spot this way and are confident in handling a soldering iron, you can try slicing out the bad section and carefully soldering the two or four delicate, flexible wires in the cut ends back together. Then seal and support the new joint with electrical tape. Otherwise, just change the headphones and leave the repair to the CE.
If you see odd readings on any of the station monitoring equipment, take it very seriously. You probably can’t fix any transmitter problems and shouldn’t try to, but odd readings may very well mean a major problem in the transmission system. Immediately contact the chief engineer or the general manager about what you’ve noticed, and then leave it to them to decide what to do. Your job as an operator is to spot and report the problems. It’s the job of the “chief operator” (chief engineer) and/or the general manager of the station to decide what action to take.
If the transmitter appears to be operating improperly and you cannot immediately reach the chief engineer or general manager, seriously consider taking the station off the air until you can reach them for advice. It is hoped that you’ll be able to reach one or both without delay and won’t have to make this agonizing decision by yourself, but if push comes to shove, the equipment and the license are more important than staying on the air.
You may be criticized for signing off the transmitter in a case like this, but let me tell you from (alas) personal experience that it’s nothing compared to what will happen to you if you decide to leave the transmitter on despite the odd readings and then a key or expensive component burns out or catches fire! You’re always better off assuming that the station monitoring equipment is exactly accurate and reporting any discrepancies immediately. (Be sure to note them on the transmitter [operating] log, too—along with the name of the person you notified about it.)
To summarize, if you develop a cooperative relationship with a really good chief engineer, this team will constitute a real competitive weapon in fine-tuning the sound of the station. As a result, you should have a great-sounding radio station. Meter readings and log entries are made not only for the chief engineer but also the F.C.C. You have specific responsibilities involving the Commission too, as we see next.