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by Glen Trew
Since it’s almost Halloween, here’s a scary thought for film/video sound professionals: On a 200-person film or video crew, only three may be in the sound department. Yet, if sound has a problem, all 200 hundred have to wait and all 200 hundred are annoyed, and some key people even start searching their contacts list for phone numbers under “Sound” while the travel coordinator is booking two tickets: yours and your replacement’s.
So, working in sound for film and video productions comes with a lot of stress that add to the fears we have about equipment problems. The question is about what the best strategies are to minimize these problems. There are always exceptions to rules of complex problems, but here are some thoughts about common myths and real solutions.
Wireless Microphone Dropouts.
When depending on wireless microphone transmission for dialog, a dropout means that portion of dialog is gone and will have to be either replaced or reshot. If dropouts are continuous, production may have to stop. How to reduce dropouts?
Myth or Truth?
Locating the antennas closer to the actors by extending them with longer cables will reduce dropouts. MYTH
Radio signals lose power in a given length of copper coax cable more so than the same distance through the air. So, assuming line-of-sight between the antennas and actors is clear, the cable should be kept as short as practical to keep the signal loss to a minimum. Signal strength loss depends on the type, diameter, and length of the cable, and frequency being transmitted. A common low-loss RG8X 50Ω coax cable (about ¼” diameter) ideal maximum length for UHF wireless is about 15-feet. Of course, this assumes a good line of sight clear of RF obstructions such as metal buildings. For these situations, the lesser of the evils might be a longer cable to get around the obstacle but may also require properly used amplifiers.
Myth or Truth?
Moving the receivers closer to the actors will reduce dropouts. TRUTH
Wireless transmitters worn by actors have relatively low output power, which is even further reduced by body absorption, the combination of which allows a relatively short range. Keeping your receiver antennas close to the receivers, and the receivers as close as practical to the actors is the best practice.
Myth or Truth?
Using high-gain antennas is always the better choice. MYTH
“Something for nothing” doesn’t happen in nature. High-gain antennas create gain in one direction by reducing it from another direction, making them directional antennas. Directional antennas can help reduce dropouts caused by the effects of off-axis interference (interference that is not coming from the direction the antenna is pointing). Though pointing these antennas at the transmitters will increase signal strength at the receiver compared to an omnidirectional antenna, it is certain that eventually the antennas will be pointing in the wrong direction, thereby being less effective than an omnidirectional antenna. Also, if dropouts are caused by interference coming from the direction the high-gain antennas are pointing, then there is no improvement. It could be that, on average, the best choice is to use the more simple design of omnidirectional dipole antennas. At the end of a year, you’ll probably have experienced fewer dropouts.
Truth or Myth?
Using one directional antenna and one omnidirectional antenna gives the best of both worlds. MYTH
It is a common misperception that diversity receivers (receivers with two antenna inputs) simply chose the antenna that has the best signal. However, this is often not the case. The most commonly used portable wireless systems in North America are made by Lectrosonics, which normally use the “ratio diversity” method. With this method, the signals (and noise) from both antennas are always being combined. When the receiver determines that the combined signal will be greater by flipping the phase of one antenna, then the receiver reverses the B antenna. Therefore, if two different antennas are being used on a receiver, or if one antenna is pointing one direction and one is pointing the other direction, one of them is always the wrong choice, or one of them is always pointing in the wrong direction, yet the signals from both the right and wrong antennas are being used. It is best to choose the same antenna type for both diversity inputs, of the design most likely to be the best choice for the situations expected. This is often an omnidirectional type such as a 2-whip dipole.
Rolling a Backup Recorder
A long dialog scene. The actors nailed it. The camera finally got it’s move right. The director is thrilled. The AD shouts, “New deal”! You reach to stop the recorder only to realize it wasn’t recording. Nothing else creates a pit in the stomach of a sound mixer faster and harder than this scenario. The first reaction to prevent this is to use a backup recorder. But should we?
Truth or Myth?
Recording to two recorders reduces the likelihood of a recording failure. MYTH
It’s simple math: If two recorders are being used, you are twice as likely to have a recorder failure. Of course, the opposing view points out that it is unlikely both recorders will fail at the same time. However, it’s not as unlikely as the simple math would suggest, because, often, whatever caused the primary recorder to fail also causes the backup recorder to fail. Maybe it’s a common remote roll device, or a common power supply, etc. when this happens, you have neither a primary recording nor a backup recording. But there’s more…
While recordings are, indeed, occasionally saved by a backup, the need to be saved by a backup recorder is often caused by using a backup. In other words, often, if you didn’t use a backup you wouldn’t need a backup. For example, several sound mixers were recently using two recorders of a particular model, with the hope of increased reliability by having a redundant recording system. They had their recorders configured so that one recorder took the metadata from the other recorder to eliminate dual entry of scene, take, notes, and track names. However, due to a bug in the firmware, configuring the recorders in this way caused them both to loose audio files. So, instead of preventing the loss of recorded audio, the backup system actually caused the loss of recorded audio. Another example happened to me recently. I had a primary recorder and a secondary recorder with the hope that if my primary recorder had a problem, the files would exist on the failsafe recorder. I had them both hooked up to a single remote roll device, and everything tested to be stable and reliable. However, after several hours of stopping and starting on the set, a voltage differential between the two machines’ remote roll circuits caused them both to occaisionally stop without warning, which took a long time to figure out what was going on. This is yet another case where a backup actually caused the loss of a recording. You can see now how rolling two recorders can actually increase the chances of losing a recording. But wait, there’s more…
Rolling a second recorder increases distractions, distractions cause operator errors, and operator errors are often the cause of lost recordings, even when the recorders may be working properly. Our job as production mixers is now more complex than ever. It’s common to assign and reassign multiple inputs to multiple tracks, arm tracks, disarm tracks, combine tracks, isolate tracks, and change them often, while continuing to mix and manage wireless microphones and many other things. Monitoring the operation of a second recorder is yet another distraction, which can and eventually will cause additional errors to be made, such as assigning an actor’s mic to an unarmed iso track, or leaving an unneeded mic assigned to an actors isolation track, resulting in lost or unuseable audio. There are many other valid examples, but the point is that running a second recorder is a distraction, and distractions increase unrecoverable errors.
Truth or Myth?
It’s better to lose a recording more often because of a backup recorder than to lose a recording less often because a backup recorder is not used. Unfortunately, this statement has a lot of TRUTH.
If production is told that a recording was lost, the first question is going to be, “Well, what about your backup”. From a producer’s point of view (keeping in mind that most producers do not understand production sound) the answer, “The backup recorder failed too”, is much better than “I wasn’t rolling a backup recorder”, even though you would have fewer such losses if you used only one recorder at a time.
What to do?
Of course, everyone needs to make that choice for themselves, but hopefully by considering as much truthful information as possible. For me, after giving this a lot of thought over the years, and living through untold hours of experiencing problems and implementing solutions, I generally believe that the best practice is to roll only a primary recorder, keeping a backup recorder nearby (such as on the truck). This will result in fewer lost recordings, on average, throughout the year. However, with advances in technology, it seems that an option that could actually reduce chances of lost recordings is the use of what I call a “fail-safe” recorder. The fail-safe recorder is a secondary recorder continuously running in the background. It would start recording in the morning and stop at wrap. It would always take timecode from the primary source, and would always have routed to it only the mono production mix and possibly the isolated primary boom (enough to get out of a catastrophic primary recorder failure). This setup would create the least amount of distraction, would have the fewest commonalities, and could easily give several days or more of archival before recording over itself. Not having to stop and start it would eliminate the most common reason a recording is lost: forgetting to press the record button, which happens to all of us more often than we’ll admit. Now that is a truth that we’ll call a myth. ☺
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Somebody had to say it. Glad you did and so well, Glen. Phew.
Agreed about the "failsafe" strategy. I roll a zaxcom cameralink all day. Lavs on one track. Boom on the other. Timecoded files make it simple enough to hunt for audio of last resort. Thanks for writing this!
Great article Glen! I had a problem once involving two files with the same name. The second file seemed to be overridden by the first one, even though they were recorded hours apart. The "backup" recorder didn't help since the master recorder controlled the metadata on the backup. I was able to rename the second file in wave agent and recover it, but I had quite a scare (and quite a few nervous emails from post until I fixed the problem.) Although the problem wasn't caused by the backup, it didn't prevent it either, as it wasn't an independent recorder. Still, producers seem to like the idea of a "backup" so I'll probably stick with it for now.
Thank you Glen for your very thoughtful insights and sharing your own personal experiences and approach to the mission critical work we do. I agree with your practice of running only one recorder --- I haven't run a backup recorder in years and have also never needed backup files from a traditional second "backup" recorder. I am somewhat surprised in your article the conspicuous lack of any mention on Zaxcom gear. You do make the true statement: "The most commonly used portable wireless systems in North America are made by Lectrosonics" but by making that statement you miss the opportunity to inform those Lectrosonics users the potential benefits to be had if using Zaxcom gear. You do mention the widespread use of wireless transmitters in production, for all talent and even the primary boom mic, and if you were to be using Zaxcom transmitters you would have a continuous timecoded backup recording of every microphone in use, those on the talent and the boom(s), even in the face of RF failures, primary and backup recorder failures, etc. Additionally, Zaxcom users have already in many cases, implemented your suggested best practice of running an automatic and continuous recording of the primary mix track. The IFB-200 that I use does just that --- a continuous unattended production timecoded recording that runs all day (providing you have the IFB-200 turned on). So, in summary much of what you suggest as to best practices to remove the Fear of Gear failure is already being implemented by use of Zaxcom gear.
Great article, thank you!
Great article Glen, and thank you very much for mentioning the unmentionable.
Almost scared me when you said that antenna distance was not a factor, until I read on and realized you were literally referring to extending the antenna line and not the entire receiver. Audio cables are better than RF cables, so I have always placed my receivers downrange and close to the transmitters and then just use XLR audio cables to get back to my cart. As for the backup recorder issue, the key is to not piggyback them but to keep them as independent as possible. Linking them is what opens the main door to issues. True, a few more buttons to push and all that, but better to have less metadata on the backup but still be able to rescue the audio! Great article!!!!
Very well put together Glen. I've printed it out and from now on I'll be giving this 4 pages to read for film maker people who have fairy tales about reality of sound in their mind. We deal with very very difficult situations from day to day. When people have more clear ideas about what we have to deal with perhaps they'll have and give more respect to audio and sound people.
Thank you very much.
High-gain antennas used incorrectly (i.e., where not needed) also overload the input stages of the receivers causing distortion. Almost every freelance gig I do uses them when line-of-sight is less than 50 ft.
I think all of your points Glen are very valid. I would suggest that the use of Zaxcom recording wireless will eliminate any possibility of loss of audio due to RF dropouts and will form the ultimate back up recording as all tracks from the wireless are time coded iso tracks that record from the moment the system is powered up to the moment it is powered down with little or any sound mixer intervention. It is also a completely separate system satisfying all of the requirements for redundancy without the possibility of affecting the master recording by distracting the sound mixer.
Re-reading your piece, Glen.
My solution to reception is the Nomad bag. I've got two always-ready hard and software presets: record in bag or bagged remote receivers, connecting up to six wires via max 2 cat5's back to the main cart potentially many hundreds of feet away. My mix back to the Nomad for IFB distro with one of the cat5 channels.
Failing that, Zax wires.
Glenn has a point re: mixer distraction. Hits no longer take me out of the mix moment 'cause SD card in the TRX so there's that. I got a better fighting chance.
Thanks Glenn, I have more problems with cellphones but not throught wireless but with mic wire.
Any tip?
Hi Jeff,
I see why the absence of mentioning Zaxcom gear though Lectro gear was mentioned might seem conspicuous, but it's not at all: The wireless topic was about myths and truths of reducing dropouts, not how to deal with them once they happened. And, since you know me, you probably already assume that nothing in the article was meant to promote one brand and ignore another. Lectro was mentioned because that's still what most people are using in the field, yet most users seem to not understand that Lectro analog receivers are always combining both antennas, adjusting the polarity for best effect. However, what could have been added and on topic is that so-called "true diversity" receivers do, indeed, choose just the antenna with the best signal. This includes analog wireless by Senneheiser, Wisycom, and Audio Ltd, but also all diversity digital systems such as those by Zaxcom, Lectro, Sennheiser, Sony, and others. So, for these systems, it might sometimes make sense to have a directional antenna on one input and a omnidirectional antenna on the other input to allow for the possibility of the directional antenna pointing the wrong way. I should also mention that the Lectrosonics analog Venue receiver system can be used in "true diversity" mode, but doing so requires two modules per channel. Dang, that took a lot of words!
As mentioned, Glenn (Sanders), the article is not intended to be a sales pitch for a particular brand. So I need to counter your claim of, "It is also a completely separate system satisfying all of the requirements for redundancy" by saying that this assumes all inputs are wireless, and, fortunately, many still opt for the higher quality of wired booms. As for "without the possibility of affecting the master recording by distracting the sound mixer" and "with little or any sound mixer intervention": After a loss due to dropouts, having to re-record one or multiple tracks onto the primary recorder takes a lot of sound mixer intervention, which can, indeed, be a major distraction. It is far better to avoid dropouts than to fix them. As for "the ultimate back up recording", please... lav mics and bias is another topic for another time.
Glen Trew has replied to Glenn Sanders: "So I need to counter your claim of, 'It is also a completely separate system satisfying all of the requirements for redundancy' by saying that this assumes all inputs are wireless, and, fortunately, many still opt for the higher quality of wired booms."
I think Glenn Sanders' comment follows along with some of my comments regarding wireless boom work --- very much in the same spirit that Glen Trew mentions that Lectrosonics wireless is the most commonly used brand of wireless, most sound teams at this point are using wireless boom. It is a small minority, certainly on episodic television production, using hard wired boom mic. For those who are using a hard wired boom mic, the IFB-200 can provide the continuous unattended distraction-free backup recording for the (non-wireless) boom mic.
Glen Trew's comment regarding distraction, Glenn Sanders refers to the lack of distraction while providing backup and drop-out protection by simply using Zaxcom equipment rather than the other most commonly used brand mentioned. Further, I am in total agreement with Glen Trew's statement: "It is far better to avoid dropouts than to fix them" but this does not negate the value of a backup if it should be needed.
Glen Trew's statement: "After a loss due to dropouts, having to re-record one or multiple tracks onto the primary recorder takes a lot of sound mixer intervention, which can, indeed, be a major distraction" comes from someone I believe has rarely if ever had to "intervene" in this way. I can say that this re-recording process is no more difficult, time consuming or distracting than any of the things we routinely do. I have been able to re-record a portion of missed dialog between take 2 and take 3, and this new "backup" recording is fully timecoded, is identified as an alternate backup recording, done deal. I will add that I have not had to use this feature often because I have almost never had wireless drop-outs (already employing some of the techniques Glen has suggested in regards to antenna placement and also some techniques that are more appropriate when using wireless systems that use receiver diversity (the other brands Glen does not mention, Zaxcom, Audio, Ltd., Micron, etc.).
Again, Jeff, the original two topics are about how to reduce wireless dropouts, and the misperceptions ("myths") about the safety of operating a backup recorder. I think it's best to keep the discussion to the original topics because diverting from them discourages discussion about these topics and reduces the need to have a future separate topic about, in this case, transmitting recorders. I think it's vital that these discussions be as credible as possible without the motivation of commercial gain. While I have complete confidence that you have no ulterior motives of this type, it is clear that Glenn Sanders used a tangent opportunity to sales pitch his products. Also, considering his well known history of contacting users of his products to covertly influence these discussions, the timing is suspicious, which reduces credibility, which is unfortunate both for the products involved and those trying to learn.
Regarding "other brands Glen [Trew] does not mention...", please reread my previous reply, '“...true diversity” receivers do, indeed, choose just the antenna with the best signal. This includes...diversity digital systems such as those by Zaxcom, Lectro, Sennheiser, Sony, and others.'
Any discussion about antenna use and techniques, and the philosophy of recording on a main recorder and a backup, vs just keeping a backup recorder nearby for when needed, is encouraged.
I find quite sad that a well meaning and informative article, turns into yet another slagging match over which manufacturer has the best gear. Thanks for taking the time to write the original article Glen, and sorry you had to spend more time defending yourself. Can't we all just enjoy all the wondrous gear at our disposal today ?
I have been using 100% zaxcom digital system for a long time. I have worked almost 7 days a week the last 4 years. I have only lost 1 transmitter recording that was indicated R for recording on the QRX but the files was corrupted. Later after checking the microSD card was corrupted and it was all my fault for not checking before I started using it.
I am absolutely 100% confident in Zaxcom's transmitter recordings and NEVER WORRY.
Unless I work on a sound stage or in a very controlled environment I can not imagine working without it. Not only I am 100% protected from drop outs but I also have developed a workflow that saves time, money and allows me to expand my sound capabilities geographically. Physics do not concern me. Thanks to Zaxcom I provide a service to producers that no other gear on the market "in the USA" can. People keep calling me back because my expertise and Zaxcom gear provide them with piece of mind and unlimited production possibilities.
It is not zaxcom vs the rest...
It is recoding before RF vs recording after RF.
And now with ZHD I can enter an award ceremony or sporting event where RF coordinator only gave me one frequency and use 5 mics.
Remote gain, remote power, remote frequency control are additional benefits that nobody else offers.
Again with Zaxcom I NEVER WORRY because Zaxcom is the ultimate backup.
Thank you Glen Trew and all that commented. I think there are valid points in every posting here that help me, and hopefully others, with the "fear factor" of our jobs. I've been "doing sound" for around 25 years and unless I'm working on an ultra-simple project with few distractions I'm always feeling a little uneasy. It bothers me that after all this time my fear hasn't gone away. In discussing this with a producer/coordinator friend, she commented to the effect, "If you're not a little bit nervous when doing your job then that's an indication you just don't care anymore and should consider another line of work". I think we're drawn to this profession because we're either stupid or because we're actually drawn to "hot seat" jobs, seeking challenges that, at times, can get so intense that a mistake or two can get you fired. We're looking to "nail it", and the overwhelming majority of the time we do-- and, yes, it's a bit frustrating when practically the entire production staff and crew have no idea how much we stress over getting things right for them.
Back to wireless dropouts-- I find it curious how infrequently these types of wireless mic discussions address live sound, where perfect dropout-free sound is the only option-- where recordings are irrelevant. About half of my work is live-through-a-PA system, chock full of wireless mics. Yes, believe it or not, some sound mixers / recordists also do live sound. Glen Trew's discussion here about proper RF practice to prevent dropouts applies to the entire user base of all types of wireless mics and monitors, not just production sound mics for narrative/reality TV/feature film/documentary work.
I think I may need to steal that "run a recorder in the background all day" idea.