Everything You Need to Know about 2.4 GHz Wireless Microphones

New 2.4 GHz wireless microphones dropped at this year’s NAMM, including the AKG DMSTetrad, and Sennheiser EW-D1. While we are not prepared to offer critical reviews of these new models, we want to revisit the pros and cons of wireless microphones that operate on the 2.4 GHz ISM band.

2.4 GHz microphones operate in 83 MHz of spectrum between 2.400 GHz and 2.483 GHz. By comparison, most wireless microphones today operate at lower “UHF” frequencies between 470 MHz and 698 MHz.

PROS

Simple to operate (under ideal conditions). The selling points for most of these models are “easy,” “easy,” and “easy.” The predictable locations of WiFi channels allow 2.4 GHz mics to sniff out where occupied frequencies are and are not, and they are also great at communicating with other mics and self coordinating (this is probably because 2.4 GHz microchips ship with more advanced radio protocols than off the shelf UHF chips). 2.4 GHz chips do not use FM modulation, and they are (at least the ones we’ve seen) all digital, so they are less susceptible to the intermodulation artifacts that plague multi-channel UHF FM systems. Mics from professional grade manufacturers like Shure, Sennheiser, AKG, Line6, and AT have tuned their modulation and circuitry to bring latency down to acceptable levels, as opposed to simply sending audio over WiFi.

International compliance. Properly manufactured 2.4 GHz microphones can be used in nearly every country without a license, in the same frequency range. UHF frequency bands are not synchronized across international borders, and the rules for wireless microphones vary from country to country. In some countries like the U.K. operating professional UHF equipment requires a permanent or temporary license, and half of the equipment sold in the UK in the 700 MHz band is illegal to use in the United States. 2.4 GHz mics give users a free pass from all the regulatory confusion.

Price. Smaller wavelengths means smaller antennas and electronic components, which means manufacturers can pack more features into a 2.4 than a UHF at the same price point.

CONS

Channel count. Manufacturers are careful to state their 2.4 GHz offerings are channel limited. The EW-D1 footnotes up to eight channels “in an ideal RF environment” (some press releases state 15 channels. I don’t know which spec is correct). The DMSTetrad specifies “up to four channels” per receiver. 2.4 GHz mics aren’t able to offer as many channels because 2.4 GHz chips operate on less spectrum, ~83 MHz, compared with available manufacturer specific blocks/bands adding up to ~230 MHz in UHF. And because 2.4 GHz is so dang crowded with bluetooth and WiFi thingamabobs, you rarely get all of that spectrum to yourself.

Range and in-line attenuation. Given the same transmission power, under the same conditions, a UHF microphone will provide greater range than a 2.4 GHz microphone. In our experience, many overestimate just how much range they actually need (if the stage is within 100’ of the performer, you shoul be OK), and 2.4 GHz microphones sometimes have more powerful transmitters to compensate for the loss (The EW-D1 and DMSTetrad both have a maximum output of 100 mW, 2X the max for unlicensed UHF). You can also use a directional antenna to significantly improve range, but remember that transmission line (cable) loss is much greater at 2.4 GHz than UHF, so long cable runs are difficult.

Latency. Since all professional grade 2.4 GHz mics are digital, latency is a bit higher than UHF analog. But the delays aren’t all that bad on digital microphones, and don’t really stand too far behind UHF digital microphones. In fact, Line6 has latency that beats some UHF digital mics. Latency on 2.4 is only an issue when shows are being recorded for broadcast, or a picky artist starts complaining about monitor delay.

IT Department Wrath: 2.4 GHz is the same band that most WiFi devices use. You can’t always expect to waltz into a facility – especially a secure one – and power up a 2.4 GHz device without someone from the IT department hunting you down and telling you to put it away. WiFi in corporate and stadium settings is carefully calibrated and, more often than not, completely full. IT professionals have tools that let them know if something is interfering with their network.

BOTTOM LINE

2.4 GHz microphones are a great choice for those who only need a few channels and want hassle free setup. For those who need lots of channels and ultra low latency, top-tier UHF mics are still the best choice.

2.4 GHz audio fidelity from reputable manufacturers should be more than acceptable for the vast majority of applications.

While they may provide additional long term security over 600 MHz microphones – which will soon be illegal – they do not guarantee complete immunity from interference. A vast sea of other devices uses the 2.4 GHz band, and their numbers will only increase as the Internet of Things explodes.

Want better wireless? Download our eBook on three essential concepts for correctly deploying and maintaining interference-free wireless audio systems.

RAD UV-1G Intercoms Land at Pro Bowl and Super Bowl

Yesterday we spoke with wireless guru James Stoffo during a rare break in his busy end of season football schedule. On Sunday, James worked with comm and wireless audio frequencies for the Pro Bowl, and next Sunday he’s headed to the Super Bowl. This year is extra special for James because he and the team at Radio Active Designs (RAD) get to see their high performance UHF/VHF intercom system, the UV-1G, put to the test in the toughest RF environments imaginable – confirming that the UV-1G is a bulletproof game changer for the industry.

So, the Pro Bowl. How did it go last night?

I’m pleased with how it went. This event takes the cake for the most units that RAD has had out so far. ATK had 24 units, the NFL was also testing a few for coach sideline communications, and ESPN has a couple of systems. So, there were upwards of 50 packs and probably eight base stations.

The environment we were in – it is an ungodly environment, just horrible – a lot of RF inside one venue. The noise floor is through the roof. I monitor the spectrum, and it pretty much looked like an upside down comb. I was nervous the whole time, and it’s only going to get worse at the Super Bowl next week.

Overall, I’m exhausted, but it is really exhilarating to walk around and see all of this Radio Active Designs equipment all over the place, instead of just in the trade show booth.

Did you get any comments from individual crew members?

Yeah. I talked to just about everybody, actually. I went and talked to the RF Techs for ESPN, whose system was rented through CP Communications, and they were thrilled to death with the system.

Henry Cohen and I have been in the wireless intercom business for a long time. We knew what we wanted and what we didn’t want out of a comm, because we’ve been burned on our own shows. We took that experience and put it into the UV-1G and everyone has been very happy with it.

The range was spectacular. We were able to cover not only the field, but the halftime stage which was on a bridge, and we were able to walk all the way across the field and into tunnels where we had equipment rooms, and bathrooms. Frankly, I was shocked at the range on the thing. If someone would have said ‘James, can this system walk this far?’ I would not have been able to guarantee it as a manufacturer, until now.

You know what it is, we’ve all forgotten, VHF bends around objects and propagates better than UHF does. VHF is something that most people haven’t had to play with in the professional community for 20 years. It went away in 1991, ‘92. Now that it’s back people are going to say ‘oh yeah! Cable loss is only 1/3rd what it is with UHF; We can run 300’ of cable and have the same amount of loss as 100’ of UHF cable.’ People are going to start finding all this stuff out that older guys with the grey hair remember. Younger guys are going to be pleasantly surprised that it’s actually easier to deal with than UHF.

And you’ve got the Super Bowl next week, how are you preparing?

Yeah, the same same guys are staying on with me for the next week to do the Super Bowl. We’re going to start bringing in different headsets, and really start playing around with some different types, because different applications require different headsets.

Is this Super Bowl going to be different from previous Super Bowls in any way? Or is it just another notch in the ole’ belt for James?

The Super Bowl was always the most stressful event I had to work all year. I actually took the last couple of years off. This is my fifteenth Super Bowl, but I took four years off. I’m going to get back into this, not cold exactly, but I know a lot of things have changed. I know the drill and I’m sure the RF environment is going to be more intense than it’s ever been, but I also have to say from an RF designer’s perspective, just being able to go back to VHF and pull out 50 or 60 belt packs from UHF is going to help immensely. Instead of having to put people 200 kHz, 300 kHz, 400 kHz apart, now we can go 50 kHz apart. My packs are 50 kHz and 60 kHz apart, so, I’m packing in dozens of frequencies where before we could only put one or two.

I am not going to go into this with any delusion that it’s going to be easy. If anything, it will be a little easier next year because there will be more VHF stuff floating around. This could very well be the most difficult Super Bowl up to this point. Until we figure out what’s going to happen with the 600 MHz auction and white space devices, I plan on pulling every single trick in the book. I’m going to have helical antennas, I’m gonna have long cables, I’m gonna have my guys out on the field so the antennas are as close to the performers as possible during the halftime show and during the National Anthem. Filters, isolators, circulators, we have all the toys here, and we are going to use them.

Want better wireless? Download our eBook on three essential concepts for correctly deploying and maintaining interference-free wireless audio systems.

Eight Indispensable Books for the Audio Professional

No formal audio engineering degree? No problem. We polled three leading educators and asked around the RF Venue lab for the most useful and relevant books that no audio professional should live without.

In addition to our own engineers, we asked three experts for their top picks:

Justin Colletti: Editor at both Sonic Scoop and Trust Me, I’m a Scientist, as well as a mastering engineer at Joe Lambert Mastering in Dumbo, Brooklyn.

Timothy Britt: Program Director for the Audio Engineering Technology program at the University of Hartford.

David Shuman: Assistant Professor of Electrical and Computer Engineering and the Audio Engineering Technology program at the University of Hartford, with a simultaneous 30 year career in music and recording.

Yamaha Sound Reinforcement Handbook – Gary Davis and Ralph Jones: A classic since 1987, Davis & Jones’ reference is THE go-to book for live sound engineers, bar none. We have heard it recommended by some of the best in the business for its technical accuracy, accessibility, and practicality. Like a fine tasting menu, Sound Reinforcement Handbook serves up bite-sized, perfectly relevant courses on acoustics, electricity, speakers, mixers, microphones, venues, and how they all fit together in the fast-paced environment of a live show.

Buy it here.

Mastering Audio – Bob Katz: Penned by legendary mastering engineer Bob Katz, Mastering Audio is arguably the most important book on studio audio engineering ever written. From his audiophile paradise in Maine, Katz’ faders have kissed more or less every great album of the last 30 years (three of which won Grammy Awards). If you aspire to mix subtle, affective tracks, grab yourself a copy of Mastering Audio.

Buy it here.

Mixing Secrets for the Small Studio – Mike Senior: The era of high profile mega-studios has come and gone, and many exceptional albums are now recorded in garages and basements with bass traps, acoustic panelling, and Pro Tools. Mixing Secrets for the Small Studio unlocks big studio potential on small budgets and in small spaces.

Buy it here.

ARRL Handbook: Since RF Venue designs products for wireless audio, and since wireless is such a critical part of live sound, we are loathe to omit the ARRL Handbook (also suggested by Timothy Britt). The ARRL Handbook dissects the fundamentals of wireless communications in clear, easy to understand language. Though written for radio hobbyists, this book’s insights are applicable to nearly any wireless device – including wireless microphones and in-ear monitors.

Buy it here.

Practical Techniques for the recording Engineer – Sherman Keene: David Shuman’s top pick, Practical Techniques for the Recording Engineer was, and in many circles still is, a standard textbook for getting young audio engineers up to speed, fast. Though out of print, Keene self publishes the text and sells it on his website. In Keene’s own words: “This book starts at the very beginning and teaches how to work with artists and the equipment you have on-hand to get really good sound in a studio or on stage.”

Buy it here.

Mix Masters: Platinum Engineers Reveal Their Secrets for Success – Maureen Droney: Book learnin’ is fine, but nothing compares to hard won tips from legendary experts, preferably over a beer. Mix Masters collects entertaining and helpful thoughts from some of the recording industry’s best producers in an informal interview format. It may not be the best reference manual out there, but few audio books do such a good job getting into an engineer’s head.

Buy it here.

Handbook for Sound Engineers – Glen Ballou: Now in its fourth edition, Handbook for Sound Engineers is a standard text for undergraduate courses in audio engineering. At over 1,800 pages, it’s not exactly light reading. But if you want to know everything about audio technology, and the science behind that technology, this if the tome for you.

Buy it here.

The Mixing Engineer’s Handbook – Bobby Owsinski: Prolific pro audio author Owsinksi’s handbook is a succinct but highly effective guide for aspiring mixers. The focus is on the essentials, with little ink spilt over trivial details or personal preferences.

Buy it here.

Want better wireless? Download our eBook on three essential concepts for correctly deploying and maintaining interference-free wireless audio systems.

RF Optix Nominated for CAS Technical Achievement Award

The RF Optix fiber optic remote antenna system has been nominated for a CAS Technical Achievement Award.

The Cinema Audio Society is a Los Angeles based trade organization for sound professionals in the film and television industry. Their members span both production and post production, and include production mixers, boom operators, foley, ADR, and post mixers.

RF Optix transmitter and receiver.

The RF Optix allows remote antenna runs of 1000 meters or more by converting RF into optical signal and transmitting over singlemode, 1310 nm fiber optic cable.

The production sound community has embraced the RF Optix as an affordable and high fidelity technology for extending the distance between lavaliered talent and sound cart. Sound crews now have the freedom to deploy wireless microphones nearly any distance away from the mixer, and across multiple walls or obstructions, without in-line signal attenuation. Fiber cable is lightweight, inexpensive, and more durable when compared with bulky coaxial cable traditionally used for remote antenna runs.

We thank the CAS and its membership for this nomination, and look forward to our continued and close collaboration with film and broadcast professionals.

Thoughts On Municipal Broadband

There has been no shortage of regulatory intrigue on the subject of public internet and WiFi.

In October, the FCC fined Marriott hotels $600,000 for blocking WiFi hotspots during conferences in Nashville. The fine provoked more conversation than most FCC fines usually do. Some lauded it as a victory for consumers. Others prophesied fallout on IT security and unlicensed wireless. While I can’t abide the egregious rates Marriott charged attendees, I wonder if the fine will change a facility’s ability to police unlicensed devices like microphones.

This week President Obama scolded cable companies for pushing legislation through state governments to block construction of municipal broadband networks which in some locations are superior to what the private sector provides.

A White House fact sheet released ahead of his public addresses laid out the argument:

“Laws in 19 states — some specifically written by special interests trying to stifle new competitors — have held back broadband access and, with it, economic opportunity. Today, President Obama is announcing a new effort to support local choice in broadband, formally opposing measures that limit the range of options available to communities to spur expanded local broadband infrastructure, including ownership of networks.”

In a video filmed and posted by Upworthy, Obama demonstrated, on his executive iPad, that many global cities outshine major US cities when it comes to broadband speed, and that some of the fastest cities in the US are small communities in rural states that fund their own networks.

Beyond the alleged dirty tactics used by cable companies, the President cares about municipal broadband for a few other reasons.

When it comes to broadband, rural Americans are left behind. Rural areas don’t have population densities high enough for cable companies to deploy infrastructure with good profit margins (which is why cell carriers are so interested in low-band UHF spectrum at 600 MHz, since more people are served by fewer base stations). In some cases like Cedar Falls, IA, which has downstream speeds of as much as 1 Gbit/s with only 37,000 subscribers, community networks trounce average speeds in larger cities, unlocking economic opportunities for places that were previously left behind because of market failures.

And internet isn’t just about equality. Broadband internet is a national priority, as laid out in the National Broadband Plan. Fast internet for all is supposed to keep America competitive. Slow internet locks America out of a global, connected, digital economy.

In his Upworthy video, Obama says there are “real world consequences to this, and it makes us less economically competitive. There are steps we can take through executive actions that will allow every community to do what Cedar Falls is doing.”

Is it any wonder Congress cares more about using the 600 MHz band for wireless broadband than for OTA TV and wireless mics?

Tom Wheeler will join the President’s efforts to encourage the growth of publicly funded municipal networks – though both of them are very careful to frame those efforts as stimulation for competition and innovation, rather than strongarmed regulation.

In a blog post from June, 2014, Wheeler greased the wheels:

“I understand that, like any venture, community broadband hasn’t always been a success. But a review of the record shows far more successes than failures. If the people, acting through their elected local governments, want to pursue competitive community broadband, they shouldn’t be stopped by state laws promoted by cable and telephone companies that don’t want competition.

I believe that it is in the best interests of consumers and competition that the FCC exercises its power to preempt state laws that ban or restrict competition from community broadband. Given the opportunity, we will do so.

The conservative commissioners reacted to the possibility of executive actions and collaboration with the FCC. In a terse statement Commissioner Pai said this:

“As an independent agency, the FCC must make its decisions based on the law, not political convenience. And U.S. Supreme Court precedent makes clear that the Commission has no authority to preempt state restrictions on municipal broadband projects. The FCC instead should focus on removing regulatory barriers to broadband deployment by the private sector.”

O’Rielly:

“It is clear that this Administration doesn’t believe in the independent nature of the FCC. It is disappointing that the Commission’s leadership is without a sufficient backbone to do what is right and reject this blatant and unnecessary interference designed to further a political goal.

Substantively, this missive is completely without statutory authority and would be a good candidate for court review, if adopted. In reality, this debate is about preempting a state’s right to prevent taxpayer rip-offs. Municipal broadband has never proven to be the panacea that supporters claim and the Administration now boasts. Instead,we have seen a long track record of projects costing more than expected and delivering less than promised.”

On that last point, O’Rielly is on to something. Publicly financed WiFi networks were hot stuff in the early 2000s but then floundered and all but disappeared. In 2013 the Economist wrote that, “…in hindsight, these efforts were doomed to failure, an expression of unwavering but unwarranted optimism by the several early metropolitan-scale Wi-Fi-router-makers who vied for hundreds of millions of dollars in equipment contracts paired with the naiveté of early network deployers.”

Has the market matured and changed in favor of a new generation of wired and wireless municipal networks? The President certainly thinks so, and the people of Cedar Falls aren’t complaining, either.

UK OFCOM Agency Publishes Study on WSD/TVBD Interference to Wireless Microphones

In November the UK’s FCC equivalent, OFCOM (Office of Communications), released a report on the impact of white space devices (WSD/TVBD is now synonymous) on wireless microphones in theatrical environments. The test was thorough and valid, and gives US based operators intelligence on the forthcoming changes WSDs might bring to the spectrum here. {For a refresher on what WSDs are and why they matter, check this out}

Way back in 2007 and 2008, the OET’s Technical Research Branch conducted studies on WSDs’ ability to sense DTV and wireless microphone signals using Adaptrum, Microsoft, Infocomm(I2R), Motorola, and Philips prototypes in laboratory and field settings. The researchers collaborated with the NFL, ESPN, and Broadway theaters. The results revealed that WSDs are not very good at sensing wireless mics:

“At both sites and all the test locations, the Philips device reported all the channels on which the microphones were designated to transmit as occupied whether the microphone was transmitting or not. The I2R device indicated several channels as available even when the microphones were on.”

In any case, the pending rules will most likely allow Part 74 users to register devices in a database for exclusive use, which will in turn inform local WSDs to stay off of those registered frequencies, whether the WSD senses them or not. Unlicensed users have more to worry about, although licensed users are far from safe.

What professionals really want to know is whether nearby WSDs will interfere with wireless microphones, either on the same frequency or different frequencies, and to what degree. To the best of my knowledge the FCC never initiated any studies to investigate these concerns, so the recent paper from OFCOM provides important intelligence as the wireless audio industry struggles to predict the impact of WSDs.

To cut to the chase, OFCOM discovered that WSDs will most likely not interfere with wireless microphones while operating on adjacent (next to or different) TV channels, but detrimentally interfere with wireless microphones on co (same) TV channels.

Tests were performed during live events, in empty venues, and under controlled laboratory conditions. Venues included the Queen’s Theatre, the New London Theatre, and a broadcast event. Microphone signal levels were examined during live shows (with WSDs safely off), and microphone signal levels and subjective listening tests in the prescence of WSD signals were conducted during rehearsals, when theaters were empty, as well as during a special performance of the ‘Les Miserables’ mounted especially for OFCOM engineers.

Engineers monitored audio for degradation during performances, and then on recordings of the performance on headphones and found “no reduction in audio quality” created by WSDs operating on 1st adjacent, 2nd, 3rd, and 11th TV channels transmitting at a power of just under 1 W EIRP (although they were able to create 1st adjacent channel interference under one circumstance when the WSD transmit at 4 W EIRP, pointed right at a microphone receiver, with the microphone at maximum range – a worst case scenario.)

This is good news. WSD signals and IMD products do not appear to spill over into adjacent channels enough to cause dropouts or detectable audio degradation. Those who register frequencies in the white space database are unlikely to encounter interference, except for certain worst case scenarios.

However, when a WSD transmitted on the same TV channel as wireless microphones, mic receivers experienced devastating co-channel interference.

“Co-channel interference at a level of 25 dBm EIRP on TV channel 48 (690 MHz centre frequency) wiped out all eight co-channel microphones,” reads the OFCOM report.

This is bad news. Since we know from the 2008 FCC study that US based WSDs are unable and will not be required to sense wireless microphones, WSDs are free to operate on any white space channel not registered by a Part 74 device with wanton disregard for cohabitants. Unlicensed users will be particularly vulnerable to WSD interference since they cannot register for protection in the database.

Want better wireless? Download our eBook on three essential concepts for correctly deploying and maintaining interference-free wireless audio systems.

Rich Topham of Professional Sound Services

Last week I sat down with Rich Topham, President of New York Based Professional Sound Services, to talk about his new Ft. Lauderdale location, the history of location sound, and good old fashioned Nagra recorders.

How did Professional Sound Services begin?

I moved to Hollywood in 1977 and opened a store with my mother and father. From that one office, it grew to where we opened a manufacturing company, Professional Sound Corporation, and offices in Sydney, Orlando, Las Vegas, and New York. I ended up selling all those other companies to employees and just keeping this company [in New York] because I wanted to move back here with my kids instead of raising them in Hollywood. And now all of my kids are in school and I’m bored, so I’m opening more companies.

Are those other companies still around?

Yes. Location Sound Services and TAI Audio were formerly mine, and Samuelson’s bought the office in Sydney, closed the office in Las Vegas and consolidated it back into Location Sound in Hollywood.

You, Location Sound, Trew, Gotham, and TAI are pretty much the only players in the retail production sound market here in the US.

It’s a boutique market. It is. And other people have tried to get in it, but they don’t have the knowledge that location sound mixers need.

Were you a sound mixer when you were in Hollywood?

I was supplying a lot of the sound mixers first, but then I wanted to do sound to get a better feel for what they were doing and what they were up against in the field. That’s when I got in the union, 695, and went out and worked on shows, commercials, movies, television series, stuff like that.

Why did you decide to (besides that you’re getting bored) why did you decide to open another PSS branch in Ft. Lauderdale?

Because I have a large Spanish speaking market that comes to me there. The majority of stuff being shot is down in FT. Lauderdale and Miami. They’re building a Screen Gems Studio, they’re building a Pinewood Studio in the Dominican Republic, and all of that money comes out of Miami. Brazilians, Columbians, all that money comes right into Miami, and I have a ton of clients that come to New York to get stuff for those productions, but it’s better for them if I have a branch down there.

What are the production companies involved? Are these American companies? Telemundo? Univision?

Univision and Telemundo are big clients now. Then, there are a number of mixers doing documentaries and reality for Discovery and The Weather Channel. A lot of travel shows down around there. A lot of commercials for TV. It’s mostly a giant Spanish speaking market. And now, with the market in Cuba opening up, there are going to be some significant opportunities coming through Florida.

Since you’ve been around for a while, what are some of the technical milestones production sound has gone through over the years?

Everything. When I first started it was all 1/4 mono tape. Then they went to two track stereo, then timecode came in. There was ADR, but once wireless came out, that solved a lot of the problems. Then it went to digital audio tape – DAT – HAB made a DAT recorder, and then Sony made a DAT recorder, and then StellaDAT the former company StellaVox that competed with Nagra made a DAT machine, too. A very expensive one. They probably only sold about 30 of them. Then it went to hard drive and disk, and now flash cards. It’s all menu driven computers, now. In the beginning it was all reel-to-reel mechanical stuff with magnetic tape, now it’s computers.

Nagra’s magnetic moment has come and gone. 

Is that an old Nagra I see back there?

Yeah. I transfer a lot of old tapes here.

Tapes. Like, musical recordings?

Dylan tapes. They found some tapes from the 70s and I transferred them for a woman. Her husband died and he was with the band and she found all these 1/4” tapes that were final mixes that I transferred for her. Stuff from the CIA and FBI too, all sorts of old stuff.

Also I probably fix five or six Nagra’s a month, and probably sell two or three of them. There’s a lot of lawyers and doctors that exchange orchestral recordings between themselves. They like the sound of the analog machines and collect them.

You mentioned wireless has changed. That’s the business we’re in, wireless, so I’m especially interested in how RF has changed.

In the beginning, it was all VHF. Most guys had like four channels on VHF. Then VHF got so crowded they were using mics between TV stations, so if you had a channel 8 it worked perfectly, but if you went to Philadelphia it wouldn’t work because you had channel 8 in operation. Then it got so crowded they started using UHF wireless on the different frequencies. They came out with switchable frequencies within the channel. There were four TV channels within one block, so that as you went to different cities you’d be able to use the different channels that were unoccupied. Now, manufacturers cover twelve TV channels or three blocks for each transmitter or receiver.

Zaxcom has a recorder that’s a transmitter as well. It will record two channel stereo with timecode for 12 hours straight. That’s useful if, for example, an actress goes out of range and you can no longer receive her, when she comes back to the cart you can actually download the recording from the transmitter into your recorder and replace the dialogue without taking it off her without anybody knowing.

When I spent some time with Jan McLaughin she was talking about the Zaxcom transmitter’s ability to record ISO tracks.

What happens is when she’s saying ISO tracks, she means “isolated” tracks. In the old days when they would record to a Nagra or two-track, the sound mixer that was on the set would mix all the dialogue down to one or two tracks so when it got to post production, if they wanted to loop [retake] something, they would have to bring all the actors in that were in the scene to loop it. More modern recorders have eight separate tracks. When multiple dialogue is all on separate tracks, if the director doesn’t like the performance, or the dialogue is bad, you only have to bring that one actor in, so it saves the studio money and basically takes control of the mixing away from the sound mixer, and into post production. They [production sound mixers] still give them a mix track, but they also give them ISOs that they can then remix to however the director might want it.

Why not just have ISO tracks and forget about the production sound mixer altogether?

Dailies. They want to see a mix for dailies, and later on they may just use that mix and never use the ISOs, but, they have the ISOs as backup.

Very high stakes.

It [ISO tracks] is not just because of noise or the mixer not mixing – these are professionals – you have an actor like Tom Selleck didn’t give a good performance and then they’ll go back and replace that. A lot of it has to do with the actors and the director, and very little to do with the sound man. Or, they may pick a lousy location, underneath the Brooklyn Bridge for example where a train rattles by every thirty seconds.

Want better wireless? Download our eBook on three essential concepts for correctly deploying and maintaining interference-free wireless audio systems.

How Dynamic Microphones Create Audio Signal

On cue from Jacob O’Neal’s excellent animation of loudspeaker operation, we set out to illustrate and animate the principles of another type of acoustic transducer: the dynamic microphone.

Thanks to Cameron Stuckey of Professional Wireless for his consultation.

Want better wireless? Download our eBook on three essential concepts for correctly deploying and maintaining interference-free wireless audio systems.