Wireless audio hop

S

scottfs

Well-known member
First of all, I've not worked in 11 months, for some strange reason. So, TBH, I've not increased my skills. A year ago, I was thinking about supplying the director with a post-fader hop from my MixPre-6 (old version). As things seem to be opening up, started getting re-acquainted with production sound stuff.

Best way to do this? I'm a one-man audio guy, working out of a bag, usually use boom plus lav 'cause I'm a belt and suspenders guy. As usual, budget is a factor.

Thoughts? Thanks.
 
G3s are popular to do this. If it were a camera hop, I'd use an EK100/SK100 (Tx/RX) pair. But since it is going to the director, you will want to use a G3 IEM instead of the SK100. The IEM provides the director with a volume control knob, whereas the SK100 does not.

Another way to go is with Comtek, or Listen Technologies, which use either 72Mhz or 216Mhz. Comtek is the defacto brand for people monitoring on set. When producers list equipment requirements, they will list that they need x Comteks. But they really mean they need x wireless monitors. Comteks are of lesser quality in regards to sound quality and overall performance compared to the G3, but they get the job done.
 
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What you’re looking for is commonly referred to as IFB (though Paul correctly points out that “Comtek” is also widely used to refer to the same, regardless of which brand system is actually used). And as Paul said, you can do this with actual Comteks or with something like a Sennheiser G3/G4 transmitter and a G3/G4 IEM receiver. Or, if you want to go all out, there are some very nice IFB systems from Lectrosonics (though they do not fall in the budget-friendly category).

Personally, I use Sennheiser G3 for wireless camera hops and Lectrosonics for client IFB. I have a Comtek kit I used before I switched to Lectro. If you go with Sennheiser, I’d suggest getting a system in a frequency block that’s different from your talent wireless so that you avoid intermod issues.

With the MixPre-6 (first and second generations), you’ll need a specialty cable to connect whichever transmitter you end up using. The only output is the 3.5mm stereo out, by default outputting main L and R mixes. You’ll need to figure out if you want a split cable that sends L and R to separate devices (such as a camera hop send and separate IFB send) or if you want the stereo signal to be mono summed to the transmitter. And the connector on the transmitter end will be different or will be wired differently depending on the transmitter used. Contact Remote Audio in Nashville about getting that done. They’ve made several custom cables for me over the years.
 
Most IFB receivers have an headphone level output, Comteks use a mono TS jack connection so the connection and level will need to be scrutinized. The Listentech's Rx HP output jack is a standard (stereo) TRS config.
If feeding a mic level input, a suitable L-pad will be needed.
 
One more thing about transmitters such as the G3/G4; they have a line and mic input. You need to decide which you are going to use based upon your mixer's output (I'm not familiar with the Mix Pre). Also, regarding custom cables, if you decide need to use the mic input (Not recommended. Use the line input if you can) then you need to add a decoupling capacitor (10uf tantalum) in the cable. The capacitor will fit inside the connector's housing. The reason for this is that the transmitter puts a voltage on the mic input to power lav microphones. You don't want to backfeed that voltage to the output of your mixer.
 
Paul F said:
One more thing about transmitters such as the G3/G4; Use the line input if you can) then you need to add a decoupling capacitor (10uf tantalum) in the cable.
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With the G2/3/4 SP-100 bodypack Tx, line level is through the plug's Ring terminal, where no bias voltage exists. If using the Tip terminal for mic level, then the capacitor is recommended. FWIW, the ListenTech 'portable' IFB transmitters, use the same wiring scheme. The Sony and other Tx with the mini-plug input are wired different
 
Paul F said:
Alex, Why the preference for Lectrosonics IFBs? Ruggedness? Features? Both?
Click to expand...

Bragging rights?

No, but seriously... both features and ruggedness. Lectro SM transmitters have an IFB compatibility mode, so they can function flawlessly as IFB transmitters without adding any notable weight to the bag. With a battery eliminator, the TX is on as long as my bag is powered. Plus, the transmitters can go up to 100mW or 250mW (there are restrictions and considerations here) for covering large sets and locations. And there are more frequency blocks available.

The receivers can be programmed with several different frequencies, and moving between them is as easy as the tap of the volume knob (R1a) or the tap of a button on the face panel (R1b). This is extremely useful if working on a set with multiple sound mixers, so producers can skip around and listen to any bag at any time.

The old R1a is now discontinued, but I really, really like the new R1b replacement. This is what I’m using. They run on LB-50 rechargeable batteries, eliminating 9V batteries from my kit (huzzah!), and they’re smaller and ligher weight than the R1a. Plus, the R1b comes in wideband blocks (Lectro A1 and B1 in the US, C1 available elsewhere).

Regarding transmitter restrictions and limitations:

If you use wireless mics and IFB to make a living in the US and you don’t already have one, you really need to file for an FCC Part 74 license. While most wireless use with radio mic systems can be done legally without a license (white space), having the license gives us standing with the FCC. The 700MHz and 600MHz blocks were auctioned off because there weren’t enough licensed users for the FCC to notice any major impact in doing so; sure, one could argue that they know darn well we’re out here doing what we do, but having the license means they can’t ignore us quite as easily, especially if there are more of us. But it also opens up some other abilities in how we operate:

100mW is the highest transmission power usable with wireless mics and IFBs without a license (part 74 is an auxiliary low power broadcast license). The Part 74 allows use of up to 250mW. There’s also a newer block showing up in wireless: Block 941 (sometimes referred to as Block 944). I wouldn’t recommend 941MHz for talent wireless, but it’s great for IFB, though there’s a limit of 100mW in using that block. Also, use of Block 941 requires Pt 74.

As a side note, Comtek systems running in the 217MHz range aren’t actually permitted for use as IFB, even though these are ubiquitous on US sets and locations. If you read the frequency allocations closely, 217MHz is specifically permitted for use with listening assistance for the hearing impaired, and for some uses for law enforcement surveillance.
 
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