Lectrosonic SMQ Wireless Transmitter

Wireless mic makers have been long been working on creating smaller, less obtrusive transmitters.
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Wireless mic makers have been long been working on creating smaller, less obtrusive transmitters. The Lectrosonics SMQ transmitter is proof — although it is still slightly bigger than their SM model. Lectrosonics also has another challenge, however: the increasingly shrinking RF spectrum.


The Lectrosonics SMQ ($1,960) includes the transmitter, four AA batteries, a charger and a leather pouch/belt clip. The 2 3/8-inch x 2 3/8-inch body of the SMQ is machined out of solid aluminum billet and weighs just over four ounces with two AA batteries installed; it's heavy enough to sag the back of a lightweight bikini unless very snugly tied, but otherwise very serviceable. Two AA batteries power the SMQ for four to five hours. Some wireless systems come with a mic, even if you already have one or don't want theirs. Lectrosonics has mic option pricing: you can buy no mic or choose from several they offer. There's a slight savings if you order the mic with the transmitter.

Lectrosonics has responded fairly quickly to the shrinking spectrum problem with frequency agile systems; the company's more recent receivers have built-in scanners to help find clear frequencies. The scanner in the UCR411a receiver supplied for this review was easy to use and very helpful.

The switches and lights on the surface of the SMQ are mounted under membranes with no exposed access to the guts of the body excepting the antenna and mic connections, and the lower screw plate holding the two AA batteries in place. This makes it water resistant, but not waterproof. The first Voice Technologies lav came with a rubber bootie at the connector to further ensure that moisture was kept from entering the mic connector.

FAST FACTSApplications
Location sound, broadcast

Key Features
Patented digital hybrid technology; dual 88.2-kHz, 24-bit A/D converter; small size, low weight, solid aluminum construction; membrane-protected switches and lights; built-in scanner; fixed HPF


Lectrosonics, Inc.



  • Small
  • Powerful
  • Versatile
  • Efficient


  • Premium price
  • Transmits only at 250 mW

Solid wireless transmitter technology from a solid companyThe SMQ transmitter is compatible with earlier Lectrosonics 100, 200, 400 and IFB receivers. The SMQ uses patented digital hybrid technology that creates a +/- 75 kHz-wide digital audio signal transmitted over an analog carrier to the receiver. The transmitter's servo input incorporates a limiter with a dual-release envelope that protects from inputs as high as 30 dB above full modulation.

Audio is digitized by the SMQ's dual 88.2-kHz, 24-bit A/D converter, then pilot tone and limiter control data are added to the stream. Each transmitter has 256 available frequencies in 100-kHz steps over a total bandwidth of 25.5 MHz.

In Use

Recording the audio, I walk-tested how much muscle 250 mW provides by pairing the SMQ with the Lectrosonics UCR411a receiver and my Sound Devices 442 mixer, and leaving the SMQ transmitter at my starting location. I found WMPB DTV's 14 kW 996 feet HAAT signal seven miles away with the scanner in the receiver. I tuned the SQM to the same frequency and set off for another walk around. I began picking up hits at about 50 yards while shading the receiver from the transmitter with my body. Getting my body out from between the transmitter and receiver gave me a few more yards, but the hits just kept on coming.

I continued to walk around the outdoor location, getting farther and farther away, with depreciating reception. The location I picked for testing posed some typical challenges users of wireless systems face: medium and large fixed objects and, in this case, several small buildings. I returned to my starting point and used the UCR411a's scanner to find a more friendly frequency, then retuned the transmitter. This time I got to 136 yards before the receiver started swishing. I got no direct hits, but at 136 yards the swishes were bad enough to make the audio unusable. Outside, even on a DTV frequency with the transmitter seven miles away, I was able to get 50 yards outside with just the rubber duck antennae on the receiver.

I did a battery swap-out and walk-tested the receiver in a 3/4 below-grade space with the SMQ transmitter hanging 20 feet away, or about 30 - 60 feet from the receiver depending on where I was in the basement. The system never took a hit.

I tried the three "Noise Reduction" modes. I settled on Lectrosonics' middle default of some, but not full. The hiss was more audible without Noise Reduction. The amount of hiss is tied to what mics are used; lavs with smaller diaphragms and higher self-noise figures obviously generated more hiss.

Changing input sensitivity and frequency on the SQM is very easy. The transmitter display is generally easy to read except that the digits "4" and "9" look very much alike because the top of the "9" so close to the upper edge of the window that it's difficult to make out, unless you're in the right kind of light.

Lectrosonics also sells the very handy RM remoter control for its SM Series transmitters. It "plays" an audible tone from a small speaker, receiving it through the lav attached to each transmitter. Input sensitivity, sleep and lock modes can be changed — as can operating frequency by hex, block or MHz — at the touch of a button on the RM. These are very cool features that mean you don't have to go wardrobe, diving to make changes after the transmitter is properly positioned.


The SQM is a very capable, well thought-out transmitter. My only suggestion would be to add a software switch to allow the unit to run at 100 mW and/or 50 mW when needed. That would provide more hours of battery life, which in some cases would be advantageous. Lectrosonics, however, does include not only four rechargeable 2200 mAh, nickel metal hydride AA batteries with each purchase, but also an Energizer 15-minute, four-AA battery charger. That's a nice thing to do.