• Brett Ainslie

Lectrosonics SRb vs UCR411a SxS test HrGA Bagalllo...3.1

Many Sound Mixers use Lectrosonics wireless systems in their audio bags on location. Many are currently using the single channel UCR411a receivers but many also use the dual channel SRb's. It's tough to say one is a "better" choice than the other or is more industry standard but we ran some side by side tests comparing the two.


Lectrosonics claims that the "SRb is very similar in range to a 411a and definitely better than an SRa. In very tough RF environments, 411a is still superior." So, a few of us Sound geeks got together in Brooklyn, NY and ran this side by side test in Block 20 using an SMQV going into an SRb and a UCR411a set to the same frequency. Below are the two tests we ran; the first being a romantic long walk down the block with the lovely Sound Mixer Allistair Johnson roughly 100 feet with line of sight. The SRb is the left track and the 411a is on the right track.



With the second test, we sent our other victim, Sound Mixer Michael Moote around the corner and across the street, risking getting hit by a bus apparently. The SRb is the left track again with the 411a on the right track.



The major differences between the Lectrosonics UCR411a and the SRb are physical and design; The SRb is dual channel as opposed to single channel, acting as two receivers in one unit; this unit is not double the size of the 411a, rather it is smaller in weight and volume. It also costs much less than the cost of 2 UCR411a's making it arguably much more efficient than the 411a, especially being in similar quality as an RF receiver. However, the difference in design and quality is highlighted by the addition of a high quality front end tracking filter on the UCR411a. 


The SR series receivers and the 401 receiver do not have a front end tracking filter. When it comes to range, it's not the receiver that gives better range, rather, the transmitter and many other factors that come into play. However, the design of the receiver will effect the capture of that signal, and how that signal is amplified, processed and sent into the mixing/recording device. The front end tracking filter of the UCR411a with its high power gain stages "produces a receiver that is unusually immune to single and multiple interfering signals close to the operating frequency and in addition strongly rejects signals that are much farther away." So in other words, the difference in quality between the SRb and the 411a should not be found in range, rather in situations where you have DC-DC power converters running physically close to your receivers and wireless transmitters in the same block also physically close to your receivers. Also, if there is a facility such as a TV station, Military base, airport, cell phone testing facility, etc., you may have more RF issues with the SRb than the UCR411a. In addition, with the FCC taking away more and more of our frequency bands from us Sound Mixers, we are being forced to run more wireless in the same block. The UCR411a would be better with this as it has added individual (12) transmission line resonators with variable capacitance to keep out the RF noise. This allows "each resonator to be individually tuned by the microprocessor for any user selected frequency in a 25 MHz band."


Left: SRb Right: 411a

In our test, we had the SRb and the 411a going into a SD 633 running off of a battery distro system in the bag. Nothing else in the bag was powered on. We did have our cell phones on us and were set up next to a telephone pole on the sidewalk in residential Bedstuy Brooklyn, NY during business hours. So this may not have been the most challenging setup to test the front end tracking filter of the UCR411a but we did notice differences in the two. The 411a seemed to hold a usable signal a bit longer than the SRb. The SRb also dropped out completely at one point and seemed to have RF noise more consistently when both receivers were having major RF issues. In my own experiences owning an SRb and a few UCR411a's, I do not notice many if any quality differences in the field working primarily in NYC. They are both top of the line units and with a thoughtful design in your bag, it should not be too difficult to avoid having any hops in the same block as your body mics and to keep the battery distribution system as far as possible in the bag along with your cell phone powered off or not in the bag at all. I am currently on a show where we have SRb's in the bags with SMV transmitters for hops and IFBs. I haven't had any issues yet but the Sound Supervisor told me he lost signals from the SRb's in the past with this setup because of the transmitters. I told him that's the difference between the two. With that said, I have run 7 UCR411a's in the same block in the same bag with another 7 in the same block in the other A1's bag on the same set and we had several major intermodulation issues with our own units being in the same block. So the 411a's front end filter is not a perfect solution to intermodulation at this time, but then again, who's idea was it to have 14 body mics in the same block running simultaneously in the same room in Midtown Manhattan?