EEVblog 1416 - Random TEARDOWN: Sennheiser EW100 True Diversity Receiver

Random teardown from the lab, a Sennheiser EW100 true diversity wireless microphone receiver.
Plus an explanation of how antenna diversity works.

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#ElectronicsCreators #Sennheiser #Teardown

[xjet]

Another benefit to diversity (when using linearly polarised antennas) is that you can set the receiver antennas to different orientations (90 degrees apart) so as to significantly reduce the up to 20dB loss associated with the transmitter antenna being 90 degrees out of plane with the receiver antenna. Pretty handy if your transmitter is mobile and changes orientation regularly.

[tkmhurter]

Hi Dave ! love your videos.
I used to work for a car radio manufacturer in the late 80s . They devoloped a didiversity receiver for the FM broadcast band. It could mix up to 4 atennas. The atennas were not switched, instead it fase shifted the intermediat frequency stage and summed up the signals and then to the demodulator. The net effect was sinthezising a directive atenna sensitivity pattern to maximise the best signal quality and reject intefering signal paths.
All done in analog domain !!

[Foobar_The_Fat_Penguin]

According to a 2019 interview with the two Sennheiser brothers, they maintain a presence at the US west coast to have a direct connection for the movie industry, and the east coast for the music industry. Also having a production facility in the country (Albuquerque) probably just makes sense.

[SeanBZA]

Not a Faraday cage, more like a massive large multimode waveguide. Complete with random absorbers and filters all throughout the volume, so that you can get a point that is 30cm away from another, yet have 60dB of signal strength difference between them.

[jeffpelletier]

The stand offs at the bottom are for the gang plate screws. Part of the rack mounting kit.

[whitcwa]

Dual IFs and dual mixers mean it is a double conversion receiver. The IFs are 241 and 10.7 MHz. Only the first LO is tunable. The service manual for a similar product, the OM100, is on elektrotanya.

[shanestuart]

The second mixer is because this is a double conversion architecture. Pretty common in the 500Mhz to 1Ghz frequency range.

[stBenTV]

The Antenna splitter can deliver power to the receivers through the antennas - saves a lot of space (and PSU pain) in a rack with many of these

[EDLEXUS]

22:00 yes, you can power these recivers from an antenna-combiner via the bnc

[Thirsty_Fox]

I love all the insight given with these teardowns. I learn so much about different design implementation methods that are otherwise difficult to discover. Even just a small comment in passing about something like the ground stitching vias can lead me on to learn about a whole new facet that I hadn't considered. Thanks Dave!

[DrB]

"Disassembled in Australia" - Awesome!

[volvo]

Can't wait for the next model, the Sennheiser "Diversity and Inclusion" receiver.

[TheDefpom]

@22:00 Those diodes on the antenna inputs will be input protection to shunt excess input voltage to ground to prevent overloading of the front end, that is a common technique to prevent front end overload.

[Evergreen]

You learn so many things just by Dave's commentary on the process. Like how the input is ran under the board so that any imperfections in the metal shield won't hurt it. You'd never know this unless you had to design one of these type of circuits.

[embeddedgirl]

live sound engineer here, these receivers are fuckin bricks. don't even need road cases for these if taking them on tour

[JaenEngineering]

The is actually rack mountable, it just doesn't have the hardware attached. The same case style is also used for the 1:4 aerial amplifier/splitter (which can also provide power over the bnc to the receivers), which might explain the extra mounting points.

[CTRIX]

Sennheiser evolution user here (for decades!) Great units for both their wireless lav kits, XLR mic plugs (as seen on ISS / NASA all the time) - and I can confirm the receiver base stations are better than the small camera receiver units which can flutter a bit at times at distance. But on the whole, 10 hours battery life... super durable casing and connectors... easy to configure... can custom name on the displays for ID, etc. Staple of the news and video production industry! I glad to hear the Dave tick of approval on them.

[Belznis]

Random teardowns are fun, but dumpster dives bring back memories. Good old days. Would love to see you doing them too.

[cavemaneca]

This is a lot more complicated than I would have expected! Halfway through the video I forgot what we were being shown and could've sworn it was a bit of test kit rather than just a wireless audio interface.

[Richardincancale]

You didn’t mention Rayleigh fading - although you did kind of describe it. The effect of the multi path is to cause a deep fade / cancellation every half wavelength you move. Polarisation diversity antennas are often used in mobile phone systems to avoid too much clutter on rooftop sites - another way to achieve diversity without two physically separate antennas.