New Inexpensive Sennheiser SX Wireless Line

[bishopthomas]

I logged onto my Sennheiser dealer page just now and noticed they have a new line of wireless mics. It's the XS Wireless series, the XSW12 being the lav system. It looks like it should fall between the Freeport (only 4 selectable frequencies) and EW100 series. I think I'm going to order one this week to check out. Here's a link:

http://www.sennheiserusa.com/professional_xs_wireless_microphone_system_12_presentation_set

 

[mbenonis]

Huh, neat. Looks like it's in the $300-$500 range, which will appeal to schools. I'm not super impressed with the RF specifications, though. For example, RF sensitivity, which tells you how far "down into the noise" your receiver will chase the signal, is remarkably worse than my reference receiver (The Lectrosonics UCR411a). The Lectro receiver will go down to 1.12 uV (~ -106 dBm) while this new Sennheiser is nebulously spec'd at "< 3 uV", which corresponds to -97 dBm. That's a difference of nearly 10 dB, which is something like the difference between a dipole antenna and a shark fin. Other comperable specs are similarly worse (hard to compare, because Sennheiser does not use standard RF specifications like Lectro does).

But I bet it works real good for garage bands and small theatres. Same rules apply of course w/r/t frequency coordination and all that jazz.

My reference receiver:
http://www.lectrosonics.com/images/TD-sheets/ucr411atd.pdf

 

[bishopthomas]

Interesting. Thanks for that information, Mike. I've never really looked at RF specs. I'm not real familiar with Lectrosonics, but I understand they are high quality units (yeah, just looked them up, $1700). It may not be fair to compare apples and oranges. I would say the Shure PGX is probably more comparable, at least in price, and therefore you should compare their specs as well. As a reference staying in the Sennheiser family, how are the specs on the 100 series, the step up in quality from this new SXW line?

MAP is $400.

 

[mbenonis]

Let's see if I can hit the right button this time...

Sensitivity on the EW100 is slightly better, being spec'd at 2.5 uV for 52 dB SNR in the audio chain (same figure of merit as the XS). BTW, Lectrosonics spec'd theirs for 60 dB SNR, not 52 dB SNR, so they actually come out even more ahead than I made it sound above. The EW100 does 15 dB better in terms of 'intermodulation rejection' (not really a standard spec, but hey), and 5 dB better in both Adjacent Channel Rejection* and Blocking**. I bet this stems from using a better front-end preamplifier in the EW100 than in the XS series, as well as perhaps the choice of mixer for the first conversion.

BTW, one thing worth noting is what Sennheiser will NOT specify in terms of performance. Things like frequency tolerance (how close are you to the desired carrier frequency), Third Order Intercept (lets you actually back-calculate how strong intermodulation products will be for a given input spectrum), AM rejection (how much variance in the input signal makes it through to the audio out), and the intermediate frequencies (gives you an idea what oscillators are inside the device). All of these are either chosen by the engineers or trivial to measure in the lab, and would make it a much more fair comparison.

Maybe I should write an article on RF performance specifications...

*ACR is a measure of how strong the immediate higher or lower channel would be to cause the receiver to malfunction. In this example, the XS specs claim that the adjacent channel would need to be 60 dB stronger than the desired channel to cause interference. BTW, the adjacent channel is not the frequency you get when you hit the "up" button, but rather something like 200 kHz away. This is something Sennheiser should have defined. They would have had to know to make the measurement! (And on an even more arcane note, this figure is actually a function of total input power and desired channel power...as both get stronger, this number will shrink because you'll hit the compression point of various stages in the RF path).

**I'm going to assume that Blocking means Image Rejection, but I could be totally wrong. FMEng, what say you?