Decided to run a quick analysis on my new Sennheiser G3’s. The idea is to put a signal through the radio packs and measure how it changes from the original signal.
Audient iD4 audio interface
The iD4 supplies a sine sweep through the headphone jack to the SK100, and the EK100 picks up the signal and inputs it through XLR back into the iD4.
The recorded and original signal are then deconvolved to produce a FIR to describe the EQ (and phase) changes that the radio packs apply;
As you can see, it’s fairly accurate, seeing only a slight bump in the Q of the HP filter, which cuts at about -6dB per octave.
Seemingly, it’s designed specifically for voice with all the important tonal information included and just enough headroom for sibilance.
It later occurred to me that my iD4 headphone out & mic preamp might be colouring the signal, so I routed a cable directly between the output back to the input (being careful of feedback!) and did the same measurement;
You can see that even zoomed in to see a range of -1dB to 1dB, it’s really not colouring the signal very much at all!
Very simple – just put a derrac spike into the transmitter and read the results.
It produced a delay of around 4-5ms; consistent with what I’ve seen others say.
Interestingly, the signal also seemed to be reversed in phase. Further investigation is required to confirm my method is foolproof and that assertion is correct.
The G3’s use a type of radio transmission that requires the signal to be compressed and expanded in a dual processor chip in the radio receiver.
I’ve not yet designed this test – but it may involve using a Z-transform, or a RMS or power analysis of different types of transients.
Stand by for future updates!