Been having issues with our Sennheiser wireless mics and our Tascam DR-40. I'm fairly confident the issue is with the mics, however it's difficult to tell. I've recorded some test audio with the mics, through the Tascam and the Canon 7D directly, the audio tracks are clean and crisp in Final Cut Pro, but I'm also getting an audible hiss. I've tried different headphones, straight through the computer speakers, changed the settings on the Tascam from 4 channel to Dual, and recorded at different levels through the 7D menu.
No change. The hiss remains. I'm unsure what changes I can make on the mics to solve the issue. Hopefully I haven't been too vague for proper assistance.
Sennheiser EW100 G3: Mic and Receiver
iMac Mid 2011: MAC OSX 10.6.8
Wireless with smaller mics like the B6 can have more because the diaphragms of the smaller mics just don't generate the voltage that lavs with larger diaphragms usually do.
Not hitting the transmitter with enough modulation from the mic causes hiss.
Running the transmitter low and the receiver high can cause hiss.
Improper connections can cause hiss.
The issue is Gain Staging; understanding what level has to be set where in different places along the chain.
You may have to reduce the sensitivity of the transmitter if you have a shouting scene or you'll overdrive the transmitter and nothing will undo that. You may have to raise the sensitivity of the transmitter if you have a very quiet person talking.
After you get that right check the receiver output and the recorder/camera input. If any input or output is turned up too high, you'll likely get more hiss. Finding the sweet spot is where it's at.