After seeing (over the Internet) the PR-4 as shown at the NAB convention last week, I wrote to the company thusly:
Hello. I'm trying to understand the degree of support built in to the PR-4 for recording stereo with two AES42 digital microphones simultaneously. I've read the manual and didn't find answers to these questions.
[1] Do the XLR inputs, when switched to AES42, supply digital phantom powering (10 VDC)? If not, how do you suggest that users power their AES42 microphones?
[2] Are the AES42 connections Mode 1 (= microphones are self-clocking) or Mode 2 (= microphone clocks are controlled by the interface)? If it's Mode 1, how does the recorder resolve the inevitable, real-world differences between the clock rates of the two inputs (e.g. does it have built-in sample rate conversion for one input)? (I think this would equally be an issue for AES3 inputs, by the way.)
[3] In the most frequent use case, an AES42 microphone provides just one channel's worth of audio data, even though the interface is inherently two-channel; the second data channel coming from the microphone is normally identical to the first. With two AES42 microphones connected for stereo, is there a way to select just one channel from each microphone's output stream, and to record two rather than four channels of data, so as not to waste storage in the recorder?
Best regards,
Today I received the following reply:
Thank you for your questions. Please find our responses below:
1. The voltage is 10V.
2. The device operates in Mode 1. Both inputs perform SRC (Sample Rate Conversion), and they share the same clock source, consistent with AES3.
3. Yes, this can be achieved. When using an AES42 microphone, the 3.5mm TRS input will be disabled. In the ARMSET settings, CH1/2 correspond to Microphone 1, and CH3/4 correspond to Microphone 2, which can be assigned flexibly as needed.
Please feel free to let us know if you have any further questions.
Best wishes
-- Looking on their Web site, I note that there isn't a separate U.S. version of this model with monitoring-while-recording disabled. Maybe the more complex routing arrangement gets them around the
(IIRC) Lectrosonics Zaxcom patent (thanks for the correction, Grawk).
-- Digital phantom powering can draw up to 250 mA (long-term) per microphone. I probably should have asked about expected battery life when two AES42 mikes are connected and powered on; it will definitely be lower than with other types of sources.