Andrew,
Thanks for the quick response. I tried making some recordings of my own and the only problem that I see is that the mic array firmware only supports sample rates up to 44.1 and not 48 KHz. It looks like the board+firmware can indeed capture audio past 4k. There was an user error somewhere on our end.
To answer your questions:
The application binary is bin/1i8o2/app_usb_aud_mic_array_1i8o2.xe.
I plug the mic array into a MacBook Pro running OS X El Capitan version 10.11.6. The following shows up in the System Information / USB tree:
USB 3.0 Bus:
Capacity: 21.1 MB (21,135,072 bytes)
Removable Media: Yes
BSD Name: disk3
Host Controller Driver: AppleUSBXHCIPPT
Partition Map Type: Unknown
PCI Device ID: 0x1e31
PCI Revision ID: 0x0004
PCI Vendor ID: 0x8086
USB3.0 Hub :
Product ID: 0x0812
Vendor ID: 0x2109 (VIA Labs, Inc.)
Version: b.e1
Speed: Up to 5 Gb/sec
Manufacturer: VIA Labs, Inc.
Location ID: 0x14300000 / 3
Current Available (mA): 1800
Current Required (mA): 0
Extra Operating Current (mA): 0
Capacity: 3 TB (3,000,592,981,504 bytes)
Removable Media: Yes
Detachable Drive: Yes
BSD Name: disk2
Partition Map Type: GPT (GUID Partition Table)
Volumes:
XMOS Microphone Array UAC2.0:
Product ID: 0x0009
Vendor ID: 0x20b1
Version: 6.f2
Speed: Up to 12 Mb/sec
Manufacturer: XMOS
Location ID: 0x14200000 / 11
Current Available (mA): 1000
Current Required (mA): 500
Extra Operating Current (mA): 0
When I open the XMOS Microphone Array UAC1.0 settings in the Mac Audio MIDI Setup application, the app shows that the device supports 8 channels of 16bit Integer samples at rates of 8000.0, 11025.0, 12000.0, 16000.0, 32000.0, and 44100.0 Hz. There isn't a 48000.0 option.
I use Audacity to make recordings. The board shows up as XMOS Microphone Array UAC1.0 in Audacity. I selected 44100 Hz for recording and then recorded a log sine sweep from 100 Hz to 24000 Hz. Looking at the spectrogram, it appears that the energy rolls off around 20k which I totally expect.
I attached the spectrogram.
sine_sweep.jpg