The AESQbox is designed to provide a portable means of testing various aspects of AES-3 and S/PDIF digital audio systems. It generates AES-3 or S/PDIF output signals over a sample frequency range from 32kHz to 192kHz. Audio sources available for the signal generator/transmitter function include a built-in microphone, a pair of tone generators (one for the left channel, the other for the right), or an external line-level stereo audio source, such as a portable MP3 player, CD player, or computer sound card.
The AESQbox also functions as an AES-3 or S/PDIF receiver. It is capable of receiving sample frequencies from 32kHz to 192kHz, and provides audio monitoring via a built-in speaker or line/headphone output jack. Connectors include S/PDIF in (BNC female), AES-3 in (XLR female),S/PDIF out (BNC female), AES-3 out (XLR male), line-level audio in (1/8" TRS female), line-level/headphone out (1/8" TRS female) and external power (5.5mm x 2.1mm coaxial jack). Power source may be a 6 volt DC "wall wart" or four "AA" batteries. Recommended headphone impedance is between 32 and 100 ohms.
Three Mode Switch Selections
IN/OUT Normal Mode
PASS THRU The digital audio received on the input is passed through to the output at the same sample rate so that the audio content may be monitored - the AESQbox is acting like both a "wiretap" and a "repeater".
CABLE TEST The analog audio is delivered to the AES output where you may then test your digital cable by connecting from the output back to the AES input, which should allow the user to hear the audio. This could also be described as a "self test" mode for the unit as well as to verify the integrity of the cable. Digital Input Section
The AESQbox recognizes digital sample rates from 32 kHz to 192 kHz. A set of INPUT SAMPLE RATE indicators shows the following sample frequencies (in kHz): 32, 44.1, 48, 88.2, 96, 176.4, and 192.
A FAULT LED indicates problems with the data stream or hardware.
The digital audio is converted to analog and may be monitored via a high quality unbalanced, 1/8" TRS stereo line/headphone output or with the built in speaker. The channel monitored by the speaker is selectable with a switch.
Digital Output Section
The SOURCE switch allows selection of MIC, TONE or AUX IN (a 1/8" TRS stereo unbalanced jack) as the analog audio source.
The built-in TONE generator provides 440 Hz for the left channel and 880 Hz for the right. The built-in MIC is an electret condenser type and feeds both the left and right channels.
The AUX IN accepts line level stereo audio. The analog signal is converted to AES/EBU digital and output via the male XLR jack and BNC.
One of the requirements of this design is to produce high quality audio. The headphone/speaker amp circuit has superb THD and noise specs and the line output will have near pro-quality sound. The idea is that this unit can also double as a quality, portable AES-to-Line or Line-to-AES converter.
The AESQbox operates on 4 AA size batteries or with a 6V external power supply (included). A POWER indicator shows that power is on and allows the user to assess battery condition - when it gets dim, time to change the batteries. Inputs and outputs are both DC and transformer isolated to prevent inadvertent damage to the unit.