ADC2 AD Converter
Two channel A/D conversion with Line/Mic inputs and AES/EBU/Firewire output – this summarizes the ADC2’s main capabilities, but doesn’t tell much about its stellar sonic quality and its plethora of features.
The ADC2 is the successor of our renowned two channel ADC1-MK2 A/D Converter. It uses state of the art A/D chips in our proven “correlation technique” configuration, which lowers converter imperfections. The analog input stages are kept balanced from the input connectors throughout to the converter chips. A high quality microphone preamplifier is built in as a standard feature. AES/EBU and optional Firewire outputs work at up to 192 kHz/24 Bits.
The ADC2 sports two separate input sections, one stereo pair for line level signals and one stereo pair for microphone level signals. The microphone input can be high pass filtered to cut off rumble noise. A 48 V phantom power source can be switched to the microphone inputs. After a relay controlled attenuator circuit, which uses 1 dB steps over a range of 42 dB, the signal hits the A/D converters. The analog input stage is kept balanced from the XLR connector to the A/D chips.
Two converter channels are used per audio channel which enhances the conversion quality. The analog to digital conversion process can run at 44.1, 48, 88.2, 96, 176.4 or 192 kHz. The parameters of the two conversion channels can be set independently, except for the sampling frequency and the POW-R dithering algorithm.
Synchronization can be from an internal crystal oscillator or external through AES/EBU (XLR) or word-sync (BNC) connectors. The AES/EBU synchronization input can also be used as a digital audio input. This allows to use the ADC2 as a peak limiter and/or POW-R dithering processor for digital audio signals.
The built in digital peak limiter allows for setting a generous headroom on the analog inputs and still get a full scale signal at the converter’s output. In addition to the peak limiter with a threshold parameter there is a digital gain control.
The output word-length can be reduced from 24 to 16 Bits with the built in POW-R dithering. It is possible to have one output running at 24 Bits and another one at 16 Bits. The output formats are AES/EBU in one or two wire technique, S/PDIF in single wire as well as Firewire for a direct connection to computers. The Firewire connection can also be used to feed a signal from the computer to the S/PDIF output of the ADC2.
For metering a large bar graph shows the level to the A/D input, the output level, overload conditions and the gain reduction in the aforementioned peak limiter. The peak hold meter with numeric readout can be used to monitor a transfer and check for overloads which may have occurred.