The 1788A-D from Aphex is an eight channel, remote controlled microphone preamp with the optional digital output module built-in. The unit addresses many of the noise issues that plague preamps including long microphone level cables, splitters and multiple inputs that reduce the sensitivity of the microphone and change its frequency, phase and transient response. The unit can provide up to five outputs per channel (two analog and three digital), all available simultaneously essentially eliminating the need for splitter boxes.
By placing the 1788A close to the microphones and controlling it remotely, the need for long cable runs is eliminated. Phantom power on a microphone line also causes the line itself to become a microphone. Having the phantom power source as close as possible to the microphone reduces the chance of phantom voltage loss within a very long cable run. A built-in limiter in the front-end of the preamp provides protection against overloading the preamp.
The installed 1788A-1 digital option provides three digital outputs that appear on a single DB15 connector and four BNC connectors for AES/EBU, along with two ADAT optical outputs. The 24-bit analog to digital converters feature selectable sampling rates that can be generated from an internal clock or an external source. The A/D converter circuit is drift stabilized which eliminates DC without resorting to a digital high-pass filter. Wordclock input and output is available on BNC connectors.
The 1788SW controller software (Windows 95/98/2000/XP or Mac OS X compatible) features a screen which displays all parameters and metering of a single unit. Up to 16 units may be called up displaying in real-time all modifiable channel status information and metering. Up to 20 scenes can be saved, modified and recalled. The software also contains a "learn" function in which the channel(s) adjust the preamp gain to a definable peak value based on the input level during the "learn" period.
- Eight remote controllable, Jensen transformer-coupled microphone preamps in a 2U rack-mount chassis
- Limiter in the front end of the preamp limits the output level of the microphone by as much as 20dB. This allows the engineer to get maximum noise performance and also allows maximum resolution for an analog to digital converter, all without worrying about crashing the preamp
- A 26dB pad allows a preamp to be run as a unity gain buffer stage. This allows the line level output of a wireless mic receiver to be fed into the preamp
- Output level trims of up to 24dB. Once the maximum input level of the device following the 1788A is defined, the output level of can be trimmed to that exact level. The input gain of the 1788A is then adjusted to achieve optimum performance. In addition to the 24db of output adjustment, each output may be muted
- Two separately trimmable, buffered analog outputs. The main output on XLR is transformerless servo-balanced and the second output is transformerless balanced on a DB-25 multi-pin connector. This allows two separate inputs to be fed at optimal levels from an optimized microphone preamp
- Includes a 700Hz test tone at two different levels which can be bussed to any selected preamp channel. The two levels are at 0dBfs (maximum output level) and -20dBfs. The test tone at 0dBfs allows easy set up for finding maximum peak input into following stages. The -20dBfs tone is useful for digital systems which use a -20dB reference tone for '0Vu'
- LED indicators for the status of each function for each channel. A twelve-segment LED meter displays headroom. Two eight segment LEDs show input gain or maximum output level on either of the two analog outputs. All indicators and metering can be monitored at the remote location
- Front panel headphone output - any channel can be selected and the output level adjusted
- 24-bit analog to digital converters with selectable sampling rates
- Three digital outputs
- Wordclock input/output on BNC connectors