• Size - The Model 1788 contains eight preamps in 2RU space. Since there is a fair amount of heat dissipation, there should be at least 1RU spacing between every preamp. In that configuration, they may be stacked to provide 40 channels of high quality preamps in a standard 16RU road case.
• Microphone Output Limiter - All preamps have a maximum input level. Once that level is exceeded, there is no way to remove that very unpleasant distortion. In order to avoid that occurrence, many engineers set the preamp so that the expected peak level at maximum sound level is still at least 12dB below the clip point. While this provides some insurance against the preamp clipping, it causes a loss of noise performance and, in the case of digital, a loss of resolution. The Model 1788 has a unique limiter (patent pending) in the front end of the preamp which limits the output level of the microphone by as much as 20dB, hence the name 'Microphone Output Limiter'. 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.
• 26dB Pad - The Model 1788 has 39dB of adjustable input gain and fixed gain of 26dB for a total maximum gain of 65dB. There is a 26dB pad which will allow a preamp to be run as a unity gain buffer stage. For example, this allows the line level output of a wireless mic receiver to be fed into the preamp.
• Adjustable Maximum Output Level - The maximum output level of the Model 1788 is +24dBm (loaded into 600 Ohms) balanced. There are, however, many input stages which have odd maximum input levels (e.g.-+18dBu). In order to retain the function of the microphone limiter and maximize noise performance of the entire audio system, the Model 1788 has output level trim of up to 24dB. Once the maximum input level of the device following the Model 1788 is defined, the output level of the 1788 can be trimmed to that exact level. The input gain of the 1788 is then adjusted to achieve optimum performance. In addition to the 24db of output adjustment, each output may be muted.
• Separate Analog Outputs - Microphones are often passively split and then fed to two or more locations. The Model 1788 has two separately trimmable, buffered analog outputs. The main output on XLR is transformerless servo-balanced and the second output is tranformerless balanced on a DB25 multipin connector. This allows two separate inputs to be fed at optimal levels from an optimized mic preamp.
• Digital Option - In addition to the analog outputs, the Model 1788 has three optional digital outputs. The analog to digital converters are 24 bit with selectable sampling rates. The sampling rates can be generated from an internal clock or an external source. The Model 1788 employs a drift stabilized A/D converter circuit (patent pending) which eliminates DC from the output without incorporating a digital high pass filter. The digital outputs appear on two DB25 connectors, one for AES/EBU and one for the T/DIF format. There is also a TOSLINK optical output for the ADAT format. There is an AES/EBU input on an XLR and a Word Clock on a BNC connector for external clock input. If the unit is being used as a master there is an AES/EBU output on an XLR. For even more flexibility with complex setups, see our Model 148 Digital Splitter.
• Test Tone Generator - There is 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'.
• Display - The Model 1788 has LED indicators for the status of each function for each channel. A twelve segment LED meter displays headroom. Two eight segment LED's 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.
• Headphone Output - As an additional feature, the Model 1788 has a front panel headphone output. Any channel can be selected and the output level adjusted.

• Connector: 8 x 3-PIN XLR Female
• Type: Jensen® Transformer coupled
• Impedance: Balanced, 1.6k ohms
• Maximum Input Level: +27 dBu (with 26dB pad engaged)
• CMRR: better than -99dB @ 60 Hz, -72 dB @10kHz
• Phantom Power: 48 VDC on pins 2 and 3

Analog Outputs

• Connector Main: (8) x XLR-3M; Aux: DB-25 (Tascam)
• Type Main: Servo Balanced; Aux: Balanced
• Impedance: Balanced , 65 ohms
• Maximum: Output Level +27dBu
• Test Tone: 700 Hz 0dBfs, -20dBfs
• Headphones: 8-600 ohms recommended load impedance, mono or stereo

Digital Outputs (optional)

• Connector: AES/EBU: DB-15 Male; ADAT Optical:TOSLINK; T/DIF: DB-25
• Type: Drift Stabilized 24 bit
• Impedance: 75 ohms (AES/EBU)
• Clock: 44.1, 48, or 96kHz Internal (or External)
• Clock Connector: BNC

Remote control

• 1788RC Hardware Remote: Full remote control functions, full metering and preamp status;
  Select one of 16 units, Create, Save, Edit, Recall up to 60 presets
• 1788SW Software (W95/98/2000/XP Mac OS X®): (For Windows 95/98/2000/XP +Mac OS) Full remote control functions, Full metering and preamp status, Select one of 16 units, Create, Save, Edit, Recall up to 60 presets, Assignable up to 20 scenes
• MIDI Controller: MIDI command protocol for full remote control, metering, and status
• Connection: Remote to 1788 Ethernet, MIDI; Unit to unit linking Ethernet Hub
• Remote Functions: Input Gain, Main Out Gain, Aux Out Gain, Polarity, Mute, Low Cut Filter, Mute, Pad, Phantom Power, Sample Clock, Test Tone, Group Assign, Snapshot, Recall Presets

Other Specifications

• Power requirements
• 90-260 VAC 50-60 Hz  60 Watts
• Dimensions
• 19"W x 3.5"H x 13.58" D   2 Rack U  (482.6mm x 88.9mm x 345mm)
• Net Weight
• 17 lbs (7.7 kg)