Urei 1176LN Blackface Rev F Peak Limiter (Vintage)
The Urei 1176 Compressor/Limiter was first introduced in 1968, created by Bill Putnam Sr. as the solid state successor to his tube-based 176 limiting amplifier. The 1176 uses a Field Effect Transistor, or FET, as a voltage divider to accomplish the task of compression, in conjunction with I/O transformers and a Class A line level amplifier. The 1176 was meant to be a ‘true peak limiter’ with a very fast attack of up to 20 microseconds, and lots of gain for a compressor – up to 45 dB.
The design of the unit went through numerous changes, taking a while to hit its stride. The originals were somewhat noisy, prompting Brad Plunkett of Urei to design the Low Noise circuit that gave the unit its ‘LN’ designation.
- Input level control
- Output level control
- Threshold: dependent on input and ratio levels
- Attack time: variable 20 µS microseconds to 800 µS microseconds
- Recovery time: variable 50 mS to 1.1 sec
- Compression Ratio: 4:1, 8:1, 12:1, 20:1, All-button
- VU Meter
- Meter select: Off, Gain Reduction, Output Level at +4 dBm or +8 dBm
- Barrier strip I/O and 1176 SA stereo-link RCA jack on rear
Revision F: Serial Numbers: 2611-7052
In 1973 some major changes were implemented. UA had developed a new preamplifier, the 1109 model, and this was the basis for changing the output amplifier from a Class A design (the 1108 model) to a Class A/B push-pull configuration (the 1109) providing more output current. In conjunction with this, the UA5002A output transformer was replaced by the B11148 transformer (used in the LA-3A), providing 12 dB of gain.
The meter drive circuit was also changed, replacing the discrete circuit of balanced bridge transistors with an operational amplifier, to simplify meter calibration.