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Summary of Contents for Universal Audio 1176LN
- Page 1 Model 1176LN Solid-State Limiting Amplifier Universal Audio, Inc. www.uaudio.com PO Box 3818 Santa Cruz CA 95063-3818...
- Page 2 Additionally, Universal Audio will produce new quality audio products designed to meet the needs of the modern recording studio yet retain the character of classic vintage equipment.
- Page 3 Universal Audio 1176LN, Limiting Amplifier. The information contained in this manual is subject to change without notice. Universal Audio, Inc. makes no warranties of any kind with regard to this manual, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose.
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Page 4: Table Of Contents
UNIVERSAL AUDIO 1176LN ................. II 1176LN S ..........................1 PECIFICATIONS ...............................2 NSTALLATION Rear Panel Connections ..........................2 230 Volt Operation ............................. 2 Stereo Interconnection ..........................2 1176 LN O ...........................3 PERATION Meter Function / On-Off Pushbutton Switches .................... 3 Compression Ratio ............................3 Input Level.............................. -
Page 5: 1176Ln Specifications
1176LN Specifications 600 Ω, bridged-T control (floating) Input Impedance: 600 Ω (floating) Output Load Impedance: External Connections: XLR Connectors / Original Jones barrier strip Frequency Response: +/- 1 dB. 20Hz to 20 kHz Gain: 45 dB, +/- 1dB Distortion: Less than 0.5% T.H.D. from 50 Hz to 15 kHz with limiting, at 1.1 seconds release setting. -
Page 6: Installation
VU meter. 230 Volt Operation The 1176LN can be configured for either 115 or 230 Volt operation. This is selected by the voltage selection switch on the rear panel. Stereo Interconnection Two 1176 LN units can be linked for stereo mode operation using the 1176 SA stereo adapter. -
Page 7: 1176 Ln Operation
The pushbutton switches located to the right of the meter are used to determine the metering mode as well as to turn the unit on and off. The 1176LN is turned on by selecting any pushbutton other than the Off selection. -
Page 8: Release Control
compression is disabled. The Attack Control potentiometer allows for an adjustable response time of 20-800 microseconds. The fastest attack time is achieved when the Attack Control is in its fully CW position. Release Control The Release Control allows for an adjustable release time of 50 to 1100 milliseconds. The fastest release time is achieved when the control is in the fully CW position. -
Page 9: Calibration
Calibration Note: There are no user serviceable parts inside the Universal Audio 1176LN. Unit calibration as well as repair should only be performed only by qualified service personnel. These calibration procedures are provided only for use by qualified service technicians. - Page 10 procedure to calibrate the 1176 stereo adapter: Remove the signals from both 1176 units Disable the gain reduction on each limiter (rotate both ATTACK controls fully CCW) Connect the 1176-SA to both limiters (This requires two RCA style cables.) Use the METER function pushbutton switches to set both units into GR mode Adjust the potentiometer on the 1176-SA until both meters read 0dB If it is not possible to zero both meters, reverse the stereo interconnect cables and repeat the preceding step...
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Page 11: Theory Of Operation
Figure 1 - Block Diagram of the 1176LN. Overview Figure 1 shows the block diagram of the 1176LN Limiting Amplifier. Signal limiting and compression is performed by the Gain Reduction section. Before the signal is applied to the Gain Reduction section, the audio signal is attenuated by the Input stage. The amount of attenuation is controlled by the input control potentiometer. -
Page 12: 1176 Ln Input Section
Figure 3 - 1176LN Gain Reduction stage. Gain Reduction Stage This stage is the heart of the 1176LN limiter, and is where the actual signal compression takes place. Compression is achieved by a Field Effect Transistor (FET) which is used as a variable resistor. -
Page 13: Ln Circuitry
Output Amplifier The output amplifier is a Darlington pair followed by a class A stage based on a 2N3053 transistor. The 1176 output stage was essentially the same as the Universal Audio 1108 pre-amplifier. The output transformer is a custom transformer designed by Bill Putnam Sr. Aside from offering output impedance matching, the transformer forms an integral part of the feedback network used to stabilize the output stage. -
Page 14: Gain Reduction Control Circuit
"Q" Bias Adj. 3.9k P.C.B. Figure 5 – 1176LN Gain Reduction Control Circuit. Gain Reduction Control Circuit This circuit controls the amount of compression as well as the attack and release time of the limiter. The input to this circuit is taken from the output of the preamplifier section, just before the volume control potentiometer (R23). - Page 15 by regulating how fast C22 is charged. Likewise, R56 determines the compressors release time by controlling the rate at which C22 discharges. The output of this stage is then applied to the gate of the FET in the Gain Reduction circuit which in turn controls the gain in the manner previously described.
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Page 16: History
The first major modification to the 1176 circuit was designed by Brad Plunkett in an effort to reduce noise--hence the birth of the 1176LN, whose LN stands for low noise. Numerous design improvements followed, resulting in at least 13 revisions of the 1176. - Page 17 “The 1176 absolutely adds a bright character to a sound, and you can set the attack so it's got a nice bite to it. I usually use them on four to one, with quite a lot of gain reduction. I like how variable the attack and release is; there's a sound on the attack and release which I don't think you can get with any other compressor.
- Page 18 also known for his work with Red Hot Chili Peppers, Natalie Merchant and Wilco. “I use 1176s real conservatively and they still do amazing things,” he comments. “I'm always on the four to one button, and the Dr. Pepper--you know, 10 o'clock, 2 o'clock, and it does everything I need.
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