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Universal Audio

Classic Limiting Amplifier
Universal Audio
2000 to present
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FET-Style Compressor with Class A Output & Custom Transformers — True to the Original

The 1176LN Classic Limiting Amplifier is a modern reproduction, yet every effort was made to remain faithful to UA founder Bill Putnam Sr.’s visionary design and intentions. The original UA 1176LN was a major breakthrough in limiter technology — the first true peak limiter with all transistor circuitry offering superior performance with a signature sound — and set the standard for all limiters to follow. The ultra-fast attack time and trademark sound have lured legendary artists and studio moguls alike to the 1176LN — Peter Frampton, Joe Satriani, Joe Chiccarelli, Vance Powell, and Mike Elizondo are just a few names on a list that’s continued to grow, for nearly 50 years.

FET-Style Compressor with Class A Output & Custom Transformers
True to the original 1176 in design, manufacturing and performance
Ultra fast attack time – 20 microseconds to 800 microseconds
Hand-built in USA; backed by 1-Year limited warranty

Input Impedance
600 ohms, bridges-T control (floating)

Output Load Impedance
600 ohms, floating, damping factor 20

External Connections
Jones Barrier terminals and XLR connectors

Frequency Response
± 1 dB 20 Hz to 20kHz

50 dB

Less than 0.5% total harmonic distortion from 50 Hz to 15 kHz with limiting

Signal to Noise Ratio
Greater than 70 dB at +10 dBm

Attack Time
20 microseconds to 800 microseconds

Release Time
50 milliseconds to 1.1 seconds

Stereo Interconnection
via 1176 SA Network accessory

dB gain reduction and dB output

Power Requirements
120/240 V

Maximum operating temperature 160°F

19" Rackmount chassis, 2U

Published Resources (click to view)
1176LN Manual

The 1176LN Peak Limiter is a compressor introduced by UREI in 1968. The 1176LN was inducted into the TECnology Hall of Fame in 2008. At the time of its introduction, it was the first true peak limiter with all solid-state circuitry.

It uses a FET for gain reduction, in a feedback configuration.
Four different compression ratios are available 4:1, 8:1, 12:1, and, 20:1
Attack time is adjustable from less than 20 microseconds to 800 microseconds
Release times are adjustable from 50 ms to 1,100 ms
Two units can be linked for proper stereo operation (not just dual mono)

The 1176 underwent a number of revisions including the addition of Brad Plunkett's low-noise (LN) circuitry to produce the 1176LN. This reduced the noise by 6 dB and redistributed the noise spectrum, producing even more noise reduction in the sensitive mid-range. Revisions D and E are reputed to sound the best.

Revision A was the original (1967/6/20) design by Bill Putnam, it had a brushed aluminium face, blue paint and red power light. Serial numbers 011-125
Revision AB improved stability and noise. (1967/11/20) Serial numbers 126-216
Revision B incorporated changes to transistors. Serial numbers 217-1078
Revision C, the 1176 LN, added low-noise circuits on additional circuit boards and reduced distortion and changed the faceplate to black. (1970/1/9) Serial numbers 1079-1238
Revision D has no circuit changes, but the additional low-noise circuitry was incorporated into a new main circuit board. Serial numbers 1239-2331
Revision E has a new power transformer that is now switchable between 110 V and 220 V. Serial numbers 2332-2611
Revision F changed the output amplifier from a class A to a push-pull design. Metering circuit now uses and op-amp (1973/3/15) Serial numbers 2612-7052
Revision G replaced the input transformer with a differential amplifier. Serial numbers 7053-7651
Revision H changed the faceplate to silver and includes a red “Off’ button. This version is branded with blue UREI logo. Serial numbers 7652-
Universal Audio Re-Issue (2000/4/1) is based on “D” and “E” models.

All Button Mode
It was common to use the 1176 in 'all-button mode' or 'British mode'. This was when all four of the ratio buttons are pressed simultaneously.

"The way the 1176 sounds, and specifically, the way All-Button mode sounds, is partially due to its being a program dependent compressor. The attack and release are program dependent, as is the ratio.

The 1176 will faithfully compress or limit at the selected ratio for transients, but the ratio will always increase a bit after the transient. To what degree is once again material dependent. This is true for any of the 1176’s ratio settings, and is part of the 1176’s sound.

But in All-Button Mode, a few more things are happening; the ratio goes to somewhere between 12:1 and 20:1, and the bias points change all over the circuit. As a result, the attack and release times change. This change in attack and release times and the compression curve that results is the main contributor to the All-Button sound. This is what gives way to the trademark overdriven tone. The shape of the compression curve changes dramatically in All-Button. Where 4:1 is a gentle slope, All-Button is more like severe plateau! Furthermore, in All-Button mode there is a lag time on the attack of initial transients. This strange phenomenon might be described as a "reverse look-ahead".

Mike Shipley says “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. I listen for how it affects the vocal, and depending on the song I set the attack or release—faster attack if I want a bit more bite. My preference is for the black face model, the 4000 series—I think the top end is especially clean.”

Jim Scott says “They have an equalizer kind of effect, adding a coloration that's bright and clear. Not only do they give you a little more impact from the compression, they also sort of clear things up; maybe a little bottom end gets squeezed out or maybe they are just sort of excitingly solid state or whatever they are. The big thing for me is the clarity, and the improvement in the top end.”

From Wikipedia, the free encyclopedia