The Universal Audio 1176
The "True Peak Limiter." Bill Putnam's solid-state masterpiece, in continuous production since 1967. The most-used compressor in professional recording history.
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Universal Audio 1176LN
Introducing the "True Peak Limiter"
The Universal Audio 1176 Compressor/Limiter was first introduced in 1967, created by Bill Putnam Sr. as the solid-state successor to his tube-based 176 limiting amplifier. The 1176 uses a Field Effect Transistor (FET) as a voltage divider to accomplish compression, combined with I/O transformers and a Class A line-level amplifier. Designed to be a "true peak limiter" with an attack time as fast as 20 microseconds and up to 45 dB of gain, it was unlike anything before it.
The design went through numerous changes over the decades. The originals were somewhat noisy, prompting Brad Plunkett of UREI to design the Low Noise circuit that gave the unit its "LN" designation. Improvements continued through 9 major revisions — from the original Bluestripe to the final Silverface — each refining the sound that became the backbone of professional recording.
"What's not to like? This is the workhorse of the industry. The most powerful compressor of them all. You can use it on any instrument and it'll do the job."
Michael Brauer, mixing engineer"All Buttons In" — The Accident That Became a Standard
Pressing all four ratio buttons simultaneously was never intended by the designers. But engineers discovered that it engages a unique compression behavior — the ratio hovers between 12:1 and 20:1, distortion increases dramatically, and the unit produces a distinctive pumping, breathing effect unlike any other compressor.
This "nuke" or "British Mode" setting became one of the most iconic sounds in recording. Engineers use it on drums for explosive room tone, on vocals for urgent, stressed character, and on room mics for that larger-than-life ambience heard on countless records from Led Zeppelin to Radiohead.
The 1176's controls are famously reversed: fully clockwise = slowest attack, fully counter-clockwise = fastest (20 microseconds). This catches every first-time user off guard.
Attack: program-dependent · Character: aggressive pump
Universal Specifications Across All Revisions
Despite many design changes, every 1176 shares these fundamental features.
| Parameter | Value |
|---|---|
| Input level control | Variable |
| Output level control | Variable |
| Attack time | 20 microseconds to 800 microseconds |
| Recovery time | 50 milliseconds to 1.1 seconds |
| Compression ratios | 4:1, 8:1, 12:1, 20:1, All-In |
| Max gain | 45 dB |
| VU meter modes | Off, Gain Reduction, Output (+4 / +8 dBm) |
| I/O | Barrier strip, 1176-SA stereo-link RCA |
A Guide to 1176 Revisions: A through H
Four fundamental eras of the 1176, spanning nearly two decades of production.
The Original Bluestripes
Bill Putnam's first design. Peerless input transformer, T-pad attenuator, FET voltage divider, 1108 preamp circuit with Darlington pair, Class A output with UA-5002 transformer. Brushed aluminum faceplate with blue paint around the Weston meter — the original "Bluestripe." Two black knobs with silver tops, red power indicator.
Resistor values changed in signal preamp stages, bypass capacitors added around the FET feed resistor. Improved noise and stability. Same Bluestripe cosmetics.
FETs replaced by 2N3391A bipolar transistor in the preamp circuit. Feedback tap added from emitter back to the gain reduction FET. Still the Bluestripe faceplate. Some Rev B units were later upgraded by UREI to Low Noise spec with replacement black faceplates.
The Low-Noise Blackfaces
Two major changes: Low Noise circuitry added to reduce drain-to-source voltage of the gain reduction FET, keeping it within its linear range. Circuit sealed in epoxy to protect the pending patent. Q-bias pot added to minimize distortion. Model designation changed from 1176 to 1176LN. New black anodized aluminum faceplate — the "Blackface" era begins. UREI logo placed over the new Modutec meter.
Same circuit as Rev C, but the LN circuit and Q-bias pot are now integrated into a new circuit board instead of being soldered on as afterthoughts.
Addition of a power transformer switch for 110V/220V operation. Virtually identical to C and D in sound. Revisions C, D, and E are generally the most revered — the modern Universal Audio reissue is based on these versions.
The Push-Pull Blackface
Major overhaul. UA's new 1109 preamplifier replaced the Class A output with a Class A/B push-pull configuration, providing significantly more output current. The UA5002A output transformer replaced by the B11148 (from the LA-3A), yielding 12 dB more gain. Meter drive circuit simplified with an operational amplifier. Around unit #6950, UREI moved from North Hollywood to Sun Valley, California.
The Op-Amp Blackface and Silverface
The final major circuit change. The input transformer was removed and replaced with a differential input op-amp stage. Produced in the new Sun Valley factory. Cleaner sound character than all previous revisions.
No circuit changes — cosmetics only. Natural brushed aluminum faceplate replaces the black anodized finish. Blue UREI badge replaces silk-screened logo. Modutec "light box" meter. Red Off button. Square fuse holder, IEC cable input replacing the attached power cord. At serial ~10750, Harman Electronics took over UREI. One-third of all vintage 1176 units are Rev G or H.
The Modern Reissue
In 2000, Bill Putnam Jr. and James Putnam resurrected Universal Audio with the 1176LN as their first release — an authentic reissue based primarily on the revered Revisions C, D, and E. The most famous FET compressor in history, back in production.
Four Fundamental Versions
In essence, there have been only four basic versions of the 1176.
The edgiest versions, with plenty of noise and distortion to provide a distinct color to any signal. The original sound.
Classic character with a lower noise floor. The heart of the 1176 sound. Modern reissues are based on this era.
Continued the classic sound with a new output transformer for considerably higher gain. The workhorse era.
Input transformer replaced with an op-amp for a cleaner sound. One-third of all vintage 1176 units are this type.
Authentic reproduction based on Rev C/D/E. Bill Putnam's sons brought the 1176LN back to continuous production.
Every 1176 at Vintage King
Hardware, reissues, alternatives, and plug-ins — from $29.99 to vintage originals by request.
Universal Audio 1176LN
The official reissue. Based on Rev C/D/E, hand-built in Scotts Valley. Class A output, hand-matched FET, original Putnam-designed output transformer. The benchmark.
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Universal Audio 6176
610 tube preamp paired with the 1176LN compressor in a single 2U chassis. Record-ready signal chain from mic to mix.
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Purple Audio MC77
Expanded feature set: stepped I/O, sidechain HPF, hard/soft recovery. One of the most respected 1176-style units on the market.
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Retro Instruments 176
Tube-based take on the 1176 lineage. Returns to Bill Putnam's original 176 tube limiter concept with modern manufacturing.
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UK Sound 176 Mono
Affordable 1176-style compression. FET design with transformer output. Entry point for hardware 1176 tone.
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Klark Teknik 1176-KT
Classic FET-style compressor at an entry-level price. All four ratio buttons, all-buttons-in mode. Remarkable value for the 1176 sound.
Shop at Vintage King →From the Vintage King Blog
1176 FAQ
What is the difference between 1176 revisions?
What is "All Buttons In" mode?
Which 1176 revision sounds best?
How fast is the 1176 attack?
Can I use a vintage 1176 daily?
1176 vs LA-2A — when to use each?
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