Hear The Gear: Retro Instruments 176 Limiting Amplifier

By Eric AllenOctober 29, 2026

The Universal Audio 176 is the stuff of studio legend. Designed by company founder Bill Putnam in the 1960s, the compressor/limiter became a studio favorite thanks to its lightning-fast attack time and rich sonic character. Although the 176 was discontinued by the end of the decade in favor of the FET-based 1176, Phil Moore of Retro Instruments brought the design back to life in the mid-2000s.

Since Retro Instruments' inception with the Sta-Level, the brand has been unwavering its dedication to reviving classic studio gear for modern recording engineers. Phil's 176 design follows suit by preserving the original's vari-mu tube design and signature compression ratios, and adding a number of handy features.

One of the most notable additions to the Retro Instruments 176 is the pull switch on the Attack knob. While the original Universal Audio 176 featured a single attack time constant, the Retro 176 gives you more flexibility. With the knob pushed in, you can dial in continuously variable attack times. Pull it out, and you engage the original's fixed time constant, allowing you to use the compressor just as you would a vintage 176.

Two other features that can have a significant impact on recording and mixing are the Interstage and Asymmetry switches. With Interstage switched "In," a transformer separates the gain reduction stage from the amplifier stage, providing a distinctive load for the variable gain stage. Switching it "Out" bypasses the transformer, giving you a different compression character to work with.

The Asymmetry switch offers another way to shape the compressor's response by changing how it detects the incoming signal. You can choose between full-wave and half-wave detection, with the additional option of selecting which half of the waveform triggers compression when operating in half-wave mode.

There's a lot to love about the Retro Instruments 176, and we're showing off what it can do in our latest Hear The Gear. Vintage King's in-house engineer Bryan Reilly used the compressor on a variety of sound sources at the Scramble Shack, experimenting with different settings to showcase its full range of capabilities. Continue below to listen and see the settings for each sample.

Retro Instruments 176 Sound Samples

VintageKingAudio · Retro Instruments 176

Drums

For recording the drum sample, Bryan used a Shure Beta 52A on kick, SM57 on snare, and Warm Audio FT Fen-tone overhead, all of which were were run into an Undertone Audio MPDI-4. He also used a AEA R84A as a room mic, which was paired with a Focusrite Red 1 Four preamp. In every example below, the signal is sent from the preamp to a BURL Audio BAD4 card.

4:1 Ratio Sample Settings

Interstage: Out
Asymmetry: -
Input: 42
Attack: 60
Release: Fast
Sidechain: Off
Output: 72

8:1 Ratio Sample Settings

Interstage: In
Asymmetry: -
Input: 70
Attack: Slow
Release: Fast
Sidechain: Off
Output: 52

12:1 Ratio Sample Settings

Interstage: Out
Asymmetry: +
Input: 100
Attack: 20
Release: Fast
Sidechain: Off
Output: 60

2:1 Ratio Sample Settings

Interstage: In
Asymmetry: Middle
Input: 40
Attack: Slow
Release: Fast
Sidechain: Off
Output: 70

VintageKingAudio · Retro Instruments 176 - Drums

Electric Bass

The electric bass examples feature a 1996 Mexican Fender Jazz Bass through an Ampeg B-15 amp. For tracking, a U 67 Reissue set to cardioid was placed about 3' in front of the amp, centered on the speaker, and sent to a UnderTone Audio MPDI-4.

2:1 Ratio Sample Settings

Interstage: In
Asymmetry: Middle
Input: 40
Attack: Slow
Release: Fast
Sidechain: Off
Output: 65

4:1 Ratio Sample Settings

Interstage: Out
Asymmetry: -
Input: 35
Attack: 50
Release: Fast
Sidechain: Off
Output: 70

8:1 Ratio | Interstage: In Sample Settings

Interstage: In
Asymmetry: +
Input: 60
Attack: 50
Release: 85
Sidechain: Off
Output: 50

8:1 Ratio | Interstage: Out Sample Settings

Interstage: Out
Asymmetry: +
Input: 60
Attack: 50
Release: Fast
Sidechain: Off
Output: 45

VintageKingAudio · Retro Instruments 176 - Electric Bass

Electric Guitar

The electric guitar examples feature a Gibson Les Paul Traditional Pro played through a Gemini 1 amp, captured with a Royer R-122 MKII and recorded through an API 3124V preamp.

2:1 Ratio Sample Settings