The colors of analog compressors. (SSL vs 1176 vs VariMu)

Analog compressors are mythological beasts.

Since the first radios started using limiters to raise the volume of the broadcasted music, they have been implemented in studio and some models have become legendary for how they very uniquely color the sound. 
As a result, nowadays you can buy all kind of clones and plugin emulations and each brand swears by the perfect imitation of the original vibe of those historical units.
Since I’ve been producing music, I’ve become more and more passionate about some of them so I ended up with my small but very precious collection of analog compressors.
I’ve recently started to endorse IGS Audio‘s Tubecore 3U Mastering Edition Vari-Mu compressor, which adds to my stereo Hairball 1176 Rev. D Fet limiter, my modded G SLL (project by Gyraf Audio) and more analog beauties.

Amazingly fat mastering vari-mu all tube all analog compressor
(Bellezebu loves its “warmth” too!)
Analog compressors: The test!

I’ve tested them next to their plugin emulations to understand better how each model really affects the sound during my mixing sessions, and to make it clearer how each emulation/clone really behaves.

Here are the protagonists of my comparison test:

UREI 1176 models
• 2x 1176 Hairball Rev D (Linked stereo)
• Slate FG 116
• Waves CLA 76 (Blacky)
• Ik Multimedia Black 76
SSL Bus Compressor models
• Custom built G-SSL (w/Sidechain filter mod)
• Slate VBC FG-Grey
• Waves SSL G Comp
 Vari-Mu models
• IGS Tubecore 3U ME
• Slate VBC Fg-Mu
• Waves Puigchild 670
Analog bus compressor
Custom made G • SSL
Some technical stuff before going to listen to the files
orHow the test was done
Analog compressors
My stereo 1176’s

I’ve used a stereo stem of drums to drive the compressors and I’ve accurately matched both input and output levels among the same models, same thing for the gain reduction.
You can imagine how that’s a not-so-easy task to do, for the reason that each unit has a different monitoring & GR philosophy, but still I’ve been pretty meticulous.

That said, this test doesn’t want to be – at all – a scientific test for comparing noise levels, exact RMS/ Peak levels, etc.
The reason why I’ve done it, instead, is because I wanted to capture to the different coloration that each compressor is capable of, during tracking/mixing, confronting hardware vs software, and that’s why the drums have been compressed twice.
Therefore the files feature a first round of compression and a second round of compression starting at 0.31 (where the first round is sent again into the compressors).


I’ve connected everything with balanced cables and the AD/DA converters are those of my Yamaha MR816x interface.
Ps: The 1176’s and SSL’s have been fed 4db input gain more than the Vari-Mu’s because I wanted to keep the studio routing/settings of the production I’m now working on, but still the i/o gain and GR are matched between sw/hw.

The settings
1176 compression

Attack: 11 o’clock
Release: Fastest
Ratio: 20

 SSL compression

Attack: 10
Release: .1
Ratio: 4

 Vari-Mu compression

Attack: 0,3 
Release 0,3 
Input Gain: 6db

Let’s listen 
(0:00 – 0:31 – First round of compression)
(0:31 – end – Double compression)

Have you made up your mind? Which one is your favorite? I have my preferences…

Download the files (right click – save as):

Dry :


Hairball: IK: Slate: Waves:


GSSL: Slate: Waves:


IGS: Slate: Waves:


Author: Enrico Tiberi

Musician, music producer, mixing engineer.

2 thoughts on “The colors of analog compressors. (SSL vs 1176 vs VariMu)”

  1. Very very nice to hear these icons side by side. This is why i like the internet, so just wanted to say thanks for taking the effort.

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