Different UA compressors for different...
Hi DrPeper. I personally don’t think of tools like compressors genre specific. To me they are job specific based on the tone and vibe of the different compressor technologies and how the affect the sound.
Once I leaned what each style of compressor did in terms of tone, vibe and sound design, I learned when to grab what compressor for the desired result/challenge at hand within a mix.
Everybody’s ears and style is different and so is what we are working on, but what helped me out in the beginning was to take a break from trying to mix songs, open up multi-track sessions and study the tools and techniques without the pressure of pulling out a mix for a client. Meaning don't actually mix it, but use the tracks to study.
What I did was sit down with a multi-track session and run every single track through one type of compressor only, say a FET, then the next day I’d run all tracks in a song through a vari-mu... so on and so forth until you begin to understand how each style of compressor affects the tone and vibe of each source in its unique way. This way you will train your ears, based in your tastes and style to the different character of each compressor and will start to know what one to reach for in a mix when you are faced with a situation that “requires” compression. Also, please go to extremes with each setting and go TOO FAR, so you can then know the limits. It's easy to back it off once you've gone too far, but you have to go overboard first to know the limits!
Here’s an excerpt from a masterclass I give on tone and compressor technologies:
Variable-μ
Variable-μ compressors use vacuum tubes designed to have a gain that can be controlled by a sidechain signal. These compressors feature smooth compression curves and can be made to have significant warmth or saturation. Attack, release and ratio are designed explicitly by external components. Disadvantages are that poorly matched tubes or poor maintenance can result in significant distortion of audio.
• Famous example: Universal Audio 175 and the Fairchild 670.
• Tone/Vibe: smooth, warm, creamy or organic
Optical
Optical compressors were first introduced to prevent the gain reduction signal from leaking into the audio path. Because of this, they are often billed as zero-distortion compressors. A big advantage of optical compression is that, depending upon the physics of the optical device used, a program-dependent release can be had "for free," with no additional components needed in the circuit. Disadvantages are that the attack and release times are coupled, meaning that unless the release time is artificially increased (which would negate the program dependence), the attack and release times cannot be set separately. Attack times are generally not exceptionally fast. Also, for stereo applications, it can be difficult to get precise tracking of compression between channels.
• Famous example: Teletronix LA-2A.
• Tone/Vibe: very smooth, slow-releasing and "organic", neutral/invisible, or very squashy/effecty
VCA
VCA compressors are the most modern designs, using large-scale circuit design to produce a variable-gain amplifier with high linearity and immunity to crosstalk from control signals. Character for these designs is obtained exclusively by design of the attack and release behaviour and the static compression characteristics. VCAs are probably the most flexible compression technology, and they can be extremely transparent. Care must be taken in design, as some of the "accidental" good properties of other technologies will not appear for free here.
• Famous examples: dbx 160VU, SSL G-Master Buss Compressor.
• Tone/Vibe: fast, clean compression
FET
FET compressors are somewhat similar to variable-mu compressors, but with properties of solid-state saturation rather than tube warmth. The nonlinearities associated with the FET can be largely eliminated by a clever trick of circuitry. FET compression knees tend to be somewhat more compact than vari-mu tubes. Attack, release and ratios are configurable as with vari-mu designs.
• Famous example: UREI 1176.
• Tone/Vibe: VCA style compression (fast &clean) but with more colour
Diode Bridge
Diode bridge compressors can be fully configurable in terms of compression parameters, in that the compression curves and the attack and release can be designed independent of the compression element. Diode bridges also provide good immunity between the control signal and the audio path. Compressors built on this technology are tonally distinctive, because the nonlinearities associated with the diodes can reach up to ten percent harmonic distortion under certain conditions. These designs are flexible and can add a pleasant character.
• Famous examples: Neve 2264, Neve 33609.
• Tone/Vibe: Pleasant character with harmonic distortion
REFERENCES:
Analog Obsession: Compression Technology and Topology
UA WebZine "Analog Obsession" April 06 | Compression Technology and Topology
What are the differences between various types of compressor?
Types of Compressors