Top 10 Best 500 Series Compressors: Best Models Shown!

Top 10 Best 500 Series Compressors

Introduction

The need for a modular rack system with outboard gear led to the creation of the 500 series rack system by API in the late 1960s. This innovation allowed audio engineers to customize their signal chains with compressors, EQs, and eventually digital gear in compact, and sometimes portable, rack spaces.

Even today, the 500 series enables even smaller studios to create custom channel strips or effects chains. Larry Droppa, API’s current owner, introduced the VPR Alliance certification, which ensures that any 500 series module released after 2006 is guaranteed to fit and work in a 500 series rack.

Choosing a compressor depends on how you want to use it and the type of sound you want to achieve. VCA compressors are typically used to control transients and offer both transparency and aggression in a mix. VCA compression is especially useful for recording percussion, providing a precise and punchy sound.

When choosing a compressor, it’s important to consider whether you’ll use it for mixing, mastering, or tracking. For example, FET compressors aren’t usually recommended for mixing and mastering because they add a distinct color to the sound. Known for their aggressive and fast attack, FET compressors are better suited for tracking and parallel compression. On the other hand, optical compressors are ideal for more natural compression on sources like vocals, strings, and bass.

We just want to let you know that we’ll list these best 500 series compressors in no particular order. The list will be randomized, as we don’t want to rank them from best to worst.

Listed below are our Top 10 Best 500 Series Compression Units:

1. SSL 500-Series 611 DYN

The Solid State Logic 611DYN E Series Dynamics Module for 500 racks captures the legendary sonic signature of the iconic early 80s SL 4000 E console channel strip, heard on countless classic recordings from that era.

The SSL E Series Dynamics Module features both a compressor/limiter and an expander/gate, each carefully designed to replicate the circuitry and key elements that define the sound of the original SL 611E Series channel strip. A genuine RMS converter is used in the side chain, while the gain section uses the same all-discrete, Class A VCA chip found in the original unit.

The compressor offers additional switchable options that let you bypass the over-easy curve, or select a linear release instead of the more typical logarithmic curve. This gives you a compressor with three distinct voices, each with its own musical character.

The E-DYN allows you to choose between over-easy and hard-knee compression to suit your material, and to select either linear or logarithmic release curves. The Expander/Gate keeps your signal clean, preventing unwanted noise from creeping into your recordings.

Whether you need to control wild sounds, smooth out dynamics, add punch, or keep your tracks front and center in your mix, the SSL E-DYN E-Series Dynamics 500 Module brings one of SSL’s most powerful tools to your 500 series rack.

IMAGE	PRODUCT	DETAILS	For US Customers	For EU Customers
	SSL 500-Series 611 DYN	Is based on the classic 611E Console Channel Strip	Buy on Sweetwater	Buy on Thomann

2. Shadow Hills Industries Dual Vandergraph

Next up on the hit parade is the stunning Dual Vandergraph from Shadow Hills Industries! This stereo compressor draws its inspiration from Shadow Hills’ renowned Mastering Compressor—a legendary piece of gear that’s found its way into the hands of some of the most celebrated mix and mastering engineers in the country (think Michael Brauer and Greg Calbi, to name just a couple).

The doublewide chassis of the Dual Vandergraph (taking up two 500-series slots) features a single large VU meter and just four controls. But don’t be fooled into thinking it’s sparse—anyone familiar with Shadow Hills’ signature design style knows it’s anything but plain.

Oversized Bakelite knobs conceal two Swiss-made, 24-position stepped rotary attenuators that let you precisely control compression amount and output gain. Two large, 5-position selector switches sit on either side of the unit, each topped with four blue, bulb-shaped lamps that show the current switch position.

The first switch either puts the unit into hardwire bypass or lets you select the ratio (1.2:1, 2.5:1, 4:1, or 8:1), with each setting featuring its own meticulously optimized attack and release times. The second switch selects the sidechain filter’s corner frequency (none, 90 Hz, 150 Hz, 250 Hz, or “bandpass”).

This stereo VCA compressor blends distinctive retro styling with an easy-to-use layout, and delivers the kind of results you’d expect from a unit in this price range!

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	Shadow Hills Industries Dual Vandergraph	Combines the gain section of the Shadow Hills Mastering compressor with the detector circuitry of the Shadow Hills Optograph compressor	Buy on Sweetwater	Buy on Thomann

3. WES Audio Rhea

As digital footprints have become a hallmark of the modern age, the demand for that classic analog flavor has never been higher. When it comes to musicality and rich-sounding compression, it’s hard to beat a vari-mu design.

With the MIX knob at your fingertips, achieving parallel compression has never been easier. Thanks to Rhea, you can now automate your mix settings directly in your DAW. Ever wanted to push your compressor harder during the chorus? It’s simple—just record automation using a touch-sensitive encoder or draw your automation right in the DAW.

Rhea lets you control the level of the signal entering the tube compression stage (Input), the amount of compression (Threshold), and the compressor’s final output (Output). This approach gives you maximum flexibility to shape your source material exactly how you want.

You’ll find that the Threshold can be quite gentle, but if you need more compression, simply use the Input knob. Keep in mind, too, that all these parameters can be automated. Don’t hesitate to adjust these settings for different sections of your track!

Rhea is a true stereo compressor, meaning the detector circuits for each channel work on a summed signal within the sidechain. This makes dual-mono mode impossible. However, you can absolutely use it with just a single mono channel—so go ahead, process a mono vocal track, and have some fun!

IMAGE	PRODUCT	DETAILS	For US Customers	For EU Customers
	WES Audio Rhea	Power consumption: 190mA per rail; Dimensions: 76 x 133 x 158 mm (WxHxD); Housing: 500 Series Module	Buy on Sweetwater	Buy on Thomann

4. Fredenstein Artistic Comp Plus

The same fast-acting FET is used for the attenuation factor in Fredenstein’s Reverse‑Mancini FET Structure, which is designed to minimize FET distortion. Make-up gain is once again provided by Fredenstein’s OPA2 discrete op-amp, paired with a metal-cored output transformer. The module draws about 75mA from each of the rack’s power rails.

As with the original, the top rotary control adjusts the input level over a range of ‑10 to +20 dB. Since the compression threshold is set internally, turning up the input gain increases the amount of compression—or “squash.”

Other controls adjust the Ratio (from 2:1 to 20:1), Release time (from 70ms to 2.5 seconds), Make-up gain (from zero to +20 dB), and the Mix knob, which blends the dry and compressed signals for parallel compression. The LED gain reduction meter shows a 16dB range in 1dB steps up to 8dB, then continues in 2dB steps. A Clip LED above the meter lights up when the output hits +24dBu (which is actually 2dB below hard clipping).

The side-chain high-pass filters are also useful for controlling how the compressor responds to kick drum and bass content in a mix. Ideally, there could be an automatic recovery-time mode, and perhaps a gentler ratio than 2:1 for subtle bus compression. Still, as a general-purpose tracking compressor module, the Comp Plus has plenty of features—especially if you have a rack that lets you use its auto-ducker function.

IMAGE	PRODUCT	DETAILS	For US Customers	For EU Customers
	Fredenstein Artistic Comp Plus	External side-chain option (possible only with additional AUX inputs from the Bento series)	Buy on Sweetwater	Buy on Thomann

5. Rupert Neve Designs Portico 543

Based largely on the Portico 5043, this Rupert Neve VCA compressor can also function as a ‘brick-wall’ limiter, thanks to a ratio control that ranges from 1.1:1 all the way up to 40:1—all with a smooth, soft-knee characteristic.

It also features a configurable sidechain, offering selectable feedback or feed-forward modes, as well as options for RMS or ‘hybrid-peak’ detection.

The main focus of this compressor is transparency; it delivers clean, almost invisible sound, especially when compared to the 535 diode-bridge compressors.

There are five rotary controls on the front panel: threshold (-30 to +20 dBu), ratio (1.1:1 to 40:1), attack time (20-75 ms), release time (100 ms to 2.5 seconds), and make-up gain (-6 to +20 dB). An illuminated button engages the compressor, while three white buttons let you activate a high-pass filter in the sidechain, switch between feedback and feed-forward modes, and select RMS or hybrid-peak detection.

A recessed toggle switch connects the sidechain to the rack’s link bus, making it easy to match and synchronize gain reduction for stereo or surround setups. Two eight-LED bar-graph meters display output level (0 to +22 dBu) and gain reduction (1-22 dB).

Engaging the switchable high-pass sidechain filter reduces the compressor’s sensitivity below 250 Hz, so compression is determined primarily by the mid-range program content—the frequencies our ears are most sensitive to. This also helps prevent the pumping effect that can happen if the gain reduction follows the bass or kick drum in a mixed track.

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	Rupert Neve Designs Portico 543	Buy on Amazon	Buy on Sweetwater	Buy on Thomann

6. Chandler Limited Little Devil Compressor

Carrying on the rich tradition of classic English console design from the ’60s and ’70s, Chandler Limited steps into the 500 Series world with the powerful Little Devil Compressor.

Built with all-discrete circuits and transformer-balanced everything, this American-made unit delivers the handcrafted quality you expect from Chandler. The Little Devil blends Chandler’s finest designs with legendary ideas from the past.

Like a “Best Of” compilation album, the Chandler Little Devil Compressor draws inspiration from many sources, including classic, long-lost, and much-loved studio models by Neve, Telefunken, and EMI.

With features borrowed from their acclaimed Germanium Compressor, Chandler Limited packs it all into the compact Little Devil Compressor module for the 500 Series.

Equipped with both Zener and germanium circuits, the Chandler Little Devil not only controls the dynamics of your sound but also shapes its tone—thanks to the warmth and body these diodes and transistors provide.

When you push it hard, the Little Devil Compressor delivers precise dynamic control and rich, musical second-order harmonic distortion—the kind you want to hear, not the harsh breakup found in cheaper units.

Selectable curves and ratios, switchable sidechain filters, variable release controls, and a true hard-wired bypass make the Chandler Little Devil Compressor a temptation that’s hard to resist.

IMAGE	PRODUCT	DETAILS	For US Customers	For EU Customers
	Chandler Limited Little Devil Compressor	In 500-module design with the concepts of the Chandler Germanium Comp and 2264 Comp	Buy on Sweetwater	Buy on Thomann

7. SSL 500-Series Bus Compressor MkII

The classic SSL Bus Compressor features a distinctive ‘dominant’ sidechain structure. In this design, the left and right channels are rectified independently using a true peak full-wave detector circuit. The louder (dominant) channel then controls the overall stereo gain reduction, applying the user-selected time constants.

The ‘soft’ knee point—where compression begins—is set by the threshold control (±20dB). Notably, this threshold is designed to change depending on the chosen ratio; lowering the ratio setting also lowers the effective threshold, helping to maintain the perceived ‘loudness’ of the compressed signal.

The original console compressor offered three ratio settings (2:1, 4:1, and 10:1), while the 500 series model adds three additional options, providing the classic choices plus 1.5:1, 3:1, and 5:1 ratios for more precise control.

Attack time can be set in six steps ranging from 0.1 to 30 ms, while release time is selectable in five steps from 0.1 to 1.6 seconds. The Auto release setting dynamically adjusts the release time based on the signal envelope.

The gain makeup control compensates for the loss in level that results from compression. This allows you to set the output so that the overall level remains consistent when the compressor is engaged.

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	SSL 500-Series Bus Compressor MkII	Buy on Amazon	Buy on Sweetwater	Buy on Thomann

8. Elysia Xpressor 500

The Elysia xpressor 500 is an exceptionally versatile stereo compressor, available in the API 500 series format. With many distinctive features borrowed from our flagship products, you get not only outstanding compression but also a level of control rarely found elsewhere.

Whether you prefer to set it and forget it or dive deep into the art of compression, the xpressor 500 is perfect for you. Its discrete audio path operates in constant Class-A mode, delivering superior audio quality with a clear, open sound and plenty of punch.

This universal compressor’s switchable semi-automation lets you set the ideal attack, influencing how the unit responds to fast and loud impulses. Its log release function follows a logarithmic curve, providing a gentle and musical compression alternative to the usual linear response.

The sidechain filter helps prevent pumping and over-compression when there’s a lot of low end in your mix. The Warm Mode switch changes the frequency spectrum, harmonics, and transient response, adding a rich, saturated character to your sound.

Its Gain Reduction Limiter controls the signal in the sidechain and sets the maximum amount of gain reduction the compressor will allow.

IMAGE	PRODUCT	DETAILS	For US Customers	For EU Customers
	Elysia Xpressor 500	Noise: 20 Hz – 20 kHz -94 dBu Dynamic absorption: 20 Hz – 22 kHz 115 dB Maximum level input / output: +21 dBu	Buy on Sweetwater	Buy on Thomann

9. SPL TDx Transient Designer 500 Series Module

Germany’s Sound Performance Lab (SPL) already has a strong reputation in this field, having invented the original “Transient Designer.” Now, they’ve released the new TDx: a 500 Series unit with a simple design and a powerful sound.

The TDx features just four knobs on the front panel: Attack, Sustain, Mix, and Output, plus a Bypass switch. The secret under the hood is SPL’s “Differential Envelope Technology,” which, according to the company’s website, “allows level-independent dynamic processing by calculating differences in generated envelopes.”

Essentially, this unit constantly monitors the dynamic envelope of the incoming signal, letting you shape and control transients and sustain in real time.

On kick drum, it can really bring out the “smack” of the beater, or extend the decay of an 808 without simply squashing the track.

The addition of the Mix knob is great for inline parallel compression, but we found the Output trim even more useful. It lets you add as much attack or sustain as you want without worrying about clipping the converters in a hybrid mix rig.

Whether you use a mostly analog mixing setup or just want a quick and easy transient designer for live or tracking use, the SPL TDx is an excellent choice for any application.

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	SPL TDx Transient Designer 500 Series Module	Buy on Amazon	Buy on Sweetwater	Buy on Thomann

10. Lindell Audio 7X-500

The front panel features delightful typography, and the knobs and switches feel truly elegant. With the compact size of 500 series modules, everything needs to be tightly arranged, and Lindell has managed this without sacrificing clarity or logical layout.

This compressor is inspired by the classic 1176 design, offering input and output level controls along with variable attack and release settings. While the 1176 provides continuously variable attack and release, the 7X uses three-position switches for slow, medium, and fast options.

Although this setup might not offer the full flexibility of the original, the selected settings work well—in our recordings, we never felt like we were missing anything.

Similarly, the ratio options are a simplified version of the 1176. Here, you only get 4:1, 12:1, and 100:1, with the last setting emulating the famous “all buttons in” mode of its inspiration.

Just like with attack and release times, these ratio choices give you plenty of useful options without losing the distinct compression character that’s on offer.

There’s also a ‘Side Chain HPF’—a three-position switch that can be set to off, 100Hz, or 300Hz. While 100Hz is common, some might find 300Hz a bit high. In our experience, though, it actually makes the unit more versatile across a wider variety of sources.

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	Lindell Audio 7X-500	Buy on Amazon	Buy on Sweetwater	Buy on Thomann

Conclusion

If you’re a fan of vintage gear but want something more affordable, the 500 series compressors are a great option. There’s a wide range to choose from, including optical compressors, VCA compressors, and more. This variety makes it easy to find a 500 series compressor that fits your specific needs.

Whether you’re looking to compress your drum bus, vocals, or even your entire track bus, there’s a 500 series compressor that can handle the job. Instead of relying solely on plug-ins, you can step into the world of analog gear without breaking the bank and enjoy hands-on control over your mix.

When you consider the warmth, saturation, and detail that 500 series compressors add to your sound, investing in this equipment is an easy choice. If you have any questions about 500 series compressors, feel free to ask us in the comment section!