IS THE 500-SERIES PLATFORM DYING?

For years, the API 500-series format was the darling of audio engineers, with new modules popping up like studio monitors at a gear expo. Preamps, EQs, compressors—everywhere you looked, another 500-series gadget promised to elevate your recordings. But the tide seems to be turning. Are software plugins stealing the spotlight? Are pricey, proprietary hardware racks losing their appeal? Is the 500-series platform doomed? Let’s unpack the trends and see if the format’s days are numbered.

REVIEW DIYRE PR502: DIY 2-Slot 500-Series Chassis

The PR502 is a kit, you buy it at DIYRE (on the web) and you get everything you need to build this 2-slot, 500-Series rack (it's below the bright red QuantAsylum analyzer system), which can be used on its own or add the $15 rack ears and it becomes a 1u rack mount package. The external line-lump switching power supply is capable of powering multiple PR502. Is it hard to put together? Is it good?

REVIEW FREDENSTEIN ARTISTIC COMP SE: Inexpensive 500-Series Compressor

SEE IMPORTANT UPDATE AT END OF REVIEW

Bargain Priced Fredenstein Artistic Comp SE in Bento 2 Rack

If you look at 500-series module pricing, it’s outrageous how expensive the majority of modules are. What’s a musician with a limited budget to do? Fredenstein rescues bargain hunters, they offer one of the lowest cost 500-series compressor modules on the market. We tested it in the High on Technology studio using a Fredenstein Bento2 chassis. (< full review on H.o.T.). This FET based compressor has got some serious moves and a lot of powerful controls for that low price, plus, it’s got parallel compression. But is it good? 

REVIEW FREDENSTEIN ARTISTIC MIC PREAMP SE 500-SERIES: Bargain or Nightmare?

SEE IMPORTANT UPDATE AT END OF REVIEW

The Fredenstein Artistic MicPre SE is a compelling 500-series microphone preamp that delivers professional features and solid performance. I tested it using a Shure SM7B microphone which requires a lot of gain. Despite some quirks with the Bento 2 chassis, the Artistic MicPre SE proved its worth across various recording scenarios, though my unit had an issue that required a replacement.

REVIEW MIDAS L10 500-SERIES 10-SLOT CHASSIS: Is it noisy?

I was previously prejudiced against these Midas 500-series racks by things other people said. A friend told me I should revisit them and she was right, the fit of modules in the slots is perfect, same as my API VPR racks (< reviewed here on H.o.T.). But what about noise from that inbuilt power supply, isn’t that a problem on these Midas (built by Music Tribe, aka Behringer) chassis?

REVIEW RADIAL KNURLED KNOB THUMB SCREW REPLACEMENT FOR 500-SERIES 4-40 x 3/8"

If you have ever struggled with mounting 500 Series modules, or had trouble finding the right screws to mount modules, you’ll love these pricey little jewels.

REVIEW WARM AUDIO WA12-500 MKII: A Punchy, Vibey 500-Series Preamp with API Roots

Warm Audio’s WA12-500 MKII is a 500-series microphone preamplifier that channels the spirit of the legendary API 312 and 512 preamps while carving its own path with modern upgrades and an accessible price point. Inspired by the bold, punchy character of those classic API designs, the WA12-500 MKII delivers a transformer-coupled, discrete signal path that infuses recordings with warmth, depth, and vibrance. The MKII iteration builds on the original’s strengths, most notably with the addition of a master output level control—a feature that elevates its versatility. While it’s not a direct clone of the API 312 or 512, it captures their essence, making it a compelling choice for engineers seeking that American console sound without breaking the bank.

REVIEW BEHRINGER 73 500 SERIES MICROPHONE PREAMP: It's real, it's here, lets go inside!

It is finally here, I paid the full price to be an early adopter and find out if this product lives up to the hype. The Behringer 73 is one of the most highly anticipated -- 500 series -- mic preamp  modules EVER, but, is it good?

REVIEW FREDENSTEIN BENTO 2: Powered Rack 1RU 500-Series with Caveats for Neve 1073LB

The Fredenstein Bento 2 is a compact, 2-slot 500-series rack designed to house API VPR Alliance-compatible modules, offering a budget-friendly solution for home and project studios. With its robust build, versatile features, and competitive price, the Bento 2 appears to punch WAY above its weight but there is a problem in there, lurking and waiting to "whine". Here’s a detailed review covering its quality, features, likes, dislikes, price, warranty, and more.

THE ORIGIN OF API AUDIO AND THE 500 SERIES FORMAT

Modern 10- Slot API 500-series rack, click to enlarge

In the late 1960s, Automated Processes, Inc. (API), founded by Saul Walker and Lou Lindauer, emerged as a pivotal force in professional audio, driven by a mission to craft high-quality gear for recording studios. API’s early innovations, including modular console designs, laid the groundwork for what would become the iconic 500 series format. This standardized, modular system revolutionized audio processing by offering engineers flexibility, portability, and exceptional sound quality.

REVIEW API VPR 500 SERIES 10 SLOT RACK

 THE KING OF THE 500 RACK CHASSIS BY API

API invented the 500 series format for signal processors. Each single slot module position is actually the same size that API uses in their world class mixing consoles. The original 6-slot API lunchbox provided a method for users to carry these powerful tone shaping tools from studio to studio.

So how does the modern API 10 slot rack compare to todays competition? Read on and discover why we spent more to get this quality API component. 

REVIEW WHAT IS AMS RMX16 REVERB

 CLASSIC 80'S REVERB SOUND IS HERE

TRIPLE WIDE 500 SERIES MODULE, MONO-IN, STEREO-OUT

I added another API 500 series rack so I could play with the AMS RMX 16 reverb processor. Was it worth the price of the rack and the module? Read on to find out.