What is the API Lunchbox/500 Series?

The 500 Series, also known as the “lunchbox” format, refers to a standardized, modular audio equipment format used in professional audio recording and processing. It was originally developed by API (Automated Processes, Inc.) in the 1980s, but has since been adopted by various other manufacturers.

The lunchbox format consists of a rack enclosure that can accommodate multiple individual audio modules, typically measuring 1.5 inches in width. These modules are commonly referred to as “500 Series modules” or “500 Series units.” Each module serves a specific audio processing function, such as mic preamplification, equalization, compression, or reverb.

The key characteristic of the 500 Series format is its modularity and interchangeability. Users can mix and match different modules from different manufacturers, customizing their audio signal chain according to their specific needs and preferences. Modules can be easily inserted and removed from the lunchbox enclosure, allowing for flexibility and easy expansion or reconfiguration of the system.

To learn more about how the 500 Series works in practice, check out this video:

API Lunchbox Alternatives

While API pioneered the format, there are now many competitors to the original Lunchbox. There are multiple sizes and configurations you can purchase, from smaller 3-slot options to behemoth 10-slot versions.

Let’s take a look at some popular Lunchbox models, as well as some accessories you may want to have handy!

Image	Product	Features	Price
	Rupert Neve Designs R6 500 Series Rack	This 6-unit 500 Series Rack comes from Neve, one of the leaders in the pro audio industry! XLR, TRS, and DB-25 ins and outs for extreme flexibility!	Check Price
	Heritage Audio HAOST4v2 4-slot 500 Series Chassis	This compact, minimal rack offers four slots for your modules! The built in channel linking means you can connect your 500 Series modules into a chain without needing XLR patch cables. This is an incredible feature for anyone who plans to travel with their unit!	Check Price
	API 500-8B - 8-Channel 500 Series Lunchbox Rack	The standard, classic Lunchbox from the original creators! This expanded 8-channel version matches up perfectly with many common 8-channel interfaces!	Check Price
	1U 500 Series Universal Blank Panel - 4 Pack	4x panels that will fit any 500 series device!!! Protects your 500 series device from dust and debris by covering your empty slots Includes 4 sets of screws.	Check Price
	HOSA Balanced Snake DB25 to XLR3M - (16 Feet) (Black) & DTF805 Balanced Snake XLR3F to DB25 - (16 Feet) (Black)	Both sets of DB-25 snake that you can use to connect to our API or Neve Lunchbox!	Check Price

Pros and Cons of 500 Series Modules

Pros of 500 Series Modules

The lunchbox format gained popularity due to its compact size, affordability, and the ability to create a high-quality audio processing chain using a combination of modules from various manufacturers. It’s also very convenient to be able to swap out modules. If you want to swap out two standard preamps, you’ll have to unscrew the first preamp from your rack, then unplug the power supply and XLR cables from the back of the unit, the install the new preamp into your rack and reconnect all cables. If the units are not the same size, you may have to move other units around in your rack.

With a 500 Series module, you can simply unscrew the small screws from the top and bottom, and then swap the two units. It’s more similar to changing out a game from your Nintendo 64 than swapping a piece of audio gear.

Cons of 500 Series Modules

The only real con of 500 Series modules is that you are required to use a Lunchbox to use your module. This seems obvious, but it can be a headache. If you decide that you want to move on from the Lunchbox ecosystem, all of your modules will become obsolete.

If you’re someone who likes to buy and sell gear often, sometimes it takes more patience to sell a used piece of 500 Series gear compared to a standard rack unit. You have to wait for someone who is also on the Lunchbox system to want to purchase. This isn’t really a big deal, but it’s still something to consider.

Two Ways to Set Up Your Lunchbox

There are two main ways to set up your 500 Series Gear, as individual units, or as one signal chain. For example, at my studio, I had two API Lunchboxes, and both had only preamp modules in them. It was a convenient way to have 12 channels of preamplification on only two power outlets, and I used DB25 to connect them to my interface.

Alternatively, you can run your audio modules in a chain, using small XLR patch cables. For example, you could have a preamp, a compressor, an EQ, and a second compressor in one 4-channel Lunchbox, connected together to make your preferred vocal chain.

If you see a Lunchbox where all of the units look the same, odds are they are using them as individual channels. If they all look different, chances are they’re being used as one continuous signal chain. In theory, you can set up your Lunchbox with any combination of signal flows. For example, you could use a 6-slot Lunchbox to house 3 individual preamps, plus 3 units that are routed together for your vocal chain.

Our Favorite 500 Series Modules

With so many 500 Series modules to choose from, you may find yourself overwhelmed with options. These are some of our favorite 500 Series modules, so take a peek and see what piques your interest!

Image	Product	Features	Price
	Rupert Neve Designs Portico 511 500-Series Preamp Module	A big, bold preamp with the flexibility of variable Silk/Texture Designed by Rupert Neve to combine classic sonics with 500-series value Sweepable high pass filter & the powerful transformer saturation of a variable silk circuit derived from Neve's flagship Portico II Channel. 66dB of gain in 6dB increments, with a +/- 6dB trim for fine adjustment.	Check Price
	dbx 580 Compact, Professional Mic Preamp	Premium low-noise mic Pre with up to 60dB of gain Variable-frequency low-cut filter Low and high detail equalization 20dB pad Polarity invert	Check Price
	Lindell Audio PEX-500 / 500 Series Pultec Equalizer	Transformer coupled Balanced inputs and Balanced Outputs Passive Pultec Equalizer. Inductor Hybrid gain make-up amplifier 3 Step Switched Eq Low Freq Boost 30Hz, 60Hz, 100Hz +/-10% 3 Step Switched Eq High Freq Bosst 6kHz, 10kHz, 16kHz +/-10%	Check Price
	SSL 500-Series SiX Channel Strip	Amazing SSL tone in a compact package Get the signature SSL compression into your Lunchbox Low cut, 2 band EQ Line in DI	Check Price
	SSL Stereo Buss Compressor Module for 500-Series MK3	The classic SSL Stereo Buss Compression that you know and love VU Metering The perfect stereo compressor for any mixer or engineer Please note: This unit takes up two slots in your Lunchbox	Check Price

We hope you enjoyed this overview of 500 Series modules and the API Lunchbox! If you found it useful, feel free to check out more of our reviews here!