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The Ultimate 500 Series Buyer’s Guide 2024

My New Microphone The Ultimate 500 Series Buyer's Guide

So you're wondering which 500 Series modules, cases and power supplies you should buy, rent or otherwise try out. In this comprehensive buyer's guide, we'll go through everything worth considering before you make any decisions about 500 Series equipment.

If you've found yourself asking, “Which 500 Series gear should I buy?” this extensive resource is for you.

Please feel free to jump around this article and read all the additional resources I have provided links to.

With that, let's get into this comprehensive 500 Series buyer's guide to help you in your next 500 Series purchase!

Related article:
Top 11 Best Audio Brands For 500 Series Modules/Equipment

Table Of Contents

What Is Your 500 Series Budget?

The first thing to consider when making any purchase is your budget. Money can be a touchy subject for some, so I'll keep this section brief.

I would never advise anyone to overspend on any audio equipment. Know what you can realistically afford, and do your best to stay within those limitations, whatever they may be.

500 Series units, like many audio devices, range significantly in price. The market is rather large, and so there should be a good selection for any budget.

A benefit of the 500 Series' modular nature is that users can slowly build up their signal chain over time. The downside, of course, is that modular 500 Series setups tend never to be “complete”, so additional gear will cost more money.

Note that some retailers offer payment plans, which could be an option.

Consider the cost-to-benefit ratio of the purchase of the 500 Series unit(s). For example, if the 500 Series signal chain is needed for business, perhaps stretching the budget is more appropriate. On the other hand, if you don't plan on making money with the 500 Series gear, perhaps a more conservative budget is appropriate.

Also, consider any additional accessories or upkeep that may be required for your 500 Series system.

Only you can determine your budget. All I'm here to say is that you should consider it.

Back to the Table Of Contents.

The VPR Alliance

The 500 Series modular format was developed by API (Automated Processes Incorporated). The format was initially brought to market in the 1970s and has since become one of the most popular modular formats for audio processors.

Because of the popularity of the format and the interest from third-party manufacturers, API created the VPR Alliance. It is a program of standardization and consistency guidelines for the 500 Series format. Manufacturers on the list are officially approved and follow complete design specifications to physically fit and electronically conform to API's rack specifications.

Not all third-party manufacturers are part of the VPR Alliance, which means their module or rack specs may not conform to the standard.

That's not to say that their products are incompatible, but rather, it's a sign that more attention should be paid to the specs to ensure proper integration within the 500 Series system. This is particularly important when it comes to power and current draw, as we'll touch on in the following section.

API is featured in top brand articles at My New Microphone. Check out these articles here!

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Choosing A 500 Series Chassis & Power Supply

The modular format of 500 Series rigs starts with the chassis (often referred to as a rack), which hosts the modules. These racks have varying numbers of slots, which the 500 Series modules fit into slots (some modules span more than one slot).

A rack/chassis is essentially a metal box with space to host the modules. Each slot has a card‑edge connector inside to connect to the inserted module and provide it with the power it needs to function. Audio inputs and outputs are provided for each slot/module.

Factors to consider when buying a 500 Series chassis/rack include:

The Number Of Slots

The number of slots is a pretty straightforward specification. It refers to the number of slots available in the rack. Racks will have two or more slots, and most modules take up one slot, though there are 2-slot and even 3-slot modules on the market.

Choose a chassis with enough slots to host your modules now and, preferably, in the future.

However, beware that having empty slots may tempt you to overextend your budget to fill them!

Form Factor & Mounting

Most racks have vertical slots for their modules, though horizontal options are also available.

The two most common styles of 500 Series racks are desktop and rack-mounted. As the names suggest, desktop racks sit on the desktop and are easy to transport, while rack-mountable chassis can be mounted into standard 19″ racks.


Typical I/O to look for in 500 Series racks are multichannel DB-25 connectors and discrete balanced XLR or TRS jacks. ADAT and MIDI I/O are less popular but common enough.

Certain chassis even act as audio interfaces, connecting directly to computers via USB or other digital means.

Some chassis offer additional routing, including internal patching, stereo linking, and audio summing.

The majority of 500 Series racks send the output from their first slot into their second into their third, and so on, creating a continuous signal chain. Internal routing allows users to patch the signal themselves, allowing for more control over the signal flow without ever having to remove the modules.

As the name suggests, stereo linking is the linking of two stereo channels to a common control. This linking is typically implemented as a single sidechain controlling both channels of a stereo compressor.

Audio summing is similar to mixing: a process that combines two or more signals together into a single output signal.

Power Supply

The 500 Series chassis will generally contain the power source (±16V power rails) for its connected modules.

The type, quality and location of the power supply impact the performance of the rack and its modules.

Be sure the rack is able to power all the modules you plan to use with it. Ideally, the modules should only draw about 80 percent of the current available from the power supply. Note that 130 mA is standard for the current draw of 500 Series modules, but many modules draw much more than this.

Switch-mode power supplies use power transistors to produce a high-frequency voltage that is passed through small transformers and filtered to remove AC and noise. They are more efficient (80%), lighter weight, and handle wider input voltage ranges.

Linear power supplies deliver DC, passing the primary AC voltages through transformers and filtering out the AC component. They are less efficient and weigh more but are cheaper to produce.

Both switch-mode and linear power supplies work well with 500 Series racks and modules. Rather, it's more important to consider the location of the power supply and how well it's shielded.

Internal power supplies make the chassis more compact and do away with extra wiring. However, their proximity to the slots can cause electromagnetic interference and noise in the signal chain.

Modules with vacuum tubes and preamp modules with transistors can be particularly sensitive to this interference. Move these modules to slot further away from the built-in PSU or, alternatively, put a rack with an external power supply and keep a reasonable distance between the modules and rack that way.

Related article: Top 11 Best 500 Series Cases (Racks/Chassis) On The Market

Back to the Table Of Contents.

Types Of 500 Series Modules

Now that we have a chassis, it's time to fill it with the 500 Series modules. The modules are the actual signal processors. With the rise in popularity of the 500 Series format, more and more manufacturers are producing modules with or without VPR Alliance standards.

Let's discuss 500 Series modules by their broad categories.

500 Series Preamplifiers

What is a microphone preamplifier? A mic preamp is a type of amplifier with the purpose of bringing mic level (or instrument level) signals up to line level for use with professional equipment. Microphones and many instruments output low-level signals that require amplification for their use in mixing consoles, recording devices or digital audio workstations.

500 Series preamplifiers come in a variety of styles from tube or solid-state, recreation or original designs. Nowadays, you can pretty much find what you need in a 500 Series preamp.

Most of these preamps offer +48V phantom power for powering active microphones. They typically also have a Hi-Z or high-impedance input for connecting instruments directly.

Preamps are also generally included in channel strip 500 Series modules.

Related articles:
Top 9 Best 500 Series Microphone Preamps On The Market
What Is A Microphone Preamplifier & Why Does A Mic Need One?
Complete Guide To Microphone Preamplifier Specifications

500 Series Dynamic Processors

What are dynamics processors? Dynamics audio processors affect the dynamic range of a signal (the difference between the highest and lowest amplitude across time. The processes can reduce or expand the dynamic range, adjust transients, limit the highest maximum output or gate/cut-out signal below a certain level.

The most common dynamic process in audio is compression, and we'll find plenty of 500 Series compressor modules on the market. Like the preamps mentioned above, there are many compressor design recreations in the 500 format, but there are also original designs.

There are a plethora of compressor circuit styles, including optical, VCA, FET, and vari-mu/tube, which can be found in 500 series modules.

Sidechain control, stereo linking, VU metering and other common functions can be found in many 500 series compressors.

At the extreme end of compression, we have limiting, which effectively keeps a signal from surpassing a set threshold. There are 500 Series limiter module options as well.

Expanders and noise gate processors aren't nearly as popular, which shows in a lack of 500 Series module options.

Compression and dynamic control can be featured in 500 Series channel strips.

Related articles:
Top 11 Best 500 Series Compressors On The Market
The Complete Guide To Audio Compression & Compressors
What Is The Difference Between Audio Compression & Limiting?

500 Series Equalizers

What is audio equalization? EQ is the process of adjusting the balance between frequencies within an audio signal. This process increases or decreases the relative amplitudes of some frequency bands compared to other bands with filters, boosts and cuts. EQ is used in mixing, tone shaping, crossovers, feedback control and more.

500 Series equalizers are generally of the parametric or semi-parametric variety, offering a set number of bands with controls over their boost/cut, Q and centre/cutoff frequencies. That said, there are also graphic EQ options out there.

EQs in the 500 Series format can be mono or stereo. They are often designed based on previous console designs, but there are certainly original units out there.

Related articles:
Top 11 Best 500 Series Equalizers On The Market
Complete Guide To Audio Equalization & EQ Hardware/Software

500 Series Effects

What are audio effects? Audio effects make up a broad category of audio processes that manipulate audio signals. They are typically broken down into distortion-based effects (distortion, overdrive, bit-crushing, etc.), modulation-based effects (chorus, flanger, ring modulation, etc.), time-based effects (delay, reverb), or spectral effects (wah, envelope filtering, pitch-shifting, etc.).

Effects go beyond the standard preamp-compressor-EQ signal chain and are popular for studio and live applications.

Popular effects include distortion/saturation, guitar effects, delay, and reverb.

Related article:
Full List: Audio Effects & Processes For Mixing/Production

Other 500 Series Modules

Other 500 Series module types not listed above include:

  • Audio interfaces
  • Headphone amps
  • Monitor controller
  • Re-amping units
  • Channel strips
  • Synthesizers
  • Wireless receivers/transmitters

If any of the above functions sound appealing to you, there are options for your 500 Series system!

Back to the Table Of Contents.

Planning Your 500 Series System

Now that we know about 500 Series modules and chassis, we need to consider our needs and wants for our 500 Series system. It's worth thinking about the present and the future when it comes to planning out your purchase.

Budget aside, what would your ideal signal chain be? How many modules would you need, and, therefore, how many slots would you need in the rack?

Is one preamp enough, or do you want a few options? Do you need a preamp at all? Perhaps your system is geared more toward mixing/mastering than tracking/recording.

There are different styles of compression and EQ. Do you know which style(s) you'd like in your signal chain? Do you even need these processes?

The same goes for effects, which are perhaps less common than preamps, compressors and equalizers.

Finally, what utility/miscellaneous modules do you need? Is re-amping a process you're into? Perhaps you need headphone monitoring directly from the 500 Series rack. Wireless connectivity may be required for certain applications. So on and so forth.

When building a more advanced system, you may need internal patching capabilities to choose which modules become part of the signal chain and in which order.

A typical signal chain order is as follows:

  1. Microphone preamplifier
  2. EQ and/or dynamics processors
  3. Distortion effects
  4. Modulation effects
  5. Time-based effects

It's also important to consider how portable the system will need to be and purchase your rack accordingly.

Back to the Table Of Contents.

Know The Additional Costs Of 500 Series Accessories


Cables (XLR, 1/4″ TRS, or otherwise) are required to send signals to and from the 500 Series unit and for routing/patching within the units that offer such functionality. Read up on the inputs/outputs of the modules and chassis for a better idea of the type and number of cables you'll need for your setup.


500 Series modules connect electrically via 15‑pin edge connectors but are physically held in place with screws on their front plate. These screws are a necessary part of a 500 Series system.

Blank Panels

Blank panels screw into empty 500 Series rack slots, thereby keeping dust and other particles from entering the unit.

Back to the Table Of Contents.

Leave A Comment!

Have any thoughts, questions or concerns? I invite you to add them to the comment section at the bottom of the page! I'd love to hear your insights and inquiries and will do my best to add to the conversation. Thanks!

This article has been approved in accordance with the My New Microphone Editorial Policy.

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