Which 500 series rack should I get?

500 Series racks...

There are lots of options, with many features, spanning a wide range of prices. " 500 Series is a standard format; all racks should perform the same right?" If only that were true.

Just like preamps, all 500 series rack units perform the same objective duty, but some are built to higher specifications than others, and thus will perform with lower noise and bring out the sonic potential of the audio circuits.   Yes, a $300 rack will power your gear and provide I/O.  The question is whether it will actually sound good and give you many years of reliable service.  It's not sexy, but power is the lifeblood of your audio gear.  The better your power supplies, the better your audio will sound.  In general you get what you pay for and we recommend not treating the rack as a commodity that can simply be compared by current supply specs and whether it has link switches.  One high quality power supply can allow all your 500 series modules to perform optimally and sound their best.  We believe there are five factors one should evaluate when shopping for a rack:

  1. Audio quality - Does it degrade the audio signal in terms of depth, width, detail, and noise compared to other racks?  Does it sound harsh and 2D, or detailed and 3D?
  2. Elecrical specifications: Noise, Current Supply, Regulation - Is ripple properly smoothed and filtered?  Are mains hum and/or switch mode noise properly filtered?  Is there enough current on tap for each module to reproduce transients with punch and authority?  Are there individual regulators on each slot?  This will isolate the power between channels, which can keep a faulty or noisy module from "polluting" the ecosystem.  All these performance specs will affect audio qualtiy.  Poor performance power supplies end up sounding bad.
  3. Input / Output connections - Are there the appropriate connectors to interface with your studio?  Will you be required to buy new cables?
  4. Mechanical build quality - Is it made of thick gauge steel which will actually shield against EMI (not aluminum)?  Is it thermally vented adequately?  Are the rack ears substantial enough to withstand the weight of heavy modules?
  5. Routing features like feed and link switches - These are nice things to have, but if the rack misses the mark in the othe four categories then these don't matter much.

While you may like how Preamp X sounds in Rack X, we might prefer Preamp X in Rack Y. Neither of us are wrong, but the fact of the matter is that all racks sound different so it's worth getting them in one's studio to compare.  While we cannot officially endorse any rack/brand in particular, we are happy to recommend the following fully assembled products, which we feel have solid build quality, low noise, plenty of current per module, and good value:

Sweet Ten Rack by Purple Audio (newest revision released summer 2017 has upgraded PSU that addressed earlier issues)

500 Series by BAE Audio

OST Racks by Heritage Audio (note that 48V does not appear to be further filtered or regulated on the PCB itself)

API Lunchbox (8 slot)

If you don't see a brand listed here that you might own or be considering, then you may assume it's not presently recommended due to lack of testing or poor performance.  We are continually re-evaluating new racks on the market and will try to keep this list up to date.  If you are into building your own gear then you may want check out the CAPI Gear 511-VPR Rack kits, which can be built with either an external linear or switch-mode supply.

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