Professional Audio

503 HR Lunchbox Rack & Power Supply – DISCONTINUED




VPR  Alliance compatible

With the proliferation of the 500 series platform, here’s a new way to rack mount three individual modules in a single rack space  for recording and live use – the A-Designs 503HR.  It has a robust external power supply with an LED display to indicate the amount of power being consumed.   A three-LED array on the face plate displays the +16V, -16V and +48V.

It also features all metal construction, XLR input and outputs , as well as a “Feed” switch on the front panel.   This allows you to come into slot 1 and out of slot 3.  It also allows
you  to  just  feed 1 and 2,  or indeed none.

The “Feed” switch is a 3-position switch used for:  Slots 1 and 2 or “Off” or “All”.  This reduces the need to use six XLR cables for a channel strip – but, if you want to do so, you still have that option available.A Designs 503HR 1U 3 slot rack

When using the 503 with the “Feed” switch, all that is needed are two  XLR  cables – male and female.   As an example, the input would go to Slot 1 and the output to Slot 3, when the “Feed” switch is in the “ALL” position.  In addition to being the perfect companion for A Designs Audio 500 series modules, the 503HR is compatible with most VPR Alliance modules, and is an  affordable solution for any trio of 500 series processors.

The 500HR can be used with all sorts of different modules to give you all sorts of customisable functionality.  Loaded with two preamps it becomes a dual-channel mic pre; with two A-Designs EM-PEQs, it’s a dual-channel, Pultec-style equaliser; and with one preamp and one EQ it is a complete pre/post EQ recording channel.  Plus, using the preamp and EM-PEQ configuration, you can bypass the preamp on your guitar/bass/keyboard amplifier to give you a totally different amp for live performance.  Preamp and compressor, compressor and delay and EQ, two different kinds of EQ, one tube and one solid-state compressor – the possibilities are literally endless!  Here are some more ideas:

When combined with an A/D converter, the device makes an excellent choice for mobile recordings for broadcast.  Also, with so many people doing voiceovers for TV and film, plus vocal production work for audio books and radio, the 500HR combined with the right modules and a laptop is again a perfect solution for those markets.  And, of course, many discerning live sound engineers will be pleased to see that they can now put a pair of studio-grade processing modules into a 1U rack.”

A-Designs 503HR rear panel


  • Compatible with all A-Designs 500-series modules.
  • Will accept API 500-Series modules and other VPR compliant modules.  Please check with the manufacturer.
  • Four basic modes of operation with various A-Designs modules.
  • Internal highly stable regulated power supply with +48V phantom power.
  • Steel chassis construction.
  • 48V LED indicator.
  • 2 x 2 balanced XLR I/O.
  • Power requirements are 100/120/230 VAC – 14W.
  • DC power output per channel is 140mA @ 16VDC.
  • Dims: 482 x 44 x 324mm, 19” x 1¾” x 8-¼” [1RU]
  • Weight (empty):  2.7 kilos / 6 lb