Legendary · First-Year · Collector's Item

PSU-402 Aurora Custom

The Genesis Power Supply — The Original Year Edition

$12,800 Reference Price — When Available · Not for Sale Online

* The last known private sale (2023, Reverb, serial #007) closed at $11,500. Prices have appreciated ~15% year-over-year.

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GENESIS UNIT

Technical Specifications

Base Unit: EMI 40205 Dual-Output Lab Power Supply
Channel A (Modified): 0–40V / 1.25A · Discrete Class-A regulation
Channel B (Modified): 0–20V / 8.5A · Ultra-low-noise topology
Regulation: Discrete Class-A (Aurora custom circuit)
Reference ICs: Upgraded low-noise precision references
Capacitors: Premium TDK CeraLink & polymer electrolytics
Output Terminals: Silver-plated copper binding posts
Transformer: Toroidal, shielded, low-leakage (Aurora mod)
Protection: Thermal switch @ 90°C, over-current, short-circuit
Units Produced: 25 (serial #001–#025)
Year: 2003–2005
Origin: Modified in Aurora Audio R&D, North Hollywood, CA

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The Story — The Genesis Unit

The Power That Started It All

In early 2003, Gran Børresen was deep in the prototyping phase of what would become the GTQ series. He quickly discovered a fundamental problem: the off-the-shelf DC power supplies available at the time introduced measurable noise into the sensitive analog gain stages he was voicing. For a designer obsessed with the last fraction of a decibel of noise floor, this was unacceptable.

Gran sourced several Electronic Measurements Inc. (EMI) 40205 dual-output laboratory power supplies — American-made, bench-grade units from the 1970s–80s that were renowned for their rock-solid regulation and low ripple. But "low ripple" wasn't enough. He disassembled the first unit entirely and began re-engineering the regulation topology from the ground up.

What emerged was the PSU-402 Aurora Custom: the original EMI 40205 chassis, but with a completely redesigned interior. The linear regulation was replaced with a discrete Class-A topology of Gran's own design. Low-noise precision reference ICs were installed. Every capacitor was upgraded to premium TDK components. The output terminals were replaced with silver-plated copper binding posts for maximum conductivity. The internal wiring was re-done with silver-plated Teflon wire.

Only 25 units were ever built. Serial #001 was installed in Gran's personal prototyping bench and used to voice every GTQ circuit that followed. Units #002–#025 were distributed to select beta testers and trusted engineering partners. Each unit was hand-signed by Gran on the rear panel, with the Aurora Audio logo applied as a discrete gold foil badge on the front face.

The PSU-402 was never commercially released. When Aurora later designed the GT-PSU commercial linear power supply, the circuit topology was directly derived from the lessons learned in the PSU-402 program. In that sense, every Aurora Audio product shipped since 2006 carries a small piece of the PSU-402's DNA.

The PSU-402 Timeline

January 2003

Gran identifies power supply noise as a limiting factor in GTQ prototype voicing. Begins researching lab-grade alternatives.

March 2003

First EMI 40205 unit acquired and disassembled. Prototype discrete Class-A regulation circuit designed and breadboarded.

June 2003

First modified unit (serial #001) completed and installed on Gran's bench. Measurable noise floor improvement: -12dB compared to stock EMI 40205.

2003–2004

Units #002–#015 built and distributed to beta testers. Circuit refinements based on field feedback. Silver-plated terminals adopted as standard.

2005

Final 10 units (#016–#025) completed. Aurora R&D transitions to designing the commercial GT-PSU. The PSU-402 program is quietly closed.

2010–Present

The 25 units occasionally surface on used markets (Reverb, eBay, audio forums). Each appearance triggers fierce bidding. Prices have appreciated from ~$2,500 (2010) to $11,500+ (2023).

Why the PSU-402 Commands Sky-High Prices

Rarity: With only 25 units in existence, the PSU-402 is rarer than any commercial Aurora product by a factor of 100+. For context, approximately 500 GTQ2 units have been produced; the PSU-402 exists in just 1/20th the quantity.

Provenance: Each unit was hand-modified by Gran Børresen himself. Serial #001, kept on Gran's personal bench for over a decade, is widely considered the "Holy Grail" unit. Its current whereabouts are unknown — rumored to be in a private collection in Tokyo.

Historical Significance: The PSU-402 is the literal power source that birthed the Aurora sound. Every GTQ, GTC, and GTP circuit prototype was voiced using one of these units. Owning a PSU-402 is, in a very real sense, owning a piece of the Aurora origin story.

Appreciation: Unlike most audio equipment (which depreciates), the PSU-402 has appreciated consistently. Audio collectors increasingly view first-generation "prototype-derived" units as alternative investments. The PSU-402 is the only Aurora product to have ever appeared at dedicated audio memorabilia auctions.