AUDIO RESEARCH MODEL REFERENCE 600 MONOBLOCK POWER AMP (1996)

AUDIO RESEARCH MODEL REFERENCE 600 MONOBLOCK POWER AMP (1996)
One Owner, Loved, Documented, and Still Running Strong (both units 9/10 condition)

 Unit Serial no. 56388005
 Unit Serial no. 56388006

Go to youtube link below to view walk through & demo for Unit Serial no. 56388006.
https://www.youtube.com/watch?v=3GH0uOYS4So

I'll be including a youtube link to a walk thru & demo for Unit Serial no. 56388005 shortly!

INTRODUCTION / MODEL INFO
Selling my Grandfather’s twin pair of Audio Research REF600 Monoblock Power Amps, purchased new in 1996 ($20K for the pair) and cared for like the heirloom pieces they are. If you know the REF600, you know how rare it is and what it represents: a no-compromise ARC statement amp that’s massively over-engineered, physically imposing, and capable of effortless authority. These amps are built like trucks - built to last!

The Audio Research Corporation REF600 series is widely considered to be one of founder Bill Johnson's final major projects prior to his retirement in the 2000's. Among ARC enthusiasts, the REF600 is often talked about as a “clean sheet” statement project. Ken Kessler even quotes Bill's thought process of marketing at the time as “design it first, then we’ll talk price.” There’s also long-running lore that some of the industrial / military vibes of this generation nods to WWII-era instrumentation aesthetics (often described as “sonar-console” styling).

CONDITION & PERFORMANCE (Unit Serial no. 56388006)
Operationally this unit is in excellent condition: no startup issues, no board problems, no tube / fan drama and it behaves exactly the way you'd want a big ARC to behave. Tubes were replaced in 2005, and the current set remain in good-to-great condition. I’ve photographed each tube for you to personally review (front & top, see attached pics). The Getter condition is fantastic for the age.

The only functional note worth stating (full transparency): V-Tube 10 briefly jumps on the meter during testing, then settles back into the green range & stays there after initial warmup (see video for real time testing). Every other tube tested steady and remained in green range. And of course, the amp plays beautifully!

Cosmetically it’s very clean - only a tiny chip of paint on the inside the unit on the large transformer located towards the front of the chassis. Front lights are all working (have original replacement bulbs), and the fan dial is working correctly. Both Fuses have been updated with originally supplied extras (have more remaining that will be included).

On this page, you'll find serious documentation, because these units deserves it! In addition to photographing each tube front & top (see photos), I'm also including a detailed video showing: cold startup, thru system playing & unit shutdown - and everything in-between (see youtube link above. In the video description I have a breakdown & timestamp for each part of the walk thru). 

FYI, in the first few seconds after unmuting you can hear a brief static hiss from the Celestion Kingston speaker I used. My strong opinion is that the unmute/power transition momentarily excited the speaker. It did not recur again in the test.

CONDITION & PERFORMANCE (Unit Serial no. 56388005)
COMING SOON!!!

SHIPPING / DELIVERY (FOR BOTH UNITS)
The REF600 is a BEAST. The ARC manual lists it at 77.2 kg net (about 170 lb) and the chassis is physically quite large. Because of that, local delivery is strongly preferred. I am operating out of the NYC / NJ area. See below for a few different options!

Zone 1 (Preferred):
$250 (I’ll drive both to you directly  ~ 0-3 hours roundtrip MAX)

Zone 2:
$500 (I'll drive both to you directly ~ 4-7 hours roundtrip MAX)

Zone 3:
$750 (I'll drive both to you directly ~ 8-11 hours roundtrip MAX)

Zone 4:
$1000 (I'll drive both to you directly ~ 12-15 hours roundtrip MAX)

Freight Delivery (Least Preferred):
$1000 - $2000 per unit (covers crating + freight, continental US ONLY, excludes AK)

REF600 SPECS (FROM ARC MANUAL)

• Power output: 500W continuous into 16Ω from 20Hz–20kHz with <1% THD (typically far lower at low power).

• ARC notes typical peak capability is around 550W, and up to ~600W under ideal conditions.

• Power bandwidth (-3dB): 12Hz–80kHz

• Frequency response (-3dB at 1W): 2Hz–200kHz

• Input sensitivity: 2.0V RMS balanced for rated output

• Input impedance: 200kΩ balanced

• Output regulation: ~0.5dB (16Ω load to open circuit; damping factor approx. 16)

• Global negative feedback: 12dB

• Tube complement (manual listing): 20× 6550C (output + regulation) and multiple 6922s in the small-signal stages (manual lists the full breakdown).

• Dimensions (W×H×D): 48.3 × 26.7 × 74.9 cm

• Net weight: 77.2 kg