McCormack Power Drive DNA-1 Amplifier

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General:

This is the very first McCormack DNA-1 to come into our shop. It's quite a nice piece with very impressive design and engineering.

Hailing from the mid 1990's.

150W per channel makes it a very capable performer, able to drive most speakers with authority and grace.

Cosmetic condition is close to perfect with no significant signs of wear.

We performed a light service where it was re-biased and thoroughly tested in our lab.

In our long term listening test it performed flawlessly and we can see why these have such a loyal following.

Best of all it comes in its original box, but we'll also provide extra packing as needed for safe transit.

The original manual completes the set.

Recommended Cables:

Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

Kimber Kable - Speaker Cables - Better

Kimber Summit Series Monocle XL Speaker Cables (PAIR) - Best

Kimber Summit Series BiFocal XL Bi-Wire Speaker Cables (PAIR) - Best If Applicable 

Kimber Kable - Power Cords - Better

Kimber Kable - Power Cords - Best

From a 1995 Stereophile review written by Robert Harley:

"Conclusion
The best word to describe the McCormack Power Drive DNA-1 is "musical." It consistently offers an involving, satisfying musical experience. Apart from the specific performance attributes detailed in the body of the review, listening to music through the DNA-1 was just plain enjoyable. This is one solid-state amplifier I could be happy with for a long time. Further, the DNA-1 represents an extraordinary value; this combination of musicality and sheer output-power muscle are unprecedented at the price, in my experience."

Specifications:
Rated power output:
150 WPC RMS into 8 ohms (21.8dBW)
300 WPC RMS into 4 ohms (21.8dBW)
500 WPC RMS into 2 ohms (21.0dBW)
(bandwidth and distortion not specified)

Output current:
50A peak per channel

Input impedance:
100k ohms

Input sensitivity:
1.2V

Frequency Response:
-3dB at 0.5Hz and 250kHz

Rise time:
±2µs

Slew rate:
50V/µs

S/N ratio:
88dB, "A" weighted

Damping factor:
>100 (1kHz, 8 ohm load)

Output impedance:
±0.1 ohm

DC offset:
±5mV

Signal polarity:
Non-inverting

Dimensions:
19" W by 7" H by 15" D

Shipping weight:
53 lbs.

The SkyFi Testing Process for Solid State Amplifiers:

We start with a visual inspection of all internal components to make sure that there are no signs of heat stress or damage. Capacitors are checked for telltale signs of predictive failure including bulging, shrunken wrappers, or physical leakage. We also inspect the PCBs for discoloration from resistors or transistors that may have been running hot. On vintage units we often spot check select capacitors for value and ESR.

If the amplifier passes visual inspection, we move on to a controlled power on sequence using a Sencore safety analyzer to monitor current draw in real time. Once the amplifier is determined to be safe to operate, we connect it to full AC mains for function and power testing. We connect the speaker outputs of the amplifier to a Sencore PA81 Power Analyzer which acts as a dummy load, DC offset monitor, and oscilloscope interface. We start with a low level 1KHz test signal at the amplifier’s input and slowly increase its amplitude while monitoring the output on an oscilloscope for signs of noise, clipping, distortion, or improper channel balance. We continue increasing the signal level until the amplifier reaches clipping. At this point we take an output power measurement and compare it to the spec sheet of the amplifier to verify proper performance. If the device under test has both balanced and single ended inputs they are both tested at this time. We finish off the bench evaluation with a 1KHz square wave check and a 20Hz to 20KHz sine sweep to assess the amplifier’s frequency response characteristics. This battery of tests will usually reveal if the amplifier has any issues that need further attention.

Before the device leaves the bench, we perform a listening test with actual music using a variety of preferred test tracks. Our benches are outfitted with familiar monitor speakers which help us identify inconsistencies that will not always show up on our test gear. The main things that we are listening for are hum or noise with no signal present, proper center image, clicks, pops, or any other obvious undesirable audio characteristics.

If the unit passes all of these tests it is moved to our long term testing rig where we simulate real word operating conditions for 6-8 hours. This allows us to monitor the unit for signs of thermal runaway or intermittent issues that only crop up when the unit has fully come up to temperature.