Conrad Johnson MV-60SE (Special Edition) Tube Amplifier Fitted With 6550C Tubes

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This MV-60 is the later and more refined Special Edition version.

Rumor has it that you can fit KT88 and KT120 Tubes as well as the installed 6550C's, but we'll leave that tweak to the next owners. This will ship with a nice set of strong pre-loved Svetlana Silver Label matched quads.

This configuration is capable of 60W into a 4 ohm load, which is how we configured the output and found optimal power.

Cosmetic condition is very good with no noticeable signs of use.

About Conrad Johnson:

In the mid-1970s, two economists—friends and serious audiophiles—Dr. William Conrad and Dr. Lewis Johnson—were highly dissatisfied with the commercially available equipment of the time and were also perplexed and challenged by the readily apparent sonic differences among components in their own systems. What made these two classic tube systems sound so different? Could the virtues of each be somehow combined? Not content to merely speculate on such issues, Conrad and Johnson decided to systematically investigate by developing and refining a vacuum-tube preamplifier.

The resulting conrad-johnson preamplifier was immediately recognized as a state of the art contender and catapulted Conrad and Johnson into the audio industry.

The most important legacy of conrad-johnson design’s beginnings is the basic methodology which took shape in the course of the development of that first preamplifier.

This methodology has enabled conrad-johnson to develop new products which have routinely been ranked among the most musically satisfying. Few other manufacturers have so consistently received such high praise for their products.

Link to Review (non SE Version):

https://www.stereophile.com/content/conrad-johnson-mv60-power-amplifier-sam-tellig-may-2003

Link to Owners Manual:

https://conradjohnson.com/owners-manuals/mv60seman.pdf

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

The SkyFi Testing Process for Tube 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.

Specifications:

Power (ultralinear operation): 60 watts per channel RMS both chan- nels driven into 4 ohms from 30Hz to 15KHz at no more than 1% total harmonic distortion or intermodulation distortion (can be re-connected internally for 8 or 16 ohm loads).

Sensitivity: 820mv to full power.

Phase: Phase correct (non-inverting) Frequency response: 20Hz to 20KHz +0, -.5dB Hum and noise: 95dB below full power output. Input impedance: 100K ohms.

Dimensions: 13.25Dx17.625Wx7Hinches. Weight: 48 lbs.