Mark Levinson ML-9 Vintage Class AB₂ Amplifier

Free Shipping on *ALL* Electronics (Excluding Speakers, Contiguous 48 US States Only)

Very desirable ML-9 from the early days of Mark Levinson.

"designed to provide virtually the same sonic performance as the ML-3 in a component of about half the power, weight, size and price."

Fully tested and delivering 100W of pure Levinson Class AB₂ power.

Super clean with little signs of use.

Very high current, capable of driving just about anything.

Includes a pair of RCA to Camac adaptors (not pictured). 

Click below to add our recommended matching cables from Kimber Kable, all brand new as SkyFi is an official Kimber dealer.

Kimber Kable - RCA Interconnects 

Kimber Kable - Speaker Cables

Kimber Kable - Power Cords

More from Mark Levinson:
The ML-9 is a basic stereophonic amplifier with many of the features of the higher-powered ML-3. the ML-9 is rated at 100 Watts continuous sinewave power per channel into 8 ohms, with both channels driven, from 20 Hz to 20 kHz with no more than 0.2% Total Harmonic Distortion. It will drive even the most inefficient loudspeakers to their full potential. In fact, the ML-9 will easily satisfy the power requirements of all but the most unorthodox applications.

The design goal of the ML-9 was to provide the same overall performance of the Ml-3 in a component with about half the power, size and price.
Thus, the audio circuitry of both models is similar. Push-pull operation is maintained from input to output. Full protection is provided for both the amplifier and the load. The power supply of the ML-9 consists of a 1,2 kVA toroidal transformer and a pair of 36 milli-Farad capacitors, allowing for energy storage in excess of 230 Joules.

The damping factor can be adjusted by means of a three-position toggle switch on each channel to meet the requirements of virtually all presently available loudspeakers. The ML-9 has been designed to drive complex loads with complete stability.

Circuit description
The ML-9 is a high quality Class AB₂ stereophonic amplifier designed to provide virtually the same sonic performance as the ML-3 in a component of about half the power, weight, size and price.

Power Supply
Consists of a 1,2 kVA toroidal transformer, a 30A bridge rectifer, and two 36,000 µF capacitors. Four 520 µF capacitors are used for added decoupling of the pre-driver stage.

Pre-Driver Stage
Consists of a differential amplifier with a cascode which drives a second differential amplifier with a cascode and a current inverter. The inverter converts from balanced to ground (differential) to unbalanced to ground while maintaining push-pull operation.

Driver Stage
Consists of a complementary emitter follower, driving a second complementary emitter follower.

Output Stage
Consists of four parallel complementary push-pull emitter followers

Protection
The on/off switch doubles as an electromagnetic circuit breaker to protect the amplifier from excessive current. The power stages are protected by an energy limiting circuit which monitors power dissipation versus time. Independent energy limiting for positive and negative information minimizes distortion while in the overload condition. This circuit offers excellent protection without effecting the sonic quality. The loudspeaker is protected by a D.C. sensing circuit that monitors the output of the amplifier. The D.C. sensing circuit is connected to the circuit breaker. Several other techniques have been employed to protect the ML-9 from external sources of damage.

Selectable damping Factor
Loudspeakers, like all electrical devices, are not perfect. We have determined that certain loudspeaker characteristics can be effected by varying the damping factor of the amplifier. For the reason the ML-9 is equipped with selectable damping capability.

Specifications
Rated Power: 100 watts continuous sine-wave power pre channel into 8 Ω with both channels driven from 20 Hz - 20 kHz with no more than ,2% T.H.D.
Frequency Response: (-3 dB) 3 Hz, 44 kHz (ultra sonic filter is a modified bessel alignment)

Input Impedance: 50 k Ω

Voltage Gain: 26 dB

Power Consumption: 400 W at rated output into 8 Ω, 50 Hz - 400 Hz (100 W at idle)

Overall Dimensions (W x H x D): 482 x 216 x 339 mm (19" x 8-1/2" x 13-3/8")

Weight: 29,48 kg (65 lbs)

Mark Levinson ML-9 - Original Sales Brochure

Mark Levinson ML-9 - Manual

The SkyFi Testing Process for Solid State Amplifiers:

We start with a visual inspection of all internal components to make sure there are no signs of stress or aging. Capacitors are checked for telltale sings of bulging or leaking, resistors are checked for signs of overheating or cracking, and transistors are checked for signs of stress or damage.

We then power up the unit carefully and run a simple 1k sine wave while monitoring the output on an oscilloscope for signs of distortion or noise. Finally, we run the amplifier to its full rated power into the appropriate resistive load provided by our Sencore amplifier tester. If there is an issue, it will usually be noticeable at this point. If everything reads clean, we will often test for THD (Total Harmonic Distortion) measured by our Keithley distortion meter, and compare it against the original manufacturers specifications. The amplifier then remains powered on to "burn in" on our test bench for a few hours to make sure there are no heat related issues. If there are balanced inputs available they will be also be tested.

Final testing involves pushing actual music thorough the amplifier. We've learned over time that some issues are only noticeable to a trained ear while listening to familiar source material. Our test bench has reference vintage KEF speakers that we're very familiar with which quickly reveal any discrepancies. Some amplifiers will then move into our listening room where they are tested with our in-house reference speakers of choice.