McIntosh MHA100 Integrated Amplifier - Headphones Or Speakers

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General:
The McIntosh MHA100 is an interesting piece of McIntosh History. 

It's a compact headphone amplifier that can handle just about any pair of cans, plus it has a capable 50W amplifier perfect for driving and efficient loudspeakers (just right for near-field listening or most sets of Klipsch Heritage Series speakers).

Its small size and excellent design make it perfect for a killer desk setup. It also has the classic McIntosh look featuring beautiful blue VU meters. 

This particular unit will come with its original box and manual, plus a new remote fresh from the factory (see stock image in our listing for the HR091 model remote).

SkyFi Cosmetic Notes:
Some light scratches on the side metal panels plus on top. Overall very good condition.

Brand Background:
McIntosh Laboratory is an American manufacturer of handcrafted high-end audio equipment based in Binghamton, New York. The company was founded in 1949 by Frank McIntosh. The company designs and produces audio amplifiers, stereo tuners and other consumer electronics products.

Ownership:
Single Owner

Connections:
RCA, XLR, AES/ABU, Optical, Coax

General Sound:
Smooth, uncolored, undistorted natural and clean

Cosmetic Condition:
8/10 = Very Good. Excellent front faceplate, one minor flaw on chassis side or top. See our detailed rating description here.

Working Condition:
Working perfectly and tested in our lab and listening room.

Included:
Unit, remote, manual and power cord.

Packing:
Original Manufacturers Packing

Specs:
- Frequency Response:
- 20Hz - 20kHz (+0, -0.5dB)
- 10Hz - 100kHz (+0, -3dB)
- Headphone Power Output: 1 watt (High); 250 mW (Normal)
- Headphone Load Impedance: 8-40 ohms; 40-150 ohms, 150-600 ohms
- Loudspeaker Power Output: 50 watts per channel (minimum sine wave continuous average power output, both channels operating)
- Loudspeaker Load Impedance: 8 ohms
- Total Harmonic Distortion: 0.005% (maximum with both channels operating from 250 milliwatts to rated power, 20 Hz - 20 kHz)
- Signal-to-Noise Ratio (High Level): 105dB below rated output
- Tone Control: Bass Boost 0 to +12.5 dB (2.5 dB steps) @ 40 Hz
- Digital Input Sampling Rates:
- Optical: 16-bit/24-bit, 32kHz to 192 kHz
- Coaxial: 16-bit/24-bit, 32kHz to 192 kHz
- AES/EBU: 16-bit/24-bit, 32kHz to 192 kHz
- USB: 16-bit/24-bit/32-bit, 32kHz to 192 kHz

Dimensions:
Width 11.5" Height 5.5625" Depth 18"

Weight:
26.5 lbs.

Recommended Cables:
Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

Kimber Kable - BALANCED XLR Connectors - Better

Kimber Kable - BALANCED XLR Connectors - Best

Kimber Kable - Speaker Cables - Better

Kimber Kable - Power Cords - Better

Kimber Kable - Power Cords - Best

Kimber Kable - Coaxial Digital Interconnect

Kimber Kable - Optical Digital Interconnect

Kimber Kable - Digital AES/EBU Interconnect

Kimber Kable - Select Series Reference USB Cable

Testing Process:
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 device has the ability to decouple the preamplifier from the power amplifier, we remove the jumpers and independently test each section. If the device cannot be decoupled, we assess the electronic condition of the piece by analyzing the speaker level output only.

We start by connecting the "Pre-Out" jacks of the integrated to a Sencore PA81 Power Analyzer which simulates real world loading conditions and gives us an oscilloscope interface. The first order of business is checking that the volume control works smoothly throughout its entire range with acceptable channel balance. This is accomplished by feeding a 1 KHz sine wave into one of the preamp’s line level inputs while monitoring the preamp’s output on an oscilloscope.

We then switch to a 1 KHz square wave to test the tone controls, loudness function, and filters where applicable. During this step we are watching for equal alteration of the test signal by both channels. This also helps us identify dirty controls that will need treatment.

Once the basic line stage functions are verified, we test each input individually. This is especially important for devices that use relays to select their sources.

If the preamp section is equipped with a phono stage we test that as well. We use an inverse RIAA filter which allows us to feed a reference test signal into the phono input with the proper RIAA equalization and level. A square wave or sine sweep is used to verify that the device’s phono stage is faithfully reproducing the RIAA curve.

Next we test the power amplifier section by connecting the integrated amplifier speaker outputs to a Sencore PA81 Power Analyzer which acts as a dummy load, DC offset monitor, and oscilloscope interface. We start with a low level 1 KHz test signal at the "Main In” jacks 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. We finish off the bench evaluation with a 1 KHz square wave check and a 20 Hz to 20 KHz 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.

If the preamp and power amp both pass these tests, we reconnect the sections and verify that the preamp section can drive the power amp to rated power with a 1KHz tone on one of the line level inputs.

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 moves to our long term testing rig where we simulate real word operating conditions for 6-8 hours minimum. 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.