Eico HF-81 Vintage Tube Integrated Amplifier - Fully Restored 1960's Magic!

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Full blown restoration of this great vintage integrated.

In rare near-mint condition with a great patina on the brass faceplate.

Vintage tubes all around.

Wonderfull collectible piece in rare condition, plus it also includes a custom cover.

SkyFi Notes on the Restoration:
This piece came to us having already underwent an extensive restoration. Here is a rough outline of what we picked up on during our testing and review process:
• Chassis painted black instead of the original stock raw metal.
• Transformer covers painted.
• Tube sockets replaced.
• Chrome tube cages added.
• Full recap including a new CE multi-section can, axial electrolytics, a mix of film and PIO coupling caps, and select micas.
• Select resistors replaced.
• Modern 3-prong grounded power cord added.
• SEP, COM Switch removed from circuit.
• Power switch replaced.
• Phono grounding lug added.

This was a top notch restoration in all respects.

Tube Notes:
The rectifier tubes are current production Electro-Harmonix. The output tubes are all vintage GE, save for one branded Zenith.T he 12AX7s are GE branded, and the 12AU7s are a mix of Sylvania & Philips. All tubes were tested on our modern and professional Amplitrex AT-1000 tube tesrter, and were also confirmed working properly in circuit.

Specifications:
Tube complement:
Four x ECC83/12AX7
Four x EL84/6BQ5
Two x EZ81

Maximum output power:
14Wpc (11.5dBW) continuous into rated load

Frequency response (at 1W into 8 ohms):
10Hz–100kHz, ±0.5dB

Tone control range:
±15dB at 50Hz and 10kHz

Harmonic distortion:
<1% at 8W, 30Hz–10kHz, at 10W, 50Hz–5kHz

IM distortion (60Hz and 6kHz at 4:1):
2% at 14W, 0.05% at 5W

Sensitivity (input for 14W):
Mag phono 4mV
Tape head 2mV
Mic 5mV
Aux and tuners 500mV

Speaker connections:
4, 8, 16, and 32 ohms

Dimensions:
15" (385mm) W
4-3/4" (120mm) H
10-1/2" (270mm) D

Weight:
24 lbs (10.9kg)

Original Manufacturer:
EICO, Electronic Instrument Company, Long Island City, NY (1960)

The SkyFi Testing Process for Tube 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 tubes are inspected for signs of stress overheating or cracking.

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 it all looks 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 the 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 also be tested.

We also test all tubes for output gain and leakage on our calibrated B&K 747 tester against the original manufacturers specifications. If needed, the tubes will be replaced from our vast NOS (New Old Stock) vintage or modern inventory.

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.