EICO HF-20 VINTAGE TUBE AUDIO AMPLIFIER – SERVICED – CLEANED – TESTED. THIS VINTAGE TUBE AMPLIFIER WORKS GREAT AND IS IN EXCELLENT CONDITION INSIDE AND OUT, ESPECIALLY FOR IT’S AGE. WE REPLACED MANY DEFECTIVE CAPACITORS AND OTHER DEFECTIVE COMPONENTS. REPAIRED ALL POOR SOLDER CONNECTIONS. CLEANED ALL CONTROLS AND SWITCHES. WE HAVE BEEN IN BUSINESS FOR OVER 60 YEARS REPAIRING VINTAGE AUDIO EQUIPMENT.
Vintage EICO HF-12 12-watt mono tube amplifier, previously modified from its original hi-fi configuration for apparent guitar/instrument amplifier use. This is an interesting restoration or further-conversion project for a tube guitar amplifier builder or vintage audio enthusiast. CURRENT CONFIGURATION – Original EICO HF-12 chassis, enclosure and transformers. Original four-position input selector removed and replaced with a front-mounted 1/4-inch input jack. Three remaining front controls: volume, bass and treble. Original rear audio inputs removed. Rear 1/4-inch speaker output jack added. Original speaker terminal strip remains, with altered connections. The 8-ohm terminal is presently unwired. Original decorative front faceplate is missing. Replacement Mallory electrolytic capacitors installed. Three-prong grounded-style power cord installed, but protective grounding has not been verified as satisfactory. Other previous wiring and component changes are visible. ELECTRICAL TESTING PERFORMED The amplifier has NOT been powered up or audio-tested. Resistance and continuity measurements were performed with a multimeter. Output transformer: – Primary end-to-end: approximately 341 ohms – Primary halves: approximately 187 and 154 ohms – Secondary G-4? : approximately 0.9 ohms – Secondary G-16? : approximately 1.3 ohms Power transformer: – Primary: approximately 40 ohms – Heater winding: approximately 0.4 ohms – High-voltage secondary: approximately 205 ohms total – High-voltage secondary halves: approximately 105 and 98 ohms No open windings were identified in the circuits measured. These are resistance/continuity measurements only and do not establish transformer performance under operating conditions. IMPORTANT ELECTRICAL CONDITION The three-prong power cord was checked for continuity between its grounding pin and the metal chassis. Meter lead resistance: approximately 0.2 ohms – Grounding pin to chassis: approximately 2.5-2.7 ohms The protective chassis-ground connection requires further inspection and verification. The power wiring, capacitors, previous modifications and overall electrical safety have not been fully evaluated. DO NOT CONNECT TO AC POWER UNTIL PROPERLY INSPECTED AND SERVICED BY A QUALIFIED TUBE-AMPLIFIER TECHNICIAN. RESTORATION POTENTIAL The EICO HF-12 originally used a push-pull EL84/6BQ5 output stage rated at 12 watts in its factory configuration. The existing instrument-style conversion offers an interesting starting point for a vintage guitar amplifier project. Actual instrument input characteristics, operating condition, output power and sound have not been verified. The amplifier could also be considered for restoration toward its original hi-fi configuration. This would require sourcing missing controls, connectors and faceplate components, tracing the wiring and making appropriate circuit repairs. Not represented as a working or electrically safe amplifier. Includes the amplifier and installed components as photographed. No additional accessories are represented as included. Please review the detailed photographs of the chassis, underside wiring, transformers, controls and connections.
Photos represent item and condition best. Top tuner model powers on. Bottom unit powers on intermittently. I do not have the capability to test beyond that.
EICO HF-32 vintage tube amplifier, a classic American hi-fi integrated amp from the golden age of vacuum tube audio. Known for its warm analog sound and strong restoration potential, this unit is highly sought after by tube audio enthusiasts, collectors, and DIY restorers. Manufactured by Electronic Instrument Co. In the USA, the HF-32 remains a staple in vintage hi-fi systems. Type: Tube Integrated Amplifier. Inputs: AUX, Tuner, Tape, Phono. Speaker Outputs: 8? / 16? Note: This listing is for the HF-32 Tube Amplifier only. Up for sale is a vintage EICO HF-32 tube amplifier, a classic piece of American hi-fi history. These amplifiers are well regarded for their warm tube sound and are popular among collectors and restoration enthusiasts. This unit presents well with original knobs and faceplate, showing normal wear consistent with age. Also available separately: matching EICO HF-90 FM tuner. Check out my tuner listing if you’re looking to complete the set. The EICO HF-32 is a respected entry point into vintage tube audio, offering strong performance when restored and a timeless mid-century design.
EICO HF-81 Integrated Tube Amplifier – Restoration Candidate – Working Iron. Some units are plug-and-play. This is not one of them. This EICO HF-81 is a largely original example and should be viewed as a restoration project. The transformers appear healthy, but the amplifier will require electronic servicing for stable, long-term operation. This is for someone who will selectively change parts for stability but retain the sonic character the HF-81 is famous for. Operational Status (Please Read Carefully). Powered up slowly on a Variac. Output transformers pass signal. Video included demonstrating that both channels produce output. One channel is weaker and exhibits distortion. The stronger channel distorts at high volume. Power switch (integrated into treble knob) does not function properly. Unit is likely running on original capacitors. Given its age, full recap and restoration is recommended before regular use. Tube Complement (Installed & Working). The original Eico factory installed tubes tested weak or shorted and were replaced with. Quad Sylvania EL84 / 6BQ5 – New old stock (NOS) and new in box (NIB). Tubes are functional, but the distortion issue suggests underlying circuit components (likely caps or resistors) require attention. Classic gold faceplate with vintage wear. Appears largely unmodified internally (based on current inspection). Why This Is Worth Restoring. The HF-81 is widely regarded as one of the most musical EL84 integrated amplifiers ever made. Properly restored examples command strong market value and are known for. Balanced push-pull EL84 output. Highly respected transformer set. The transformers are the heart of these units – and this one passes signal. Collector seeking original platform for rebuild. If you’re looking for a fully restored, daily-use amp, this is not that listing. If you want a strong foundation with working iron and upside potential, this is an excellent candidate. Will require recap and service. Distortion present in one channel. Power switch requires repair. See video for operational demonstration.
EICO HF-90 vintage FM tube tuner, a classic American hi-fi component from the golden era of vacuum tube audio. Manufactured by Electronic Instrument Co. In the USA, this tuner is sought after by collectors and restoration enthusiasts for its period-correct design and compatibility with vintage tube amplifier systems. Ideal for pairing with classic integrated amps such as the EICO HF-32. Type: FM Tube Tuner. Output: Audio line output. Note: This listing is for the EICO HF-90 FM Tube Tuner only. Vintage EICO HF-90 FM tube tuner, a classic piece of American hi-fi history. Designed to pair with tube amplifiers, this tuner offers a timeless mid-century look and is a great candidate for restoration or integration into a vintage audio system. Cosmetically solid with original components and dial. Shows normal wear consistent with age. Unit has not been powered on or tested. Looking for the matching amplifier? Check out my tube amp listing for the EICO HF-32 to pair with this tuner. The HF-90 is a well-regarded tuner among vintage hi-fi enthusiasts and is commonly paired with EICO tube amplifiers to complete a period-correct system.
EICO HF-89 stereo tube amplifier – Complete bench test and serviced. This amplifier includes everything as shown including all tubes, Wireworld power cord, speaker wire adaptors, and even a bottom plate not shown in photos. Note that all capacitors and resistors were replaced as needed by a qualified technician. Also note that RCA inputs were added. In my opinion this updated vintage factory built amplifier betters most attempts to copy vintage gear and by far betters Chinese attempts.
EICO HF-12 Mono Integrated Tube Amplifier – Modified, Tested, Great Sound. A classic mono integrated amplifier from EICO’s golden era, the HF-12 is well regarded for its musical EL84 output stage and straightforward, no-nonsense design. Tested and fully functional at time of evaluation. Modified to use a solid-state rectifier in place of the original EZ81 tube. Provides more stable operation and consistent voltage. Evidence suggests some of the capacitors were replaced in the past by the prior owner. Exact timing and scope of this work are unknown, but several current capacitors do not look like original factory capacitors. A full recap is recommended for long term reliability. Three 12AX7 tubes (installed and included). Brand may vary but all tested strong, no shorts and gas detected. Old tubes were all replaced for reliable performance. Classic EICO iron and EL84 sound signature. Strong, engaging mono presentation-excellent for vintage speakers. Clean cosmetics consistent with age. Some corrosion typical of age. Solid platform for continued enjoyment or future restoration. This is a vintage tube amplifier.
