EICO HF-89 Stereo Tube Amplifier
Archived listing from the original vintage-amplifier.com. Prices, seller details and purchase links have been removed; this page is a reference record, and nothing here is for sale. About this archive.
Eico HF89 tube amplifier . Some say that is almost as good as Marantz 8B , I don’t know , never heard 8B but Eico is certainly one of the best vintage amps I had pleasure to listen to. It is a classic circuit operating near Class A and getting 50Watt a channel from UL connected pair of EL34 tubes.Yes it is a hot running amp. Output transformers are huge . Look at the picture where you have HF89 next to venerable Dynaco St70 and compare . I did minimum maintenance required to safe operation of the amp to preserve it’s voicing and vintage character. I have to say that that amp was original built with high quality parts and there is nothing cheap about it.
What I did :
- Replaced coupling caps with vintage matched paper in oil capacitors (Astron AFQ 0.1/600V)
- Replaced all small electrolytic bypasses with axial nichicon and sprague capacitors
- Replaced PSU and bias rectifier diodes
- Replaced input RCA connector with modern gold plated RCA’s
- bypassed input mono switch
- bypassed last PSU cap with two nichicon 80uF/450V to give input stage little cleaner supply.
- used rubber to decouple power transformer from chassis (it was little noisy)
- Replaced rubber feet.
6SN7 ‘s and 12AX7 are of Russian production. To get a full picture of what this amp is capable off, you simply must source some NOS driver tubes. I like Russian power tubes but much prefer western driver tubes. Now ,the cosmetics of the amp are so ,so. It was industrial looking amp to begin with and those scratches on chassis do not make it more beautiful.
There is a little bit of hum and slight mechanical noise from hot running power transformer. Not a big issue with 86-90 dB speakers but with higher efficiency speakers it will be noticeable. Measured ESR of PSU caps is low which means the caps are still good but the amp would still benefit with PSU capacitor change . It is a major surgery and it will be up to you how far you’re willing to change the amp to suit your needs. A great sounding amp!
About this model
The HF-89 was EICO's big stereo power amplifier. The manual rates each channel conservatively at 50 watts, and the seller describes the output stage as an ultra-linear pair of EL34s per channel, running hot and close to class A. Radiomuseum dates the model to 1961.
The listing is one of the most thorough in the archive: new paper-in-oil coupling capacitors, new bypass capacitors, new power supply and bias rectifiers, a cleaner supply for the input stage, and a power transformer decoupled from the chassis to reduce mechanical hum. Its comparison photograph next to a Dynaco Stereo 70 shows how much larger the HF-89's output transformers are. The seller's view that the HF-89 can stand comparison with the Marantz 8B is an opinion, not a measurement, but it is a common one.
| Maker | EICO (Electronic Instrument Company), USA |
|---|---|
| Type | Stereo power amplifier |
| Year | 1961 (Radiomuseum) |
| Rated output | 50 W per channel (manual) |
| Output tubes | EL34, ultra-linear push-pull (listing) |
| Small tubes | 6SN7 and 12AX7 (listing) |
Questions collectors ask
How powerful is the EICO HF-89?
The manual rates it at 50 watts per channel, conservatively.
What output tubes does the HF-89 use?
EL34s, connected ultra-linear in push-pull, according to the archived listing and owner reports.
Is the HF-89 hard to restore?
It is a large amplifier with a lot of capacitors. The archived listing shows a careful partial restoration and recommends replacing the power supply capacitors as well.
Sources: EICO HF-89 manual (ManualsLib); Radiomuseum: EICO HF-89; Wikipedia: EL34.
