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The delightful EICO HF12

Posted by Bambi B (A) on February 11, 2008 at 09:20:25

In Reply to: Eico HF12 posted by izzbo1@yahoo.com on February 10, 2008 at 21:52:31:

PHOTO: EICO HF-12

izzbo1,

Yes, the EICO HF-12 is an mono, tube, integrated amplifier, meaning it reproduces one channel from tubes, and has a preamplifier section and a power amplifier. The preamplfier uses three 12AX7 tubes and the power comes from 2- EL84's. The EL84's are the two taller tubes set an an angle on the chassis. The HF-12 was available wired, as a kit, and apparently set into consoles.

By the way, if your HF-12 has it's original tubes, and they are in good order, they may be worth seperately as much as you paid for the whole unit- if EICO labelled they may well be Mullard 12AX7s and EL84s.

Two thoughts: One, is that the HF-12 is respected for a suprisingly refined, sweet and open sound from a fairly simple circuit, but remember the "12" in the model number means 12 Watts, so you'll want to look for a speaker that are quite efficient, I would think 93 dB or more. I think Van Halen uses amplifiers that are at least 30 W,...

The other thought is to have some patience with getting your HF-12 organised to use. It looks cute and friendly, but the HF-12 still uses lethal voltages and importantly, is full of nearly 50 year old parts. The proper way to start it up after sitting a long time would be to remove the tubes, carefully clean the pins and test them to see where you are in tube life, the RCA jacks and speaker connections, clean the control potentiometers. The last step is to plug it into a variable transformer that can bring the voltage up gradually. This last step is usual for any kind of tube gear that hasn't been used in more than 6 months, and we might assume yours hasn't, and "reforms" the capacitors- I think of it as "putting the parts on notice they're going back to work". A sudden full voltage might ruin capacitors.

> Important: It is harmful to run tube amplifiers without having a "load", that is: it must be plugged into speakers whenever it's to be turned on.

The EICO HFs I think are delightful and for a long time were almost a gift on the market, until a positive "Absolute Sound" review of the stereo HF-81 tripled prices.

As you get involved with your HF-12, you might benefit from an archive search and posting on "Vintage Asylum" of this same site and particularily ask for comments by regular poster mhardy6647 who is enthusiastic about his HF-81 and very knowledgable and sensible:

http://db.audioasylum.com/cgi/search.mpl

I have an original "HF-14" which is nearly identical to the HF-12, but has a more modern silver faceplate and promises "14W", but I'm told the extra 2W rating is only a different way of measuring the power. I haven't heard this one, but if I try it and it lives up to it's reputation for sound, I've thought of getting a second HF-12, bypassing the tone controls and using the two together as dual-mono integrateds.

As mentioned before, take care before starting it up and consider the speakers.

And, come back and let us know how it works!


Cheers,

Bambi B

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