Eico HF-81 Amplifiers

HF-81

User Reviews (11)

Showing 1-10 of 11  
Todd Sytles   AudioPhile [Feb 16, 2017]

Wow!!! what can I say in stock form... just a really good cleaning of pots and sockets. ready for this... blows away my Mcintosh MC 240's, 40's, 275, and even betters my Marantz 8b and Mcintosh Mc 225. Ya it is that good. Timbre, detail, tone every aspect is just amazing!! all models were to spec.My Preamp was a restored Mx110z. This Eico is just outstanding. Paid $430.00. Was afraid to add caps but 6 were out of spec. Put Orange drops in her.( Now even sounds better.) Cant say enough about it. After years of searching. I'm Just done. Any Mac or Marantz will just be sold on line if I come across some. Always on the hunt. Just a side note .Leave as original as you can. Cheers!!!

OVERALL
RATING
5
VALUE
RATING
5
JCTrumpet   Audio Enthusiast [Nov 05, 2007]
Strength:

Depth of sound with a good, natural "middle range". Separate bass and treble controls for each side make it good to "tweak" the sound for each individual recording in your collection.

Most people use 1-3 watts per channel when they are listening to music, so 14 watts per side is more than enough to irritate the neighbors for us.

Weakness:

If you like lights and meters more than sound, then you might call this a weakness because the EICO HF 81 doesn't have any. It's about the sound.

I am very pleased with the EICO HF 81. As someone who is new to tube technology this integrated amplifier was quite a surprise to my ears. I am a public school band director and a free lance musician. So when listening to any recording
the comparison made is "how close does the recording sound against when I am in the middle of a performance group or an audience?"

Originally, when I improperly hooked the HF 81 up 10 years ago the decision was to store it. A few months ago, after doing an internet search on and reading about the EICO HF 81, I hooked it up correctly......WOW! Woody Herman's Big Band had presence and warmth that were not there on my solid-state integrated amp. The 14 watts per side are more than enough to drive my Advent/2 speakers or Peavey PR12's (they are PA speakers with an 97 dB efficiency rating).

My listening diet is mainly small combo Jazz, Big Band, Polkas and anything that
shows group energy and clarity. This integrated amp makes it happen.

A major confession is that I repaced the original Mullard tubes in the HF 81. They had lived a long life and were going out of balance. So I repaced all of the pre-amp and amp tubes with JJ Tesla and the rectifier tubes with Electro -Harmonics. This added to better balance and warmth of sound. Before I did this I went through the HF 81 and cleaned the pots and checked the connections.

I whole heartedly encourage someone looking for a clean sounding, modest looking integrated amp to buy an EICO HF 81. I'm still amazed that an integrated amp that is as old as I am, sounds good !

OVERALL
RATING
5
VALUE
RATING
5
Syuji   Audio Enthusiast [Nov 01, 2001]
Strength:

Great sound!!

Weakness:

None!!

This is a great amp. I use it with Accoustic Energy Aegis One speakers. Music sounds as if they are playing live. Incredible!! Poweful enough for midium size room. Zen amp and McIntosh MC-240 didn't sound any nearly good as Eico HF-81.

Similar Products Used: Zen amp and McIntosh MC-240. NAD C 340.
OVERALL
RATING
5
VALUE
RATING
5
Roger W. Stevens WA3FLE   an Audio Enthusiast [Apr 18, 1998]

OK, time to get up on the wayback machine. This is a familiar model to those of you probably in your 50's by now. Or perhaps you are younger and now playing around with single-ended triode amps, attempting to create (at great expense) what this amp reproduces almost effortlessly--MUSIC with a solidity, yet a delicacy and immediacy that is startling, especially with good source material. Remember, we're talking pre-digital by about 15 plus years here. I wish I knew the exact dates, but someone does out there.
This is roughly a 15 watt-per-channel integrated amp that uses 6BQ5 (EL84) push-pull output tubes, self (cathode) biased. Some say it's nearly impossible to design a bad sounding amp with 6BQ5's (or 6V6's, for that matter). It has a pretty complex preamp section, especially when you compare it to a Dynaco SCA-35. The Dyna uses a 12AX7 and a 7199 in each channel, whereas this old bear uses two 12AX7s and a 12AU7 in each channel--in other words, an all-triode design, up to the output. And there, it uses separate cathode bias resistors for each output tube pair, instead of a single common resistor for all four, as in the Dyna (which requires a matched quad of output tubes, as opposed to two matched pairs). And finally, where the Dyna uses a Williamson Ultralinear output transformer configuration and a solid-state full-wave rectifier, this guy uses a Williamson non-Ultralinear design (no screen taps on the OPT primary), and a PAIR of 6CA4 rectifier tubes. Oh, last thing--the Dyna uses PC board construction, and this unit is all point-to-point.

So what, you say? Well, save a couple of out-of-tolerance resistors that had to be replaced, and a set of gnarly looking, but OK-testing coupling caps (six in all) that I replaced with Orange Drops just to be sure, this thing is a totally timeless design, and nearly bulletproof. Also, it has a certain wackiness to it that can fake you into thinking it's just some crappy kit for the home hobbiest. For example, they call the balance control "Focus", it uses very cheap looking brown plastic knobs, and there's a slide switch on the inside that serves to drive both amp channels in parallel with one side of the preamp, so assumedly you could drive an external amp with the other side, although I haven't yet for the life of me figured out where that signal comes from.

So, having said all this, and tweaked it a bit, and stuck in decent used NOS (aren't they all?) tubes, how does it compare to more modern, expensive amplifiers? Well, along with a Cambridge Audio CD-4SE CD player, a rebuilt Dynakit FM-3 tuner, a refurbished Philips GA-427 turntable with a Stanton P5000S cartridge, and driving a pair of PSB 800i speakers, it is easily the most fun system in the house. Here's the kick--it flat-out boogies. And here's kick number two--cymbals sound like cymbals. This thing not only has balls, but it has resolution, or what they like to call "an ability to resolve" in the trade rags. Not bad for $177.50 up on eBay, a couple of weeks work, and some junk-box parts. Hell, another one went for a lot less a couple of weeks ago.

This is one of those "they'll never believe it" amps. Those in the know feel that it is one of the all-time great designs, so I had to get one and see what they were talking about. They were absolutely right on. In my grand experiment with low-power vintage integrateds, I also grabbed a (mis-represented and extremely marginal) Dynaco SCA-35 for $127.50, which required somewhat more effort, new NOS RCA 7199's, and a matched quad of Tesla 6BQ5's. But even with my best pair of Amperex Bugle Boy 12AX7's in the front end, it just doesn't have it next to the--I can't believe I'm saying this word--Eico. In fact, when compared to the Eico, it's a downright girly man. The HF-81 is much quieter (less hum), has way more available volume, and operates cooler. Although it has roots in the ST-35, arguably the best sounding Dyna ever, I would call the SCA-35 "polite", which isn't necessarily a bad thing. I think it has some of what the British strive for in their recent designs.

There is true gold to be mined in the old stuff. Five proper stars for this bugger.

OVERALL
RATING
5
VALUE
RATING
Paul   [Dec 30, 1998]

I wholeheartedly second Mr. Stevens enthusiastic review. Since I'm from the Showme state, I bought and HF-81 for $160.00 from Audiogon. It arrived ingood condition as advertised and transforming it to original spec took only miniminal effort. The result was astounding. As Mr. Stevens points out, the
Eico is very sassy, but the sonics are great!!!

I can't get over the fact that it's only 15 watts. I purchased another 'name-brand' , tube amp for thousands more, but if it only sounded like the
Eico, I would still own it.

OVERALL
RATING
5
VALUE
RATING
Gordon   an Audiophile [May 09, 1999]

Every time I hear a "high-end" stereo at a friends house or a local hi-fi hut I come home and just smile ear-to-ear with my Eico HF-81. Found with matching tuner at a yard sale for $10, the Eico immediately had me selling my Rotel 970 integrated. The Conrad-Johnson engineer that cleaned and modded the unit for me absolutely loves this unit. My only complaint is for the hum of the transformers. Hopefully I will find the engineer who can rid the hum leaving me with the amp I'll keep for a very, very long time.
System: Signet SL-266 speakers, Toshiba DVD transport, MSB Link D/A, Kimber Silver Streak, MIT Speaker Hose, sand bags n' inner-tubes. Wow!!!

OVERALL
RATING
5
VALUE
RATING
Kent Johnson   Audio Enthusiast [Oct 17, 1999]
Strength:

Great sound

Weakness:

Not readily available

I noticed these reviews of Eico HF-81's and felt that I had to add some comments of my own. At the risk of indulging in one-upmanship, I found my Eico HF-81 at a garage sale with a mono FM tuner for $4!

I replace the obviously burned resistors and virtually all of the capacitors. Doing this myself cost about $20 using very good quality parts. I used the unit with its original RCA tubes for about a year when it started making some nasty sounds from one channel. The noise turned out to be from a bad connection in a tube socket. Fortunately, I have a friend who repairs tube amps for musicians. He found the problem, replaced the main filter cap, and put in new Sovteks except for the original RCA rectifier tubes. Even with these repairs, I probably have under $100 in the unit.

I have listened to the unit for several years with a great deal of enjoyment. While everything sounds good, it seems particularly well suited to Ella Fitzgerald albums. As mentioned in other reviews, it's a very musical amp. There is a naturalness to the sound that is very satisfying. I am continually amazed that an amp of this vintage, 1960, can sound so good. It's better sounding than any other integrated that I have had in my living room system. This includes various solid state units and the Luxman 105U. While the power is low (probably nearer 10 watts than 15) it's really not an issue. The sound is involving.

My Eico is used in a modest system of Infinity RS-2000 two way speakers, Denon DCD 3000 CD player, slightly modded, and DH Labs interconnects and speaker wire.

My main system also has "old" by audiophile standards tube equipment. I think if a lot of people actually heard some of this older equipment, they would be a lot more skeptical of the claims for great sound that come with a lot of newer equipment.

OVERALL
RATING
5
VALUE
RATING
5
John   Audio Enthusiast [May 04, 2000]
Strength:

Plays Music like you probably would not believe

Weakness:

none

The reviews here are absolutely true.. the EICO HF-81 looks like some inexpensive hobby amp...nothing could be further from the truth..this is a great little amplifier and very worthy of a place in the audio hall of fame..
I got mine on Ebay for $180 and it arrived in perfect condition...the insides were very clean.. some caps looked new but other than that it was original...i have played around with it changing a few tubes but overall it just does its thing:it makes beautiful music..
My most definitive statement about it is that the music sounds alive...Excellent sonic resolution..or definition..very fast and sounds like it is dealing easily even with difficult passages..
I am driving it with a soundblaster Sblive card for cd music and MP3's.. It is driving a pair of Klipsch Fortes which are pretty sensitive but i seldom drive the HF-81 over 50% with the Fortes..I also use it to drive a pair of old EV 12TRXB speakers which sound heavenly with it..
People are finding out about this secret,though..because i saw one go for $293 on eBay a week or 2 ago...

Similar Products Used: Denon 85 wpc 5 channel...Decware Zen SET...Macintosh MA-230
Eico HF-20 monoblocks HH Scott 299..Eico ST-40
OVERALL
RATING
5
VALUE
RATING
5
pat the tube guy   Audiophile [Aug 19, 2000]
Strength:

CLARITY, DYNAMICS, phono preamp

Weakness:

needs some modifications to bloom fully

i make and modify amps for audiophiles and the RECORDING INDUSTRY..making preamps, compressors, phones amps, ect for famous film and recording studios.
i have physically modified or made over 1000 pieces of tube gear, stopping the counting over 10 years ago.
you will have DEFINATLY heard my work, if you have seen any TELEVISION or MOVIES of note, in the last decade.
having said that, i have to say, that of ALL The historical designs of amplifiers, NOTHING comes closer to an ideal one box unit, especially if you use RECORDS, to the EICO HF81.
THis said with some caveats: on mine, i have changed all coupling caps to polypropaline. FURTHER, i used to use the tone control section to boost bass for my video setup..until added BIAS regulators to the output tubes.
this is a simple circuit, and can be seen under this line at my web site..: CATHODE REGULATION for EL84's / 6BQ5's .
My web site is http://nanaimo.ark.com/~pat/index.htm
i will add that on my OWN units, i took the 150 ohm resistor and replaced it with 100ohm fixed and 100ohm variable so i could fine tune the adjustment. It has more apparent bass, and WAY more clarity than the stock unit, mostly because the stock unit uses a potted tone control network, and you cant get the benefit of modern high end polypropaline caps, if you leave disk caps in the signal path. I would be happy to advise anyone who wants to do this mod. I also changed tubes to black plate 5751 where 12ax7's were used originally. There were several generations of eico hf81's..some had 7247 in the tone circuit...there is NO black plate equivelent tube to the 7247..i prefer to remove the tone circuit entirely, and while at it, remove the mono/blend switching, balance pot, as well..I also found on all the units i have worked on, that since the power transformer is closer to the circuit on one side, it helps to put a copper barrier between the tube rectifiers and the tone control circuitry.
this helps tame that lopsided hum, but i still prefer it WITHOUT all that nasty stuff. I make high end systems still, and have a recording studio, where i use the higher powered stuff..but the eico STILL has something i havent heard from anything else, ( with the bias mods, you wont miss the boosted bass) and the price is still reasonable. I Have schematics, manual, and mod info available to those daring enough to try it. Its still my favorite vintage design..they can keep all the mac's and marantz stuff!

Similar Products Used: hundreds of tube amps
OVERALL
RATING
5
VALUE
RATING
5
James   Audio Enthusiast [Sep 24, 2000]
Strength:

Simple circuit, easy to modify/rebuild; well built and pleasing sound

Weakness:

Gets hot, tube replacement and the can capacitor is too close to an output tube. NOS rectifers

A 42 year old integrated that uses cathode biased EL84's in a push-pull configuration operating in class A, then AB at higher volume, tube rectification, and a nice preamp/phono section. Listening to this amp, despite it's weaknesses, is pleasing, toneful and reproduces music with good depth. Good lay out of the controls, symmetrical in appearance and that brass faceplate is a nice touch with the brown enclosure. I recently finished rebuilding this amp with modern components and so it sings again, but without the hum and hiss. For those of you who already own this amp or just aquired one for modification go to this site-
http://home.netcarrier.com/~rstevens/frames.html

Similar Products Used: Fisher KX-200
OVERALL
RATING
5
VALUE
RATING
5
Showing 1-10 of 11  

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