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Eico HF-81 Challenges The AES SuperAmp !

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Nice job with the amps and description.

Do any of you: Chris, mdeneen, homeless, NOS440 think, in addition to bias, the EL84s may have an advantage in that they are mated with a smaller output transformer? The repolarization energy is lower and there will be less, here it is again, crossover distortion. I have been looking for a high quality 10 watt push-pull transformer to check this out. Just a thought. I wish MagneQuest would build a Cobalt 10W PP.

Homeless, I think you've given the Eico HF-81 a new life. I certainly won't pass one up, even if all that's left is the output transformers.


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Leok, I tried to write you a mail and it got returned. You can see EICO iron go on ebay every once in awhile for very little, most times less than $100 for the full set. You have to keep your eye out. There was a set for the ST-40 that went awhile back for near $70.

I just got through updating the MagneQuest site and talking to ole Mike Lafevre for WAY too long on ye olde phone. He is about out of the Cobalt unfortunately and only has a choke and two preamp cobalt parafeed outputs. If you DO manage to get these beasts, they are NOT cheap! It is hard to get him to do custom work since he is so busy with regular orders but stuff is coming down the pike. I'll drop you a line if anything pops up.

Keep an eye out on ebay for transformers though. They come up about once a month or so.

Ed, I can tell you right now that ole Craig loves his 222-C. The LK-48 is the Kit version of this amp. The 222-D is very similar besides a few minor things. Both of these amps would drive the Heresy great (there has been enough discussion concerning the two in the last week to fuel a month). Remember, that with the kit version, you are taking an extra chance, although many people did meticulous jobs wiring their amps in proud fashion. And many more used it as a learning tool! Most EL-84 amps sound damn good. I am giving up recommending which is best as it really is almost a moot point.


This message has been edited by mobile homeless on 03-26-2002 at 08:37 PM

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Well my experience and knowledge of what Scott has made will make this a long reply.

First off mobile is right I love my 222C. But it really didn't shine until I installed a proper bias adjust circuit. Mobile disagrees on this but I think its essential for a good working amp. The 222C has only tube Bias balance adjust and no way to adjust the actual Bias voltage. The 222D has all the Bais adjustment pots built in so there's one less mod it would need to be perfect. The LK-48 suffers from the same lack of bias adjust and was a kit so wired by a home hobby person most likely but you could order them wired.

Now the LK-72B is a interesting find I would love to have one that was wired descent this is a kit too !! This is the Kit version of the 299D and it uses 7591 output tubes. Which are expensive and somewhat harder to find than 7189/6BQ5's that the other Amps use (solvtek I think makes new ones now) .

Any of the Amps that this guy has would play well on any speakers above 90db rating and of coarse really sing with any of the Heritage vintage klipsch. I have my 222C hooked to almost the cheapest currently available Towers SF-2s and they sing some beautiful music for the money invested.

Again let me tell you if this guy is reasonably priced on these I would be interested in whatever you don't get and especially the LK-72B (just because I don't have one based on the 7591 tube).

Now my recommendation to you is ..... Well it depends I have a few questions. Who is this guy ? Does he restore these or what ?? Is he offering you a guarantee ?? If he just has them laying around and he play around with them as a hobby like myself and just say's they check out okay then I would only think about the 222D because its factory wired and would tend to have less demons.


here's a sight with tons of Scott Info


This message has been edited by NOS440 on 03-26-2002 at 09:33 PM

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Just to clear things a bit, when an amp is designed with a proper cathode bias circuit, it can sound great. As well all know, it's the sum of the whole circuit here. The bias arrangement on the 222-C and the EICO HF-81 is actually a bit different in stock form. You designer can optimize a cathode bias circuit to work very well. Having a unit with fixed bias (user adjustable) does not make great sound on its own. I have had amps with both. There really are a lot of things going on here to just make statements concerning bias in this way. I think to have the proper bias optimized is VERY important but to say that any self biasing tube amp has problems is not the whole picture. This is not to start a whole debate yet again. I am very aware of the pros and cons of fixed bias amps and I have lived with both. And I have liked both a lot as well. If the circuit is designed well, a self biasing amp can be excellent. The 2A3 amps I have had (the last two pairs passing though my door) have all been self biasing units and were designed as such.

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Mobile I have a few question's for you on this bias front and the HF-81.

1) Do you pay extra for matched sets of tubes for your Hf-81 or any other amp you own ?

2)Have you ever tested them in circuit to see what there doing and if so did all the voltages and reading match tube to tube ?

3)Would you rather not bother with matched tubes ?

I'm not saying that the amps w/wo bias adjustment are going to be head over heals better than the other sound wise. I'm saying it just makes life easier and cheaper. I still say that there is no such thing as a matched set of tubes. The dealer would have to burn them in for weeks before they would settle to there permanent state. I have checked my 222C a number of times over the last few months and it needed mild adjustment everytime out of a brand new set a JJ 6BQ5's its finally to the point where there stable and these were suppose to be a matched quad with the test results written on the box.

Like I said before you may have better luck getting matched sets then some unknown Joe getting tubes from these dealers. They know who you are and know if they rub you wrong they will lose more than your business but a ton of people you know. Do you see what I'm getting at ??


This message has been edited by NOS440 on 03-27-2002 at 03:22 AM

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Posting oscilloscope photos, what a great idea for expanding the general edification on this forum... and more motivation for me to track down what is wrong with my HF-81 so we can use it for this demonstration. I hooked up the HF-14 directly to a little tuner Eico(FM5) and some speakers in my studio, sounds fine without any preamp. The Eico HF-90 tube tuner that I thought I would use was yet another item that although described as working is not. Meanwhile I ordered the manual for the HF-81 from AGTannenbaum so I can actually see how they expected it to be wired.

My romance with some of this old small Eico stuff-- well suffice it to say, the honeymoon is over.....

-as-is-ed and is-as-ed



currently upgrading

to all tube components

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I am feeling like some of this smaller and older Eico stuff would be fun if they worked when I got them but may not be worth spending time trying to fix . If it ends up being a really simple problem, maybe it would be interesting to see what these older units were supposed to be like. As soon as I get a digital camera I may start reversing the entropy by selling on eBay.

I found something in my barn today which is kind of interesting. It is the amp section out of an old Bell & Howell film projector ( mostly 6V6s). This amp would have been used to convert an optical track signal to an audio signal. Also has a microphone input so that the narrator of a silent film could be talking to the audience. Pretty small output transformer.

It might be interesting to know if converting optical signal to audio was anything unique, probably not, that was done with the sensor which probably put out a pretty good voltage. Now that I think of it there is another old "parts" projector in the barn, same model, I should scrounge the optical sensor off of that. Maybe one could make some strange kind of electronic instrument out of this stuff. Something that would translate any kind of optical variation into an audio analog. The question is , what?

Remember, Norman McLaren made films by painting in blobs for images directly in the frame. He later developed a whole vocabulary of other marks and blobs he painted into the optical section of the film strip. This resulted in some weird electronic noises that went along with his quaint hand painted images that were projected.

One could take the guts from an old projector and make some instrument that could scan some kind of optical pattern and turn that into sound. Now the fun part will be to devise the part of the instrument that would produce a varied optical strobing of some kind. Here is where a creative insight will be necessary.

OK, say you have a dancer (or drummer maybe) and a light source. Somehow you focus on a spot where the light is modulated by the dancer's movements or the drummers rhythms.....No this would not be audible frequency.....

...maybe you need to make something out of old bicycle parts or old film rewinds, something you can spin creating something that makes light strobes in the audible frequency range.....then again maybe you just rig up the sensor on a long wire and walk around until you find something optical that creates sound.

OK, here it is:

You have a cylinder about a foot high, say a foot in diameter. Put it on a variable speed turntable . Now you make paintings of patterns in black and white which you wrap around the cylinder. You speed up the turntable and hold the optical sensor on different parts (levels) of the pattern painted scroll looking for patterns which create interesting sounds. Now you have some feedback, you start noticing which painted patterns lead to the more interesting sounds, then next time you paint patterns with some understanding of what it will produce. You make many paintings.

You find a way to mount the sensor so a person can operate the movement of the senor over the rotating scroll with a lever. Now this whole shebang is set up as an installation piece. The person interacting with the piece can choose from a number of already painted scrolls, or you can have paper and felt tip pens handy so the spectator can experiment with there own scribblings to see what kind of sounds they might produce. Sounds like a project for the Exploratorium!

Like old Bobby D. once wrote...he needed a dump truck to unload all his ideas....

Actually this piece would be worth building. And to think I created it , thinking out loud, right here on the this forum. whoopdeedooo....

Now I see how Tim Hawkinson's mind works. He would probably not draw the patterns by hand though. He would find some analog to his own body and create from that the patterns which would then be converted to sound. Eg. "the sound of my freckles", "the sound of my foot print", or "the sound of my whole body print", "the sound of my handwriting", etc....

I even think I have some junk turntable I could use, although it would be easy enough to create one with some kind of makeshift turntable, any electric motor and something to vary the speed. For the cylinder part, picture a Zoetrope-like thingy.....

Definitely no reason not to make me one of these things herein described. Celebrating my freedom to do so. My old colleague and friend Steve would insist.

If you are open to art, fully explore his site and story.


-Phenakistoscoped and Praxiniscoped



currently upgrading

to all tube components

This message has been edited by Clipped and Shorn on 03-30-2002 at 02:46 AM

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Clipped & Shorn, the trip to Steve's url was enlightening... and perhaps he will indeed be one day free enough to move beyond the pen's constricted "Vens." Having worked with client's whose white powdered muse led them not only thither but too often beyond yon...

Steve's analogy of the difference between the lack of restraint in two dimensional sketches and the three dimensional constraints of his sculpture brought me back to your concept of images translated into sound.

A question arose, "Is cacophony art?"... and the answer grudgingly formed, "Yes... but variable deafness may be the only way to endure it!"

That brought me back to your post... but I would suggest that instead of taking a sensor made for a different purpose and hope it would translate into serendipitous yet pleasing tonal runs... why not build a sensor that would respond in the range of human hearing from the measurable structure of the graphic composition?

Music, as we Klipschers know it, is the manifestation of structured sound. For all its spontaneity, are not graphic arts "structured"... if even in the subtractive way that an agnostic might define God?

And, need your creation be limited to the input of one sensor? For is not "music" an admixture of tones, pace and harmony? And from a digital perspective, do not graphics have pixels that define subtractive primary colors into tonal variations. And, with the pseudo-harmonics of color attributes removed, are not the gray scale pixels left the bedrock of digital imaging?

While the probably outcome of analog translation approximates baseline cacophony... an analysis of digital structure may well produce the inspiration of great works and advertising ditties yet undiscovered.

The mind reels... and yet is not that where the reel movies really began? -HornEd

PS: Since this is the "Two-Channel" portion of the Forum, I expect your scanned graphic art to be in stereo!cwm34.gifRolleyes.gif

This message has been edited by HornEd on 03-30-2002 at 10:01 AM

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I looked at Dubov's works last night.

You would think they would at least give him more time to do his work.

(Is he that threatning?)

The Block/Frame ideas in his Sculptures are bizarre, and Amazing.

The Skylab series and his current pencil drawings are amazing

as well.

The real weird thing, is he claims his best work has been done in prison.

I think he would a good contibution to society, if they ever let him free.

(If he wants to be free?)


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Looks like his "life withough parole" was finally cut to 30 years. This was achieved through his lawyer who is paid apparently by the sale of his work on the outside. I am sure that this change makes quite a psychological difference even though according to my calculations it won't be until the year 2017. He will be in his mid to late 70s by then.

Note: the hours allowed to inmates for access to the shop have been extended, and Dubov now spends 3.5 hours a day in the shop, 5 evenings a week.

Later today I will see if I can take apart that old projector to see exactly what comprises the optical sensor unit.

Regarding how to create media to demonstrate this mechanism, another approach might be to take old film strips with optical tracks and blow up the soundtrack area very large to be printed on paper, then wrap this paper around the cylinder. As the turntable spins and the sensor is aimed, you might hear a garbled voice saying something like:

"frankly my dear,....I don't give a damn...." or "play it again ...Sam" or "ET call home".... "My name is Clipped and Shorn"...

This little piece is not meant to be high tech or even to aspire to creating the heights of beautiful music. It is meant to be an intentionally crude low tech humorous albeit insightful demonstration along the line of Tim Hawkinson's work.


-metroed and paramounted



currently upgrading

to all tube components

This message has been edited by Clipped and Shorn on 03-30-2002 at 03:56 PM

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Isn't the Eico an integrated amp?

I only ask this because your AE-25 is being used with the AE-3 preamp. My limited experience so far has shown me that a preamp has as much to do with the sound as the amp if not more.

I was running my Superamp with just a volume control the first week I had it. When I put my Sonic Frontiers Line 1 in the loop - there was a dramatic change in signature. The sound wasn't as incisive and I felt it was better balanced from top to bottom.

My guess is the Eico is a little rolled off at the top which is taming that awful Heritage treble Smile.gif



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Aren't you just the busy one! Jeepers.

I really, really, like my Superamp. I can even live with the Chinese KT88's. It's such a quick sound. I don't know how else to explain it.

My Bryston is sitting on the floor now on top of my Anthem. No one will buy them and I have absolutely no idea what to do with them.

The last time I put the Bryston in the system it lasted but a 1/2 an hour. I guess I'm just hooked on the sound of all that even-ordered distortion.

Someday I might even upgrade to amp that has even more distortion.




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Sorry to be off the board. Been up to my *** in aligators.

My Superamp is out getting a once over and have been living with the HF-81. Got to say (again), it's a wonderful little amp. Music has it Smile.gif Hope you can get it into working order.

JCT, when the Scott gets back and your life settles down, please give me a call. Would love to hear your gear ... Toddlers included (I'll bring mine Smile.gif !






Eico HF-81

Eico HFT-90

AES AE-25 "Superamp" (in temporary retirement)

AES AE-3 Pre-amp (in temporary retirement)

New Tube 4000 CD Player

1976 Klipschorns (KCBR's & ALK'ed)


Klipsch 1968 ALK Cornwall "II"s (LF/RF)

ALK Belle Klipsch (Center)

Klipsch Heresy (RR/LR)

Klipsch KSW-12 sub

Sonic Frontiers Anthem AMP1 (driving Cornwalls)

Sonic Frontiers Anthem AMP1 (driving Heresy's)

Denon AVR-4800

Toshiba SD-3109 DVD

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