HF-81 arrived today, yep, it's ugly all right

[Tom Mobley]

I was told it wasn't big on cosmetics, and he was right. But, this thing really kicks some serious patootie when I turn it up a little.

The shipping wasn't what it could have been, two of the tubes came mostly out. Sort of bent over with the pins bent. Fixed them up a little, put them back in and cranked it up, loud popping and scratchy static from the right, nothing from the left. Screwed around with it a little bit, called the guy, he had said it worked good. Swapped the two EL-84's in the back sockets and like a miracle the thing comes to life and starts kicking out some serious tunes. Got it hooked up to the DIY LaScala's in the garage, noting but a cheap JVC CD changer hooked up but it still sounds better than anything else I've heard. Even my crummy ears can hear this.

It has the transformers with the lips around the edges of the covers, three output tubes that have only "Made in Great Britain" in white around the base and one much newer looking Sylvania. The three look really old, have lots of black burned-looking areas in various places on the inside of the glass.

It's generating a lot of heat, the PS is hot but most of it is coming from the two EZ81 in front of the PS. Are these the rectifiers?

After several hours of playing at very low levels the scratchy, buzzy static started from the right speaker again, I think I hear a 60Hz buzz. This probably means the PS caps are bad, right? Shut it down.

Looks like the bottom might be all original, rats' nest wiring deal.

A bunch of the other tubes are Amperex, have the little cartoon on them.

Should be a real adventure to get fixed up. Craig, oh Craig, old buddy, old pal-o-mine, you've got a lot spare time with nothing much to do, right?

Tom

[Jim Cornell]

Tom

Im ganna be looking for a 2 channel amp, taking my time to do it!

The EICOs look like something youd see in the garbage!

What i need to know is,

1- will a 14 watt tube amp produce the same kick *** volume as a 100 watt solid state?

2-Looking at tube amps, even mcintosh 30 watt mono amps are $600.00

3- is there a cheaper 2 channel tube amp out there thats not 60 years old?

4- should i take a chance on a dynaco - 70?

I like the power of the volume knob, under 2, i wonder if tubes would do the same, at the same volume as solid state!

My pioneer SX 950, i caint turn it up to 2, it gets pretty loud!

Will i defeat the purpose of using the pre outs on the pioneer, to run tubes, or will this damage the tube amp?

Just a few questions, looking for answers!

Regards Jim

1980 Klipschorns

1984 Chorus

Pioneer SX 950

Sony 300 Disc CD

Sony 200 disc CD

[mobile homeless]

I cannot believe it was shipped with the TUBES IN THE SOCKETS. REPEAT, if anyone buys ANY tube amp, be sure to tell the ebay/audiogon loon to REMOVE the tubes from the amp and wrap carefully. Never ship an amp with tubes in the sockets. This bending of the pins back is very sketchy, btw. Always be very careful inserting and removing tubes making sure the pins align correctly and gentle rocking back and forth to remove and insert (not with large motions - very tiny). At least it sounds like you got some excellent tubes in the Mullard and/or Amperex. Of course, the condition is unknown. Get some backup tubes from a trusted source or seller. For new, Ei EL-84 will do if NOS is not available. Ditto with JJ but I think NOS kill these options. (btw, RCA/GE/Sylv EL-84 do nicely for NOS and are cheaper than Mullard or other options)

You need to buy some contact cleaner and go over the tube sockets, pots, and switches. Crackling can be a lot of things here, so dont jump to conclusions.

Also, there are numerous details that can be addressed before "shipping" the amp yet again, something I never like to do in the first place.

1. Makes sure you have your speaker wire connected properly and not touching any other outs. Should be on the 8 ohm screws.

2. Have your Function switch set to "normal." Make sure ALL the knobs are on correctly rotating them to stop positions to see if they align up. This is a simple point that people miss. Make sure tone controls are set flat (remember that right treble turns amp ON and off).

3. Hook your digital source to the TOP RCA jacks. Have the selector switch to Source A

4. Run the unit with the cover OFF for best cooling. It is VERY important to make sure that internal selector switch near the rectifier side is switched to the POWER trans side of amp. This switch combines the channels internally if to left side.

5. USE THE HUM POT next to the power trans to reduce some of the hum. This hum pot can work wonders with some low level hum. Gently adjust it to right or left to bring hum to lower levels. Have someone stand right next to the woofers to tell you when this is happening if you cant do it.

6. Once again, CLEAN all the tube sockets with contact cleaner (can be purchased at Radio Shack for $8 if needed immediately). Spray volume and "focus" and work knobs till scratchiness leaves.

The power transformer runs VERY hot with the EICO HF-81 so dont be alarmed here. Ditto with the rectifiers but the main heat is really coming from the power trans which, when driven hard, can actually be almost too hot to leave your fingers on.

You will more than likely need to replace the PS caps sooner or later. This is a job that can be done on your own with some practice soldering. Anyone can learn to solder and work on these amps. Craig will be the first to tell you this as he literally picked it up and learned all in the last nine months or so.

But be patient and try some simple trouble shooting and learn the amp's character. Tube amplifiers require a bit of interaction and attention to detail that can be rewarding on all sides.

Take a look at this page and compare the pic and labels with your own amp to start to learn the parts.

http://home.earthlink.net/~eico_hf81/eico_hf81_wiring.htm c>

Glad you got a unit that works at least! With careful attention, and some care in setup, you might get it to sing sooner than later. The PS caps will need replacing sooner or later and if your are up to the challenge, makes a good first test (after you practice).

kh

EICO HF-81

http://home.earthlink.net/~eico_hf81/ c>

ps- Make sure you have the tubes in the right sockets. You should have four 12AX7, two 12AU7, two EZ-81/6CA4, and four EL-84. Please see this pic for proper placement as well as connector layout: http://users.rcn.com/fiddler.interport/HF81LOUT.GIF c>

Links system one online / alternate components / Asylum Listing f>s>

This message has been edited by mobile homeless on 09-17-2002 at 07:36 AM

[mobile homeless]

No offense, Jim... but lord, you have been here for quite a long time, pre-dating the tube explosion over the last year or so. Just curious, did you ever READ any of the posts concerning tube amps? These questions sound like they are coming from a first timer forum member who hasnt been reading posts or perusing the archives.

Where have you been???

kh

Below, behold an EICO HF-81 not found in garbage:

This message has been edited by mobile homeless on 09-17-2002 at 07:50 AM

[Tom Mobley]

Jim,

The other guys here are much better qualified to answer these questions than me, I'm brand new to the tube game as of yestersay afternoon. I have a newish Nakamichi AV-400, 100W/side, couln't turn it up to 1 if there was anybody else in the house, didn't sound very good with my LaScalas. I had the Eico turned up to 4-5 in the garage, ear bleed volume and primo sound. I think those guys are right when they say "it's all in the first watt." Looks like the high power SS amp with the volume knob turned down to nothing is the problem, not the solution.

I paid $140 for this one, but it's rough looking and needs a lot of work internally. But I don't mind fooling with stuff. And, I was expecting to see some problems.

mh-

Yeah, the guy botched the shipping. There was a set of RCA jackes mounted on the back of the cage, wired to the 16 ohm taps. I think he didn't know what they were and didn't want to take it apart.

This thing is filthy, buy stock in contact cleaner companies.

1) OK

2) OK, they were all over the place. DIdn't know that about the on/off, was amazed that there was no switch.

3) Top set of RCA jacks have one that's really loose, I used the second, adjusted the switch.

4) OK, had the screen off after I figured out the RCA speaker jack thingie. Wondered what that little switch on the chassis was.

5) Haven't gotten as far as the hum pot level yet. It had some noticeable hum out of the right speaker just before it went back to scratchy poppoing static, but the left was dead silent between tracks, on Pause, etc.

6) Own stock in any contact cleaner companies? This thing is about to get a major wash down. The labels for the tubes and jacks are on the bottom, still pretty readable. The EZ-81's are producing more heat than the P/S, which was too hot to leave a finger on after a couple hours playing at a very low level.

What do those aluminum tubes around the tubes do? RFI shielding?

One thing for sure, this thing cooks when it's happy.

Tom

[dubai2000]

Kelly,

you must be getting tired of being asked the same things again and again, but thanks for your detailed response to Tom's post. After all I (and other first time buyers of vintage tube gear) might encounter similar 'problems'.

Wolfram

[Tom Mobley]

Yes, Kelly, thank you for taking time to post that detailed response. I appreciate the time and typing. I'm real happy with the way this is going so far, I think it's going to turn out good.

Hey, if I'd had 6 or 8 hundred bucks laying around I would have bought one of the nice ones, but I don't. I figure by the time I get done fixing this one up I'll know all about it, be able to keep it running for the foreseeable future. I'll probably have the same money in it, but I'll be able to piece it out a little at a time instead of taking a big hit in the wallet.

Tom

[mobile homeless]

No problem. Glad to see people getting all these old vintage pieces aglow again!

But seriously, I have two units and do not have over $50 in either piece (one has a whopping $10 in it). I got them both for $100 a piece but those days are getting rare. But the idea that you need to drop heavy $$$ into them is not necessarily true. IF you can learn to do the work on your own, the price of the parts is less than a service call on a typical solid state amp. And it is much easier to figure out and work on as point to point wiring is more sturdy than circuit board work.

Learning to trouble shoot and isolating the problem is the hardest thing and takes some time. Sometimes, the problem is easy, sometimes it takes a bit of sleuthing. But these amps are not that complex. Buy some books, get some advice, procure a good Volt meter, get a Weller or equiv. iron, practice on an old piece of junk...and you will learn faster than you think. The NET is a GREAT resource. I still have a ways to go but have managed to plod through a lot of mess through trial and error. Before the NET, it was a lot harder to get into this hobby. Suddenly, the info, parts, and amps are there!

Part selection is important, but this is my opinion. I had a hard time with this topic last year. Choosing your parts with care and learning the sonic differences takes time. Enter in tube rolling and the price CAN AND WILL go up quite a bit, however. But NOS tubes of proper selection take the amp from "good" to sublime, depending on choice.

Getting the amp to look as good as it sounds is actually pretty fun and not that hard. Both tbabb and Chris Robinson did GREAT jobs with their amps. The brass plate polishes to a shine more often than not, and the parts can be sanded and painted with ease. I redid my whole first amp you see above in a matter of hours, not counting the paint drying.

Putting in new PS caps can be done in a matter of minutes, believe it or not. An hour of being very careful and meticulous (very conservative estimate from removing old to intalling new) will yield a near perfect job with the parts cost coming in anywhere from $10-$40 depending on how picky you are. Two Sprague ATOM 40uF 450v caps are relatively cheap (I would tie the down securely too, just like the stock units). There are other options here as well.

System setup also yields BIG improvement in sound. I found that many do very little in this regard but the dividends are GREAT.

kh

This message has been edited by mobile homeless on 09-17-2002 at 09:03 AM

[BryanJ]

Tom, did yours possbily come from New Era?

I also had a guy on audiogon "proposition" me and it sounded like a beater also.

Hey, I'm not knocking it, with some personal TLC it will feel as if family

Bryan

[BryanJ]

Never mind my last post, damn that speed reading course. I do indeed miss details!

[NOSValves]

Tom,

Mobile is correct and the scratchy sounds and the hum just before it represented itself is most likely a tube starting to lose its contact in the socket. Use some quality contact cleaner and spray each tube pin hole. I use a bad tube to work the socket and spray them a few times if things are real bad. Also spray into all the volume and tone control pots while turning them there is a slot right where the wires solder to it to get the cleaner inside the Pot. Give the stereo selector and input selector a real good shot also while turning it back and forth. After this if the PS transformer is still running to hot to touch even for a short time then I myself would start to worry. Heat can kill them babies. I know that HF81s Power trans run hot but they shouldn't be so hot that you can't touch them for say 20 secs without pain.

So get to work on that baby because I have 3 amps rebuilds sitting here right now. I'd be more than happy to do it for you but you have to wait your turn

Mobile,

I do have one problem with your suggesting people become home techs 400+ VDC is nothing to play with and soldering in new parts is relatively easy I agree but you also have to test these voltages out. I really think basic testing should be done before its even used or turned on for that matter. Just think you should warn people that the insides of these amp are dangerous when there on. Heck they can even jolt you after there off ! Just thought I would put up the disclaimer warning !

enjoy Craig

This message has been edited by NOS440 on 09-17-2002 at 04:58 PM

[mobile homeless]

Well, the much higher voltages with tube amps should be a given here. I wouldnt do any of this without some study of some good texts along with any primers you can find online. All of these recs come with the WARNING: HIGH VOLTAGE addendum. And yes, these caps can hold a tremendous charge, long after power has been turned off. Bleeding some of these caps is necessary (with Radial units, a careful touching of a metal screwdriver with insulated handle across the lugs a few times is one trick)

Some believe in the ole one hand in the pocket rule so your body can never become a conductor path. It's a smart precaution.

Be smart and Careful.

kh

ps- I will say again, the EICO HF-81 transformer run at high volume WILL BE too hot to the touch even for as little as a few seconds. I have been around five HF-81 and every one has had very hot power trans when running full power. This is even mentioned in the full factory manual.

This message has been edited by mobile homeless on 09-17-2002 at 05:19 PM

[NOSValves]

There ya go we agree again !! this must be a record

[mobile homeless]

Scary, isnt it?

I am sorry about that 6CA4/EZ81 "4 seconds left" bid on ebay. I sat there and suddenly realized it was you holding that bid. Good thing there are some alternatives hanging about.

kh

[Tom Mobley]

Hmpf. Five cans of contact cleaner and it's like new again. Killed all the bugs in the side yard, too. See, the unexpected benefits of tube amp ownership abound.

It really does look a lot better. There was some kind of gunk layered on the chassis, like layers and oil and dust built up over years. Enough contact cleaner and a tooth brush got it down to the native corrosion. Transformer bells are pretty rusty too, but I can fix that.

The tube pins didn't want to clean up so I improvised with paint can cap with about a quarter inch of easy off oven cleaner in the bottom, soaked the pins for a minute, clean and bright as new! Clean up with a little bottled water, fine now. (I think I can hear Kelly shuddering all the way to Az, my hearing must be improving too. )

Are those two big orange caps with hose clamp bracket the PS caps? I have a bad feeling about those. Is there a consenus on a good replacement for them? Sort of middle-of-the-roadish? Auricap?

I think this thing has every original cap and resistor in the bottom.

Sure sounds better.

Tom

(Kelly, you exchange with Roger is very informative, thanks for taking time to post it.)

EDIT: numerous typos

This message has been edited by Tom Mobley on 09-17-2002 at 07:38 PM

[NOSValves]

Get Sprague Atoms and up the Value a little to say 40 or 50 uf or MFD whatever you want to call it. They are nice caps for reasonable bucks.

Craig

This message has been edited by NOS440 on 09-17-2002 at 08:21 PM

[mike stehr]

And make sure you turn it off when you solder them in!

Craig, This was one of some reasons I ditched the integrated sections of my HF-12's, to try to get the power supply trannies to run cooler.

It didn't really matter, they still run hot.

And both units power trannies run about the same heat wise, I gave up worrying about it.

They have been reliable.(Knock on wood.)

This message has been edited by mike stehr on 09-17-2002 at 08:54 PM

[mobile homeless]

Tnanks for the comments...

I would go no higher than 47uf with the PS caps and I now think I favor 33-40uf. With the tube rectifiers and no choke-loaded PS, you dont want too much rectification. The bass via the EICO is already very nice, perhaps one of the strong suits as is the amazing midrange openness and clarity. Stock capacitance is 30uf. 47uf would be acceptable.

Ultimately, I would rather see an ELNA Cerafine there but the room is problematic. As long as you are above 350v for the rating, you are fine. 450v is the stock for the ATOM.

Angela has some really good CAP pages on their site, all worth reading. Take a look at the various types from Paper in Oil to Film and foils. Be sure to take a look at the cap comments too. Interesting. I am also a BIG proponent of Copper Foil Paper in Oils but this is too much for the little EICO. If I build one, I am going to try the OIL caps in the power supply.

http://www.angela.com/catalog/capacitors/

kh

ps- Tom, the FIRST comment on that TWEAKS page on my EICO site goes into detail about the PS cap replacement with a pic of a Sprague ATOM as well. Also, the carbon resistors in these old amps actually sound very sweet. They do havea problem with drifting but actually sound pretty nice in some ways.

This message has been edited by mobile homeless on 09-18-2002 at 12:39 AM

[Tom Mobley]

mh,

Looks like the Sprague Atoms you mention and posted a picture of are about it. All of the other nice ones I found are too large in diameter for the chassis.

I really want to replace the rectifier tubes, there's two dissimilar in there, not enough markings to ident one of them. The stuff inside of them is not the same at all. You still think the JJ Tesla's you mention on your page are good? I'm thinking about buying the Spragues, the JJ EZ-81's and a set of new JJ EL84/6BQ5's. They're cheap on ebay, and I don't have a tube tester to go through a bunch of used ones, can't afford NOS Mullards or similar. At this point I just want to make sure there's no real junk in there.

The reason I'm concerned about the PS stuff is that there is a little wax on the bottom plate, it looks like it ran down the leads from the PS.

Tom

BTW, after the cleanup extravaganza I ran the thing for about 6 hours last night, it really cranks the tunes out.

[mobile homeless]

WEll.... I dont really like the JJ EL-84 as much as I thought I would but along with the Ei, are probably the safest new bet. I have heard some good things about teh Ei EL-84. Regardless, the NOS EL-84 are a WHOLE lot better and worth it to me.

As for rectifiers, I would browse ebay for some Mullard or Amperex EZ-81/6CA4. They come up quite often (as stated, I just got a pair myself for $26). The Mullard EZ-81 is definitely the best but RCA/Sylvania are not bad either and you see them around.

What are the 12AX7 and 12AU7 again? Or did you tell me?

What is your CD player and cable situation?

kh