Eico Hf-22 tube mono block info wanted

mcgarick

Super Member
Greetings

I picked up these mono's on Craiglist this evening and know nothing about them, other than they work, and the guy who had them used them up till he died and little while ago...The daughter sold them to me.

So, any information would be appreciated...

I heard an Eico HF-87 at a tube repairmans house in Ballard WA and it was pretty glorious in a musical type way..

I.E non HIFI music lovers type sound, which I like. (I like it all)

They have 6L6 power tubes in them, and what I would like to know is.. what else I can use in their place. el34's and/or kt88's?

I found little on the web about them......

Any information welcome.

Thanks!
 
I'd use them as designed - B+ voltage isn't high enough to take advantage of other tubes. Any 6L6 should work fine in this amp.

But... EL34 can be used with the following caveats:
1) heater current is higher - check power transformer temperature.
2) cathode resistor will probably need to be changed.
3) pin 1 will need to be wired to pin 8 on the power tube sockets
 
Output transformers are the same as used in the HF-20 (6L6) AND the HF-35 (EL34)

Nice sounding units!!
 
BTW: Eico definitely DID use a different power transformer, in the HF35, than the HF22.

That said- you might be able to get away with it, using a GZ34 rectifier, if you used EL34s. Less heater draw on the rectifier, might offset at least some of the extra heat, due to the increase in the heater current from going to EL34s instead of 6L6s. The GZ34 would also increase B+ (just make sure it doesn't exceed the power supply cap ratings!)... which might benefit EL34s.

A 5V4 would probably also work. Not quite as much B+ as with the GZ34, but also, like the GZ34, only 2a on the heater (as opposed to 3a for the original 5U4).

You'd DEFINITELY need to re-bias the outputs, though (probably different cathode resistor needed)...

Personally, I'd leave the amp as-is with a good set of 6L6GCs or 7581s in it. It sounds FANTASTIC as is. IMHO, the EL34 over-works the output transformers... so the bass isn't as good (it starts to saturate on the lowest bass at 35w, where it's absolutely clean at 22w)...

Regards,
Gordon.
 
Thanks for the info everyone.

The only other tube amps I've had were some ASL's integrated amps and Quicksilver mid mono amps, which were good but I like the Eico sound much better. I cleaned the dust off and put them in my main system, they sure sound better after a few hours, quite a big difference.
Now, I'm wondering about other Eico gear, I love the natural musicality these offer. I'm leaving them totally stock.
I was really, really lucky to look at Craigslist at the right time!

I couldn't believe it and did about a 2 minute research and then called the guy.

Does anyone know when they started making this model?

I took a very nice Percision Fidelity M-8 amp out and put these in, I think I prefer these, but time will tell. Different flavor......
 

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These 22's might be a little on the rare side...I could find little about them on the web. How come there no EICO web site with history and models? Scotts got a real nice one.

Seems there should be considering Eico's sonics are top shelf.

They're used to be a really cool monster receiver web site that was fun to look and read, but I think it's gone.....too bad people can't salvage sites like that, great info resource.

How's the Eico HF-85 preamp?

Is it as good as the power amps??
 
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These 22's might be a little on the rare side...I could find little about them on the web. How come there no EICO web site with history and models? Scotts got a real nice one.

Seems there should be considering Eico's sonics are top shelf.

They're used to be a really cool monster receiver web site that was fun to look and read, but I think it's gone.....too bad people can't salvage sites like that, great info resource.

How's the Eico HF-85 preamp?

Is it as good as the power amps??
mcgarick, did you ever get a HF-85 preamp for your pair 22’s?
Was wondering the same. There’s one listed now on that auction site now.
Also realize this is an old post.
 
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