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Eico AF-4 stereo SET EL84 amp

Something about that type of plastic in that it's maybe organic based, and one thing I also don't like on my HF-12's , but can live with!
 
Shadowdog said:
Something about that type of plastic in that it's maybe organic based, and one thing I also don't like on my HF-12's , but can live with!
Click to expand...

I ended up getting the knobs "decent" on my 85, but it took lots of hot water and Dawn dish soap soaking, along with a toothbrush to help them. I don't know if you could ever get them perfect though. Kinda like finding a really clear set of Heathkit 151 knobs.:no:
 
That's what the manual says -- why is anyone's guess... the AF-4 also has that separate/combined switch and a (i.e., one) preamp output. In the context of some of the HF-81's eccentricities, it's kind of hard to understand some of the EICO engineers' intentions from this distant temporal perspective :-P
 
Yeah, I just looked on ebay and don't see any Eico preamps that don't have their own Power. Never heard of one either. How strange.........handy, but strange. I wouldn't think a phono stage would be any kind of load to worry about, especially if you made a separate little DC supply for the phono tube fils.. Maybe a wal wart would work ok. Heck, you could use the one in the RCA manual probably and it would sound fine I bet. :scratch2: Ah, so many tubes, so many projects, so many ideas, and no time to speak of. Hey but only 46 Mondays left by my best calc. :yes:
 
Actually, yes there were two versions of their mono preamp the HF-65 -- one was self powered, and the other one... was... not.
EDIT: Well... I think I got that not quite right. There was an HF-61 and an HF-65. Both mono preamps; different cosmetics. Just looking at Google images, at least the HF-61 existed in a self-powered version; I am not sure about the HF-65.

The HF-65 was certainly a cute little rascal...

hf_65_435071.jpg

hf_65_435072.jpg
 
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Very nice op. I heard a pair of HF 22's a while back and I was hooked. I am starting out with a HF20 and pray mine turns out as nice as your project did.
 
I still want -- someday -- to acquire one of the big stereo EICO power amps... an HF-87 or HF-89. While I'm dreaming, I'd like a pony, too... ;-)
 
Id like to get an AF-4 to match my renewed HF-85 pre. I now the 4 doesnt need a pre but the pair would be a great combo in their own rite.
 
mhardy6647 said:
Actually, yes there were two versions of their mono preamp the HF-65 -- one was self powered, and the other one... was... not.
EDIT: Well... I think I got that not quite right. There was an HF-61 and an HF-65. Both mono preamps; different cosmetics. Just looking at Google images, at least the HF-61 existed in a self-powered version; I am not sure about the HF-65.

The HF-65 was certainly a cute little rascal...

hf_65_435071.jpg

hf_65_435072.jpg
Click to expand...

Strange, what with the AF 4 being stereo. Does the owners manual say what he 200vdc is for? :scratch2:
 
Update March 2016:

I have been rotating my AF-4 into service pretty regularly and it sounds great

but...

One channel is now cutting out intermittently

I think it has to do with the 1M ohm dual volume pot. but I'm not sure...

edit: In the end it was a cold solder joint
 
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I relaced the tone pots in my hf85 with dual lin. ALPHA pots from AES
and the vol pot with APLS 500k analog pot.
no LDNS sw.
had to do some shaft extnsion.
of course the old knobs go bye bye and nice new ones are used. with set screws.
works like a champ.
If you can ""restore"" the Eico pots more power to ya.
I kept the old pots for posterity. dont know if they're any good.
 
I talked to Mark O. at Old Radio Parts and he can rebuild the pots for me

so that is an option for sure

I just want to be sure the pots are really causing the channel drop out before I commit
 
near as I know it's the resistance track that wears over time, some alot from lots use.
Only way to tell is measure R while turning the pot and see if its doing funny things or smooth as R is variedd.
 
Well, I re-tensioned all the tube sockets after tapping them and having them make noise. Cleaned them with my mini files.
Thought that did it. Nope, still lost a channel

Using the wood chopstick, I tapped around the coupling caps some more and lo and behold it made the channel drop out, touch again and the channel restored. Found the original cold solder joint. Re-flow the joint, Playing nice now and so far, no channel loss

By George, I think I got it!

Time will tell

From now on, every tube amp I rebuild will get the chopstick test

Kit amps...go figure
 
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Its cheaper for sure
This is the first kit amp I have encountered and up till now its been pretty good

So, I will hold off on the new pots for now
 
No joy

Played great for about an hour, then I powered it down, let it cool and when I fired it back up, no left channel

The saga continues

so depressing
 
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Omegaman said:
Played great for about an hour, then I powered it down, let it cool and when I fired it back up, no left channel
Click to expand...

NO! I powered it down and then installed the bottom plate and top screen, while doing so, I inadvertently displaced a 12dw7 tube causing the channel to not work

I just believed the worst, it must be break time

Anyway with the 12dw7 in place the amp is again playing beautifully and this thread can fade back to obscurity

The truth is the amp simply was jealous and wanted attention
It got a series of cleanings and service tasks and I poor babied it till I was ready to get rid of it out of frustration

then it started being nice to me again

my Corvette did the same thing
 
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