[Flyquail56]

...About the only reason I hesitate is that I am using two small powered subs and there is no pre out on the HF-81 so I would have to take it from the speaker outs at high level...

You may be in luck. The tape out on the HF-81 is between the linestage section and the voltage amp of the power amp section. Incredibly dumb for a tape output, but it actually makes it a pre-out. I've never used a subwoofer myself, but it should work for you.
There's a link to the schematic here:
http://home.earthlink.net/~eico_hf81/

Best regards,
Mike

[BrassEar]

Thanks Mike. I confirmed what you wrote in some AA searches.

Now I just have to find one on Audiogon or Ebay without spending $800 or so.

[S Clark]

You could pick up two HF-12's.  In theory, they should sound better than the HF-81 and two good ones will run you about $250-300.

[Atlplasma]

...About the only reason I hesitate is that I am using two small powered subs and there is no pre out on the HF-81 so I would have to take it from the speaker outs at high level...

You may be in luck. The tape out on the HF-81 is between the linestage section and the voltage amp of the power amp section. Incredibly dumb for a tape output, but it actually makes it a pre-out. I've never used a subwoofer myself, but it should work for you.
There's a link to the schematic here:
http://home.earthlink.net/~eico_hf81/

Best regards,
Mike

Hi Mike:

Are you saying it's possible to connect a sub to the ST-70 through the tape output? I'd be curious to try it but don't want to damage my equipment. Any special precautions one should take?

[Flyquail56]

Hi Mike:

Are you saying it's possible to connect a sub to the ST-70 through the tape output? I'd be curious to try it but don't want to damage my equipment. Any special precautions one should take?

For an ST-70, it is possible, but probably not a good idea. According to the schematic, the tape output on the ST-70 is wired the same as most equipment. It takes the signal right after the selector switch. In other words, it is upstream of the volume control. Using the tape output on the ST-70 (and most equipment) to send a signal to a subwoofer doesn't work well at all because one would have to control the volume of the subwoofer at the subwoofer. The sub will get a signal with no attenuation at all. Constantly trying to keep the levels matched between the main amp and sub each time you change volume would, to me, be a giant hassle.

The HF-81 is fairly unique in having the tape out placed after the linestage. A few other Eico amps are similar, the mono HF-12 and HF-20, for example. That is what makes it suitable for use with subs, because it is really a "preamp-out".

Best regards,
Mike Hazel

[Flyquail56]

Thanks Mike. I confirmed what you wrote in some AA searches.

Now I just have to find one on Audiogon or Ebay without spending $800 or so.

I hope you find a good one. I've had mine for a few years, and bought it from an old friend. I paid a fair price for it, but not quite ebay prices. As terrific as they are, I agree that the thought of paying two to three times the price of other EL84 powered integrated amps can be hard to rationalize. They're worth looking for, though. 

Best regards,
Mike

[Atlplasma]

Hi Mike:

Thanks for the design clarification.

Steve

[Atlplasma]

Well, ltr317 was absolutely right about the build quality on the spade adapters. I was working with my ST-70 to do the loudness switch mode and bumped one of the adapters. Disaster. One of its forks snapped right off.  Does anyone know of a similar product with better quality?

Steve

This is a bit off topic, but I'm wondering if anyone has used spade adapters on their vintage units. My speaker wire is a fairly heavy gauge, so I was considering buying some adapters off Ebay. Any opinions on using these things?

I bought some off ebay from a Hong Kong vendor.  They look nice but the ends are too thin and break off easily.  Also, when you tighten the speaker screw the soft metal on the adpater spreads and loosens the screw over time.


Did they look like this? These seem pretty beefy.

http://cgi.ebay.com/16x-Adapter-Fisher-Mcintosh-Eico-Amp-Banana-Plug-SPADE_W0QQitemZ280294595247QQihZ018QQcategoryZ32838QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[BrassEar]

Gave up one the Eico and picked up a Scott 299B (LK-48). The Stereophile article permanently inflated the HF-81 IMHO way beyond its worth. Most are selling for $600-800.

The HF-81 is almost SET-like in its midrange presentation but many of the Scott units have better bass and dynamics.

[Mossback]

Generally speaking Eico Gear is of very poor quality. It used cheap output transformers like the Acrosound 330, those old Chicago transformers all suck.
There is little support because after all these years the EOM supplier (Heyboer) still supports Eico power supply transformers and some outputs. In fact Hayboer is so lame they will one-off build you an upgraded power supply transformer for your old Eico at a fair price. 
What ever you do don’t get two Eico HF-12’s and use the TAPE OUT as an input from your preamp. Better you spend more on an Eico HF81.
There is a Yahoo group for Eico.

[Atlplasma]

I agree. Awful stuff that only continues to put out warm tube sound after 45+ years of continuous use.  From what I hear, Scott is pretty bad as well. I think any owners of Scott or Eico stuff should just leave their junk at my doorstep.   

Steve

PS. Seriously, it is too bad that so much old gear is going sky-high price-wise. Wish it weren't the case.

[S Clark]

PS. Seriously, it is too bad that so much old gear is going sky-high price-wise. Wish it weren't the case.

The HF-12's are still a bargain.  They are usually on Flea-bay for $75-125 depending on condition. I have picked up several over the years just to have in available in my physics classes.

[silentv0ice]

i'm in Kuala Lumpur , Malaysia. I have an Eico HF81... up and running. Any Body here, has a spare volume port to sell?

[Atlplasma]

You might check the Eico group on Yahoo. They are hardcore Eico folks.

Steve