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Eico ST-70: good unit?

J

jnporter

New Member
I might have a shot at a deal on an Eico St-70 that has recently been partially rebuilt to replace aged, possibly unsafe components. The owner said it is good to go for a few more years now. I can't find any listening reviews for it on the net, unlike the HF-81's, HF-87's, etc. Is it considered as decent an amp as the Dynaco St-70? Thanks.

Jim Porter
 
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It's a great integrated amp, for the money (i.e., it has a built in preamp).

There are a number of modifications that I feel are essential and others that I think are very helpful. The tone control circuit and loudness switch aren't too good, and there are a lot of ceramic caps in the sound path - not a good idea IMHO. I'm not a big fan of the plastic knobs, and so I've made different faceplates & etc. for the front.

I'm gutting the tone control section of an Eico 2080 amp, which has a similar circuit, and replacing it with a remote controlled volume pot, so I can park my lazy self across the room and adjust the volume without getting up out of a chair . . .

I compiled a separate list of recommended ST-70 mods. PM me with an e-mail address and I'll dig it up for you.
 
Grab it, I have had an Eico ST-70 as my "main" amp for quite a while. its just GOOD, ugly as sin but it sure sounds pretty.
 
jnporter said:
I might have a shot at a deal on an Eico St-70 that has recently been partially rebuilt to replace aged, possibly unsafe components. The owner said it is good to go for a few more years now. I can't find any listening reviews for it on the net, unlike the HF-81's, HF-87's, etc. Is it considered as decent an amp as the Dynaco St-70? Thanks.

Jim Porter
Click to expand...
The EICO ST-70 and Dynaco ST-70 are different animals. The EICO is an integrated amp with 7591 output tubes and the Dynaco is a power amp with EL34 output tubes. Both are GZ-34 tube rectified.

The EICO is a good sounding amp when properly set up, like many 7591-based amps. Some prefer the lower power ST-40 (also with 7591 output tubes).

BuzzK said:
It's a great integrated amp, for the money (i.e., it has a built in preamp).

There are a number of modifications that I feel are essential and others that I think are very helpful. The tone control circuit and loudness switch aren't too good, and there are a lot of ceramic caps in the sound path - not a good idea IMHO. I'm not a big fan of the plastic knobs, and so I've made different faceplates & etc. for the front.

I'm gutting the tone control section of an Eico 2080 amp, which has a similar circuit, and replacing it with a remote controlled volume pot, so I can park my lazy self across the room and adjust the volume without getting up out of a chair . . .

I compiled a separate list of recommended ST-70 mods. PM me with an e-mail address and I'll dig it up for you.
Click to expand...

Yes, they're not the prettiest of amps and do need a few mods. Do you have pics of your different faceplate & knobs?
 
Sorry - these are crappy photos . . . but you'll get the idea.
 

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Hi Jim,

Some years ago it was an Eico ST-40 that really got me interested in tubes. I bypassed the preamp section and used it as a power amp. Much better sounding that way I think. After that a friend bought the big brother ST-70 and we did similar mods to it, including triode connecting the output tubes and removing the global feedback. I also replaced the voltage amp tube with a 12AU7 with a CCS anode load the put a CCS in the shared cathodes of the 6SN7 differential stage.

It's provided a lot of good sound for him for 5+ years.

John
 
BuzzK said:
I'm gutting the tone control section of an Eico 2080 amp, which has a similar circuit, and replacing it with a remote controlled volume pot, so I can park my lazy self across the room and adjust the volume without getting up out of a chair . . .
Click to expand...

Useful. Love to see your write-up of that.
 
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