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EICO ST70 Purchased. Any info?

nomar247

nomar247

New Member
I just purchased this EICO ST70 from a local yard sale. The owner couldnt tell me much about it, said it hasnt been used in years. Its in pretty rough shape but decided to take a gamble. I paid $50 in as is condition.

This is my first piece of tube equipment, ever.
(I own all Klipsch speakers and was told a million times to buy tubes for them)

I also heard there is a certain way to break in tube equipment. Is this true?

Any info on this EICO ST70 amp and how to get it started would be greatly appreciated. Thanks.



 
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Nice grab!
If the tubes are good you have about 5x what you paid right there. That 5AR4 on the right looks a bit white, so it may be toast, which is too bad as that probably is the best (and most expensive) tube in there.

FWIW, that's one filthy chassis. I'd pull and test the tubes and then clean up the chassis. It almost certainly will need to get recapped, but you can bring it up slowly on a variac to see if it actually works. You will need a 5AR4 to do that though and if that one is a whitehead and dead, you'll need to buy or borrow one.

I'd find a tube guy locally and get him to lend you a hand. It's a nice amp and certainly worth some effort, but it might be too much for a beginner to bite off. But you aren't going to lose any money on it as the parts (tubes and trannies) are worth a decent sum on their own
 
Yeah, I've heard a local audio repair shop in Alameda Ca called Champlifier. The bench fee is $35.

I'll bring it in and see whats what. Hopefully it can be resurrected.

Ballpark range of what restoration cost these days?
 
nomar247 said:
Yeah, I've heard a local audio repair shop in Alameda Ca called Champlifier. The bench fee is $35.

I'll bring it in and see whats what. Hopefully it can be resurrected.

Ballpark range of what restoration cost these days?
Click to expand...

35 an hour is an excellent rate, esp. if the guy is older (yeh, I'm a profiler, what the heck). If you want to take it slow, you could ask him about changing all the electrolytics (because we know they are bad), cleaning the switches, sockets, and RCA connectors, and checking replacing the coupling caps with a decent film (orange drops or the like). I bet you could probably get in an out for around 200 to 300 maybe. Plus whatever tubeage you may require.
 
IF you take it in, do so knowing that those tubes are worth $350+ if the 5AR4 is a good Mullard. Don't let anybody tell you that they are all worn out and they replaced them with new Chinese tubes. You have $100 in 7591s there, a $75 Mullard 5AR4 if it's good, $75 to $150 in 3 Mullard 12AX7s and $50 in 2 Mullard 7247s, if they are all good and they may be. Dirty doesn't mean bad..:no:

Favors like that you can do without. :yes:

Here's a link you may want to look at..

https://sites.google.com/site/vintagetubeaudio/eicost70page-1
 
Thanks for all the advice. Greatly appreciated.

When I do get this up and running, can I use this alone with a cd player?
Or will I need a pre-amp?
 
Congrats! Really Nice amp when rebuilt!

Yes just plug the CD player into tuner or aux. Anywhere except phono. It is called an integrated amp as it already has a preamp built in including a phono section.

Anyway recap it fully as you risk the transformers if you don't and never run it without a load (speakers or a 16 ohm 25W resistor when testing etc.) or you risk the Output Transformers.

Here's another site with more info.

http://www.tronola.com/index.html
 
You didn't buy this amp -- you STOLE it. Don't turn it on with that white rectifier in there. It could kill the power transformer.

These are excellent amps if properly reworked. I wouldn't trade my customized Eico ST-70 -- it's very musical.
 
Rectifier is toast - and it doesn't look like a 5AR4 to me.
The ST-70 is a nice amp with a couple of well-known, serious design "features" (mistakes!), the fixes to which are well documented.

Probably not the very best starting point for a tyro, but as an erstwhile kit, the design and layout is pretty straightforward and there is plenty of room below decks for the fat fingered (like me) to work on the amp.

For the record, Gary Kaufman kindly fixed mine up for me (i.e., I haven't even touched its innards myself) :-)

 
Andyman said:
IF you take it in, do so knowing that those tubes are worth $350+ if the 5AR4 is a good Mullard. Don't let anybody tell you that they are all worn out and they replaced them with new Chinese tubes. You have $100 in 7591s there, a $75 Mullard 5AR4 if it's good, $75 to $150 in 3 Mullard 12AX7s and $50 in 2 Mullard 7247s, if they are all good and they may be. Dirty doesn't mean bad..:no:

Favors like that you can do without. :yes:

Here's a link you may want to look at..

https://sites.google.com/site/vintagetubeaudio/eicost70page-1
Click to expand...

I gotta ask, who got you Andy? There are "some" guitar players that insist on new tubes and back up tubes, so it's all up front, but yeh, stealing Mullards and other high end glass is pretty chicken chit. I always want the amp to sound it's very best when the dude gets it back, so it wouldn't even make sense for me. I've donated a Tele or Mullard just to keep a piece all European up front. Tell ya what though, some of these newer Russian tubes are contenders too.
 
It's a great amp and you got it at a great price. Don't be scared of it, but it would be good for a tube tech to have a first look.

There's lots of info on these here, but remember that these were also built as kits so there are full build instructions with diagrams and schematics available. Just go online an look around, or ask for help here. There is also an Eico user group on Yahoo.

Welcome to tubes; you make well keep a SS amp on the side, but I predict this will be your daily driver.
 
I'd love to keep it, but its a bit much for me at this time.

I'm either gonna sell it as is, or have it sit in my garage for a long while before having it repaired.

I'm on the fence. Should I let it go, or would it be worth it to keep and repair later on?
 
mhardy6647 said:
Rectifier is toast - and it doesn't look like a 5AR4 to me.
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Hard to tell with the white, but it's supposed to be a 5AR4, and I've seen ones that look like that. I don't have one around right now to give a harder look at. Maybe the OP could snap a new, closer pic. It would be a shame if it were a Mullard though.

jaymanaa said:
I gotta ask, who got you Andy?
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Nobody, but I've read a couple stories here over the years about guys bringing in vintage stuff and getting them retubed with Chinese tubes that didn't seem to measure up. I've tested a few tubes and most of the old Mullards, Teles and Amperexes, in fact most in general, test fine.
 
Andyman said:
Hard to tell with the white, but it's supposed to be a 5AR4, and I've seen ones that look like that. I don't have one around right now to give a harder look at. Maybe the OP could snap a new, closer pic. It would be a shame if it were a Mullard though.



Nobody, but I've read a couple stories here over the years about guys bringing in vintage stuff and getting them retubed with Chinese tubes that didn't seem to measure up. I've tested a few tubes and most of the old Mullards, Teles and Amperexes, in fact most in general, test fine.
Click to expand...

Yeh, take the PAS II for example. No vents in the chassis and still the Mullards test find after all these years. If I'm working on other peoples gear, it's usually the power tubes that get changed due to large imbalances. So I do have a big box of orphan power tubes.
 
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