Eico ST-70 vintage tube integrated amp restoration/upgrade
Comments
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Just Windex (so far). The printing on these is very sturdy (not so for all vintage hardware!).
I am not an expert cleaner/cosmetic restorer (that's an understatement).
There are some good threads on cleaning and restoring at www.audiokarma.org -
I just got an ST-70 (and matching ST-96 tuner) from my dad. The last time he turned it on it was working perfectly (that was 25 years ago). Any precautions I should take before I fire this baby up? I'm so stoked! :cheesygrin:Sony KDL-55HX800 55" 3D tv
Pioneer VSX-1021K Receiver
Sony PS3
CS2- Center
Monitor 70 - Mains
R50 -Sides
CS1-Rears
PSW110- Sub
All Cherry finish :biggrin:
Infinite Baffle dual 18s in the works
HEY!! Check out my band on iTunes!!
http://itunes.apple.com/us/album/world-without-heroes/id448355575 -
I just got an ST-70 (and matching ST-96 tuner) from my dad. The last time he turned it on it was working perfectly (that was 25 years ago). Any precautions I should take before I fire this baby up? I'm so stoked! :cheesygrin:
Here's a reasonable primer for starters -
http://www.audiokarma.org/forums/showthread.php?t=778
Also, read through the work that Fongolio's done to his - he did basically what needs to be done. Don't want to discourage you... but it's not gonna be plug and play four-plus decades after its genesis.
There's a fair to good chance that most or all electrolytic capacitors in an amplifier that old (and unused for decades) are bad. It is sometimes possible to reform them -- it is often possible to blast them irreversibly by just plugging an old amp in and turning it on. Other capacitors in the circuit may also need to be replaced for the amp to operate properly (and this means not just "sound good" but also "operate without endangering the output tubes and output transformers").
The other important caveat - do not operate a transformer-coupled vacuum tube amplifier unless there is a load connected to the output transformer (i.e., a speaker or "dummy load" resistor connected to the speaker terminals for each and every channel of the amp). While there are some vacuum tube amplifiers and some circumstances in which open-circuit operation won't destroy the output transformer - the bottom line is that it is far better to be safe than sorry.
HTH, as they say. -
The link mhardy6647 provides is excellent advice. One more point....make sure the volume level is all the way down before turning on the variac. I speak from experience on this one. Good luck and congratulations, once restored the Eico ST-70 is an excellent sounding integrated.SDA-1C (full mods)
Carver TFM-55
NAD 1130 Pre-amp
Rega Planar 3 TT/Shelter 501 MkII
The Clamp
Revox A77 Mk IV Dolby reel to reel
Thorens TD160/Mission 774 arm/Stanton 881S Shibata
Nakamichi CR7 Cassette Deck
Rotel RCD-855 with modified tube output stage
Cambridge Audio DACmagic Plus
ADC Soundshaper 3 EQ
Ben's IC's
Nitty Gritty 1.5FI RCM -
First, I absolutely love this now old thread. Makes me smile everytime I see an e-mail notice for it pop in my Inbox.
Talk about the 70's Boston sound. Big fan of HUMAN Speakers here, but I don't remember hearing the 110's.mhardy6647 wrote: »(speakers are a pair of EPI 110C, from my favorite local emporium)
I may have to drag my 100's out of storage... and my Heathkit... I need a nostalgia fix...More later,
Tour...
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"It's easy to get lost in price vs performance vs ego vs illusion." - doro
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I didn't remember them either - there's nothing really different about them from an EPI 100. The price was right, though (cost me a pair of foam surrounds in toto).
Winslow Burhoe's still in the business, by the bye. -
I've had my hands in one of those. Not a bad little amp. I had to replace all the input jacks, change the source selector and put a gutted the phono stage and changed it to what Scott used to use in the 2xx series. Had to add another transformer as the scott design was dragging the system down. Very quite phono stage now ans silky smooth. I also re-ran wires to clean up some of the rats nest. I'll have to throw some pics up when I find them.
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Not as a consequence of this thread :-) but... now that I am officially retired and finally have a little time to play in the new hifi room, I am doin' some organizing. Finally re-installed my real CD player and DAC and did some quality listening with the SE 2A3 amp on the Duplexes.
One of the short-term goals was to improve the segregation of the soiled state and vacuum tube hardware in the room... separate but equal ;-) One of the biggest feng sui disconnects in the room was having a Yamaha CR-1020 sittin on the shelf above the 2A3 amp, and a perfectly good EICO ST-70 (the one, I'm sure, I mentioned in the early days of this thread; kindly rehabilitated by Gary http::/the-planet.org Kaufman for me) sitting over on the sideboard, wedged up against a Pioneer SX-1050. Grabbed a tape measure; made a few measurements, lugged a couple of components around and rectified that situation.
Hooked the CDP/DAC to the ST-70 and - what the heck - the pair of Polk Monitor 5Bs that had been keepin' me company in my work-week apt down in MA. Threw in a copy of The Commitments sound track.
Result? Not too shabby. Not shabby at all. If there are folks who think the Monitor 5s don't have much LF... c'mon over and allow me to dispel that notion. -
^Hows about a pic of all that prettiness????"....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
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The light has failed... tomorrow.
Heck, who know that Monitor 5s had slam? -
The EICO did.
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dudeinaroom wrote: »The EICO did.
Well played, sir. Well played.
OK some photos. The Polks really had me tappin' my toes last night - unfortunately, this particular pair of Monitor 5 family members (I call them "5B", but I don't think that's really what they are) has the infamous "Silver Coil" tweeters. They betrayed their legendary piercing qualities when I spun a copy of the (somewhat bright) remastered CD of the Black Crowes' Shake Your Money Maker.
ST70 and M5bs by mhardy6647, on Flickr
Today, I swapped a few other low-ish sensitivity, monkey coffin-type speakers in... and ended up spending a hour or more listening to a pair of refoamed dump-find EPI 110C. That EPI inverted dome tweeter is not quite a sweet as the peerless, but it's considerably less "hot" than the SL2000 in the 5s, their dispersion is excellent, and these very modest EPIs are almost astonishingly transparent sounding given their age and ultra-simple construction values. The crossover, as some of you doubtless know, is just a single cap on the tweeter (first order); the woofer runs free. I may have put in decent XO caps in these when I refoamed them, but I can't remember - it's entirely possible that they still have their 1970s NP electrolytics in 'em.
At any rate, fine sounding little loudspeakers.
EPI 110C by mhardy6647, on Flickr -
I really need to get my butt in gear and rebuild my ST-70. My grandfather built it from a kit in 1962. I do plan on modding it as has been done in these threads over at AK.
http://www.audiokarma.org/forums/showthread.php?t=379470
http://www.audiokarma.org/forums/showthread.php?t=392447 -
Like that other ST-70 (ahem... Dynaco, ahem) modifications are indeed required 'for best results' ;-)
Yes, get on the stick! It's a good sounding amp, with some cojones to boot. -
I have used it on and off over the years and am impressed with the sound. I can only imagine how good it must be with all fresh caps and all the unneeded stuff removed. I have also acquired the replacement front and rear panels. I just need to find the time to get to work on it.
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Nice work
