Early models had the best output transformers one can find. To die for mid range sound. Simple design, many after market mods.

Weaknesses of a Dynaco ST 70?? NOT!

What's this??! "3500 Watts - Was Available Assembled Or As A Kit (1972-1977)"

Who edits these pages anyway??! Sigh. More like 35 watts per channel and my machine is one of the good ones from the early sixties. It was given to me by my older brother. What a guy eh? I knew nothing of tubes but he swore by them. I was like the masses, brainwashed into solid scrape and redbook CD's. Ahhh the industry sure knows how to play us and make the old bucks eh? Well anyway, this Dynaco was pretty much stock as a rock. Had some critical caps upgraded as well as some resistors but that was about it. I plugged this into my preamp and...and...AND. My jaw almost hit the floor! WOW this is how the music should sound. The clean, rich sound that never was there was right in my face. I had no idea what I was missing. I quickly jumped onto the basic mods of this baby. The cap can upgrade from Triode. Other cap upgrades. New 7199 tubes and a quad matched set of el34's. Mmmmmmmmmm how I ever lived without tubes is totally beyond me. Especially this nice little Dynaco ST 70
The more I read on line the more I saw how popular this little gem was. The are often popping up on e bay but the price is getting out of hand for them. Was a day when you could buy these for a song. Not anymore. Typically they can go for up to 400.00 I HIGHLY recommend getting this amp if you can. It is fun to tweak and more fun to listen to. They truely don't get much better. Enjoy!

Warm tube sound; smooth response, full bass when properly modded

High Maintenance; knowledge of electronics or willingness to tinker helpful

It's funny to write a review on a product that hasn't been available new for over twenty years, but these amps are gems. If you are someone you know enjoys garage or yard sailing, keep your eyeball peeled for these--they can sometimes be snapped up for less than $20, but as their popularity resurfaces, that won't last for long.

Buying a ST-70 is like buying an piece of antique furniture--don't be surprised if you have to work on it to get it right. If you're not into breaking out a soldering iron to fix your amplifier or make it better, then don't bother; this is not a "plug and play" rig. If you are willing, the internet has many sites where you can get all the restoration and modication tips you'll ever need!

What was decpetive to me was my first ST-70 ran great right out of the box, even though it was close to forty years old! I thought it was going to be like the old tube televisions of the sixties; tube goes bad, replace it and you're done until the next tube goes bad. Wrong. First of all, try to find someone with a tube tester these days! You'll have to look far and wide, but someone should have one lying around. If the tube is bad, well, replace it, but check the mod sites on the web for clues to see if your amp is really running up to snuff. I was quite surprised after only about a $30 additional investment my 70 was running 500% better than the day I first plugged it in! Hint: replace the four way can capacitor, and the input RCA jacks and the output terminal strips and you will be amazed at the improvement in sound quality! I didn't think something as trivial as the latter two items would make such an impact, but I was wrong!

These amps are popping up on ebay all the time, so at least for right now, they are fairly plentiful and really cheap, especially when compared to new tube amps!

Similar Products Used:

First tube amp

Tube sound, easily modified

These amps are old, so getting one going is a lot of labor, but that is part of the fun.

I love this amp. At first I was disapointed not only because of fuses blowing and tubes exploding, but also I found it's sound so hard hitting. After some research and some hours on the soldering iron, this amp has a few modifications and it's sounding great with no problems. I've played with tubes and input filters, selinium rectifiers etc., but the amp really improved when I switched it into triode operation. Now it sounds the way I want it to. It is warm and smooth sounding and I couldn't be happier. I can't wait to mess it up with more tweaks and mods!

Similar Products Used:

Scott, Harmon Kardon, some other old tube amps

I purchased a Dynaco Stereo 70 that had been modified by PRO MUSICA in Urbanan, IL. That was back in 1974. The was my entry level into esoteric audio. Two years later, I started to work for a high-end audio store. I compared it against various amplifiers we had at the store and finally replaced it with an Audio Research amplifier. I sold my Dynaco amp in order to purchase the ARC amp. Shortly after, I regretted selling the Dynaco and vow that if I found an identical unit, I would purchase it again. Twelve years later I found an identical modified Dyanco Stereo 70 and purchased it. I am still impressed by it's sound quality. It is not a perfect amp, but I would not purchase any other amplifier that cost less than $1500.00

Folks,
Could you compare the ST-70 with the current version of it that "Sound Valves" of Ohio makes? Is the new one better? If so, how? Thanks.

NB: I am giving 3 stars to the SV version.

I inherited my Dad's DYNACO ST 70 about four years ago when he passed away. He built it from a kit about 1965 or so. I grew up on tube sound and never heard anything better until my Grandfather bought a Marantz and Mcintosh combination. Well needless to say that ST 70 has been retubed and new quad capacitor put in and is pumping up the jams to my Maggie MMG'S. Anyone who is curious about tube sound should check out a ST 70, yeah the bass is mushey and does'nt kick up a storm. The mid-range is where the sweetness is, especially if you like jazz. So check out a Dynaco ST 70 you just might get hooked.

This is the classic mustang of the amplifier world. It may not be as good as some of the new, far more expensive models, but I challenge anyone to find a better amp than this for it's price, even twice it's price. Considering that if you find one you can pick it up for under $500 (sometimes far less), and there is more documentation and upgrades out there on this amp than any other, this amp simply cannot be beat. My father's ST70 has all original parts, and is older than I am, but it still sounds good.

I bought my dyna ST-70 used from a local hi-fi store,for $165...Had to get a new power xformer,and p.supply capacitor,spent $55 on a set of new EL-34 tubes(which lasted 3 years)--During the three years I've used it.I've run a pair of Dali 3's(Danish speakers)with it, and a pair of 1981 Magnepan SMg's--the ST70,even being a tube amp,has done fairly wonderful with the "maggies"-especially on acoustic music like 1940's Big Band stuff,and other jazz,and other Pop music. The Maggies/ST70 combo can get loud,but don't try it on Heavy Metal, or on complex opera music. Overall ST-70 rating:3-1/2stars out of five.<<<

Just want to say that in all the reviews of the ST-70 no one mentions the designer, David Hafler! You all also will never see credit given to him from the companies that ripoff and tweak his design....what a shame! he should have recieved a Nobel Prize! Maybe he did, ANYONE?
The Dyna St70 ,for certain speakers, ie electrostatics,some ribbons, tweaked WATTs, the st70 sounds ten times better than ANY SOLID STATE AMP, yes even krell, Levinson! Real hifi people know this! The deal is, few will admit that a $200 rust bucket sounds better than a $3000 shiny new KRELL! When setup the right way you'll here it! Just go listen to that krell on a pair of very revealing speakers....HARSH, better matched for low frequencies, SUBS, or huge box speakers though!

Many will disagree, but the 70 watts of tube is better matched with efficient large speakers! The big misnomer is that smaller amps are a better match with small speakers. The thing is you need need more power to push enough air from a small cone driver! I wonder what all those low wattage Triode amps are used with!

Anways, the Dyna St-70 is the best value in HIFI period! The PAS kicks too!If you want significantly better sound with tubes You'll pay a few grand! Most of the MODS for the St-70 are a waste! Van Alstine mods, are they still around? I hope not, a waste too!
Bottom line is go listen, don't look!
TUBE HIFI RULES!!!!

AY

Fisher x-100-a integrated tube amp35+years old-an absolute gem,amazing sound quality,requires good tubes
good spikes good cables and suitable speakers.