good mid, vocal and acoustic

lack of bass power, little bit rolled off at the top

I bought the st-70 at the local hi-fi repair shop couple months ago. The amp is with some mod: new power cord, new black cap, new sovtek power and rect tubes, upgraded in and out jacks. When i first auditioned the amp, it sounded ....ahhhhh. Then the owner of the shop replaced the el34 with 6550. What a suprise, everything came back into focus and the amp sounded really sweet, so i bought it.

My current set up: Nad 522 cd player ( want to get a better player but current digital revolution and the format issue really discourage me from investing a lot into this medium for now), meridian 201 pre (wonderful sounding solid state pre, lacks bass slam), st-70 power amp and feeding my awsome proac tablette ii (image and vocal king) and Mission power sub. (not the best but it will do for now since i only use it to pick up the last octave of the music, and i usually don't play loud)

I really enjoy the sound of my system. Vocal, musicality and harmonic wise its alot better than my friends krell/sonic frontier/dunalvy system.

One thing for sure power sub is a great addition to any tube powered system. Just set the crossover of the sub to around 40-50 hz and the volume down.

Some say that I'm a bit obsessed with sound. Others would say that I'm obsessed with noise. Anyway, to produce that noise that makes one happy one requires a good amplifier in one's stereo system. I was lucky enough to score a Dynaco ST 70 tube amplifier and am now using it in my main home stereo system (I've relegated my Carver M 1.0t to my office system). The Dynaco pumps out 35 watts a side and is quite musical. It excells in bringing out the best in vocals--male and female. The sound is full, warm and inviting. The midrange is superb. Bass is a bit lightweight and highs are a bit attenuated; however, the overall presentation is smooth and luscious and the mids are to die for. Used Dynaco ST 70's are still available if one pays attention to the market place. I would recommend highly this amplifier as a first foray into tube amplification. There are also kits to rebuild this amp--ask your high end stereo dealer--if you are handy with a soldering gun. The Pas 3 preamp is the complement to this amp if you can find one. I had one, but it needed to be rebuilt and the kit price was a bit high (the one I found was 400 bucks). If one looks carefully one can find the up-to-date versions of the Dynaco tube amp and the matching preamp at good, discounted prices. (I saw both pieces recently going for half price in one catalog). See if you can find a used Dynaco! It's the budget way to get into tube amplification. For tube amplification at bargain prices one can't beat the Dynaco ST 70!

Bullet Proof Dependability. And unbelievable "High End" performance for the money. The industry's best kept secret...

Keeping things in perspective, this amp has no weaknesses. Show me another amp with this kind of performance for $450.00 bucks.

First, Congratulations to Mr.David Hafler for designing a true classic American masterpiece.

I feel this is one of the best amplifiers aver made and makes a strong argument for "where has amplifier technology gone in 40 years?". Yes this amplfier does sound better than the big esoteric brands at the same volume level and I know because I have compared them at the AV speciality retailer that I am employed at.

This amplifier is an absolute pleasure to own. I do recommend that users update the components with the best parts you can afford. I own two Stereo 70's and was fortunate enough to compare my updated work in progress model with a stock factory built model. Both amps are at the same level of updates now.

It was not mentioned however all users of the Stereo 70 should replace their El34's with matched pairs of SVETLANA EL34G's. This is the best EL34 ever built period. ARC and McIntosh use Svetlana also in their current designs. They are worth every single penny. Forget that NOS stuff.

I believe in upgrading "same value" components for todays technology you cannot go wrong with this approach.

If you have not done it, replace your .1uf/450v supply caps with .1uf/600v MIT RTX polypropolene caps. The energy storage is greater and this translates into improved bass performance. Again, worth every penny. ARC uses these caps in there really expensive products. I used HOLCO resistors on my top board and discarded the carbon resistors. Not rocket science, just opted for updated parts. Used Mil spec rated Clarostat pot for bias control- awesome, rock solid bias control. Computer grade Aeon Polypropolene caps underneath for AC filtering, new quad filter cap, 16AWG ac cord w/fat plug (Home Depot $5.00). Monster Cable RCA conectors, New 5 way binding posts. 16AWG speaker wire (don't need to spend more...) Spray paint the Cage Black High gloss lacquer and you will have an amplifier that will beat the pants off of just about anything made on the market today. NO JOKE. Bigger tube amps run hotter and louder, they do not nescessarily sound better. That's the key.

I enjoy depth, sounstaging, rich REAL bass, Smooth silky natural highs, uncannily transparent and smooth midrange. Acoustic instruments sound well...Acoustic! for a total investment of $450.00! wha??? and time. I upgraded 5 others for friends. (no more...)

It really is the truth and I am having a blast! My next significant purchase will be Martin Logan Aerius i's. I will of course have to check to make sure the Dyna can drive them properly.

Sources for the parts mentioned

Welbourne labs (Quad filter cap)
Parts Connection (just about everything else)
Newark Electronics (Milspec Clarostat pots)
Speaker Builder (Aeon Poly caps)

If you do not do anything else get those Svetlana's!

Similar Products Used:

Used with McIntosh C22 Commemorative, Magnavox CDB-650 (that's right), Mission 751 Speakers.

The Dynaco ST70 is over hyped as the budget key to heaven and guess what; prices are way up.So what's the real tube deal...the EICO st70 surpases the Dynaco in every way[if we are talking about the musical experience].Switch the power tubes to 6L6's [easy mod]and presto! no expensive tubes to fret about.And talk about iron-its like moving a refidgerator!-but you won't feel bass challenged like a dynaco listeners.

Value,Ease of parts replacement

Awkward to use

The ST 70 was my first and only venture into tube amplifiers. I bought mine on a recommendation from a fellow audio enthusiast. I had always listened to music through a large powerful Japanese solid state amp, which I had purchased in the service while overseas. By my standards, I paid a lot for the receiver and was really satisfied with the sound. After about 15 years of owning this receiver, my interest in audio increased. Somehow, I got a hold of and read a book by called Good Sound by Laura Dearborn. She had several good things to say about the ST70. She also talked about how to set up the speakers and general the listening position. I made these position adjustments to my existing system and it did make an improvement in the sound. Also, I talked to a friend who was into audio and he encouraged me to spend a little money and get a PAS3 and a ST70. He told me I had a good chance in finding this equipment at a Ham Radio flea market or antique Radio Flea Market. Sure enough, the first show I went to had the equipment. I think both components cost me around $350. I set up the equipment, connected to a my other existing equipment which consisted of a Marantz 63E CD player and a 20 year old pair of JBL L36 speakers. The sound was different than with my receiver and in some ways better, but it also sounded like I had some heavy blankets draped over the speakers. I was a little disappointed but I figured that maybe some parts in those old Dynaco components needed to be replaced. Not knowing too much, I went after the obvious which were the 4 EL34 tubes on ST70. About a 2 weeks passed before I located a set matched set of Selvetlania EL34s. I put them in, did a rough bias adjustment and sat down to listen to my Linda Ronstadt For Sentimental Reasons CD.

I stunned with the sound. What I was accustomed to listening to was not nearly as enjoyable. I continue to be impressed each time I listen. Now, background vocals come into focus. Most times, I can clearly decipher instruments and follow each little nuance. Individual sounds (Instuments and vocals) of the music seem to be spaced apart

I have now owned this combination of equipment for around two years. I have replaced all critical caps in both the preamp and ST70. Maybe there was some small improvement in doing this. But nothing compared to making the basic change to the Dynaco tube gear. I really don't have the extra money to get new speakers but will upgrade them next when the budget allows.

I can not say how the amp compares to other tube or expensive solid state equipment. I never had the opportunity to listen. I can say that if you currently own a mid 70s piece of solid state gear you make the swap and enjoy.... Don't wast 15 years like I did.

Similar Products Used:

Solid State Gear Amps

what happens when a tube or something goes out? don't know where to get parts

this amplifier is a beauty. she's very very rich. her timbre true. she plays music like she were the musician. so expressive. treble, cymbals, are just so expressive, transparent, and transcient. vocals and mids, all warm and defined. I look forward to getting a secong one and monoblocking them! Can't wait.

Similar Products Used:

sony ES, denon 3801, onkyo 787.

an excellent powerful sound when hooked up to vintage advent speakers.(very good on the 100-40 Hz frequencies)

bad on the high freqs(10000 up Khz. and cant go any lower than 40 Hz without dips and distortion.

this amp is now my main power for all my music needs.
I use panasonic/technics preamps and sources on it. I also have some vintage Advent speakers hooked on to it with altec lansing 12" speakers in the cabs.I also put on the tweeter crossovers to overdriven to make up for the lack of treble response from the phase splitters. All of this equipment turned on and driven produces a very huge sound.I am glad i have an amp like this to use daily and not feel bad when killing the tube life on it.the ST 70 is not the claimed 35w/c but is more like 25 rms with an 8 ohm load.And i still laugh at the sap i got it off of for 40.00
$cdn he he he ..... Overall its my favorite amp next to my citation Harmon Kardon tube amp.

Similar Products Used:

harmon kardon power amps (citation series)and fisher intergrated tuner control amps

Great transformers and a build quality. When properly configured & restored, these tube amps still offer a level of performance matched only by FAR more expensive amps.

NOS 7199 driver tubes are a bit hard to come by and pricey, I don't care for the current Sovtek 7199 offering. Older phenolic boards and electrolytics on stock units will most likely need to be replaced if you buy one. Chrome chasis tend to rust if not kept clean and dry.

About two years ago I began a quest of sorts to put together a reasonably priced stereo system that would truly stand out amongst the multitude of mid line consumer electronic systems available today. Rather than plunk down ten grand on a brand new system, I found it infinitely more enjoyable experimenting with various components available for next to nothing on Ebay. Ultimately I ended up with an interesting hybrid system consisting of both old (3 near mint Stereo 70's) and new (Adcom, Paradigm) components. At the start, I knew that I wanted to go back to tubes. But at the same time I wanted the flexibility of a home theater system and a more more modern front end. Lets face it folks, a remote is a GOOD thing! Enter the Adcom GTP750. I know some purists cringe at the thought of marrying a solid state preamp with a tube amps. But I have to say that this particular combination deleivers exceptional sound and incredible flexibility without any significant compromises. I chose the 3 amp configuration to accomodate the Adcom's 2 front, 2 center, and 2 rear channels. The Adcom also has a sub out, so I added a modified JBL sub woofer .
The subwoofer does a nice job doing some of the grunt work, deep bass passages in movies etc. It can also be used to take a bit of the load off the tubes in musical applications, essentially freeing up the Stereo 70's to do what they do best .. reproduce silky smooth mids and highs.
But even in straight 2 channel mode, one Stereo 70 does a remarkable job. In Adcom's 5 channel stereo mode all three amps are pitching in, so the demand on each is reduced substantially. Even my audiosnob friend couldn't beleive his ears.In any mode, the sound is smooth, rich and detailed. And the occasional claim I've read about the 70 being a bit weak on the low end ... well..select your speakers intelligently and this will NOT be an issue unless you have a highly unusual demand for bass. Again, these amps must be PROPERLY restored before they will deliver the clarity, detail, and soundstaging you would typically expect in more expensive amps. I've been running these amps almost daily for well over a year now without a hitch, and I would highly recommend them to anyone looking for an extraordinary amp(s) at a reasonable price. These amps are well loved and fetching three to five times their original purchase price for a reason, they sound GREAT...period. The Stereo 70 is every high end audio dealer's worst nightmare. Expect to pay between $300 & $400+ for a decent example of a Stereo 70 on Ebay nowadays. You should also assume that some or all of the caps will need upgrading. That can run anywhere from $15 to $50.00 or so, depending on what needs to be replaced. Oh, and if the old selenium rectifier is still in the unit, replace it with a comparable diode right away. I also suggest running these amps "cageless", unless of course you have small children or curious pets. They look GREAT without the cages and run a bit cooler as well. Below is a brief summary of my current system configuration for those of you looking for ideas:

Front End: Adcom GTP-750 DD/DTS 5.1 preamp/tuner ($1200)
Front Amp: Dynaco Stereo 70 ($230 Yahoo Auctions)
Center Amp: Dynaco Stereo 70 ($210 Ebay)
Rear Amp: Dynaco Stereo 70 ($300 Ebay)
Front Spkrs: Paradigm Monitor 7's (gift)
Center Spkrs: Paradigm Atoms ($180)
Rear Spkrs: Paradigm Atoms ($180)
Subwoofer: JBL ($250 + parts)
CD Player: Adcom GTP600 ($225 Ebay)
Turntable: Micro Seiki DD30 w/ Grado cartridge ($100 Ebay)

Similar Products Used:

Far too many to mention here.

unbelievable sound, easy to find parts

a little ugly needs to be modified in order to bring out the sound its capable of

a historical amp, one that can be found at unbelievable prices and puts out unbelievable music. Mine has been modified by putting in two new power capacitors, and bigger transformers, and two more tubes. it is unbelievable, as good as i herd at the 96' HiFi show in New York. I have a few so email me if you have any questions.

my music system-

CD player-Dennon DCD-1800
Preamp-yamaha DSP-E492 reciever
speakers-homemade Altec Lansing 804 drivers
2nd speakers-modified Altec Lansing voice of the theatres different horns and cones
subwoofer-homemade Altec Lansing 15" driver in 6 ' case

Similar Products Used:

harmon kardon citation, marantz 2000, fisher tube amp, present day VAC

Dear folks, there is just one word that would describe this amp - amazing, period.
I've tested(at my place, way differnt than at the retail store)many amps: McCormack, Conrad Johnson, Audio Refinement, the latest NAD Silver series(so well rewieved),McIntosh MC-240 (Close to the "Holly Grail" MC-275), etc.
Well, the Dynaco, the little old rusty junk box outperforms everything so far.
It's just unbelievable.
Of course, you guys, need to have a good speakers in order to hear the difference.
Five Stars!!!

P.S. By the way, whenever you can, get a pair of DYNAUDIO Contour 3.0 speakers and listen for your self.