Dynaco Stereo 70 Amplifiers

Stereo 70

3500 Watts - Was Available Assembled Or As A Kit (1972-1977)

User Reviews (64)

Showing 1-10 of 64  
tom_hubbard   Audio Enthusiast [Nov 24, 2010]

This review is for the Dynaco Stereo -70 in kit form sold by Bob Latino. I built one of these about 4 years ago and foolishly sold it . ( on my "upgrade "merry-go-round) In that time I`ve owned Naim 5i, Audio Refinement Complete , Monarchy Pro 70`s, Creek 5250SE. Nothing stood out like the Dynaco. When I owned it I thought " this is the only amp that ever made a real difference" but somehow let it go anyway.It somehow gets all the frequencys right from the lowest to highest registers. Some of the amps were too bright , some too dark but this kit gets it ALL right. Purchased it again from Bob with the Russian PIO caps and thicker chassis. Well, the magic is back. This time it stays.Only amp that makes my Cain and Cain Abbys and Dynaudio Audience 42`s disappear.Other associated equip. is Musical Fidelity A-5 CD, CJ PF-R pre. The combination works extremely well together.The kit is the steal of the century. Try it and you`ll be hooked!

OVERALL
RATING
5
VALUE
RATING
5
tominredbank   Audio Enthusiast [Jun 26, 2008]
Strength:

Allows me to tweak for all I want ( isn`t that what it`s all about?) The most TEXTURED sound I`ve heard yet. That word is one that needs to be understood more in audio. Layers of sound in sax, guitar and bass. Not just tweaking up the amp to produce more artifical "detail"40 watts per channe lcan still comfortably drive most speakers

Weakness:

Aboslutely none. I can see why this amp has been so popular for so long

This review is for the Dynaco ST-70 in kit form offered by Bob Latino. I was searching for Dynaco amps on Audiogon and came across an ad for NEW Dynaco ST-70 kits. The kit uses all new parts (stainless steel chassis WOW!) and modifications in crucial areas also. The driver board is upgraded to use 3 -12at7`s and has a bias adjustment for all 4 power tubes. I had to give it a try. I called Bob and had it at my door in 3 days. The kit was a joy to assemble. ( I`ve never done one before) Step by step instructions and a color pictorial, After 100 hours burn in I was amazed. I`ve been in this hobby / obsession for over 40 years and never heard such a smooth but still detailed sound. Being a tweakaholic I called Bob to see if I could get my hands into it and make my own mods. Shortly after I had 4 Russian PIO caps at my door. Again a 100 hr. burnin and the sound was even more detailed, A distinct "punch" to the bass, layers of TEXTURE to instruments, unbelievable. ( to potential buyers I would go with these caps from the start)To top it off , changed out the 3- 12at7`s with NOS GE triple mica, and the EL34`s to Electro Harmonics platinium matched from Upscale Audio and I`m set. The closest thing I`ve heard to tube sound is my Monarchy monoblocks and this little 1959 design puts it to shame. Considering the high cost of some good tube amps you absolutely can not do better than this.

Similar Products Used: Monarchy SE`100 delux, Monarchy SM-70 Pro, Plinius, Exposure, Naim
OVERALL
RATING
5
VALUE
RATING
5
scarey   AudioPhile [Mar 08, 2005]
Strength:

Better sounding everytime i roll my tubes... Bass HA sounds like it is supposed to. no boomieness just there as it was recorded. MUST be the cables :)

Weakness:

None well except the fuse in rear where the iec plug goes.

Here I have a QEI Modified stereo 70 also equipped with a Joe Curcio Premium Mod. I need to find schematics on the QEI quantum electronics Mod Called BIG CAPS.. Best sounding Amp i Have Ever heard especially the price...

Similar Products Used: You Name it
OVERALL
RATING
5
VALUE
RATING
5
COZVA   Audio Enthusiast [Jun 19, 2003]
Strength:

Reliable Amazing sound Full body sound Natural sound

Weakness:

NONE!

Hello! I live in Israel and the unit is the Newer Series 2 under Panor Owners was received together with a ARC-SP-9 also series 2 preamp. Together only one word: SUPERB Original "National" brand made by the German factory Siemens EL-34 tubes, I also changed the Chinese driver by American ones Raytheon. Perfect match with my Gifted ARC-SP-9 Mk-2 preamp.

Similar Products Used: Marantz 8b power Quad 306 SS power Rotel SS power
OVERALL
RATING
5
VALUE
RATING
5
Matt   Audio Enthusiast [Apr 21, 2003]
Strength:

Built like a tank Excellent power & output trannys (cloth) Virtually no audible signal distortion with properly matched and biased tubes Hum is absolutely inaudible over signal Elegant, classic styling

Weakness:

Lacking in the bass department (actually it's just fine; over the last 15-20 years the audio industry has convinced us that thumping, overpowering bass is "normal" and should be the main criteria in determining what makes a good amp/sound system. Original components are mediocre at best, although even the best components found in more expensive amps of the same era weren't meant to last 40 years! Crappy input/output terminals, slide switches, and power cord No driver board cover on early models Nickel plating not as shiny as chrome

The ST-70 is an excellent amplifier, with a clean, well-defined warm sound. It should be known, however, that in order to achieve the performance of this amp I had to spend an additional $200 or so for new capacitors, switches, power cord, RCA inputs, output binding posts, one tube (7199), and a driver board cover. I also spent a week replacing components and polishing/painting the chassis and tube cage. Although there are an overabundance of mod kits for the ST-70, I left the circuit design completely stock. I've tried some of the mods in the past, and personally I feel that the 7199 tubes (designed specifically for audio) are sonically superior to any other signal tube being utilized in a mod kit. The Dynaco is an excellent choice for any audio system, especially for the budget-minded individual. Unfortunately demand for this amp has greatly increased, but the supply is there. They can usually be purchased on eBay for around $350, but I recommend looking for an original, unmodified amp. (I'm a little leary of the electronic knowledge of others, not to mention their soldering skills!) I'm rating the value a 4 out of 5 simply for the fact that 10 years ago this same amp in the same condition could be purchased for $25 at your local Goodwill or pawn shop. It gets a 5 out of 5 overall, but again consider the fact that I put a lot of time, effort, and money into my amp to acheive great performance. P.S. I don't mind answering questions/swapping photos/talking shop with others - email weedzie1@yahoo.com

Similar Products Used: All kinds of tube and ss gear (I'm currently using a Dyna PAS 2 with this amp)
OVERALL
RATING
5
VALUE
RATING
4
Audiopurist   AudioPhile [Apr 06, 2003]
Strength:

Transformers

Weakness:

Bass, dynamics, midrange.

I must agree these amps have some of the best transformers available for such a cheap price. The tube characteristic sound is truly there, but the stock unit is far from audiophile quality. After listening for a few days the deficiencies of the amp showed up more and more; sloppy bass, compressed midrange, diminished soundstage, fair dynamics, blurred instrument separation. You know what's next, modification of course! With a new constant current cascode driver board and regulated power supplies, and yeah the old shiny cap can had to go. The new capacitor bank has higher capacity and voltage rating. You can us you pick of driver tubes - 6DJ8, 6922 or 6N1P. Email me for pictures.

Similar Products Used: Conrod Johnson, Audio Research, Quick Silver
OVERALL
RATING
3
VALUE
RATING
4
lpd   Audio Enthusiast [Mar 25, 2003]
Strength:

Fantastic, swirling mid-range only tubes can supply!!!

Weakness:

Cheaper/affordable parts ie. rca connections, speaker connections, bias pots....

Well what can I say about this classic piece of history. The shiny nickel plated chassis is home for some of the best hand wound trannies money can buy!!! (That is if you have the original trannies with cloth leads). I picked mine up from an ol' codger/engineer. He has been hoarding vintage tube/ss gear in his house/storage sheds/garage and crawlspaces for years, and traded me the 70 for a sand amp (brand not worthy of even an honorable mention). Anyhow this unit was bone STOCK when I received it, and I intended to change nothing, thats right, nothing until I sampled the original design of the amp. Ok....parts fail and wander in values, but lets face it, these amps are classic designs built with cheaper, affordable parts and top of the line transformers. The selenium stack was the first to go (for safety reasons, besides does not affect the quality of sound in my ears). In goes a diode. Filter caps and a new can put on deck. A new quad of Svetlana EL34's and a Mullard 5AR4, and NOS RCA 7199's and I'm in heaven. At first I found the bass somewhat mushy and tublike, but with a VM I realized I was biased too low and ramped her up to the suggested bias voltage and voila....shangri la!! OK.. its not perfection, but I love this little jewel, and don't plan on selling/trading or parting with it..might even be buried with her when I go.

Similar Products Used: Harmon Kardon, Fisher, Acoustat, McIntosh
OVERALL
RATING
5
VALUE
RATING
4
glenjo   Casual Listener [Jan 28, 2003]
Strength:

Tubes! And I've tweaked them a bit. Yeah!

Weakness:

Tubes! And I've tweaked them some. Opps!

They'll have to pry my Dynaco Stereo 70s and my Spica TC-50s from my cold dead hands!

Similar Products Used: Fisher, McIntosh, Sherwood, Harmon Kardon, and quite a few others not worth mentioning by name.
OVERALL
RATING
5
VALUE
RATING
5
Bob   AudioPhile [Dec 29, 2002]
Strength:

The output transformer design and real world performance. Availability of new parts to keep showing up wannabee gear that only has big $$$ apeal.

Weakness:

Input and output connections, both of which can be upgraded fairly inexpensively. The cosmetics... well, we are not talking storage and use under ideal conditions most times, but a little bit of polish can do wonders.

Purchased in 1963 after direct A/B double blind comparisons with Marantz, McIntosh, Citation, Scott, Fisher and others It is an amp that lives on yet today with few but mega$$$ competition. To have this amp work to original specs requires replacing everything but the output transformers. That original pc board has to go in favor of nice fiberglass in your choice of original 7199 configuration with upgraded caps and resistors OR upgrade circuits. The old quad power supply capacitor needs to go in favor of one of several increased capacity & increased voltage pc/electrolytic units. JJ-Tesla outputs are my choice when looking to reproduce unamplified real music such as big bands, jazz, choral and symphonic material. The stuff that should be a basis of musical comparison. Old speakers and speaker technology have been greatly improved upon with the possible exception of Leonhardts, KHL 9's and some other electrostatics. If you are listening to geeetars and fuzz what difference does it make?

Similar Products Used: There is NOTHING similar... but I drive my amp directly from the output of my CROWN reel-to-reel using live master tapes made with microphones that cost more than the average 1960 automobile.
OVERALL
RATING
5
VALUE
RATING
5
pangl   Audio Enthusiast [Dec 12, 2002]
Strength:

Fast and transparent. Drive difficult loads easily. Tight bass is aplenty. Best bangs for your hard-earned bucks.

Weakness:

Generates good deal of heat. Binding posts are not tri-wire friendly.

I purchased mine from a completely mod/updated one from a local audiophile who is very knowledgable about this wonderful vintage amp. One thing that strikes me at first listening is how fast and transparent this amp sounds. The tighest and abundance of bass surprised me a big deal too. Driving my Alon IV (nominal 4ohm, minimum 3ohm, 87db) is not a problem - even when I shotgun tri-wire. The high is crystal clear too. The mid is sweet yet remains faithful to the original recordings: It is not as thick as some SET tube amps, however. On the down side, this unit generates a considerable amount of heat. Also, my unit still has the screws-type speaker outputs thus shotgun tri-wire is a real challenge. Each previous rating is midleading in certain ways, as this amp seems to be under the microscope extensively for mods and updates. So each one may sound different from another. But one thing is certain, that the updated mod will work with other modern gear better than the bone (no mod, no update) unit.

Similar Products Used: Antique Soundlabs DT1006(845) SET monoblocks, Classe CA200, Mark Levinson #23, Kora Galaxy Reference, Sonic Frontiers Power 2 and 3, Conrad Johnson MF2300, and (shamefully) Marantz MA700 monoblocks
OVERALL
RATING
5
VALUE
RATING
5
Showing 1-10 of 64  

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