Dynaco s st 70 series 3 stereo tube amplifier produces 35 watts per channel stereo and switchable between both 4 and 8 ohm outputs. Dec 14, 2016 david hafler released the dynaco st35 twochannel power tube amplifier nearly 50 years ago as a lower cost alternative to the popular st70. Dynaco mark 3 dynaco stereo 70 homebrew tube amp corner faqs and. Download the dynaco dynakitst70 manuals for free hifi. Dynaco stereo 120 repair information update my dynaco. Dynaco continued to build both mono and stereo amplifiers until 1977.
Modifications for the dynaco st70 basic amplifier stock amplifier shown. Stereo headphone box takes input from one audio power amplifier and drives. If the page is blank click here original dynaco st70 manual. The el34 output stage is pushpull and the dynakit st70 amplifier is rated at 35 watts per channel. One of the most frequent failures in the dynaco st70 is the original quad electrolytic capacitor. Dynaco st 120 upgrade info techtalk speaker building, audio.
Ive designed a replacement capacitor board for the st70. The layout was changed to use the contemporary components and 6gh8a tubes. This entry was written by admin, posted on may 29, 20 at 3. Dynaco amp schematics to assist you with your amplifier repairs and modifications.
Hard to find parts including dynakit original dropin replacement components typically ship within 24 hours of ordering. This dynaco st70 driver board pc3 has been developed and designed to be a dropin replacement for dynaco 7199 board. Using classa pushpull stereo topography, versions of this amplifier in the past have been characterized as a robust, with a reliable design of exceptional value. Dynaco stereo 80 manual stereo power amplifier hifi. Imagine what wed have had, back then, if hafler and johnson had formed a company. Increases both the capacitance and voltage rating to 600 vdc. Comments are closed, but you can leave a trackback. I wrote that 6th street bridge blog post above and as a fun fixitupper, a dynaco pat is. Including our custom made transformers, which are made to original specs right here in the usa. To that great mix, dynaco added a version of their quadaptor, which allowed the recovery of 4channel ambience into rear speakers. Modified updated dynaco st70 stereo tube power amp,repair,no tubes. But, hey over 350,000 stock st 70s were sold, making it the most popular tube amp ever.
Dynaco st70 6gh8 6gh8a ecf82 driver board pcb pc3 kit dyna. Due to coronavirus covid19 we have limited staff working on location. This dynaco st70 is in pretty rough shape and is in need of some repair and restoration work. Dynaco st 120 upgrade info the schematic shows one lm3886 chip amp per channel. Dynaco dynakit stereo 35 st35 tube amplifier schematic and. It is still rich in the midrange, but a lot less lush sounding than the original. Select picture or schematic to display from thumbnails on the right and click for download. In the case of the dynaco st70 for example see attached schematic coupling capacitors c10 and c11 are 0. An extremely cool operating amplifier, the sca 80 will deliver a full 40 watts rms per channel from 20 hz to 20 khz with both channels driven simultaneously. As shown in the photo on the previous page, i removed the original four section can capacitor, and replaced it with an input cap of 100 mfd its the large cap with two 50 mfd. The unit contains two 40 watt amplifiers on one chassis with a common power supply. Ignored for years by many tube enthusiasts, due to modest power output, its become a hot item since the start of the new millennium, with new releases of complete amplifiers, clone boards, transformers, tubes and other parts.
For a generation who adored it, there have been those in following generations who are quite vocal about it, to the point that the only. Dynaco st70 6gh8 6gh8a ecf82 driver board pcb pc3 kit. Another option is to build up the power supply from the various replacement capacitors making. This a drop in replacement for the original dynaco st70 pc3 driver board but with modern epoxy fiberglass pcb. High performance power supply modifications to an st35. The dynaco stereo 80 amplifier uses special power supply buffering circuitry. New dynakit st70 advice steve hoffman music forums. The company was incorporated in october 1955, with business premises located at 617 n. Output tube changes the original triode electronics board design manual included modifications to this board and to the amplifier to allow using other output tubes in a st70. It is being included here to allow the owner to experiment, and. Dynaco dynakit stereo 70 st70 tube amplifier schematic. Any vintage stereo repair or restoration involves cleaning. Below you will found our manuals on the dynaco st80. Ozren bilan room acoustics audio site links audiologs.
Unfollow dynaco st70 to stop getting updates on your ebay feed. Congratulations on your purchase of the dynaco stereo 80 amplifier. The dynaco st70 surely must represent the greatest amplification paradox of all time. This board shouldnt be doing to the amp what it is doing. Dynacos st70 series 3 stereo tube amplifier produces 35 watts per channel stereo and switchable between both 4 and 8 ohm outputs. Founded by david hafler and ed laurent in philadelphia, pennsylvania in 1955, dynaco was an american hifi audio system manufacturer popular in the 1960s and 1970s for its wide range of affordable, yet high quality audio components its best known product was the st70 tube stereo amplifier. Dynaco st 120 upgrade info techtalk speaker building. Dynaco 70speaker recommendations steve hoffman music forums.
Founded by david hafler and ed laurent in philadelphia, pennsylvania in 1955, dynaco was an american hifi audio system manufacturer popular in the 1960s and 1970s for its wide range of affordable, yet high quality audio components its best known product was the st 70 tube stereo amplifier. Dynaco sca80 manual integrated amplifier hifi engine. Dynaco st70 7199el34pp valve amplifier, amplifier, electronic. Ce manufacturing replacement capacitor is the most common solution, but it is hard to find and expensive. Dynaco dynakit stereo 70 st70 tube amplifier schematic and. Scan of the dynaco dynakit stereo 70 st70 tube amplifier schematic from the instructions manual. As shown in the photo on the previous page, i removed the original four section can capacitor, and replaced it with an input cap of 100 mfd its the large cap with two 50 mfd sections paralled, and two 470 mfd capacitors. Replacement cap for c11 in the driver power supply.
Some of you have complained that you want more meat technical information on audio equipment. Please obtain the items outlined in the following list. The dynaco st 70 surely must represent the greatest amplification paradox of all time. This product was designed to provide the highest combination of quality and value available, which is the dynaco tradition. The driver circuit had a single 7199 pentodetriode tube per channel, and. Worse, direct replacements are both expensive and offer no improvement in reliability. Later during the 80s sound valves columbus, ohio bought the. Find the right dynaco parts to restore, repair or upgrade your original dynaco vacuum tube amplifier. The dynaco stereo 80 amplifier uses special power supply buffering circuitry found in no other brand of amplifiers in this class. Follow any comments here with the rss feed for this post. The dynaco stereo 80 is an all silicon transistor basic power amplifier for use with.
Jan 25, 2009 carl dynaco st 70, nice little amp in my opinion with a few judicious updatesmods not the last word in accuracy but a nice warm tube sound kinda in the mc30 sound neighborhood for a lot less cash. The equipment was available as both factory wired and as kit form. Dynaco st70 repair and restoration vacuum tube power. In addition, we offer an array of new select dynakit classic vacuum tube. The most famous product was the st70 amplifier of which over 300,000 units were manufactured factory wired and kit combined. Download the dynaco st150 manuals for free hifi manuals. The service manual functions as a repair guide for troubleshooting and sometimes contains tips for refurbishing and modifications. This introduces another large low frequency rolloff within the feedback loop. Dynaco st 35 schematic service manual dynaco st 70 ii schematic owners manual dynaco st70 schematic assembly manual dynakit sca 35 schematic assembly manual. Scan of the dynaco dynakit stereo 35 st35 tube amplifier schematic from the instructions manual. Here at dynakit you will find the right parts to restore, repair or upgrade your original dynaco vacuum tube amplifier. Vta driver board kit rebuild pages amplifier dynaco pat4 assembly manual. The dynaco driver board is the weakest part of the st70 design, and after 20 or 30 years it is due to be tossed out and replaced.
If the power supply doesnt work, then the amplifier certainly wont work. Later during the 80 s sound valves columbus, ohio bought the entire remaining inventory of original dynaco parts. Improve, renew, restore and repair your dynaco stereo 120, stereo 80, stereo 400, pat4, pat5, fm5 or af6 tuner, or. Unfollow dynaco st 70 to stop getting updates on your ebay feed. The owners manual is used as an reference guide, instruction manual and instruction book. These amps smoked the dynaco from the beginning of the bandwith to the last and final note.
This board replaces the large can capacitor in the power supply section of the dynaco st70 amplifier. In use with varying program material, the unit justifies its design efforts to. Dynaco diagrams, schematics and service manuals download for free. One of the most frequent failures in the dynaco st70 is the original quad. Photos of a dynaco st35 tube amplifier kit from dynakitparts which was put together by jim wisconsin, usa. Dynaco vintage hifi service manuals available youtube.
Arc offered kits, to remake the st70, using only the chassis and transformers. I selected the amp because i wanted to try tubes per the advice of this board and a friend of mine had restored about 8 dynaco st70s and said he would do one for me for the cost of the parts. The energy storage capability of the filter capacitors of the original dynaco st35 is 8. Some people would rather repair their stereo 120 without updating it, maintaining the original design. Dynaco st70 series 3 stereo integrated tube amplifier.
Update 2002 test of dynaco st70 tube amplifier modifications by roy mottram note. Stereo 120 had an electronically regulated power supply and larger power transformer. Dynaco stereo 35 tube amplifier for sale us audio mart. Pa060s power transformer nearly twice the lamination stack size of the original, a470s output transformers, c354 choke. Download the dynaco st80 manuals for free hifi manuals. Improve, renew, restore and repair your dynaco stereo 120, stereo 80, stereo 400, pat4, pat5, fm5 or af6. Below you will found our manuals on the dynaco st 80. Below you will found our manuals on the dynaco dynakit st70.
The downloadable schematic has been replaced with a high resolution pdf file as of 2007. The kimmel design makes the st70 sound like a modern amp, much more extended highs and tight bass. All parts needed for a complete upgraded dynaco st70 type kit except for the tubes. The m60 mkiii c3 amp was a redesign of the dynaco mkiii. An extremely cool operating amplifier, the sca80 will deliver a full 40 watts rms per channel from 20 hz to 20 khz with both channels driven simultaneously. All connections to the board are marked with the original number markings on the top and bottom silkscreen layers. The 6bq5 output stage is pushpull and the dynakit st35 amplifier is rated at 17.
Output tube changes the original triode electronics board design manual included modifications to this board and to the amplifier to allow using other output tubes in a st 70. Tools required before you begin you should have a few basic tools on hand to help you identify and repair the problem. I then had the urge to try this schematic on a pair of heathkit w7s. The dynaco sca80q was dynacos tremendously popular integrated amp. It is a new design that is intended to look like the original dynaco, but with modern performance. Our famous original dyna st70 rebuild plans by frank van alstine. Dynaco stereo 70 tube amplifier dyna st70 el34 amp dynakit good condition.
Arc offered kits, to remake the st 70, using only the chassis and transformers. If you dont, will takes the stock dynaco chassis, strips everything off of it and has it sandblasted and. It was, however, built on the exact same size chassis as the vacuum tube stereo 80, and so looked very similar to it. The tubes4hifi version was done in a similar manner to this. Dynaco st70 will vincent includes extra tubes for sale. David hafler released the dynaco st35 twochannel power tube amplifier nearly 50 years ago as a lower cost alternative to the popular st70. The most famous product was the st 70 amplifier of which over 300,000 units were manufactured factory wired and kit combined. Phono upgrade 23 pages amplifier dynaco pas2 assembly instructions manual. The stereo 80 was the little brother of the stereo 120. Instead they found a short stay in my second system coupled with an upgraded dynaco st80. I bought a stocklooking used dynaco st70 that was dirty and had one bad tube. Triode, usa customer service mf 9am4pm ct 18007743201 email us anytime.
Mine has tungsol 6u8as and black plate rcas in the driver board, with gold lion kt77s and mullard rectifier. If the dynaco st70 is great, then the heathkits are world class. If you are reading this you probably already know about his work. Our famous original dyna st70 rebuild plans by frank van. Dynaco st70 capacitor board st70 power supply capacitor board this board replaces the large can capacitor in the power supply section of the dynaco st70 ampli. Regretfully selling my dynaco st70 custom made by will vincent, in asnew condition. But, hey over 350,000 stock st70s were sold, making it the most popular tube amp ever. We also offer an array of new select dynakit classic vacuum tube amplifier kits based on the original legendary designs. View and download dynaco sca 80 assembly manual online. Heres a scan of the serviceuser manual from my collection, stereo 80 manual 9 meg download pdf.
The magazine ad from 1994 below introduces the modernized vacuum tube dynaco stereo 80 and the upgrade to the pas3 preamplifier, the modernized pas4 vacuum tube preamplifier. Exact replacements for the original can capacitors are dif. It is a modified circuit, with custom wound transformers that are more than adequate. Dammig och saknar tva av fyra fotter men det ska ordnas. Mint dynaco stereo 80 st80 amplifier woriginal manual. Below you will found our manuals on the dynaco st 150. Dynaco stereo 80 manual stereo power amplifier hifi engine. It was arguably the best selling power amplifier of all time, and is arguably the most maligned such device as well.
Later ones i modified but they were never part of my serious system. Bass control treble control cio 50,000 ohms special. Exact replacements for the original can capacitors are difficult. We hope this web page and the hints it offers could make it easier. For more information about jims build and his impressions of the st35 kit, see the dynaco st 35 tube amp kit thread on the message forum.
Plenty of dirt to clean on this dynaco st70 tube amplifier. It follows the original wire hole layout, but it was modified to use widely available 6gh8 6gh8a 6kd8 ecf82 tubes instead of the obsolete and hard to find 7199 tubes. The sca80 is a onepiece, transistorized integrated package combining the stereo 80 power amplifier with a preamplifier having all the quality and many of the features of the pat4. Lm3916n bar graph driver datasheet in pdf format, drives a 10 led bar. The schematic is a technical drawing or diagram of your system, a perfect supplement to the service manual. Hello again, am glad that the feedback i am getting from many of you indicates that you are happy with the information and ideas i have been describing. The dynaco stereo 80 is an all silicon transistor basic power amplifier for use with separate preamplifiers such as the dynaco pat4 or pat5 or for use with tape recorders or tuners such as the dynaco fm5 which have their own volume controls. I have a st400 that i cannot find the trouble but it was a much more powerful amplifier. This page has sca80 schematics, information about the stock sca80, and about kits. Schematic diagram alternate ac line connections in case of difficulty service and warranty information 16 28 30 operating instructions installing your sca80q optional connections. Another common problem with vacuum tube amplifiers is the value chosen for the interstage coupling capacitors.
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