I finally went on a hunt to purchase a complete dynaco set up. In a vta st70st120 tube amp kit, the vtatdb replaces the 3 lug terminal strip. I would like to have it refurbished and updated for electrical components, inputs, and outputs. The input jacks are gold plated and have a wider 916 of an inch spacing to allow for newer design thicker interconnects. This is acceptable for most modern day preamplifiers though many older preamps such as the dynaco pas3x may have some matching issues. Dynaco stereo 70 series ii amplifier manual created date. Can someone advise on input impedance of rectangular patch fed. Legendary dynaco st70 has been relaunched the absolute. Restoration module this is an exact replacement for the original dynaco pc3 board fabricated from milspec materials. Replacing 7199 with 6gh8 and comparing thd in a dynaco st70 vacuum tube amplifier duration. The canadian company is making good on its promise to reintroduce the legendary dynaco st70 tube amplifier. A stock st70 uses the front panel power takeoff sockets as a tie point for the input board tube filament wiring.
This also minimizes the effect of cable capacitance between the preamplifier and the power amp. Here at dynakit you will find the right parts to restore, repair or upgrade your original dynaco vacuum tube amplifier. Review and measurements of dynaco st 70 audio science. Pa060s power transformer nearly twice the lamination stack size of the original, a470s output transformers, c354 choke. After having searched this forum i thought it might serve me best to initiate a new thread. The amplifier requires an input load impedance source of less than 2,000 ohms. There was something about a dynaco st70 that appealed to me. Next, was to add two 100ohm safety resistors and attach the transformers ground and 8ohm leads. In the case of the dynaco st70 for example see attached schematic. It is possible to change the input filter capacitors to permit higher impedance drives if absolutely necessary. One of the most frequent failures in the dynaco st70 is the original quad electrolytic capacitor. Actually the m125 is even easier to assemble than either the st70 or st120 amp kits. To date, i have run my st70 on the infinity p363 towers, the philharmonitors, and the def tech sm350s. The output transformer inside the dynaco st70 is often considered to be one of.
Five minutes later, i was listening to remotesensing negative feedback. Pan orient corporation panor bought the dynaco trademark in the 90s and was using 6gh8a tubes in dynaco st70 series ii amplifiers. Some of you have complained that you want more meat technical information on audio equipment. I just got this st70 today from a retired gentleman who was downsizing due to. The dynaco st70 amps were available in either factory built or in kit form. This entry was written by admin, posted on may 29, 20 at 3. Dynaco stereo 80 manual stereo power amplifier hifi. The dynakit stereo 70 is a complete dual 35 watt power amplifier kit which offers the highest possible fidelity, at low cost and in a compact arrangement. The return of the legendary dynaco st70 tube amplifier. I have to say i enjoyed the upgraded sound more than the stock sound, which i found a bit too warm and fuzzy along the edges. A gz34 5ar4 rectifier tube is used in the power supply. The st70 is a great relatively inexpensive introduction to what tubes can do and it gets you about 75% to true audio nirvana that last 25% is quite a slog, cant say ive completely made it there. Our famous original dyna st70 rebuild plans by frank van. I dont know what the load current will be or the equivalent resistance.
Maybe it was the chrome chassis, the brown steel cage covering the tubes or just the way it looks. 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 st70 used four el34 output tubes, one gz345ar4 rectifier tube, two 7199 input driver. Well known as the bestselling tube amp of all time, the iconic dynaco stereo 70 amplifier has been revamped and redesigned in a series 3 model in the relaunched hafler dynaco line, now under the auspices of radial engineering ltd. They also manufactured other tube and solid state amplifiers, preamplifiers, radio tuners and. Of all the audio manufacturers, both past and present, dynaco is admitedly my favorite. It is still rich in the midrange, but a lot less lush sounding than the original. Dynaco is best remembered for its highly regarded vacuum tube stereo amplifier, the stereo 70 st70. By choosing any point along the length of the transmission line, the input impedance of a given feed point can be calculated and is often.
Go a bit furtherimproved power supplies and better inputdriver stagesand a modified stereo 70 can embarrass most of whats out there in the subthou solidstate world. The original st70 came from the factory with mullard el34 they were actually labeled dynaco. Anyone ever built an xlr input board for a dynaco st70. It just does not put out enough punch and power for the klf 30s. It uses a patented circuit of outstanding performance characteristics, along with top quality parts, including the new dynaco superfidelity a470 transformers the finest available. Worse, direct replacements are both expensive and offer no improvement in reliability. Both amps had the input located at the front of the chassis, and the output terminals located at the back of the chassis. It uses the 7199 circuit from the original it is not a redesign using the inferior 6gh8. So much so that i could hear the transformer audibly singing the input tone. The dynaco project pas electrolytic capacitor replacement and dc power. It doesnt get more classic than a dynaco stereo 70. All parts needed for a complete upgraded dynaco st70 type kit except for the tubes. Our famous original dyna st70 rebuild plans from audio basics, july, 1982 article by frank van alstine. Ive designed a replacement capacitor board for the st70.
The input stage provides an open loop gain of about 50, while the cathode coupled phase splitter provides a gain of about 56 for an overall gain of between 250300. Introduced in 1959, the st70 was available as a kit dynakit intended for assembly by the purchaser or as a complete factorywired unit dynaco. This board is a must for any serious restoration of the dynaco stereo 70 to full stock condition. I would like to pool the tremendous knowledge base here as i am interested in experiencing the klipsch and horn s. Most were kits and 90% of the ones i have seen were assembled by amateurs that did a terrible job of wiring and soldering. In a stock st70 the board replaces lugs 5, 6 and 7 of the 7 lug terminal strip. The vtatdr may also be easily retrofitted to any vta st70st120 tube amp kit. The dynaco st70 series 3 tube amplifier is 35 watts per channel and switchable between both 4 and 8 ohm outputs, with classa pushpull stereo topography.
Including our custom made transformers, which are made to original specs right here in the usa. My uncle had the stereo 120, pat4 preamp, fm3 tuner, and a25 loudspeakers. Now in series 3, dynacos st70 is perhaps one of the most successful tube amplifiers of all time. I have a dynaco st70 that has been in storage for several years and has few hours on it. The input impedance of the st70 ii was quite highover 330k ohmswhich is typical of many tube amplifiers. The el34 output stage is pushpull and the dynakit st70 amplifier is rated at 35 watts per channel. Note that is the st70s 7199 tubes were discontinued is production a long time ago and the popular mod is to use 6gh8a instead. Proper impedance matching of a microstrip patch antenna to the feed line is paramount for efficient radiation. I have recently acquired a dynaco st 70 amp that i plan to pair with a bottlehead foreplay preamp i am going to build. Another option is to build up the power supply from the various replacement capacitors making.
The vta board itself has an input impedance of about 270k i believe. Scan of the dynaco dynakit stereo 70 st70 tube amplifier schematic from the instructions manual. Hard to find parts including dynakit original dropin replacement components typically ship within 24 hours of ordering. I have built a dynaco st70 from the bob latino tubes 4 hifi kit. However, just adding the plugs wont get me balanced input without a proper board for it. 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. They were originally built from 1959 up to the early 90s and according to wikipedia over 300,000 st70s were produced, this is an amazing number of amps, and thanks to this huge volume of these fine amps in the field, an entire industry has sprung up around this amp. If your original st70 comes with a dead power transformer or output transformer, these can be replaced with replica transformers from either dynakitparts, triode electronics. Dynaco stereo 70 series ii amplifier manual keywords. In a vta st 70 st 120 tube amp kit, the vtatdb replaces the 3 lug terminal strip.
The kimmel design makes the st70 sound like a modern amp, much more extended highs and tight bass. The high end show 2016 in munich marks the relaunch and advanced design of the newest iteration of the dynaco stereo 70 st70. New vta st70 page 4 talkin tubes the klipsch audio. It uses a patented circuit of outstanding performance characteristics, along with top quality parts, including the new dynaco. The first step was to tape off the 4ohm and 16ohm leads. Ce manufacturing replacement capacitor is the most common solution, but it is hard to find and expensive. In a stock st 70 the board replaces lugs 5, 6 and 7 of the 7 lug terminal strip. As with the st70 and st120 amp kits, the assembly manual is. The stereo 70 ii may thus be easily driven by virtually all modern control. This classic tube amplifier used to be the best value on the block. The series ii had output tubes by siemens labeled dynaco made in east germany. Unfollow dynaco st70 to stop getting updates on your ebay feed. The unit contains two 40 watt amplifiers on one chassis with a common power supply. The impedance match and bias conditions utilized in the.
Dynaco st70 series 3 advanced classic tube aplifier. Abstract the theory of characteristic modes tcm for pec bodies is showing great promise and application in the analysis, design, and. Follow any comments here with the rss feed for this post. This amp was designed to be inexpensive and to get maximum performance for dollar paid. Abstract this letter presents a waveguide modal analysis for evaluating the input impedance of a circular patch antenna fed by a centered. The dynaco st70s signal source was of course unbalanced, as was the amplifiers input stage. 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. So for above testing i kept the max input voltage at 1 volt or it would skyrocket in distortion. You could built it yourself or buy one complete but this 35 watt per channel amp changed audio. The vtatdr may also be easily retrofitted to any vta st 70 st 120 tube amp kit. The amplifier then does not amplify the input signal, it amplifies a signal being the. Preamp, fm3 stereo fm tuner and dynaco a25 speakers. The dynaco or dynakit stereo 70 also known as the st70 vacuum tube amplifier was one of the most popular tube amps of its time. Exact replacements for the original can capacitors are difficult to find.
The original dynaco input board had a 38 inch spacing and most replacement st70 input mounting boards have a 12 inch spacing. The easiest way to repair and restore these amps is start from the bare chassis and rewire the whole thing using new stranded wire. Dynaco dynakit stereo 70 st70 tube amplifier schematic. The measured specifications show that the stereo 70 is an amplifier of unequalled performance, and its listening quality is also unrivalled by any regardless of price. In addition, we offer an array of new select dynakit classic vacuum tube. New dynaco st 70 series ii vs original st70 part i italian version if there is one name in hifi which is synonomous with excellent sound, and at the same time with excellent price, that name is dynaco. This board replaces the large can capacitor in the power supply section of the dynaco st70 amplifier. Speaker recommendations for dynaco st 70 2channel home. Mine has tungsol 6u8as and black plate rcas in the driver board, with gold lion kt77s and mullard rectifier.
Dynaco stereo 70 manual stereo power amplifier kit. Most people call it a vta70 vacuum tube audio to distinguish it from the original dynaco st70. The chassis is about the same size as the st70st120 but there is only the wiring for one channel instead of two channels. Comments are closed, but you can leave a trackback. The dynaco stereo 120 was the first powerful 60 wattschannel transistorized stereo power amplifier in wide production. Page 2 of 2 38 posts go to page previous 1, 2 previous topic next topic.
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