Dynaco gold output banana jack boards st70 mkiii mkiv ebay. One half of the first tube is used for each channel as a voltage amplifier. This is my attempt to document the differences between the original dynaco design of the mark iii amplifier using the 6an8 vs a new design diytube poseidon driver board using a 12ax7 and 12au7 or. Picture of mint condition pair of dynaco mkiv mono amps. Put a set of nos tung sol 6550s gray plate no holes or black plates, nice driver tubes like a 6an8 and a mullardhammond gs 34 or 37 even better. Get the best deals on dynaco vintage amplifiers and tube amps when you shop the largest. Stereo 70 driver board 7199 board replacement modules a. Of note however, this is an area where heathkit really shined, steering very clear of such. The original dynaco driver met these needs with a single pentode gain stage at the input, followed by a simple splitload phase inverter to drive the output stage. Biasing and balancing 1connect a voltmeter on a setting to handle up to 2vdc across either kt88 cathode 10 ohm resistor. The scan below is the dynaco dynakit mark iii tube amplifier schematic from the instructions manual. Thats when these things were laid out with black tape type material by the way. This board is a must for any serious restoration of the dynaco stereo70 to full stock condition.
The irons are still good as are the original driver boards. St70 baseline2 dynaco sca35 st35 tube amplifier upgrade. Dyna, dynaco, st 35 tube stereo amplifier, factory wired. These amps smoked the dynaco from the beginning of the bandwith to the last and final note. 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 stock board and parts kit includes, transformers, choke, upgrade cap board and driver board, rca jack. In the march 2001 issue of audio xpress there was an article titled the cure for the common dynaco mkiii. The amps had been serviced recently elsewhere and the work done was trivial compared to what was actually needed. Really fun to build and a hell of a good time while learning to become much more adept at understanding schematics and the overall design of the dynaco mark iiis. New 6sn7 octal driver use for dyna mk3, vta m125s or vta m70s the bare. I am leaning towards the vta boards and the sds power supply. Dynaco dynakit mkiii manual power amplifier kit hifi engine.
Dynaco continued to build both mono and stereo amplifiers until 1977. Each amplifier requires one 12au7 plus one each of either 12au7, 12bh7, 6cg76fq7 or 6n1p. Stereo 70 driver board 7199 board replacement modules. Abj amplifier banana jack upgrade kit for the dynaco stereo 70, mark iii. Ii was sold for several years until its replacement in 1956 by the mk. Dynaco mark iii poseidon board vs original dynaco 6ana driver. Unfollow dynaco mk iii to stop getting updates on your ebay feed.
Dynaco vintage amplifiers and tube amps for sale ebay. Its nice to know at least one person comes around this forum. The dynaco dynakit mark iii amplifier is rated at 60 watts. With your circuit, one of the first things i noticed was that different recordings are clearly different, indicating to me that the amplifier is neutral, rather than co. Mark 23 original dynaco owners manual curcio audio.
Dynaco st70 6gh8 6gh8a ecf82 driver board pcb pc3 kit dyna. Kara chaffee described a modification for the mark iii which replaced the 6an8 driver. Turn off your mk iii and replace the pulled rectifier tube. The basic modification consists of replacing the driver board, performing easily done minor modifications revising a few connections to the output tubes, and installing to the power supply, your choice of input and output connectors. Assembling the triode electronics dynaco mk iii preamp driver boards. Oct 09, 2016 assembling the triode electronics dynaco mk iii preamp driver boards. Dynaco mark iii mk 3 restoration part 3 bg070 blueglow electronics. Dynaco gold plated input jack board stereo 70 st70 st 70 dual use. Driver boards for dynaco mark ii and mark iii triode electronics. It was supposed to be a relatively inexpensive mod which improved the sound.
Dynaco mark iii poseidon board vs original dynaco 6ana. All four boards make use of two driver tubes as opposed to the stock versions single tube. New listing dynaco stereo 120 amplifier and pat 4 preamp clean but asis. Mar, 2015 this is my attempt to document the differences between the original dynaco design of the mark iii amplifier using the 6an8 vs a new design diytube poseidon driver board using a 12ax7 and 12au7 or. I then had the urge to try this schematic on a pair of heathkit w7s. There are currently several on the market, one called the poseiden from diytube, one from tubes4hifi that incorporates additional electrolytics on the board itsself, one from curcio audio and one from triode electronics. The dyna mkiii has a basic design flaw that none of the other dynaco products have.
Does anyone have any specific details about this article. Dynaco dynakit mark iii tube amplifier schematic and manual. Therefore applying the same circuit that we developed for the stereo 70 to the mark 3 resulted in a dramatic improvement over the stock amplifier topology. Dynaco mark iii restoration and modification hudson valley hifi.
Our new boards for dynaco mk4 are identical circuitwise cascode input with longtail pair phase inverter to our mk3mk2 boards, but resized to fit the mk4. Unfollow dynaco mk iv to stop getting updates on your ebay feed. Dynaco mark iv amplifier audiogon discussion forum. The sca80predo kit provides a complete set of replacement components for the preamp circuit boards. The dynaco dynakit mark iii is a monoblock amplifier with a 6an8 input stage and a pushpull kt88 output stage. Recently i stumbled on a nice original condition pair of mk. Dynaco mark iii mk 3 restoration part 3 bg070 youtube.
Your dynakit mark iii is a complete 60 watt power amplifier. This design reduced distortion and improved audio quality. Modifications for the dynaco tm mkiii mono power amplifier basic features. The original dynaco 6an8 design we believe was inferior to the 7199 driver used in the stereo 70. Dynaco mark iii mono block questions tapeheads tape, audio. A pair of custom dynaco mk iii monoblock amplifiers. Recently we had an original owner pair of dynaco mark iii amplifiers brought to us for restoration and modification. This dynaco mk iii sports a specially designed driver board produced in the 1980s at musical concepts.
I am looking for input on the dynaco mk iii monoblocks. The capacitors in the power supply are not rated at a high enough voltage for the power. Also, is it possible to use other tubes with the original desgin. Modifications for the dynaco tm mkiii mono power amplifier. How to upgrade a dynaco mark iii a pictorial 2channel. Restoration module this is an exact replacement for the original dynaco pc3 board fabricated from milspec materials. While there are many driver boards available for the dynaco st70, most follow the same common formula. Topologically it is really very similar to the amp board above, but with some provision for power supply atop the driver board. This is my attempt to document the differences between the original dynaco design of the mark iii amplifier using the 6an8 vs a new design. This dynaco st70 driver board pc3 has been developed and designed to be a dropin replacement for dynaco 7199 board. Dynaco st70 series 3 advanced classic tube aplifier. Our newest version includes a filament jumper allowing use of tubes with 9aj or 9lp pinout, thus allowing use of.
If the dynaco st70 is great, then the heathkits are world class. It will make your sca80q preamp boards cleaner and quieter than new. The dynaco mark iii is the highest power amplifier that was widely sold under the dyna name. Diytube mark iii poseidon driver board triode electronics. One each of the other tubes is used per channel as a combined phase splitter driver in a longtailed pair configuration. One of them is missing some parts like resistors and a can cap etc. This is the same driver stage used in our full premium mk3 modification package and. Our driver circuit is a modern all triode driver design, for totally neutral uncolored sound. The only marking on the boards i can see is a mk iiivi etched in copper on the solder.
By 1975 dynaco was phasing out its tube gear and moving into solid state gear. Diytube mark iii poseidon driver board driver board designed by shannon parks over at. Oct 24, 2011 the dynaco mk iii monoblock was introduced by dynaco was back in 1957, just after the mk ii and the pam1 preamp and two years before the famous st70. Triode usa dynaco mk3 tube diy amp kit triode electronics. Cleaned layers of gunk and greasy dirt off chassis and driver boards. More or less together, they founded the dyna company with the intention of not only producing transformers, but highquality audio circuitry using them. The trouble is that many amps sound hard on top or thin on the bottom and all have some sort of dynamic relationship with the speaker. The dynaco mk iii, i find to sound cold compared to the st70. I ordered the boards and components as a kit and sourced the coupling capacitors from mouser. Dyna mark iii amp and the sds labs quad cap board wife warming her toes on the mkiiis. My dynaco mkiiis are the dynakitparts version and i use the high gain tubes4hifi driver boards which use three 12at7s. Rio is a 50 ohm, sw resistor, used rather than the choke shown on the hookup diagram notes for sunn amplifiers. Ii was sold for several years until its replacement in.
I have finally gotten the pair of dynaco mark iii mono blocks ive been wanting for sometime. So shannon, with poseidon boards you can mod mkiis and drive them with different tubes. Dynaco mkiii mods diy canuck audio mart hifi and audio forum. I am happy with the product quality and the performance of the vta driver boards. This board shouldnt be doing to the amp what it is doing. The second deviation would be a more modern driver board for the mk iii. 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. The dynaco mk iii monoblock was introduced by dynaco was back in 1957, just after the mk ii and the pam1 preamp and two years before the famous st70.
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