How to upgrade a dynaco mark iii a pictorial 2channel. Modifications for the dynaco tm mkiii mono power amplifier. 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. Dynaco mark iii poseidon board vs original dynaco 6ana driver. The 6922 tube driver stage favored by curcio may be accurate and may measure well, but 6922 tubes tend to sound cold compared with the original dynaco drivers. With the owner we decided on the new 6sn7 driver board from the guys at tubes4hifi. The 12au7s have lower gain then the tubes used on tubes4hifi, but i think now the tube4hifi amp can be order with a lower gain version now. Unfollow dynaco board to stop getting updates on your ebay feed. Ii was sold for several years until its replacement in. Your dynakit mark ii is a complete 50 watt power amplifier kit which offers the highest possible fidelity, at low cost and in a compact arrangement. This dynaco mk iii sports a specially designed driver board produced in the 1980s at musical concepts. 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.
This a drop in replacement for the original dynaco st70 pc3 driver board but with modern epoxy fiberglass pcb. The other benefit of the dynaco is that at 60 watts, i could use them with a pair of paradigm studio 100s i have in storage if i didnt like them better than the fisher. Dynaco mark iii mk 3 restoration part 3 bg070 youtube. Stereo 70 driver board 7199 board replacement modules a. 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.
Thats when these things were laid out with black tape type material by the way. Restoration module this is an exact replacement for the original dynaco pc3 board fabricated from milspec materials. 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. The triode board can use any common tubes, and i think that is what makes it a good design. Dynaco mkiii mods diy canuck audio mart hifi and audio.
I have used a pair of dynaco mk iii amps in my home stereo system for over 15 years. Dynaco mkiii monoblock tube amplifiers curcio audio. This board shouldnt be doing to the amp what it is doing. Diytube mark iii poseidon driver board driver board designed by shannon parks over at. I ordered the boards and components as a kit and sourced the coupling capacitors from mouser. This dynaco st70 driver board pc3 has been developed and designed to be a dropin replacement for dynaco 7199 board. Dynaco mark iii in the march 2001 issue of audio xpress there was an article titled the cure for the common dynaco mkiii.
Hard to find parts including dynakit original dropin replacement components typically ship within 24 hours of ordering. The other compelling option i have been looking at is a pair of mc30s. Dynaco mkiii mk iii mk3 mk 3 tube amplfier restoration kit. Each unit also has the pwb m3p power supply regulator board. The dynaco mark iii is the highest power amplifier that was widely sold under the dyna name. Dynaco mark iii poseidon board vs original dynaco 6ana. A nos 5ar4, a capboard, and a choke will provide the best regulation. I solder the parts on the board where indicated see parts list for part numbers 2. Desolder the wire at the pc board you can leave the other end connected to the quad capacitor. The layout was changed to use the contemporary components and 6gh8a tubes. Recently we had an original owner pair of dynaco mark iii amplifiers brought. Here is a kit to electrically restore your dynaco mk iii to like new condition.
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. Assembling the triode electronics dynaco mk iii preamp driver boards. Dynaco dynakit mkii manual power amplifier kit hifi. This is the same circuitry used in the highlyregarded bob latino tubes4hifi vta st120 amplifier. About the only thing that i decided to salvage was the power cords and the transformers. Those look to be original 196070s dynaco mark iiis to me. The dynaco dynakit mark iii amplifier is rated at 60 watts. Find the green not greenwhite wire one from the output transformer hooked to pin 4 on an el34, there is also a. Dynaco mark iii restoration and modification hudson valley hifi. With the exception of replacing one tube, they have given me many hours of listening pleasure. Dyna mark iii amp and the sds labs quad cap board wife warming her toes on the mkiiis. Older upgrades to both units using the curcio audio pwb1a premium all triode driver stage circuit boards. Diytube mark iii poseidon driver board triode electronics. This board will replace the driver tube with two 6sn7, and replace the selenium rectifier with a modern silicon diode.
The power supply uses a gz34 tube rectifier and clc filtering. New dynaco mark 3 mk iii 120 watt tube amps with vta. The dyna mkiii has a basic design flaw that none of the other dynaco products have. They do look to be near original with little work done to them, the only thing i can see that has been replaced up top is the one single yellow colored cap on the circuit board per amp.
Here at dynakit you will find the right parts to restore, repair or upgrade your original dynaco vacuum tube amplifier. Dynaco mark iv amplifier audiogon discussion forum. The capacitors in the power supply are not rated at a high enough voltage for the power. Your circuit is especially wonderful for the mkiii, which ive never thought was a very good sounding amp to. But you may have to alter the voltage divider resistors in the bias supply for the proper voltage. Dynaco dynakit mkiii manual power amplifier kit hifi.
The markiiis used a different tube set in the driver and i think thats the primary difference. This elegant dyna mk iii upgrade was performed recently. I then had the urge to try this schematic on a pair of heathkit w7s. Kara chaffee described a modification for the mark iii which replaced the 6an8 driver.
They were fitted with a new triode electronics driver board and all the rest new components including the dynakit stainless chassis. The owner of the amps wanted them restored and modified with a new driver board which will accept different driver tubes. 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. Dynaco mkiii mk iii mk3 mk 3 tube amplfier deluxe restoration kit. The original dynaco 6an8 design we believe was inferior to the 7199 driver used in the stereo 70. Dynaco dynakit mark iii mk 3 chassis with bottom kt2.
Triode electronics sds labs capacitor board for dynaco mk3, mk2 and sunn ampufiers easy installation instructions. The white stripe on the 100 uf indicates the negative side of the capacitor. Dynaco mk3 mkiii pair of monoblock amplifiers, recently rebuilt. It uses a circuit of outstanding performance characteristics, along with top quality parts, including. This driver board came with great quality components, as well as great instructions on how to assemble the kit. There was a nigher power amp the mark vi, but it wasnt widely available. The kits i built up were the aforementioned dynaco st400 and pat 5. The mark 3 amps were originally equipped with kt88 or 6550 output tubes.
If youre dead set on modding your vintage dyncaco amps, there are a number of popular mods available these days. This started off as a project to rebuild a couple of dynaco mkiii mono amplifiers. Dynaco dynakit markiii mk iii for sale us audio mart. Dynaco mark iii restoration and modification hudson.
All connections to the board are marked with the original number markings on the top and bottom silkscreen layers. The scan below is the dynaco dynakit mark iii tube amplifier schematic from the instructions manual. The second deviation would be a more modern driver board for the mk iii. Driver boards for dynaco mark ii and mark iii triode electronics. The dynaco dynakit mark iii is a monoblock amplifier with a 6an8 input stage and a pushpull kt88 output stage. Dynaco dynakit mark iii tube amplifier schematic and manual. Many of my friends told me to join the 20th century when they first saw them, but i.
For more information please see our dynaco page here is the driver board instructions note that sprague 715p716p orange drop capacitors will not fit this board. Topologically it is really very similar to the amp board above, but with some provision for power supply atop the driver board. They cost about three times as much as the dynaco option and have half the power. 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. If the dynaco st70 is great, then the heathkits are world class. New 6sn7 octal driver use for dyna mk3, vta m125s or vta m70s. The el34s will be able to handle the 15 extra volts, as well. Modifications for the dynaco tm mkiii mono power amplifier basic features. Amp is sold, but you can still find these on ebay, so be happybut buy a restored one, or take it to a tech, because you are only dreaming of plugging one of these into a wall socket, without starting a fire or having the thing blow or burn out. 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. There are several good aftermarket boards on the market for the dyna amplifiers. The other end should be connected to the dynaco driver pc board pc1 terminal number 5.
Details about dynaco mkiii mk iii mk3 mk 3 tube amplfier restoration kit. When the mk iii was introduced to drive the power hungry ar 3 speakers, the mk iiis transformer added a 4 ohm tap, changed the rectifier tube to the gz345ar4 which did not sag as much as the 5u4gb, and added a choke under the hood. Each unit includes 2 eh 6550 output tubes, 2 sovtek dual triode 6922 driver tubes. A pair of custom dynaco mk iii monoblock amplifiers. In addition, the bias circuit will now utilize two trimmers mounted on the top of the board to dial in balanced bias for each tube individually. My uncle had the stereo 120, pat4 preamp, fm3 tuner, and a25 loudspeakers.
New dynaco mark 3 mk iii 120 watt tube amps with vta drivercap board upgrades the tubes4hifi vta mark iii driver upgrade boards have been called the best mod you can get for the mark 3 amps. Uses the same 12ax7 and kt886550 tubes as the infamous svt but is only 60100w vs 300w for the svt. Here are the instructions for changing thr mk4 to triode operation. The dynaco stereo 120 was the first powerful 60 wattschannel transistorized stereo power amplifier in wide production. In addition, we offer an array of new select dynakit classic vacuum tube. Anyone use a dynaco mkiii monoblock tube amp for bass. Our newest version includes a filament jumper allowing use of tubes with 9aj or 9lp pinout, thus allowing use of. My dynaco mkiiis are the dynakitparts version and i use the high gain tubes4hifi driver boards which use three 12at7s. All four boards make use of two driver tubes as opposed to the stock versions single tube. The mk iii was set up to handle 6550s and kt88s no more suggestion of using el34s was in the owners manual. This board is a must for any serious restoration of the dynaco stereo70 to full stock condition. Dynaco mk3 electrolytic cap upgrade assembly, installation. Ii was sold for several years until its replacement in 1956 by the mk. Dynaco dynakit st70 vacuum tube stereo amplifier vtast70 octal driver board.