Dynaco st70 driver board

Vta70 driver board bare pcb for dynaco st70 amplifier. An all triode vta driver board made of milspec epoxy fiberglass. There is a single bias control for each pair of tubes which is not optimal. Dynaco st70 series 3 advanced classic tube aplifier. Dynaco mark iii poseidon board vs original dynaco 6ana. This is very important as if the grid drive is reversed, it will turn your st70 into a power oscillator damaging not only your amplifier, but your speakers and likely your hearing in the process. Dynaco never gave a parts layout on their pc3 driver board for the st70. One output tube handles the positivegoing signal and the other the negativegoing signal. Mark3mark2 upgrade driver board with parts one dynaco mark 3mark 2 upgrade board with parts and instructions. This board is a must for any serious restoration of the dynaco stereo70 to full stock condition. Comments are closed, but you can leave a trackback. Here is a very nice example of the venerable dynaco st70 power amplifier.

Note the location of input and output resistors on the circuit board and unsolder. Review and measurements of dynaco st 70 audio science. Best seller and best performing modification for 30 years now. 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.

Dynaco st70 series 3 tube power amplifier the absolute. The st70 used four el34 output tubes, one gz345ar4 rectifier tube, two 7199 input driver tubes, two output transformers, one power transformer, and a preassembled printed circuit board pcb containing the driver circuit. The benefits of upgrading your dynaco st70 amp with. This is unique for dynaco because in the st70 only one driver board was shared by both channels. The vtatdr may also be easily retrofitted to any vta st70 st120 tube amp kit. This replaces the pcb using the old 7199 tubes, with three 12au7. All connections to the board are marked with the original number markings on the top and bottom silkscreen layers. Dynaco st70 6gh8a 6gh8 complete stuffed pc3 driver board with tubes nos platinum matched pair of 6gh8a ei philipsthis is dynaco st70 driver board pc3.

Here is a nice example of the venerable dynaco st70 power amplifier. One of these tubes has been replaced, for reasons which will be discussed further in the section on the driver board. The driver output circuit boards are separate for left and right. Here at dynakit you will find the right parts to restore, repair or upgrade your original dynaco vacuum tube amplifier.

The vtatdr may also be easily retrofitted to any vta st70st120 tube amp kit. One of the most frequent failures in the dynaco st70 is the original quad electrolytic capacitor. Clearly, these are superb tubes to use in a reference dynaco st70. Unlike the original, all wiring on the sr70a is pointtopoint with connections to the amplifier made to turret terminals. A simple led bias meter and supply for the dynaco st70 and.

Stereo 70 driver board 7199 board replacement modules a. Tubes4hifi vta70 driver board for dynaco st70 assembled. R20 and r22 are located on the quad cap as in the original circuit. A new updated st70 can be had from bob latino in the states. Recently, i got bitten by the nostalgia bug and picked up a pair of old factorywired dynaco st70s in pretty nice condition. Tubes4hifi vta70 driver board kit for dynaco st70 ebay. The layout was changed to use the contemporary components and 6gh8a tubes. This is our classic version vta70 modification and uses a ccs constantcurrentsource. The triode usa dynaco st70 boards emulate the simple but highly effective due to the short signal path and single gain stage original dynaco circuit, but with lower hum, noise, distortion, and a wider voltage swing across heavier loads, than a 7199,6gh8,6bl8ecf80, 6u8ecf82 or 6an8 are capable of.

Take your st70 amps from 1960s performance to 2019 performance,it will sound 10x better and run cooler. The kit uses all new parts stainless steel chassis wow. The kits that bob latino sells do not include the cage, but you can get them from other dynaco parts suppliers. The 7199 driver board was not the best to begin with, and the fact that. Since acquiring the legendary hafler and dynaco brands in 2014, radial engineering has been carefully working on the dynaco st70 series 3 tube amplifier, in an effort to create a truly worthy successor of one of the most. The vta 70 is unquestionably the best circuit ever put in a dynaco st70 period whats so nice about the board is the fact you have a separate bias pot for. Overall i am in love with the new sound of my st70. Its developed and designed to be drop in replacement and it follows original wire hole layout, but its modified to use widely available 6gh8. Dynaco st70 totally restored and upgraded stunning. This dynaco st70 driver board pc3 has been developed and designed to be a dropin replacement for dynaco 7199 board. Dynaco mark iii poseidon board vs original dynaco 6ana driver board duration. Tubes4hifi vta70 driver board bare pcb for dynaco st70. It uses octal tubes, which are right in line with the lovely classic sound of the dynaco. A custom dynaco st70 kit id imagine that the venerable dynaco st70 is the most well recognized tube amp in the world.

None of this major overhauling is necessary and is a waste of time. Worse, direct replacements are both expensive and offer no. Dynaco st70 power amplifier uses a pushpull output stage, where two tubes divide the amplification function. The driver tubes were also relatively new zenith labeled uncarbonized 7199s, of unknown american manufacture. This a drop in replacement for the original dynaco st70 pc3 driver board but with modern epoxy fiberglass pcb.

Dynaco st70 with vta driver board kit rebuild assembly manual in addition to the rebuild kit you will need 3 transformers 1 x pa060 power transformer, 2 x a470 output transformers. A custom dynaco st70 kit diy audio electronics from. Mapletree audio design sr70a special red driver module. The 7199 driver board was not the best to begin with, and the fact that 7199. Dynaco st70 with cloth leads on output transformers. He also sellls a 60 watt mk111 version on a single st 70 chassis. Unlike the st70 which had the driver board separate from the output tube sockets, the st35 has the driver and output circuits on one circuit board. One of the most popular amplifiers of all time, with over 300,000 of them originally sold, it still remains one of the best tube amplifiers you can buy today due to its outstanding output iron. Dynaco st70 with vta driver board kit instruction manual. Hard to find parts including dynakit original dropin replacement components typically ship within 24 hours of ordering. Sds labs and triodeelectronics power supply boards. Mapletree audio design sr70a special red driver module for dynaco st70 installation instructions rev. I replaced the coupling caps on the pc board and bypassed the selenium rectifier with a silicon diode. Rca blackplate nos 12au7 driver tubes in vta70 driver board.

Anyone here do any upgrading of their dynaco s themselves using the sds labs cap boards andor the various driver boards available. I to have many dynaco mods from the top of the line curcio to a welborne labs circuit to a get this puke vanalstine that i had bought used. 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. They also never listed the parts that were on the driver board in the. The board uses a cascoded 12au7 into a long tailed pair phase inverter. Driver board and abqst70st120 auto bias is pre assembled as it mostly uses surface mount parts. Triode usa tube amp kits transformers tubes dynaco.

I got my st70 bone stock and replaced the output tubes with a matched quad. Also popular are rebuild kits with newly engineered driver boards that. Dynaco was a bit a head of some of the other kit builders from that era as their kits had less construction required using preassembled circuit boards, which the builder had to do less wiring to make the amps run the first time. This entry was written by admin, posted on may 29, 20 at 3. Its not unusual for folks to run these amps without the cage because it looks cool, i guess. Introduced in 1959, the st70 was available as a kit dynakit intended for assembly by the purchaser or as a complete factorywired unit dynaco. Follow any comments here with the rss feed for this post. It didnt work on the left side and a tube plate glowed red and i couldnt set the left side bias. In a stock st70 the board replaces lugs 5, 6 and 7 of the 7 lug terminal strip. Number and unsolder all wires from the driver board. I was searching for dynaco amps on audiogon and came across an ad for new dynaco st70 kits. Our newest version of the ef86 board has been slightly revised to accept 6922, 6dj8, 7308, and 6cg7 in the phase inverter.

Cage has been repainted and is in fair condition with some small rust spot. In a vta st70 st120 tube amp kit, the vtatdb replaces the 3 lug terminal strip. Dynaco upgrades lets talk audio and diy 2channel home. Dynaco st70 cage and driver board for sale canuck audio mart. It was introduced in 1959 and was sold until mid1990. The original dynaco st70 was sold with a perforated sheet metal cage that covered the transformers, tubes, and the driver board. He sells new kits and turnkey st70s with an updated driver board and power supply, and trannys newly built to original specs, except for the mains tranny which is heavily upgraded. 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 predriver section of this amp is constructed using a printed circuit board. Note the location of input and output resistors on the circuit board and. This board also contains an on board bias supply for the output tubes.

Driver for dynaco st70 including module ab for autobias, tes. Restoration module this is an exact replacement for the original dynaco pc3 board fabricated from milspec materials. Unscrew the input board from the chassis and remove. Stemming from over 6 decades of innovation, the latest dynaco amplifiers and preamps deliver music with the dynamics and excitement that is only possible when mixing chemicals inside a glass tube. The dynaco st70 series 3 tube amplifier is now finally.