St 70 driver board capacitor upgrades

Took me about 8 hours to assemble spread over a few evenings. This entry was written by admin, posted on may 29, 20 at 3. St70 capacitor board installation instructions populating pcb board 1. Although looking near stock, this st70 kit has several upgrades which make it a more reliable and much better sounding amp. The kimmel design makes the st70 sound like a modern amp, much more extended highs and tight bass. A original 7199 tube design or b our new 6gh8a tube design. Really easy to install just make connections to the output tubes, power transformer, input connector and choke. Ava modification consists of a new driver pcb which also contains upgraded power supply capacitors. Triode electronics sds labs capacitor board for dynaco mk3, mk2 and sunn ampufiers easy installation instructions.

Everything needed to complete the amp came in the kit, minus the tubes, which are 3x jj ecc82s on the driver board, jj gz34 rectifier, and sovtek 6550 output tubes. This upgrade to the original st70 was first introduced in 1988. Exact replacements for the original can capacitors are dif. These sds labs and triodeelectronics power supply boards replace the original can capacitors in dynaco mk3, mk2 and st70. Stock st70s had bias setting potentiometers mounted in the chassis just in front of the power transformer. You may also purchase the board and parts as a kit. This page documents the build of my custom st70 from a stock dynaco st70 stereo amplifier. All you need to complete the kit is a soldering pencil, some rosin core solder, a screwdriver, pliers and a wire cutterstripper to build your own vta st120. Dynaco st70 freshly rebuilt w famous classic vta 70 driver board. New updated version this is a new, updated, version of the classic, sds labs, dynaco st70 capacitor board. Unsolder all wires from the driver board, the bias potentiometers and remove all remaining parts from the long terminal strip. The original driver board was made of an inexpensive phenolic material with open solder traces on the. Driver circuitry is refined with all new sonically selected coupling caps and many resistorcapacitor upgrades to improve noise figures and inherent drive linearity.

The vtatdr may also be easily retrofitted to any vta st70st. Get the best deal for dynaco vintage amplifiers and tube amps from the largest online selection at. 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. A supplementary cap module scm with an esl reduction capacitor your kit comes with a very easy to follow instruction manual and a clear pictorial specific to the vta driver board. The amp sounds absolutely awesome with the dynaco a25s. Ultimate performance dynaco st70 with professionally built and assembled curcio audio engineering driver and power supply premium modifications. St70 power supply capacitor board this board replaces the large can capacitor in the power supply section of the dynaco st70 ampli. Stereo 70 driver board 7199 board replacement modules a.

I had an st70 quite a while back that i used for headphones. Dynaco sca35 sca35 tube restoration rebuild kit repair service fix capacitor. The best can capacitor you can put in there as a replacement quad cap for the st70. 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. Dynaco tube amplifier technical articles and upgrades st. The blank board can be fitted with a 25mm x 25mm snap lock capacitor. The st70 came with a cheap power transformer that was a frequent source of trouble. Dynaco st70 ccs 12ax7 12au7 complete assembled driver board. I used some of the original parts and fabricated a new chassis and cabinet.

The original old input driver circuit board and outdated electronics have been replaced with new high quality electronic parts which hand pick modrestore advice needed i recently acquired my fathers old dynaco or dynakit st70 stereo 70 tube amplifier that he used with his first real stereo system starting back in the 60s. Triode, usa customer service mf 9am4pm ct 18007743201 email us anytime. Also popular are rebuild kits with newly engineered driver boards that one can use to improve an existing st70. New updated version this is a new, updated, version of the classic, sds labs, st70 capacitor board. Sadly it is not uncommon to see a 7199 driver tube, even a brand new one, that is too weak to produce a credible sine wave at anywhere near full output. 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. In a vta st70st120 tube amp kit, the vtatdb replaces the 3 lug terminal strip.

This is a new, updated, version of the classic, sds labs, dynaco st70 capacitor board. The build was straightforward and it sounds fantastic. I was searching for dynaco amps on audiogon and came across an ad for new dynaco st70 kits. As well as our upgraded dynaco st70 heavy duty stainless steel chassis, triode usa dynaco st70 driver board ef86 or 6au6 model, or no driver board, and our triode usa dynaco st70 upgraded capacitor board. The pc10a replaces the obsolete, increasingly hard to find, and expensive 7199 driver tube with either a 6gh8a or 6u8a. Dynaco st70 freshly rebuilt w famous classic vta 70. While there are many driver boards available for the dynaco st70, most follow the same common formula. The kit uses all new parts stainless steel chassis wow. Solder all resistors onto the board where indicated in the parts list. See the schematic by clicking here for more details, click here. Dynaco upgrades lets talk audio and diy 2channel home.

Input rcas upgraded to modern gold plated jacks with wider spacing to accommodate thicker rca. Brand new modern dynaco replacement driver board with brand new 6gh8a tubes installed. Additional components have been added to prevent stability issues that can occur when these tubes are simply used with adapter sockets in the original pc10 board. Our st70 dynaco upgrade cap board replaces the original aluminium can capacitor and increases capacity from the original 30202020 to over 500ufs, using high quality capacitors which are bypassed by metallized polypropylene caps for superior high frequency response.

There are many makers of these caps including cornell, united chemicon, nichicon, mallory vishay and so on. Perhaps the most significant upgrade available for the st35 our new power supply capacitor board with efb converts your st35 from cathode bias to a new and innovative enhanced fixed bias mode. Installation instructions for kta st70 pcb upgrade kit. The new 16 gauge stainless steel chassis is identical in size, shape and markings to the older original nickel plated steel frame except it weighs 1. In addition, we offer an array of new select dynakit classic vacuum tube. Here are the instructions for changing thr mk4 to triode operation.

Dynaco vintage amplifiers and tube amps for sale ebay. It came with a new power transformer and a completely new pcb board. The vtatdr may also be easily retrofitted to any vta st70st120 tube amp kit. As such, it has a reputation of being a bit temperamental, and a. In the long run, you could also consider replacing the power transformer. My idea is first to restore the original board, listen to the music and after a while look what possibilities there are for the st70 like another pre. We thank you for your suggestion and in response we are very pleased to announce two new modules for the st70.

Our famous original dyna st70 rebuild plans by frank van alstine. This board is a must for any serious restoration of the dynaco stereo70 to full stock condition. This is an industry standard format for electrolytic caps and as such allows for tremendous variety in the selection of caps. It is still rich in the midrange, but a lot less lush sounding than the original. So, within an hour you will be enjoying your st70 like never before. Our famous original dyna st70 rebuild plans by frank van alstine enjoy the. Remove bottom cover, and carefully unsolder all connections to the pcb. Increased output power both channels driven lower distortion. You can get seriously highend sound out of your dynaco stereo 120 power amp. The triode electronics kit eliminates the superfluous holes in the chassis and makes use of a cap board inside rather than the tall quad cap, along with a different driver board. Hard to find parts including dynakit original dropin replacement components typically ship within 24 hours of ordering. I opted to supply the tubes myself to defer some of. Install new pcb with center socket closest to front apron of the chassis.

Ultimate performance dynaco st70 professionally built. Back then, i bought a van alstine kit to update the unit. Improve, renew, restore and repair your dynaco stereo 120, stereo 80, stereo 400, pat4, pat5, fm5 or af6 tuner, or sca80q highend sound on a budget. Mine has tungsol 6u8as and black plate rcas in the driver board, with gold lion kt77s and mullard rectifier. First is our stereo70 upgrade system on board sob a complete amplifier on pc board.

Make sure to have the banded end as marked on the pcb board banded end facing edge of board 3. Feel free to download our comprehensive instructions to see for yourself just how easy it is. The kit includes all of the parts including the tubes necessary to populate a single circuit board that replaces the original dyna circuit board, the large power supply capacitor, and the bias potentiometers. This board gives the amp the bass definition that the st70 original lacked. Dynaco st70 upgrade capacitor board triode electronics. Further detail improvements can be made to the st70. For the st70 i like to keep it original, but on the other hand i would like to have a good sound of course. The mods included upgraded power transformer, extra choke, extra capacitors on the power supply side of things, triode pentode switch and of course their new style vt70 driver board. Our sob module installs completely inside of your stereo70 and includes a complete power amplifier using our upgrade driver circuit and our quad cap module plus lots of other enhancements all on one pc board. Dynaco st70 with vta driver board kit instruction manual. Dynaco vta st70 stereo tube amplifier for sale canuck. The original dynaco stereo 120s power supply was a classic, clever, dynaco design. The white stripe on the 100 uf indicates the negative side of the capacitor.

Unfortunately, its performance depends upon unpredictable parameters in the transistors. With parts means all board parts, you solder on board yourself. Ultra clean, super detailed sound with an open soundstage and excellent imaging. There were all used in my personal st70, and sound very good. A custom dynaco st70 kit diy audio electronics from. Since this one has the vta st70 driver board designed by bob latino, the bias pots are moved to the driver board the four yellowtan squares on the driver board. Restoration module this is an exact replacement for the original dynaco pc3 board fabricated from milspec materials. In the case of the dynaco st70 for example see attached schematic coupling capacitors c10 and. You may purchase the board blank or fully assembled. Updated with 5 way speaker binding posts to accomodate spades, bare wire or banana plugs. Shannon, thanks for the tip, last night i was eager to try out my st70 and figured the new cap should be better than the old quad capacitor so i decided not to check it as i was given a pair of dynaco a25 speakers and wanted to hear them for the first time.

In a stock st70 the board replaces lugs 5, 6 and 7 of the 7 lug terminal strip. Here at dynakit you will find the right parts to restore, repair or upgrade your original dynaco vacuum tube amplifier. Another option is a capacitance upgrade from our standard 188uf on board, to 400uf. If possible it is recommended that you refer to the original assembly information if possible. Stereo 70 driver board 7199 board replacement modules.

Kta st 70 driver board shown for informational purposes. Pa060 s dynaco st70 upgrade power transformer replacement made in. Up for sale is a dynaco st70 stereo tube amplifier with tubes and updates. This is an older madeinusa st70 with the high performance transformers.