Vintage Tube Amp

NEW Dynaco 70 / Dynakit Stereo 70. This Listing is for. Custom Built by Funtastic Vintronics. These are brand new amps with new tubes – 100% – not a rebuild or a restoration. Made and hand assembled in the. One at a time. Mundorf MCap ZN Capacitors – 600v – 5% – Values are increased to. 1uf for Improved Bass Response. (2) tested and matched Vintage NOS 6GH8A Tubes – Premium Brands like GE, Sylvania, RCA etc. (4) New EL34 Nesstone. Plate Current Matched – Amazing Sound. (1) New GT 5AR4 / GZ34 Rectifier Tube – Provides a Soft Start – High Current Capability. 1% Accuracy Ultra Low Noise. 500v Rated Resistors by PRP – made specifically for Audio use. 70 Watts Total Output – 35 Watts Per Channel – Pure Clean Real Analog Power. Genuine Dynakit PC-3 “B” Circuit Board – Made Specifically for 6GH8A/6U8A Driver Tubes – No tube Adapters here. Bias Circuit uses (2) 100uf 100V Capacitors with Flameproof Metal Oxide Resistors. Dynakit PA-060 Power Transformer (120v Windings) – Notice its Size, the Increased Lamination Stack! Dynakit A-470 Output Transformers – (4,8,16 Ohm Taps) – Grain Oriented Laminations – Interleave Wound. Dynakit C-354 Shielded Power Supply Filter Choke – (1.75 Henries, 62 Ohms, 10%) – No Nasty Leaks. 9 Brand New High Quality Black Tube Sockets. 600v & 1000v Solid Core and Stranded Wiring Used Throughout the Entire Amp. Genuine Dynakit Multi Section Filter Capacitor – Factory Correct Values 80/40/30/20uf – 525v Rated. New Dynakit Stainless Steel Mirror Finish Chassis (Non-Magnetic) – Beautiful Museum Quality Look. Brand New Dynakit Perforated Steel Cover w/ matching badge. Power Supply has Diode Rectification. Flashback Prevention Safety Diodes Installed at the Rectifier Tube. Additional shielding on under chassis components to reduce EMI / interference. Careful wire routing to reduce movement & electromagnetic signal interference (EMI). Assembled With Alpha Fry 60/40 rosin core solder – for the Very Best Quality Connections. Power Transformer Isolation Bushings Installed – Prevents the Transfer of Mechanical Hum to the Chassis. Custom Silver RCA Input Jacks – Slightly Wider Spacing allows for Larger Modern Input Cables. Original Screw Style Speaker Output Terminals – Vintage Correct – Full Function (4,8,16 Ohm + Common/Ground). Heavy Duty Rubber Feet with Steel Bushings. Assembled with Great Attention to Detail Using High Quality Parts – 48 hr Minimum Burn in Tested – Sounds Incredible. Operates From a Standard Wall Outlet – No Voltage Reducer or Variac Needed – Built for Today’s 120v+ Voltages. Arrives With Bias Preset. Just Install the Tubes – Simple To Do – Instructions are Included. Front Preamp Sockets are Wired for Bias Set Only – Reduces Audio Signal Interference. The photos shown here are of several different amplifiers, meant to provide an example of the units offered for sale. Yours will look like the ones in these photos. Some pictures may show different brands of tubes. The tubes that are included are described in this listing. A Vintage Vibe with Modern Reliability. So how does it sound? Very musical with a highly detailed imaging & voice and plenty of solid, clean wonderful bass. This amp is absolutely dead quiet – no hum, no buzz, no hiss, no snap-crackle-pop! It sounds like it is supposed to. If you’re in search of that golden age of audio sound with stunning vintage looks, you’ve just found it. This is your bad boy. This is a 100% brand new amp, a very high quality build, total listening satisfaction. This ST-70 delivers dramatically improved sonics as the result of being carefully and thoughtfully built, all new, from the ground up, with technologically advanced components and all high-end parts. Is used with only a couple of re-engineered elements on the PCB solder traces to accommodate the 6GH8A tubes without having to use an adapter. Enjoy the rich smooth tones of analog audio and even order harmonics that only vacuum tube amplification can produce. It reveals musical qualities with fantastic realism and depth you may have never imagined possible. The legendary original design up to date with highly improved levels of sound quality, looks and performance. Because of the ST-70′s naturally high impedance (470K) it is compatible with virtually any solid state or tube preamp. This amplifier puts out 70 watts total, 35 watts per channel. It is fairly safe to say that most people today would have no idea of how wonderful a Stereo 70 amplifier is capable of sounding like. “Original condition” amps or those “updated” or having any number of “modifications” from mild to wild can still leave a lot to be desired. “Restored” is more than popping in a few capacitors and some tubes. Much more will need to be done to fully bring about that great sound the amp once had. Although they will play music, they are still incapable of reproducing the sound quality they possessed when new, 50 years ago unless they are fully restored. Resistors become noisy and drift out of tolerance due to age and heat. Circuit board and component materials begin to deteriorate causing signal degradation, solder joints and tube sockets can be loose, oxidized, worn and have poor quality connections causing signal interference and noise. Capacitors lose their range and clarity, their values having changed with time. Hiss, buzz, hum, pop and fuzziness are not normal or desirable qualities. Isn’t the great smooth sound of a time long gone by what you’re really after, those sweet tones produced only from tube amplification? Like a musical time machine, this amplifier will take you back to the beginning, like when these amps were new. But there’s even more to consider here. All of the components used in this amplifier have greatly improved characteristics over the ones available and used 50 years ago. That makes the sound quality of this amp even better than one would have been then, as a new one 50 years ago. Take a good close look at this one. Don’t cheat yourself out of what you’re really wanting; superb sound, high build quality, safe and reliable operation, great looks and that comforting pride of ownership. Pay particular attention to the size (height) of the power transformer on this amp (the middle one). Transformers are the heart and soul of a tube amp, period. Dynaco wasn’t messing around when they designed and built their originals. Notice how tall this new Dynakit transformer is compared to the original Dynaco PA060 power transformer. This is a real case of bigger is better. These new Dynakit transformers were reverse engineered from the original Dynaco designs using modern technologies and insulations. An increased lamination stack on this power transformer allows it to run cooler and provide better regulation. These transformers wont buzz or hum like the originals often do either. A major factor to consider here too is that the original transformers were designed to run from yesterday’s 117 Volt household current. Today’s household current is often 125 Volts or more so the use of a “step down” or “bucking” transformer is necessary to retard the voltage down to a safe operating level for amps having the original transformers. The new transformers are made for today’s higher household currents or VAC (Voltage). These transformers can be operated directly from your household outlets without secondary devices needed to reduce the voltage. These are USA made transformers that meet and exceed every aspect of the originals. If there were some sort of “magic” in the use of cloth leads, Dynakit would have certainly insisted on using them again. There’s simply no magic in cloth covered lead wire, period, it is inferior. In any comparison, these new transformers are just better than those old originals. Modern advancements in materials, methods and technologies used in the production of these transformers has resulted in superb transformers that operate quieter and cooler than the originals while providing less distortion, more power with increased reliability. The new A470 output transformers are also greatly improved, like the power transformer. The output transformers are interleaved/layer-wound and incorporate high quality M-6 grain oriented laminations. These also use better quality wire with better insulation, the primary is wound the same as the original A470 using the same number of turns on the same number of sections. These are made using the same patented Dynaco winding method, and made on the same core size and material type as the originals. These transformers are in one word, exceptional. I have selected the Groove Tubes 5AR4/GZ34 as the rectifier tube in my Dynaco 70′s for more than 2 years now. It has the highest current capability and has been 100% reliable, it also looks right at home in the amp. I believe it to be the best current production rectifier tube of its type on today’s market. Same story for the NessTone EL34/6CA7 tubes, they’re all I use now. These output tubes are hand selected and tested here in the USA and then identically matched as a quad (4 tubes) by their plate current test. Results using the ROE computerized testing system. I have had nothing but satisfied buyers and zero failures, they sound amazing. This amp also comes with 2 NOS Mullard or Amperex (as requested) 6GH8A tubes, tested and matched. The 6GH8A like the 7199 tube is a vacuum tube combining both a pentode and triode in a single glass envelope. Each section has a separate cathode and is electrically independent, the pentode is used for the input stage, and the triode as a phase inverter. The Dynaco ST-70 Series II came from the factory with a 6GH8A driver board and tubes. According to Dynaco published research and literature the 6GH8A tube actually outperformed the 7199! I also offer this amp in a 7199 version, identical in build with the exception of the 7199 driver board and tubes. The photos show the ST-70 using the updated Dynakit PC-3 board made for 6GH8A tubes. Amplifier makers like HH Scott, Harman Kardon and Eico, among others, have used the 6GH8A since back in the late 50′s. I honestly find no audible difference in the 7199 and the 6GH8A so long as both tubes are of equal quality. Good quality tubes are essential for the overall sound quality simply because they are a part of the circuit, the circuit can only sound as good as it’s parts will allow. Good circuit design is critical, the Dynaco circuit is genius. The 6GH8A, also no longer in production, appears to be in abundant supply and is very affordable. Like all tubes, some brands and build styles offer both sonic and reliability advantages over cheaper, inferior made tubes. This amp comes with. 2 NOS Mullard or Amperex (as requested). 6GH8A tubes, tested and matched. Tube installation instructions with a numbered easy to follow pictorial is included. Bias will be pre-set but due to variations in AC wall voltages the bias should be checked and adjusted as necessary for your specific location. Proper bias is essential for best sound quality and performance of the amplifier. Proper bias is also key to getting the most life out of your tubes. You are responsible for proper bias adjustment and maintenance, you will need a voltmeter that measures/reads DC volts and a small slot head screwdriver to turn the adjusters and to remove and reinstall the amplifiers cover. Bias should be set to 1.56 volts DC. Each unit is custom, a hand built, made to order unit. Your unit will look identical but wire color and routing may be slightly different from unit to unit, these are hand built units. Turnaround time is running 4-5 weeks right now. The manual with instructions, pictorials, diagrams, schematics and supplemental documentation is included. The item “Dynaco Dynakit ST-70 Stereo Tube Amplifier, New, Not Vintage EL34 Push Pull Amp” is in sale since Saturday, February 6, 2021. This item is in the category “Consumer Electronics\Vintage Electronics\Vintage Audio & Video\Vintage Amplifiers & Tube Amps”. The seller is “funtasticvintronics” and is located in Coweta, Oklahoma. This item can be shipped to United States.

• Model: Dynakit Stereo 70 / ST-70
• Modified Item: No
• Country/Region of Manufacture: United States
• Custom Bundle: Yes
• Included Tubes: (2) 6GH8A – (4) EL34 / 6CA7 – (1) 5AR4 / GZ34
• Type: Tube Amplifier
• MPN: DYNAKIT Stereo 70 / ST-70
• Brand: Dynaco
• Bundle Description: fully assembled amplifier with cover and all new tubes