(any "SOLD OUT" items can be duplicated to a very similar likeness for you - ask if you're interested)
"Evolution Series 70 Enhanced" Dynaco based ST-70 Tube Amplifier
Two Channels - 35 Watts Per Channel - 70 Watts of Analog Tube Powered Audio!
Ready to SHIP NOW!
This amp is built on a "one of a kind" Genuine Dynakit Stainless Steel chassis that was a preproduction piece made back in 2004 for manufacturing quality assurance and fitment inspection. This chassis was never polished to the mirror finish like the production version. This chassis was stored away at the Dynakit warehouse until I purchased it. There are a few minor scratches from being handled off and on over the years but these were there when I bought it and are not glaring issues by any means. The markings on the underside of the chassis are from manufacturing and would have normally been polished out but since this chassis was not for resale/production use these were left as you see them.
The amp comes with a brand new Dynakit Stereo 70 perforated steel cover in Dark Grey and has a specially made solid aluminum matching badge. This is a really cool looking amp and you'll never see another one like it. This is a brand new build with all new parts, completed on April 14 of 2021. Photos are of the actual amplifier you will receive.
The amp has the Dynakit Bias Balance Control upgrade so the output tubes are equally biased then balanced for the ultimate in equal stereo output and superb tube life. The additional adjusters are neatly installed behind the two front mounted octal sockets. The adjuster is visible at the center hole of each of these sockets and a small flat head screwdriver is used to turn them when making adjustments or setting the bias and balance. You will need a voltmeter capable of reading millivolts (.40-.50mV)
The Upgraded Premium Dynakit multi section capacitor is the bad boy version rated for 550V (600V surge) and uses four discreet (individual) caps inside the metal can style enclosure. The bias section has two 100uF 350V F&T capacitors with Takman 1% 2W 10K metal film audio grade resistors and makes good clean smooth power. All of the other resistors under the chassis are industrial duty metal films for super quiet and dependable operation. Additional shielding on all leads help reduce interference from stray EMI and electrical fields.
The transformers are new production by Dynakit. The huge PA060 power transformer and two A470 output transformers are wound for modern day voltages. These operate cooler, produce less distortion and will outperform vintage transformers in every category. The current production Dynakit transformers were reverse engineered from the original Dynaco designs, but 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 is that the original transformers were designed to operate on 117 Volts. Modern household AC current is often 125 Volts or more so the use of a "step down" or "bucking" transformer is necessary to reduce the voltage down to a safe operating level for amps having the original transformers. 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 better than those old originals, no offense intended. Modern advancements in materials, methods and technologies used in the production of these transformers has resulted in superb transformers that produce cleaner power, operate quieter and run cooler than the originals while providing less distortion and 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.
The custom black circuit board uses the stock Dynaco circuit for 6GH8A or 6U8A tubes. This industrial duty PCB is 2mm in thickness, providing sturdiness, with improved durability. The thicker PCB provides well insulated and more isolated traces for superb stereo separation and premium performance. The Cornell Dubilier 940 series capacitors provide a rich, warm and detailed sonic presentation. These caps are sheathed in black heat shrink to mimic the old Black Cat or Pyramid caps found on the original Dynaco tube amplifiers. The small capacitors are Murata MLCC with C0G (NP0) dielectric and provide improved sound characteristics and better linear stability than the traditional silver mica type. All the resistors are 1% metal films and carbon films for spectacular clarity and dependability. The board is populated with two test matched NOS GE 6U8A tubes. These are premium grade tubes and sound fantastic. The tube sockets are heavy duty ceramic type, these are the very best sockets to provide protection of the circuit board from heat generated by the tubes.
The rectifier tube a a new production GT 5AR4/GZ34 type for a nice smooth supply of DC and a time delayed start up to protect the tubes during initial power up. Original box is included. The rectifier tube is protected with two diodes on the tube socket that will prevent flashback current from entering and damaging the rectifier during the event of a sudden power on-off-on sequence.
The output tubes are a factory matched quad of 6CA7 big bottle type from Electro-Harmonix and sound wonderful and very smooth. These are an EL34 class of tube. The larger sized tubes give the amp a really nice look too. These tubes were identically matched by Ip for Gm with tests conducted using 400V at the plate, 250V for the screen and -17.52 bias. Original boxes with test data are included.
The back of the amplifier has 4 and 8 ohm banana jack binding posts. The unused 16 ohm output taps are used directly in the NFB circuit. The 16 Ohm outputs can be wired up if needed, however you would have to sacrifice either the 4 or 8 ohm output terminals. There is also a traditional fuse holder using the standard 3AG slo-blo fuse. The amp has a 3 prong heavy duty grounded power cord.
Note the meticulous wiring, this Evolution 70 also has a genuine Dynakit C-354 shielded design filter choke. This amp is dead quiet, zero hum and sounds just incredible. All wiring was done with 20 and 22 AWG solid core wire using Kester 60/40 rosin core solder.
The amp has even more great features. The RCA inputs have wider spacing to accept todays bigger and better RCA connection cables. The cover is a brand new genuine Dynakit with a custom made "Evolution Series 70" dye sublimated aluminum badge.
The amp is warrantied for 6 months excluding the tubes. You will be responsible for shipping both ways for warranty work but the work and parts are free of charge. Abuse, neglect and acts of god and nature are excluded. Be smart and use appropriate AC power protection to prevent power surges and lightning strikes. Warranty details can be provided before you purchase and will be included, printed on paper.
This amp sounds absolutely stunning and will be a great centerpiece for your audio collection. I could easily just keep this one myself but I have too many already.
All amps come with a 3 wire grounded power cord, be prepared to invest in a ground isolator or adapter to avoid and prevent ground loop feedback / hum if this surfaces as a problem when installed into your system. This is a very common issue where 3 wire / grounded cords are involved. The Hum-X device, when installed correctly, will eradicate the ground loop properly, while retaining the full and safe function of the ground. The Jensen Iso-Max is also highly effective between your source (preamp) and amp to eliminate hum that may be generated from the source (preamp) rather than through the power cord.