- Pre-Orders Only at this time - 4-5 weeks for delivery
- This custom built amp is based on the Dynaco ST-70
- New Genuine Dynakit PA-060 and A-470 transformers (125V)
- Custom stainless steel chassis in a brushed finish with the most desired features so many have always wanted.
- The cover is black and comes with a great all new tube set
The Evolution Series 70 Enhanced Tube Amplifier
The custom made red circuit board is a stock Dynaco circuit, made specifically for 6GH8A or 6U8A tubes. Look closely, this is not the cheap China made knock off you often see sold. This is an industrial duty PCB, 2 mm in thickness, providing improved durability and minimal flexing stress during tube swaps. This thicker PCB provides well insulated and better isolated traces for superb stereo separation and premium performance. When 7199 tube production ceased years ago, Dynaco developed and released this circuit. Thousands of late model Dynaco 70 amps came with this circuit version and 6GH8A tubes. The MCap Series Mundorf capacitors help provide the rich, warm and detailed sonic presentation. 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 6U8A or 6GH8A tubes. These will be premium brand grade tubes. This is a spectacular driver board and sounds excellent.
Under the chassis you are instantly drawn to the meticulous wiring and will find some additional components. This amp disposes of the old fashioned multi section filter capacitor which provided only 90uF of capacitance. Also gone is the original style bias supply section. These components are now combined on the green capacitor board seen in the right rear corner of the chassis. This capacitor board features 10 Nichicon electrolytic capacitors and 6 film capacitors for very quiet, clean and smooth power. This upgrade brings capacitance up to 505uF, considerably more than the stock 70, you can definitely hear the difference. Damping factor is increased considerably too, so the bass response is excellent. This Evolution 70 has a genuine Dynakit C-354 shielded type filter choke. This amp is dead quiet, zero hum, has huge power reserve on tap and sounds just incredible. This amp rivals the best ST-70 I've heard. Wired with 20 and 22 AWG solid core Alpha and Carol wire using Kester 60/40 rosin core solder.
The soundstage, clarity/detail is excellent. Strings, horns and voices are as if they are right in the room. Bass and drums are defined, crisp, tight and the ability to sustain bass is just superb due to the increased capacitance. This amp performs considerably better than a stock Dynaco 70. The amp handles and presents all types of music extremely well, it has all the "magic"! It earned top ratings in all categories,.
This custom built 2 channel tube amp has a Triode stainless steel chassis with a brushed finish and has some great features. The front panel has a very clean and industrial looking design interrupted only be the input jacks. The gold plated inputs are high grade parts with wider spacing and longer sockets to accept todays bigger and better RCA connection cables.
The back of the amplifier reveals more great features like the 4 and 8 ohm banana jack binding posts. The unused 16 ohm output taps are terminated under the chassis, used directly in the NFB circuit. The 16 Ohm outputs could be wired up if needed but since this chassis is drilled for only two binding posts and a ground, you would have to sacrifice either the 4 or 8 ohm output terminals. An updated heavy duty rocker style power switch and a heavy duty IEC power socket with a removable heavy duty 16/2 grounded cord are standard. There is also a traditional fuse holder using the standard 3AG slo-blo fuse.
The transformers are new production by Dynakit, what else?. 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 bias readings on this amp are taken at the two red test jacks located just in front of the power transformer while using the chassis for ground. Just like the original Dynaco Stereo 70, bias is still set at 1.56VDC.
The cover is a genuine Dynakit in Satin Black with a special custom made "Evolution Series 70" dye sublimated aluminum badge.
Includes a solid state rectifier "tube" (seen in some photos) that really gives this amp some extra punch. This "copper cap" rectifier also has an inrush current limiter inside so it provides a nice warm up time like the GZ34 tube would. The solid state rectifier reduces voltage sag and "soggy" bass under load and makes this amp a real bass beast. This option also features extra protection with the two additional 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. Bulletproof!
The output tubes are a factory matched quad of EL34 / 6CA7 big bottle type from Electro-Harmonix and sound wonderful and smooth. These larger sized tubes give the amp a really nice look. Tubes are identically matched using 400V at the plate, 250V for the screen and -17.52 bias. Original boxes included.
So, compared to the Dynakit mirror polished chassis this chassis is not quite as refined, I consider it slightly industrial and matter of fact looking. It's internally welded at the corners, that manufacturing method does not provide the smoother, more accurate vertical lines at the corners as found with the Dynakit chassis. Fingerprints are not nearly as noticeable with this chassis however, which a big plus. This is a beautiful, very heavy duty and well made chassis. This amp is ready to go now, it looks and sounds just amazing, it has it all! If you are looking for a 50 year old amp, this isn't it! This amp will "get it done" all day long and create no worries about it.
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.
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.
Shipment is prompt, professionally packed and will be fully insured
Ships UPS Ground Only
Warranty is for 6 months from the date of purchase, warranty coverage is offered the original purchaser only.