The Evolution Series 70 Enhanced Tube Amplifier

In several listening sessions using multiple styles of music fed through a PAS-M tube preamp (not included) I was most impressed. The clarity and detail is excellent. The guitars, horns and voices seem as if they were right in the room. Bass and drums are defined, crisp, tight and sustained bass is just superb, much better than a stock Dynaco 70. The amp handles and presents all types of music extremely well, it has the "magic" and earns top ratings in all categories.
The front panel has a very clean industrial looking design interrupted only be the input jacks. The inputs are high grade parts with wider spacing and longer sockets to accept todays bigger better RCA connection cables.
The bias readings 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 70, bias is still set at 1.56VDC.
The cover is a genuine Dynakit in Satin Black with a custom made "Evolution Series 70" aluminum badge.
The back of the amplifier reveals more great features like 4 and 8 ohm banana jack binding posts. The 16 ohm taps are simply terminated under the chassis if ever needed. An updated 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 a standard 3AG slo-blo fuse.
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.
Under the chassis you are instantly drawn to the meticulous wiring and some additional components. This amp disposes of the old fashioned and traditional multi section filter capacitor which provided only 90uF of capacitance. Also gone is the original bias supply section. These are now combined on the capacitor board as seen at the right rear corner of the chassis. The cap board features 10 nichicon electrolytic capacitors and 6 film capacitors for very clean and smooth power. This brings capacitance up to 505uF, considerably more than the stock 70, you can definitely hear the difference. The Evolution 70 also has a genuine Dynakit C-354 shielded design filter choke. This amp truly rivals the best I've heard. All wiring was done with 20 and 22 AWG solid core wire using Kester solder. This amp is dead quiet, zero hum and sounds just incredible.
The custom circuit board uses the stock Dynaco circuit for 6GH8A or 6U8A tubes. The industrial duty PCB is 2mm in thickness, providing well insulated and isolated traces for superb stereo separation and premium performance. 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 give much better sound and stable performance 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 Raytheon JAN-6U8A tubes. These are communication grade tubes made in 1962 for the US military. Original boxes included.
RECTIFIER OPTIONS: (your choice)
 
Option A: New production Genalex GZ34/U77 type (seen in some photos) 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. 
Option B: A fully 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 warmup 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 from the 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 incredible. The bigger sized tubes also give the amp a really nice look. These were identically matched by Ip at 57 and also for Gm at 7,600 with tests conducted 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 one is not quite as refined, I consider it slightly industrial and matter of fact looking. It's internally welded at the corners, that method does not provide the smoother and 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 chassis will have a few light marks here and there as usually present on any chassis, these occur during the manufacturing and build process. In other words it is not a 100% perfect museum quality piece. This is a very heavy duty and well made chassis. This amp is ready to go now, don't miss out on this one!
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, acts of god and nature are excluded. Be smart and use appropriate AC power protection to prevent damage from power surges and lightning strikes. 
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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 will eradicate this properly while retaining the function of the ground.
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Shipment is prompt, professionally packed and will be fully insured
Ships UPS Ground Only
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