Brand New - All New - Custom Dynaco ST-70 Tube Amplifier "Evolution Series" Build
Bias Balance Control - Upgraded Capacitance - Binding Posts - Mullard Tubes
Assembled - Tested - Ready to Ship Immediately
This amp makes it easy to enjoy the rich smooth tones of pure analog audio and even order harmonics that only vacuum tube amplification can produce. Vacuum tubes reveal musical qualities with fantastic realism and depth you may have never imagined possible. Built with high quality components, this all new amplifier brings the legendary original design up to date, and then some. Your favorite music can sound even more beautiful. The ST-70's naturally high impedance (470K) makes it compatible with virtually any solid state or tube preamp. This is truly an amazing 35 watt per channel Audiophile Grade Tube Amplifier. It's easy to use, super reliable and best of all it sounds heavenly.
Most people today have no idea of just how wonderful a Stereo 70 amplifier is capable of sounding like. Isn't it the great smooth sound and sweet tones produced only from tube amplification what you seek? then consider this...all of the components used in this amplifier have greatly improved ability and characteristics over the components available and used 50 years ago. That makes the sound quality of this amp even better than it would have been then, as a new one 50 years ago. Take a really good close look at this amp, this is not a "garage sale or estate find". This is a brand new, all new Stereo 70 that offers superb sound, high build quality, safe and reliable operation and great looks. Yes, you can hear the difference. The soundstage is buttery smooth with a very spatial and lifelike sonic presentation. Not enough can be said for a properly built and well equipped Dynaco 70. No wonder they sold over 380,000 of them. The value and return ratio achieved by the Series 70 is unsurpassed. This amp has evolved.
This "Evolution Series 70" amp has many features and upgrades not found on an "out of the box" Dynaco 70. The amp has an upgraded driver board utilizing the original Dynaco circuit made specifically for 6GH8A or 6U8A tubes. When 7199 tube production ceased, the engineers at Dynaco developed and released the 6GH8A circuit. The PCB is 2mm thick, that's about double the thickness of other PC boards typically found in today's market. The high degree of trace insulation provides improved signal integrity and better stereo separation. This thicker PCB also provides improved durability by eliminating flexing of the board during tube swaps.
This upgraded build features the superb Vishay HQ1839 series 850 volt rated .22uF and .1uF axial-leaded metallized polypropylene coupling capacitors. The small (82 & 390pF) capacitors are 1000 volt rated Kemet and Murata MLCC type with C0G (NP0) dielectric. These caps provide improved sound characteristics through their better linear stability, these are much better than traditional silver mica type caps. The resistors are Vishay metal and carbon films for spectacular clarity and dependability. Ceramic tube sockets provide excellent heat shielding for the circuit board. Two test matched NOS Tungsram (pre-war Hungary) 6U8A tubes with vibration dampers are included. Great sounding tubes from that by gone era!
The multi section filter capacitor is upgraded from the stock 30/20/20/20uF cap to a more capable 80/40/30/20uF cap and it's rated for 525 volts with 1%, 1 watt Panasonic resistors. This is a genuine Dynakit filter cap, it provides higher reliability and increased energy storage for improved bass response. The bias supply is diode rectified and features 100uF @ 100V capacitors made by F&T (Germany) and has 1% tolerance Vishay metal film resistors. There's also a Dynakit C-354 choke and it is the fully shielded version for superb performance.
This amplifier is equipped with the Dynakit "bias balance control" system. This allows equalizing and then balancing of the bias current between the individual output tubes for enhanced sonics, extended tube life and higher overall reliability. Bias is initially adjusted using the original bias pots. Then using the additional secondary adjusters located at the center holes of the front octal sockets, the balance is adjusted between each EL34 tube. This equalizes the current between each pair of output tubes. All four bias pots have safety resistors installed to protect the amplifier should a bias pot fail. Easy to follow bias setting instructions are included.
The output/power tubes are a brand new perfectly matched quad of EL34/6CA7 by Mullard. These are premium grade tubes, hand selected and plate current matched by the factory. The tubes are burned in and have been tested for microphonics. Nice quality excellent sounding tubes! Original boxes with test data are included. These tubes bring out the subtle details that you've been missing and the low end is super smooth. The Mullard Reissue EL34's have a spectacular balance of tone, excellent soundstage and 3D imaging across the sonic spectrum.
The rectifier is a brand new Mullard 5AR4/GZ34. This rectifier is spectacular sounding and features excellent reliability with a gentle start / warm-up period. The rectifier tube socket provides enhanced protection for the tube by having two diodes installed underneath on the socket pins. These diodes prevent reverse current or "flashback" from damaging the tube in the event of a sudden on-off-on power sequence. The tube ships with its original box.
The Genuine Dynakit PA060 power transformer and two A470 output transformers are wound for modern day household voltages, the amp is plug and play. You do not need a voltage reducer to use this amplifier, just plug it in. These transformers 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 using modern technologies and insulations. An increased lamination stack on this power transformer allows it to run cooler and provide better regulation. These are USA made transformers that meet and exceed every aspect of the originals. The new A470 output transformers are interleaved/layer-wound and incorporate high quality M-6 grain oriented laminations. 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 are exceptional transformers by any standard.
- The amplifier is built on a trophy quality Genuine Dynakit chassis, it's mirror polished stainless steel and is just a work of art.
- The factory painted cover is satin black and has a custom made solid aluminum badge.
- The amp sits on 4 oversized rubber feet for improved chassis ventilation and has a nice solid stance.
- The outputs on the back of the amplifier are 4 and 8 ohm binding post / banana plug terminals with gold plating. You can use bare wire or banana plugs with these terminals.
- The amp is 16 Ohm capable but would require some minor wiring adjustments to make it functional. (due to the use of binding posts vs. screw terminals - limited space)
- Slightly wider spacing for the RCA inputs makes room for larger interconnects and the gold plating offers great contact and corrosion resistance for long life.
- There is a standard fuse holder using a 3AG slo-blo fuse.
- The 15 amp grounded power cord is secured by a Heyco retaining bushing.
20AWG solid core wiring throughout, soldered with Kester 63/37
This amp has been burned in and real world tested for over 24 hours, it sounds phenomenal and is rock solid.
The amp shown in the photos is the amp you are going to receive, nothing else in the photos is included. (Amplifier + Cover + tubes + manuals/documentation)
The tubes will be removed and individually boxed, then boxed again, then packed carefully inside the larger box.
Tube installation guide, all assembly and operating manuals, bias instructions etc. are included
Shipped insured for full value - signature required*
Professionally packed - Promptly Shipped
No P.O. Box delivery
*All insured shipments require a signature at time of delivery. Delivery changes are not possible once the item is shipped.