Dynaco/Dynakit ST-35 with Gillespie EFB, Tubes and Cover

This Dynakit Stereo 35 features *Enhanced Fixed Bias* by Gillespie Designs, includes the Matching Gillespie PC-13 Amplifier PC boards and includes new tubes and the cover. It also includes several custom features not found on the standard ST-35 like a power switch, an inrush current limiter and banana jack binding posts.

EFB™ converts the ST-35 to fixed bias operation and reveals the Stereo 35 Amplifiers full potential. The 17.5W rated power output will be maintained with both channels driven, and distortion significantly reduced. The *EFB™ feature, when combined with increased power supply capacity, provides an outstanding upgrade for the ST-35.

The ST-35 Capacitor EFB™ Board replaces the original multi section power supply filter capacitor as well as all the associated resistors and high voltage rectifier diodes. Besides larger overall capacitance, additional metalized polypropylene bypass capacitors are added. The original cathode bias resistor is replaced with an innovative Enhanced Fixed Bias feature that allows the ST-35 to perform to its full potential with both channels driven.



Although factory rated at 17.5W per channel output power, this is really only true if only a single channel is driven. With both channels driven, however, power output is typically closer to 14W per channel, and distortion is significantly higher. This is largely due to various compromises related to the use of the simple, but economical, cathode bias system Dynaco used in the stock amplifier.

The EFB modified ST-35 still requires a matched quad of output tubes. This minimizes the extent of changes required and maintains as much of the original design concept as possible and it facilitates the best sonic results. As with any tube amplifier, having matched output tubes is always a worthwhile investment, it pays off nicely by achieving matched performance from both channels.

*EFB™ is a trademark of D. Gillespie Designs

STANDARD FEATURES:

  • Genuine Dynakit Mirror polished stainless steel non-magnetic chassis
  • Dynakit PA-774 power transformer and matched Z-565 output transformers
  • D. Gillespie ST-35 Capacitor EFB™ Board
  • D. Gillespie PC-13 Amplifier Board Set with upgraded tube sockets 
  • CDE / Audyn Capacitors
  • (4) Tung-Sol EL84 tubes
  • (2) Electro-Harmonix 12DW7/ 7247 Preamp Tubes
  • Upgraded 1% Metal Film resistors
  • Assembled entirely with Alpha Fry and or Kester 60/40 rosin core solder with Carol and or Alpha brand stranded and solid core wires
  • 6 Amp rated power on/off toggle switch added and a custom retro-look power cord
  • Amphenol CL90 inrush current suppression / limiter (thermistor) installed
  • Operates from a standard 120-125v wall outlet, no need for a variac or bucking transformer (voltage reducer)
  • Hand built and thoroughly tested - 24 hour burn in - extensively auditioned for sound / operation quality before shipped
  • Manuals and all supplemental documentation included on CD-Rom

 

INCLUDED TUBE SET:

  • Tung-Sol EL84  matched Quad
  • Electro-Harmonix  matched  12DW7 / 7247

     

    DETAILS AND DESCRIPTION:  

    Now, here's the big question, do you really want an amplifier that sounds and looks 50 years old?  Romantic - yes, nostalgic - sure, practical? - Not really. Keep in mind that an original condition 50 year old tube amp is going to sound 50 years old, not like it did 50 years ago when it was new. If that is really what you want, that's fine, this one probably isn't what you're looking for. This amp is 100% new, and needs nothing, it sounds, works and looks far better than any Stereo 35 ever did 50 years ago. If that weren't enough, we've raised the bar bit more with this version, the Stereo 35 with EFB™

    The Amplifier Kits are purchased direct from Dynakitparts.com. We then add the upgraded features and components that further elevate the performance, giving you a beautiful, unique and spectacular sounding amplifier.

    Banana post output terminals are included on this version of our ST-35

     

    This amp is absolutely dead quiet, no hiss, no hum, just crystal clear music is all you hear

    An inrush current limiter (CL90) has been incorporated to regulate and soften the power on process, this feature helps protect the tubes and extends component life. This new chassis is heavy duty (non-magnetic) type 304 mirror finished stainless steel with durable black epoxy silkscreen lettering. The perforated cover is available finished in Original Brown, Black or Dark Metallic Grey. Four 1/2" tall rubber feet with steel bushings are installed instead of the small "bumpers" that are supplied with the kit. This is done for better isolation and improved chassis ventilation. 
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    Each channel uses its own discrete amplifier board, these are Gillespie PC-13 boards, they’re made in the USA. These heavy duty boards faithfully reproduce the original and brilliant Dynaco Stereo 35 circuit, layout and color, they're made to military specs using modern materials of the highest quality. The stereo separation this unique design provides is amazing. 

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    The boards have upgraded tube sockets. The resistors are rated at 1% tolerance to ensure the signal circuit is quiet and accurate. Original capacitance (uf/mfd) values were kept as recommended to avoid creating low-frequency instability. The screening tolerances are tightened up for improved sonics and component voltage ratings are slightly increased for higher reliability. The tighter screening tolerances of the resistors and excellent quality capacitors help give this amp its great ability to reproduce complex musical passages in superb detail while keeping all the magic and smooth musical warmth you want. Great sound comes from great circuit design, not magic parts. Having high quality parts in a great circuit simply enhances the already good design. This amp obviously holds great advantage over a new unmodified or original condition ST-35. The warmth, depth and detailed sonic range of this amps soundstage are incredible.

     

     The heart and soul of any tube amplifier are its transformers. The new PA-774 power transformer and matching Z-565 output transformers are exceptional quality Dynakit transformers that meet or exceed the quality and performance of the originals and they're made in the USA. The Z-565 output transformers use M-6 grain oriented laminations and they are interleaved wound just like the originals. With these new Z-565 transformers, this ST-35 will accommodate a pair of either 4 or 8 ohm speakers making it much more compatible for use with modern speakers than the 8 and 16 ohm design of the original Z565 transformers. The new PA-774 power transformer is wound for today's real world 120v + line voltage as opposed to the originals which were wound for the 112-117v of the early 1960's. Modern windings are a huge and convenient improvement which allows this amp to operate directly from a standard wall outlet without the need of a voltage reducing device. Another big improvement is the fact that the PA-774 incorporates Class "B" insulation & wiring which is better designed to handle significantly higher operating temperatures. Based on findings from a tear down and close inspection of some number of original production Dynaco PA-774 power transformers, it was concluded that all of these old units were of a Class A design with a maximum operating temperature of only 221 degrees Fahrenheit. The new production PA-774 units are designated as "B" classification, a NEMA Class 150 C design having a maximum operating temperature of 302 degrees Fahrenheit. Operating close to or beyond a transformers temperature rating will eventually result in a premature failure of the unit. The bottom line is the new production Dynakit power transformers are designed to handle measurably higher operating temperatures than the original Dynaco power transformers resulting in near zero failures, extended service life and enhanced durability. The power transformer is mounted on rubber isolation bushings. 

     

    So what about all the fuss made over those “magic” cloth lead transformers? The truth here is there’s no magic in those cloth lead wires whatsoever. Cloth covered leads simply indicate early manufacture (pre-1970) and for many brands, those old transformers are in fact better quality than their new production counterparts and replacements. This is certainly NOT the case with the new Dynakit transformers which incorporate the latest design advancements in metals, insulation, resins and construction. The results of this well executed transformer design and painstaking production effort are quieter and cooler operating transformers which effortlessly provide increased performance over the originals.


    1963 STATEMENT FROM THE DYNA COMPANY


    The Dynakit Stereo 35 is a dual power amplifier of deceptively simple appearance and circuitry. Behind its seemingly conventional design is an extremely sophisticated circuit configuration representing the most recent advances in power amplifier engineering and construction. This high degree of technical refinement, combined with the conservative use of premium-grade components, has resulted in a typical Dynakit design offering superb performance at low cost. Each of the two channels in the Stereo 35 is rated as a 17.5 watt amplifier. Although not evident from this simple rating, the power stated is available on a continuous basis at any frequency from 20 to 20,000 cycles per second. A music power rating would make the Stereo 35 a 45-watt amplifier, although even this rating would not disclose that full power is available at low distortion throughout the audio spectrum. Nor would such a rating indicate that the Stereo 35, even when driven to power output levels beyond its rating, is able to handle these overloads gracefully, with minimum detriment to the sound. As a result, the Stereo 35 can, if necessary, duplicate the sound intensity of amplifiers with much higher power ratings when called upon to do so. The heart of the Stereo 35 is the special Dynaco Z-565 output transformer, a patented design tailored specifically to this circuit. The transformer is free of resonances, has extended frequency response (from 6 to over 60,000 cycles), and is wound by special techniques on a carefully designed core to insure low distortion over a wide frequency spectrum. Transformers of this calibre have never previously been used in low-cost equipment of moderate power rating.

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    • Each unit is custom, a hand built, made to order unit and wire color / routing may be slightly different from unit to unit, these are hand built custom units. 
    • *bias will be pre-set but due to variations in AC wall voltages the bias should be checked and adjusted for your location before using the amplifier.  
    • *EFB™ is a trademark of D. Gillespie Designs


    Included with your shipment: 
    Warranty Information Documents (printed on paper)
    The manuals, instructions, pictorials, diagrams, schematics and supplemental documentation are all included on a CD-ROM.

    SHIPPING is Fully Insured with Tracking
    All insured shipments require an adult signature at the door upon delivery, so plan accordingly please. We do NOT ship to PO box addresses, so you must have a valid physical street address. For safest shipping, all of the tubes, the fuse and fuse cap will be removed and individually boxed, numbered and labeled. A numbered pictorial for quick easy tube installation is included, all you'll need is a screwdriver for removing the cover. Includes the printed Dynakit Stereo 35 assembly and operating manual stamped with the serial number that belongs specifically with this unit along with other supplemental documentation referencing the wiring, transformers, circuit boards, parts, bias instructions etc.


    Unpacking your shipment:
    Tubes, fuse and Fuse cap are removed for shipment - numbered and boxed, all packed carefully for secure shipping. Tube installation instructions with a numbered easy to follow pictorial included. 
     

    This item is covered by a warranty:

    warranty is limited - warranty is for 6 months from the date of purchase, warranty coverage is offered the original purchaser only. Proof of purchase is required to file for an RMA.

    RMA is for warranty work only, it is not for a refund. Issues from abuse, misuse, neglect or external damages are not covered. Signs of tampering or repairs by anyone other than funtastic vintronics voids all warranty coverage.

    Damage from moisture of any kind, electrical surges, lightning and static electricity are not covered. Coverage is limited to replacement of any original components which have failed under normal operating conditions. Faulty components will be replaced with no charge to you for parts or labor. Vacuum tubes/valves are not covered by warranty. Damage caused by faulty tubes is not covered by warranty.

    Shipping both ways is the responsibility of the original owner/purchaser of the unit. You must request an RMA number prior to making any warranty claim. Your RMA must be approved prior to shipping. Please follow appropriate packing methods to prevent shipping / transportation damage. We strongly suggest insuring your shipment for the replacement value of the item being shipped.

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