Category Archives: Dynaco

Dynaco | High Quality Audio Components

Founded by David Hafler and Ed Laurent in Philadelphia, Pennsylvania in 1955, Dynaco was an American hi-fi audio system manufacturer popular in the 1960s and 1970s for its wide range of affordable, yet high quality audio components. In 1950, David Hafler and Herb Keroes started a Philadelphia-based company called Acrosound in order to build and sell audio-quality output transformers, primarily for home electronics hobbyists.[1] The two men refined and developed the Ultralinear audio circuit pioneered by British audio electronics engineer Alan Blumlein, using taps from the output transformer to feed signal back into the output stage screen grid circuitry.[1] The Acrosound transformer circuit was later used in many home-built and commercial hi-fi amplifiers in the early 1950s.[1] In order to appeal to a wider consumer market, Hafler decided to design and build entire power amplifiers as build-it-yourself kits, complete with preassembled, tested circuit boards that only required the customer to wire the boards to the transformers, controls, and power supply to complete the project.

Dynaco Dynakit Mark-IV
Dynaco Dynakit Mark-IV

Today, Dynaco is best remembered for its highly regarded vacuum tube stereo amplifier, the Stereo 70 (ST 70). Introduced in 1959, the ST 70 was available as a kit (Dynakit) intended for assembly by the purchaser or as a complete factory-wired unit. The ST 70 used four EL34 output tubes, one GZ34/5AR4 rectifier tube, two 7199 input (driver) tubes, two output transformers, one power transformer, and a preassembled printed circuit board (PCB) containing the driver circuit. It produced 35 watts per channel (wpc). The driver circuit had a single 7199 pentode/triode tube per channel, and used the driver tube to handle both voltage amplification and phase splitting. The output transformers are an ultralinear design, whereby part of the primary winding is fed back to the output tube’s screen grid. This design reduced distortion and improved audio quality.

A masterpiece of efficient circuit design, the ST 70 provided reliable, high-quality audio amplification at an affordable price. The popularity of the ST 70 contributed more than any other single product to continuing consumer interest in tube-based stereo amplifiers at a time of increasing market dominance by solid state audio products. Because of its excellent value for cost, Dynaco tube amplifiers were often referred to as “the poor man’s McIntosh.” More than 350,000 ST-70 amplifiers had been sold when production finally ceased, making the ST 70 the most popular tube power amplifier ever made. Dynaco Catalogs for download at http://home.indy.net

Dynaco Dynakit Stereo 70 Power TUBE Amplifier ST70 DYNA ~WORKS AND SOUNDS GREAT~

$599.99
End Date: Thursday May-25-2017 12:43:43 PDT
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vintage stereo integrated amplifier Harman Kardon A402, full works | USA / Japan

$350.00
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2 CONN 6026 MONO BLOCK TUBE AMPLIFIERS 6L6 or 7027A - RESTORED Plug 'n Play 35W

$695.00
End Date: Wednesday Apr-26-2017 9:58:35 PDT
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1960's DYNA Preamplifier PAS Model~Newly Serviced~ & DYNACO Microphone~Original

$749.00
End Date: Friday May-19-2017 13:51:21 PDT
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Dynaco | Dynakit Stereo 70 | Tube Amplifier

Dynaco | Dynakit Stereo 70 | Tube Amplifier
Dynaco | Dynakit Stereo 70 | Tube Amplifier
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Item location: United States | Ships to: United States
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1960 Dynaco Stereo 70 tube amp. 1 owner since new. All original with the exception of the bias capacitors, rectifier diode & output tubes. The original 7199 tubes (dated 1960) and GZ34 test very strong on my Hickok 539C. The EL34 tubes are new Electro Harmoix. The circuit & transformers are all original. I replaced all the high voltage caps in the bias section and it is working excellent right now, all voltages are correct and stable. The selenium rectifier was also replaced and the bias voltage is now very responsive and stable. The amp sounds very nice, no hum or unwanted noises.

You can enjoy this amplifier the day you receive it. The cosmetics are very good with only light tarnish on the chrome chassis. The original owner engraved his ID # on the back and bottom (see photo). Both channels sound very nice through any speakers you pair it up with. The bias is perfect and the amp runs very cool and quiet. Please see all the photos I uploaded. You will be able to use this amp the day you receive it & you will not believe the audio quality!! Guaranteed to be as stated or full refund. Local Pick Up Is Preferred. Email any questions.

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Dynaco | Amplifier & Preamp & Tuner Set | SOLD

Dynaco Tube Preamp Amp Tuner Set
Dynaco Tube Preamp Amp Tuner Set

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Item location: United States | Ships to: United States
Sold for US $860.99

This listing is for a complete Dynaco stereo system which my dad built back in the 60s. It includes the Pre Amplifier, Amplifier and Tuner. It is complete and functional.

 

DYNACO COMPONENT DESCRIPTIONS

Dynaco FM Tuner
Dynaco FM Tuner

DYNACO FM TUNER ( FM-3)
– Four IF limiters, wide band balanced bridge discriminator, time switching multiplex system.
– Automated stereomatic multiplex circuit locks in and signals stereo automatically. Never any problems with recording off the air.
– Self contained multiplex integrator
– 11 tubes and 6 diodes which develops FM’s full potential.
– Cathode coupled tuned RF input and oscillator mixer use slug-tuned coils for easy alignment.
– 55 watts
– 13 pounds | Not used for 25 years | Original assembly manual included.

Dynaco Preamplifier
Dynaco Preamplifier

DYNACO PREAMPLIFIER (PAS-3)
– All feedback design for unmeasurable distortion, low noise, complete freedom from overload and consistent performance at all volume control settings.
– Exclusive Dyna feedback tone controls provide necessary correction at the extremes without altering the natural balance of the midrange.
– Equalization accurately controlled with 1% components. Low noise resistors used in all critical stages.
– 30 watts
– 11 pounds
– Not used for 25 years.
– Original assembly manual included.

Dynaco Amplifier
Dynaco Amplifier

DYNACO AMPLIFIER (STEREO 70)
– Full utilization of the performance capabilities of patented Dynaco output transformers.
– Firm, perfectly defined bass and smooth, natural highs. Absolute stability provides a transparency which delineates the most subtle orchestral nuances.
– The Stereo 70 is noteworthy for ultra conservative operation at only 65% of capacity, and filter capacitors at less than 85% of rated voltage.
– 70 watts continuous, 90 watts IHF Music Power. 35 watts each channel
– Power consumption 175 watts

Other Dynaco Amplifier

Dynaco MARK III Mono Tube Amplifier Factory Built w Box Manual & Tags

$799.00
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Dynaco 416 Power Amplifier

$900.00 (0 Bids)
End Date: Tuesday May-2-2017 16:00:01 PDT
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Dynaco Dynakit Stereo 70 Power TUBE Amplifier ST70 DYNA ~WORKS AND SOUNDS GREAT~

$599.99
End Date: Thursday May-25-2017 12:43:43 PDT
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DYNACO STEREO 70 TUBE AMPLIFIER, PRE-AMPLIFIER, TUNER RESTORED

$1,100.00
End Date: Thursday May-25-2017 3:13:46 PDT
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