Dynaco
| Company type | Private |
|---|---|
| Industry | Audio equipment manufacturing |
| Founded | 1955 in Philadelphia, United States |
| Founder | David Hafler, Ed Laurent |
| Defunct | 1980 |
| Fate | Dissolved; brand acquired by other companies |
| Headquarters | Philadelphia , United States |
Area served | United States |
| Products | Hi-fi audio equipment including tube and solid-state amplifiers, preamplifiers, radio tuners, bookshelf speakers |
| Parent | Tyco, Inc. (from 1969) |
Dynaco was a notable American manufacturer of hi-fi audio equipment during the 1960s and 1970s, recognized for delivering high-quality sound products at accessible prices. Established in Philadelphia in 1955 by David Hafler and Ed Laurent, the company's most renowned product was the ST-70 tube stereo amplifier. Their portfolio also included both tube and solid-state amplifiers, preamplifiers, radio tuners, and bookshelf speakers. The firm was dissolved in 1980, and its brand name is currently owned by Radial Engineering Ltd.
Early company history
In 1950, David Hafler partnered with Herb Keroes to create Acrosound in Philadelphia, specializing in manufacturing audio-grade output transformers aimed at home electronics enthusiasts. They enhanced the ultra-linear amplifier circuit originally developed by British engineer Alan Blumlein, utilizing transformer taps to feed signals back into the output stage's screen grid, a design widely adopted in early 1950s hi-fi amplifiers. To appeal to a broader audience, Hafler introduced power amplifier kits that featured partially assembled and tested circuit boards, simplifying the building process compared to competitors’ kits that required full assembly and testing.
Following his split with Keroes in 1954, Hafler met audio engineer Ed Laurent at New York's Brociner Electronics. Laurent had created an innovative single-tube driver circuit for power amplifiers. In 1955, Hafler and Laurent established the Dyna Company (which later became Dynaco), concentrating on transformers and superior audio circuitry. Incorporated in October 1955 at 617 N. 41st St, Philadelphia, Dynaco’s inaugural product was the Mk. II 50-watt power amplifier, offered as either a kit or fully assembled unit. This was succeeded in 1956 by the more powerful 60-watt Mk. III amplifier. Hafler also authored a design article on a high-power adaptation of the Williamson amplifier employing ultra-linear circuitry along with Dynaco transformers. The company soon moved its operations to 3912 Powelton Avenue, Philadelphia, where it remained for several years.
Products
Dynaco gained widespread recognition primarily for its vacuum tube stereo amplifier, the Stereo 70 (ST 70), launched in 1959. This model was available as a kit (Dynakit) or factory-assembled and incorporated four EL34 output tubes, one GZ34/5AR4 rectifier tube, two 7199 input tubes, output transformers, a power transformer, and a preassembled driver circuit printed circuit board (PCB). It delivered 35 watts per channel by employing an ultralinear output transformer design that minimized distortion while enhancing sound fidelity.
The ST 70’s efficient engineering provided dependable and high-quality amplification at an economical cost, maintaining consumer interest in tube amplifiers despite the growing prevalence of solid-state technology. Nicknamed "the poor man's McIntosh," it became the best-selling tube power amplifier ever made with over 350,000 units sold.
In 1963, Dynaco released the smaller 17.5-watt per channel Stereo 35, followed by the SCA 35 integrated tube amplifier in 1964. An updated iteration of the ST 70 called the Stereo 70 II was produced in 1992 by Sound Valves for Panor Corporation. Today, upgraded components and rebuild kits for the ST 70 remain on the market; its design has also inspired other amplifiers such as Ars-Sonum's Filarmonia SE. Dynaco continued manufacturing mono and stereo amplifiers until 1977, with its last vacuum tube model being the powerful Mk. VI mono amplifier delivering continuous 120 watts in 1976.
Beginning in 1966, Dynaco ventured into solid-state audio equipment with the Stereo 120 power amplifier rated at 60 watts per channel. Despite undergoing several circuit improvements, early reliability problems hindered its widespread acceptance. The company's solid-state capabilities were further demonstrated by the affordable PAT-4 preamplifier introduced in 1967. In 1969, Dynaco launched the Dynaquad four-channel matrix decoder system which sparked interest in quadraphonic sound reproduction. The robust Stereo 400 amplifier (200 watts per channel) featuring speaker protection appeared during the 1970s alongside other products like the FM-5 tuner and SCA-80 integrated amplifier. Their solid-state kits were distinct for including prewired and factory-tested circuit boards that reduced assembly errors compared to competitors such as Heathkit.
Dynaco also marketed bookshelf speakers from Denmark’s SEAS 'A-Series', developed collaboratively with David Hafler and SEAS engineer Ragnar Lian. These were sold from around 1970 until Dynaco’s closure in the early 1980s. Among these models, the highly successful Dynaco A-25 reportedly sold between six hundred thousand and one million units. The A-25 utilized a patented aperiodic bass system employing controlled acoustic resistance to minimize resonance and impedance fluctuations, providing competitive performance at $79.95 each in 1969 (equivalent to $468 in 2011). The larger A-35 featured a dual-chamber sealed walnut cabinet designed to improve fidelity. Dynaco’s speaker range extended from compact models like the A-10 up to floor-standing units such as the A-50, many of which retain strong resale value decades later.
Coinciding with the A-25’s release was Dynaco’s introduction of the QD-1 speaker adapter which created four-channel sound effects from stereo outputs using phase difference signals. While effective for early stereo recordings made with two bidirectional microphones, its usefulness diminished as multitrack recording techniques became common.
In 1969, Dynaco became a fully owned subsidiary of Tyco, Inc. Founder David Hafler remained with the company until 1974 before moving on to Ortofon and eventually establishing Hafler Company to continue producing quality yet affordable hi-fi products.
During the late 1970s, Dynaco launched Phase III loudspeakers designed by Ed Laurent that garnered positive reviews from audiophiles but did not achieve commercial success; Laurent later joined SEAS Corporation. After Dynaco ended U.S.-based operations, its Canadian branch produced speakers such as A-150, A-250, and A-350 models in Canton, Massachusetts; however, these received unfavorable critiques and were discontinued by the mid-1980s.
Sale of company
In 1979, ESS Labs, LLC took ownership of Dynaco; however, the Dynaco division ceased operations in 1980, with its assets subsequently purchased by Stereo Cost Cutters, which later became known as Sound Values and Sound Valves.
By 1991, the Dynaco trademark was acquired by Pan Orient Corporation (which later rebranded as Panor Corporation), and in 1993, they began offering electronic audio products under the Dynaco name. Panor released updated models such as the Stereo 70 II and the Stereo 160, a 75-watt per channel all-tube stereo amplifier featuring selectable pentode/triode operation modes, adjustable tube bias settings, and 6550 output tubes.
While Panor continues to hold the Dynaco brand and trademark rights, it is no longer directly affiliated with the original enterprise established by David Hafler.
On June 30, 2025, Dynakit, Inc submitted an application to register the Dynaco trademark in the United States.
Dynaco tube equipment
Between 1955 and 1976, Dynaco manufactured tube audio amplifiers, preamplifiers, and tuners.
| Model | Type | Channels (Power) |
Year Introduced |
|---|---|---|---|
| Dynaco Mark II | Power Amplifier | Mono (50 watts) |
1955 |
| Dynaco PAM-1 | Preamplifier | Mono | 1957 |
| Dynaco Mark III | Power Amplifier | Mono (60 watts) |
1957 |
| Dynaco Stereo 70 | Power Amplifier | Stereo (35 watts per channel) |
1959 |
| Dynaco PAS-2 | Preamplifier | Stereo | 1960 |
| Dynaco Mark IV | Power Amplifier | Mono (40 watts) |
1960 |
| Dynaco FM-1 | FM Tuner | Mono | 1961 |
| Dynaco Stereo 35 | Power Amplifier | Stereo (17.5 watts per channel) |
1963 |
| Dynaco SCA-35 | Integrated Amplifier | Stereo (17.5 watts per channel) |
1964 |
| Dynaco FM-3 | FM Tuner | Stereo | 1964 |
| Dynaco PAS-3X | Preamplifier | Stereo | 1966 |
| Dynaco Mark VI | Power Amplifier | Mono (120 watts) |
1976 |