Brociner Electronics
| Company type | Private |
|---|---|
| Industry | Audio equipment manufacturing |
| Founded | 1955 in Philadelphia, United States |
| Founder | David Hafler, Ed Laurent |
| Defunct | 1980 |
| Fate | Ceased operations; trademark currently held by Radial Engineering Ltd. |
| Headquarters | Philadelphia , United States |
Area served | Worldwide |
| Products | 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 affordable yet high-performance audio products. Established in Philadelphia in 1955 by David Hafler and Ed Laurent, the company’s signature offering was the ST-70 tube stereo amplifier. Their product range included both tube and solid-state amplifiers, preamplifiers, radio tuners, and compact bookshelf speakers. Dynaco ceased operations in 1980, with its trademark currently held by Radial Engineering Ltd.
Early company history
In 1950, David Hafler partnered with Herb Keroes to create Acrosound in Philadelphia, focusing on manufacturing high-quality output transformers for home electronics enthusiasts. They improved upon the ultra-linear circuit concept initially developed by British engineer Alan Blumlein, incorporating transformer taps to feed back signals into the output stage’s screen grid. This transformer design became a standard in early 1950s hi-fi amplifiers.
To broaden their customer base, Hafler introduced power amplifier kits that came with pretested circuit boards, making assembly easier compared to rival kits that required users to build and test printed circuit boards themselves.
After separating from Keroes in 1954, Hafler met Ed Laurent at Brociner Electronics. Together in 1955, they launched the Dyna Company (later known as Dynaco), with a vision to manufacture not only transformers but also premium audio circuits. Officially incorporated in October 1955 at 617 N. 41st St, Philadelphia, their inaugural product was the Mk. II 50-watt power amplifier, offered as either a kit or fully assembled unit. This was followed by the Mk. III amplifier in 1956, which delivered 60 watts.
Hafler authored a 1955 article describing a high-power variant of the Williamson amplifier employing ultra-linear circuitry paired with Dynaco transformers; this design differed somewhat from the Mk. II and Mk. III models. Subsequently, Dynaco relocated its production facilities to 3912 Powelton Avenue in Philadelphia for several years.
Products
Dynaco gained widespread recognition for its celebrated vacuum tube stereo amplifier, the Stereo 70 (ST 70), launched in 1959. Offered both as a kit (Dynakit) and factory-built unit, the ST 70 utilized four EL34 output tubes, a single GZ34/5AR4 rectifier tube, two 7199 input tubes, along with output and power transformers plus a preassembled driver circuit PCB. It delivered 35 watts per channel using an ultralinear transformer configuration that minimized distortion and improved sound fidelity.
The ST 70’s efficient design provided dependable and high-quality amplification at an accessible price point, maintaining consumer interest in tube amplifiers despite growing competition from solid-state technology. Nicknamed "the poor man's McIntosh," it sold over 350,000 units, becoming the most widely produced tube power amplifier ever.
In 1963, Dynaco introduced the smaller Stereo 35 with 17.5 watts per channel output and followed up with the integrated tube amplifier SCA 35 in 1964. An updated Stereo 70 II version was produced by Sound Valves for Panor Corporation in 1992. Kits and upgraded components based on the ST 70 design continue to be available today and have inspired modern designs such as Ars-Sonum’s Filarmonia SE. Dynaco manufactured mono and stereo tube amplifiers until ceasing tube production in 1977.
The company's last vacuum tube model was the robust Mk. VI mono amplifier released in 1976, capable of delivering continuous power of 120 watts.
Beginning in 1966, Dynaco ventured into solid-state audio equipment with the Stereo 120 power amplifier rated at 60 watts per channel. Early reliability challenges limited its market success despite ongoing improvements to its circuitry. The introduction of the PAT-4 preamplifier in 1967 showcased Dynaco’s ability to produce affordable solid-state designs. In 1969, Dynaco contributed to quadraphonic sound development through the Dynaquad four-channel matrix decoder. The decade also saw high-powered products like the Stereo 400 (200 watts per channel) featuring speaker protection circuits alongside devices such as the FM-5 tuner and SCA-80 integrated amplifier. Unlike competitors like Heathkit, Dynaco’s solid-state kits included factory-wired and tested circuit boards that reduced assembly complexity and errors.
Dynaco also marketed Denmark-produced SEAS 'A-Series' bookshelf speakers developed collaboratively with David Hafler and SEAS engineer Ragnar Lian. Sold from around 1970 until Dynaco’s closure in the early 1980s, models such as the highly popular Dynaco A-25 achieved sales between 600,000 and one million units. The A-25 employed a patented aperiodic bass reflex design utilizing a damped vent to reduce system "Q" and impedance fluctuations, delivering competitive sound quality at $79.95 in 1969 (approximately $468 adjusted to 2011). The larger Dynaco A-35 featured a dual-chamber cabinet designed for improved fidelity. Dynaco’s speaker lineup ranged from compact models like the Dynaco A-10 to floor-standing units such as the Dynaco A-50. These speakers continue to hold value on resale platforms including eBay, reflecting their lasting reputation.
Alongside the A-25 speaker, Dynaco released the QD-1 adapter which created four-channel surround sound effects from stereo sources by exploiting phase differences for ambient enhancement. This system worked best with recordings made using two bidirectional microphones but became less effective as multitrack recording techniques advanced.
In 1969, Dynaco became a fully owned subsidiary of Tyco, Inc., with founder David Hafler remaining until his departure in 1974 to join Ortofon before founding Hafler Company in 1977 to continue producing affordable high-quality hi-fi gear.
During the late ’70s, Dynaco introduced audiophile-grade Phase III loudspeakers designed by Ed Laurent; however, their late arrival limited commercial success. Laurent soon moved on to SEAS Corporation. After U.S operations ended, Dynaco’s Canadian branch launched speakers including the A-150, A-250, and A-350 models manufactured in Canton, Massachusetts; these received poor market reception and were discontinued by the mid-1980s.
Company Ownership Changes
In 1979, ESS Labs, LLC took ownership of Dynaco; however, the Dynaco division ceased operations in 1980. Subsequently, its assets were acquired by Stereo Cost Cutters, which later rebranded as Sound Values and Sound Valves.
The Dynaco trademark was purchased in 1991 by Pan Orient Corporation (which later became Panor Corporation), and by 1993, electronic audio products were once again marketed under the Dynaco name. Panor launched updated models such as the Stereo 70 II and engineered the Stereo 160, a 75-watt-per-channel all-tube stereo amplifier featuring selectable pentode/triode operation modes, adjustable tube biasing, and 6550 output tubes.
While Panor holds the rights to the Dynaco brand and trademark today, it no longer maintains any direct connection to the original enterprise founded by David Hafler.
On June 30, 2025, Dynakit, Inc submitted an application to register the Dynaco trademark in the United States.
Dynaco Vacuum Tube Products
From 1955 through 1976, Dynaco manufactured a range of tube-based audio equipment including amplifiers, tuners, and preamplifiers:
| Model | Category | Channels (Power Output) |
Launch Year |
|---|---|---|---|
| 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 |