Dallas Industries Vox AC-50 Amplifier Head 1973-1979

Dallas Vox AC-30 - Front View

Dallas Vox AC-30 - Rear View

Dallas Vox AC-30 - Rear View

Dallas Arbiter, a British company owned by CBS, purchased Vox from Stolec Industries in 1972. Under the ownership of Dallas Industries, Vox reissued this excellent hand wired AC-50 amp in 1973 that remained in the product line until 1979.

Dallas Industries was familiar to the UK music scene. Not only did Dallas produce the famous "Fuzz Face" guitar pedal used by many musicians in the late 60's, they also produced the "Sound City" line of amplifiers and were the Fender distributor in the UK.

Here is a brief history of the Vox AC-50 amp head.

The original "small box" AC-50 head was introduced by JMI Vox in late 1963. It featured one channel with volume, bass, and treble controls. This first version featured two cathode biased EL-34 power tubes and a GZ-34 tube rectifier. The preamp and tone controls were based on the top boost channel of the AC-30.

In 1964, the AC-50 became a two channel amplifier. Cathode biasing of the output tubes was dropped due to failures in the field. As the size of the cabinets for the head and the speaker enclosure grew in both height and width, the term "big box" is often used to describe this and subsequent versions of the AC-50.

In 1965, a third revision occured. The GZ-34 tube rectifier was replaced by a silicon diode bridge. This change allowed the amplifier to have more head room and slightly increased power for better bass guitar performance.

The Dallas Industries reissue of the Vox AC-50 was based on the circuitry of this third version of the JMI amp and was marketed by Dallas primarily for use as a bass guitar amp.

This amp was first introduced in a 1973 Vox catalog produced by Dallas Industries. Click here to see this 1973 Dallas catalog.

Early in their ownership of Vox, Dallas decided that prnted circuit construction was not suitable for the higher current levels of tube amplifiers. The new AC-50 amp head featured the original hand wired, tag strip construction used by Jennings in the 1960s. A view of the hand wired Dallas AC-50 chassis, circa 1974, can be seen at left. The new amp was made with the same care and attention to detail as when Jennings made the AC-50.

Like the 1965 Vox "big box" amplifier head, the chassis of the Dallas reissue AC-50 was mounted to a plywood slider board. This allowed the chassis to be removed from the head enclosure like a drawer, facilitating ease of service and made a tube exchange quick and easy.

For ease of adjustment, Dallas moved the twin potentiometers used to adjust the output tube bias to the top of the chassis, adjacent to the EL-34 power tubes.

At the point of introduction in 1973, Vox installed a Thomas Organ style rectangular Vox logo on the AC-50 head, as shown at upper left. Starting in 1974, the large -V-O-X- logo from the AC-30 combo was used.

The silk screened control panel had a blue/gray finish, unlike the neutral gray finish used by JMI. The dual channel head had four inputs and six chicken head knobs.

The amp shown at left was 220/240 volt, 50-60 hz model for Europeans mains voltage, with no provision for adjustment to the 120 volt/60 hz US voltage standard.

Unfortunately, there was little reason for Dallas to offer 120 volt Vox amps. Dallas Industries could not export Vox amps to the US during the 1970s because Whirlpool, the owner of Thomas Organ throughout the 1970s, retained the registered trademark rights for Vox in America. Whirlpool defended their trademark rights and denied Dallas the opportunity to sell UK made Vox products in the US market.

Dual 1/4" speaker output jacks were recessed into the back of the amp. A two way switch allowed selection of either a 8 or 16 ohm output impedance.

The particle board cabinet was finished in traditional basketweave vinyl with black Vox diamond grill. Two pin corners and an original style Vox logo handle were fitted.

Vox offered three different bass enclosures for use with the AC-50 amp head. The first, the B212, was a 2x12 closed back enclosure reminiscent of an AC-30 cabinet. This model even offered an optional set of chrome plated swivel side stands. The FB.118 enclosure featured a single Fane 18" speaker and revisited the Foundation Bass cabinet made by JMI in the 1960s. Lastly, a FB.215 enclosure was built to the specifications and size of the 1965 JMI Vox T.60 enclosure, but with 2 x 15" Fane speakers.


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Photos and editorial content courtesy Gary Hahlbeck, North Coast Music

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