The V119 Vox Churchill PA Amplifier...1967 - 1969
The V836 Vox Power Booster...1967 - 1969

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The self-contained, powered PA mixer has long been an
essential piece of equipment for gigging musicians. It combines the functions of a multi-channel audio mixer, reverb and a power amplifier into an "all in one" package.

Over the past thirty years, landmark powered PA mixers such as the Mackie 808S and Peavey XR-600 were joined by models from Yamaha, Behringer and others. In the 1970's, the six channel Shure Vocal Master dominated the PA market place. The four channel "tuck and roll" Kustom PA head was popular in the late 1960's.

While all of these powered mixers were compact in design and had innovative features, they all owe their existance to the pioneering V119 Vox Churchill. The powered PA mixer was a Vox first.

The Churchill Mixer Section
The audio mixer section of the Vox Churchill featured four channels with 1/4" Hi-Z inputs and individual level controls, one 1/4" input with a level control for a crystal microphone, and one 1/4" line input with a level control for a tape recorder or tuner.

A two position high frequency roll-off switch labeled "Normal/Speech" was included on the each of the five microphone channels. Master Gain, Bass and Treble controls affected all six channels simultaneously.

Reverb was generated by a two spring Hammond Accutronics delay line. The effect could be used on all six channels or switched to operate only on channels four through six.

The Churchill mixer section included a variable Feedback Cancel control. This innovative feature was designed around a sweepable "notch" or twin-T band-rejection filter.

Feedback is frequently caused by a slender band of frequencies typically located in the frequency range between 25 and 200 cycles. The Feedback Cancel control in the Churchill was a early version of a sweepable frequency parametric equalizer. It offered the ability to carve a narrow band of these troublesome frequencies out of the audio spectrum. The circuit was actuated by a "pull" switch on the Feedback Cancel control.

Two VU meters were included on the front panel. One meter measured the line voltage. The second meter measured "Output." In the Owner's Manual for the Churchill, Vox claims that the purpose of the Output meter was to monitor "the overall sound level with recording studio control precision. A switch permits the operator to select the proper meter range for accurate readings. In one position of the switch the meter reads near full scale for maximum power. In the second position, the meter has increased sensitivity and reads near full scale for 1/4 power."

It is my opinion that the readings from the "Output" meter are whimsical.

The Churchill Power Amplifier and Output Section
The Churchill PA head shared it's modular power amp and power supply chassis with the V1141 Vox Super Beatle and V1182 Westminster amp heads. It was rated at 120 watts RMS, 240 watts peak.

This power amp module was powered by four 2N3055 power transistors. Each transistor was mounted to a stamped aluminum heat sink. A 2N3054 transistor was used as a predriver to provide adequate signal to power the output transistors. The 2N3054 is mounted to a separate heat sink.

An interstage transformer isolates the mixer and power amp circuitry.

Unlike most solid state amplifiers, the Churchill utilized an impedance matching transformer. Mounted to the rear of the
mixer chassis, this transformer allowed the Churchill to be connected to various types of speaker loads. The output from the solid state amp was sent to the input of the matching transformer. The output taps from the matching transformer were wired to screw terminals on the speaker connection panel.

The rear of the Churchill featured the speaker connection panel. Terminals were provided for 2, 4, 8 and 16 ohm connections. A jumper wire joined the output from these screw terminals to four XLR "speaker out" jacks, wired together in parallel pairs. The two pairs of speaker jacks were then wired to "SPKRS" switch located below the terminal block. The SPKRS switch could then be set to connect the parallel pairs of jacks in either series or parallel.

25 V. and 70 V. terminals were also offered for speaker connection. 25 and 70 volt or "constant voltage" speaker systems are often found in permanent commercial sound installations such as churches and schools. Such systems require that a matching transformer be located at each speaker. Constant voltage wiring is ideal for commercial installations as it allows the connection of a large number of speakers to the amplifier without concern for total speaker impedance.

The V836 Vox Power Booster
Just above the vertical terminal strip on the speaker connection panel of the Vox Churchill was a 1/4" output jack called "Booster" (see photo above). That jack was used to send a line level audio signal from the Churchill PA head to the Vox V836 Power Booster.

The V836 Power Booster combined the 120 watt Churchill power amp module and impedance matching transformer into one package, making it essentially a Churchill PA head less the mixer section. The Power Booster provided an additional 120 watt amplifier to power additional speakers in a sound system. An additional panel mounted "Booster" output jack on the V836 allowed additional Power Boosters to be "daisy chained" to add additional amplification.

A Complete Vox PA
Let's take a look at prices for an all Vox PA.

Vox offered the 4x10 Grenadier X and 4x12 Grenadier XII  columns and the JBL equipped Winston PA enclosure for use with the Churchill PA head.

The Churchill PA retailed for $499.99 in 1966. Adjusted for inflation, the Churchill PA head would retail today for about $3549.00.

In 1966, Grenadier X columns retailed for $519.98 a pair, Grenadier XII were $599.98 a pair. Adjusted for inflation, a pair of Grenadier X columns would retail today for $3599.00, Grenadier XII columns would be $5650.

Lastly, a pair of JBL equipped Vox Winston PA enclosures retailed for $3000 in 1968. Adjusted for inflation, a pair of Vox Winston enclosures would retail for nearly $20,000 today.

North Coast Music manufactures many replacement and restoration parts

for the V819 Vox Churchill PA Amplifier under license from Vox. These parts are
available exclusively at North Coast Music. Some are shown below.


The VOX Showroom!

Photos and editorial content courtesy Gary Hahlbeck, North Coast Music

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