The V-13/V113, V1131/V1132 and V1133 Royal Guardsman Heads

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Thomas Organ introduced three generations of the Royal Guardsman head in the two year period between 1965 and 1967.

V-13 or V113 Royal Guardsman Heads - Introduced in early 1966, the first generation V-13 and V113 Royal Guardsman circuits were electronically identical and documented on a single schematic from Thomas Organ in Sepulveda CA. The amp head was rated 60 watts RMS, 120 watts peak into a 4 ohm load. The solid state Royal Guardsman was designed by Thomas to be the "made in the USA" replacement for the UK produced JMI Vox AC-50 tube amplifier.

The three channel amplifier featured tremolo in the "Normal" channel, reverb that was selectable to either the "Normal" or "Brilliant" channel and MRB or "Mid Resonant Boost" in the "Brilliant" channel. The "Normal" channel included a "Top Boost" rocker switch while the "Bass" channel featured a sweepable frequency tone control called "Tone-X."

The amplifier was housed in a trapezoidally shaped cabinet reminiscent of the JMI Vox AC-30SRT amp head. The
plywood cabinet featured eight plastic "one-pin" corners, a Vox logo handle, six plastic air vents with Vox logos, a horizontal Vox name plate in the upper left corner of the grill and a "Super Reverb Twin" badge in the lower right corner of the grill (see photo at right).

A "round top" Amphenol three pin XLR jack was mounted to the rear panel of the V-13, V113, and earlier V1131/32 amplifiers for speaker connection. While using what would normally be considered to be a microphone jack in this application might seem a bit unusual, Thomas Organ was simply following the Jennings (UK) Vox tradition of providing locking XLR speaker cables with heads and cabs. Jennings used these locking speaker cables for an important reason. Many JMI Vox tube amp heads were prone to electronic damage if the speaker cord accidentally pulled out of the amplifier during performance.

Two separate foot switches were provided with the amp. A two button foot switch with a 1/4" TRS (stereo) plug controlled the reverb and tremolo. A second single button "egg" shaped foot switch remotely controlled the MRB feature via an electro-magnetic relay located inside the amp. When the MRB button was depressed on the foot switch, you could actually hear the clicking sound of the relay from inside the amplifier.

V-13 & V113 Reverb/Tremolo Pedal

V-13 and V113 MRB Pedal

Foot Switch Jacks
on Rear Control Panel

V1131 and V1132 Royal Guardsman Heads - The V1132 Royal Guardsman was introduced in mid 1966 and offered the same features as the V113 amp (reverb, tremolo, MRB, Top Boost and Tone X) but the effects were controlled by a new three button foot switch that consolidated the previous two foot switches into one.

The V1131 Royal Guardsman added a Distortion Booster, or "fuzz tone," to the amplifier. There was no control panel switch for the distortion effect. It was controlled by a new four button foot switch that included a red indicator lamp to indicate that the fuzz tone was engaged.

Circuit Design and Layout - The V1131 modular preamp section was originally designed for the Viscount/Buckingham series
amps by Thomas Organ/Vox engineer Sava Jacobson. The entire V1131/V1132 preamp section was interchangeable with those used in V1151 Viscount, the V1121/V1122 Buckingham and the V1141/V1142 Super Beatle amps. The preamp section was sealed inside an rectangular steel enclosure that also included the control panel.

The preamp circuitry was designed on three printed circuit boards. One of these three boards included the Distortion Booster circuitry, another was dedicated to the reverb circuit. The third and largest circuit board included individual preamp and tone control circuits for all three channels, along with the components for the Top Boost and MRB switches plus tremolo and Tone X.

The foot switches controlling the V1131 "Fuzz" and "MRB" circuits actuated electro-magnetic relays located inside the preamp chassis that enabled the effects. When the "D" or "M" button was depressed on the four button foot switch, you could actually hear the clicking sound of the relay from inside the amplifier.

On the basis of amps I have recently inspected, I am led to believe that the fuzz tone circuitry was actually present in the V1132 chassis, despite the fact that fuzz tone was not included in the list of features for the V1132 amp. It appears that the only real difference between the V1131 and V1132 Royal Guardsman amp heads was the foot switch included with the amp. When I connected a Vox four button foot switch (Reverb, Tremolo, MRB and Distortion) into a V1132 amp head and actuated the distortion button, the V1132 proved to have fuzz tone.

The V1132 Royal Guardsman head did not have a serial number plate specifically produced for the model. Thomas Organ simply covered the original "Model V1131 Amplifier" model designation on the serial plate with a paper sticker that read "Model V1132 Amp." I believe that this simple method of changing the model number facilitated the rapid creation of the V1132 on the V1131 production line. Exchanging the four button foot switch normally equipped with a V1131 to the three button version completed the V1132 conversion.

The Further Evolution of the V1131 and V1132 Royal Guardsman
Thomas Vox Royal Guardsman amp heads were still in a period of evolution. Not only had the V-13 and V113 been replaced within months of their introduction with the improved V1131 and V1132 models, even more revisions were in the works in future months for the second generation V1131 and V1132 Royal Guardsman heads.

The V-13, V113 and early V1131/32 Royal Guardsman heads were equipped with "frosted" red and green pilot indicator lenses (see photo, near upper right). These were changed to translucent, or clear lenses in the later production of the V1131/32 amp models (see photo, near lower right).

Red and Green "Frosted" Pilot Lamp Assemblies

Red and Green "Clear" Pilot Lamp Assemblies

An "E Tuner" circuit was also added to later production runs of the V1131 and V1132 heads. This circuit provided a reference "E" pitch that would assist in tuning a guitar. This circuit dipped into the Thomas home organ parts bin, using a tunable inductor coil and a transistor in a basic organ oscillator circuit. The "E Tuner" was connected to the volume control of the Bass channel. When initially added to the amps, a rear panel rotary switch activated the reference tone. Later models utilized a slide switch.

Some of the changes introduced by Thomas Organ to the V1131/32 models were aimed at reducing production costs. The solid aluminum escutcheon at the rear of the control panel of the V-13, V113 and early V1131/32 amps was replaced with a thin aluminum stamping in the later production of the V1131/32. While nearly identical in outward appearance, the stamped part was susceptible to damage when removing the chassis from the cabinet for service. The photo at left shows both the solid and stamped escutcheon and the damage that could occur to the stamped part.

Thomas Organ dropped the use of plywood in their cabinets as a further cost savings measure during the production of the second generation Royal Guardsman heads. The new cabinets were made of particle board, a cheaper, heavier and far less durable material.
Thomas Organ also replaced the "Super Reverb Twin" badge that had been mounted to the lower right corner of the grill on the V13, V113, and early versions of the V1131/32 heads with a new "Solid State" logo.

The "round top" Amphenol three pin speaker output jack installed on the rear panel of the V-13, V113 and early production of the V1131 and V1132 Royal Guardsman head was replaced with a similar "flat top" panel mounted jack from Switchcraft (see photo at left).
By mid 1967, the V1133 Royal Guardsman amp head replaced the V1131 and V1132 models, completing the two year evolution of the Royal Guardsman head.

V1132 Pedal
"Three Button" Pedal
V1131 Pedal
"Four Button" Pedal
Foot Switch Jack
on Rear Control Panel

V1133 Royal Guardsman Head - Introduced in 1967, the third generation V1133 Royal Guardsman head again expanded and refined the abilities of the previous Royal Guardsman models. The new amp retained the same three channel design and retained all the features of the V1131. The amp was rated 60 watts RMS, 120 watts peak into a 4 ohm load.

A new, one piece, and in a sense, "universal" preamp circuit board was designed by Thomas Vox lead engineer Stan Cutler to replace the two or three board preamp circuit board arrangement used in the V-13, V113, V1131 and V1132 amps. This new board was designed to incorporate all of the eight individual preamp and effects circuits found in the Viscount, Buckingham, Royal Guardsman, Beatle, Sovereign and Westminster amps. The individual circuits included on this board were the first, second and third channel preamps, tremolo, reverb drive and receive, Repeat Percussion, mixer and "Watchdog" compressor/limiter.

Thomas Organ would install electronic components only into the sectors of the preamp board that would be consistent with the features included in a particular amp model. No electronic components would be installed in circuit board sectors where the channel or effect was not included with the given model. As an example, the extensive list of features included in a V1143 Beatle head required a completely populated preamp circuit board. In contrast, the V1182 Westminster bass head preamp board would omit the electronic components to support the tremolo, reverb, and Repeat Percussion effects plus the second, or "Brilliant" channel.

As the Royal Guardsman was a three channel amp with reverb and tremolo, it would utilize a nearly completely populated preamp circuit board. Only the Repeat Percussion sector of the preamp board remained unused in the Royal Guardsman. The Repeat Percussion effect was unique to the V1143 Beatle amp.

FET (field effect) signal transistors were used in the preamp to minimize noise and hiss. New, modern switching FET transistors in the Distortion Booster and MRB circuits replaced the electro-magnetic relays used in the prior Royal Guardsman models.

The "E-Tuner" circuit that had been introduced in the later production of the V1131 and V1132 heads continued in the V1133. This circuit dipped into the Thomas home organ parts bin, using a tunable inductor coil and a transistor in a basic organ oscillator circuit.

V1133 Pedal

Foot Switch Jack
on Rear Control Panel
What Year Was My Royal Guardsman Head Built?
After looking at hundreds of Thomas amplifier serial numbers, I have come to the conclusion that the first digits appear to provide a clue to the year the amplifier was produced. Serials starting with "9" were from the first full year of production, 1966. Those starting with "I0" or "10" were produced in 1967 while those starting with "I1" or "11" were built in 1968. Following this same pattern, a serial starting "I2" or "12" indicates 1969.

North Coast Music manufactures many replacement and restoration

parts for the Royal Guardsman under license from Vox. These parts are
available exclusively at North Coast Music. Some are shown below.


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Photos and editorial content courtesy Gary Hahlbeck, North Coast Music

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