Sheldon TrueTone Series Handbook

Issue 6 1/2/2007

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Handbook

TrueTone

Issue 6 1/2/2007

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About your

TrueTone

Amplifier

The

TrueTone

range is a hand built, high quality range of all valve amplifiers originally designed
for the discriminating Blues/Rock guitarist. They are however extremely versatile and can fulfil
a range of roles from country clean to rock via jazz, blues and all points in between.

All amps in the range benefit from an unprecedented Unlimited Lifetime Warranty.

The

TrueTone 1

The TT1 range are 35-50W class AB amplifiers that give the player an unprecedented ability
to tailor their own sound by selecting the type of output valve used in the amplifier, and a
choice of two pre selected factory set pre-amp configurations one HOT one COOL!
We deliberately chose this path to get the best tone, performance, and long maintenance
from the amp.

The output section can be selected by the player to suit his own style. This can be done by
either the factory, dealer or even easily by the player themselves simply by following the
simple procedures set out in this handbook, giving a freedom of choice rarely encountered in
other amplifiers.

Front panel controls:

•

Input: standard input using a single jack socket.

•

Volume: controls the input gain level set low for a clean sound and higher for

more overdrive.

•

Compass: this is a variable tone rotary, set at North it will not overly emphasise any

particular frequency. Heading SW will bring in a little sparkle, heading SE will
bring in sparkle and grind, with an emphasis on the upper mid range, and it will
also boost gain slightly.

•

High: Controls the high frequency content, as in a normal treble control but with a

much wider response.

•

Middle: Controls the middle frequency content. With the middle control set low or

off the tone controls are voiced to be able to give a similar response to the fabled
clean tone of a blackface Fender, with more Mids introduced as the control is
increased. With the middle control set high the response is more 'Marshall' like.

•

Low: This controls the low frequency content, again with a much wider response

than conventional guitar amp tone controls.

•

Special Sauce: With the accompanying footswitch or the panel mounted switch,

(which both select this feature), this control gives a boost by lifting the tone stack
from ground via a potentiometer, this allows a pre-set level boost that can be
used for soloing. A LED beneath the control and on the footswitch, indicate when
this control is active. (Plugging in the footswitch bypasses the panel-mounted
switch). With the control set fully clockwise the tone controls are effectively
bypassed and the natural tone of the amplifier is dominant. This can be fine tuned
using the compass and freeze controls, which remain in circuit.

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• Freeze: Essentially a hi-cut control which is located within the power amp section
and can be used to tailor the overall high frequency response of the amp from icy

sharp to smooth and mellow.

•

Master: The master volume is a subtle but effective variation on the standard type

used in most guitar amps and uses a technique called 'Boot strapping' to increase
the apparent impedance of the control pot used. This has the benefit of reducing
the tonal change often associated with Master volume controls on low settings.
Although part of the power amp, for maximum effectiveness the master is not
included in the feedback loop as in some designs.

•

Ready…: This is the power switch and turns on the amplifier

•

Go!: This is the amplifier stand-by switch and can be set to off when the amplifier

is on but not in use for longer periods. This can lead to longer power valve life.

Rear panel controls:

• Mains inlet: A standard IEC connector allows connection to the mains supply.

• Voltage selector: Allows a choice of mains input voltages either 230v or

115v.NOTE: for UK use this must be set to 230v.

• Mains fuse: This is a 2A slo-blo 20mm fuse(UK only).

• HT fuse: This is a 500mA slo-blo 20mm fuse(UK only).

•

Triode / Pentode: This switch configures the output valves to either full power

(pentode) mode or half-power (triode) mode. In triode mode even harmonics are
emphasised and will give a sweeter and rounder overall tone.

• Impedance selector: Allows matching to the correct impedance of the cabinet to
be used.

• Speaker outlets: Two parallel wired jack sockets are provided to allow more than
one cabinet to be used.

• Bias controls: Two test points allow monitoring of the bias levels of both sides of
the push-pull output circuit using a simple voltmeter. The centre ground
connection allows a meter to be connected between the cathodes of each side of
the push -pull output section power valves, (

TP1 & TP2), and ground across a 1

ohm resistor. This will indicate in millivolts on a test meter what the bias current
flowing through each side is. This can then be adjusted by using the

Range and

Balance pots located beneath the test points. A more detailed procedure is set

out later in this user manual.

• Footswitch: The supplied footswitch is connected here and selects the

Special

Sauce feature. Any two-connector cable such as speaker cable can be used here,

as no audio signal is present.

• Optional Effects send and return and Reverb controls are located on the rear
panel.

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Table 1

The following table shows the available options for the TT1’s output section.

Output valve

configuration

Output power

& Voltage

Settings

Characteristics

4 x Sheldon-6V6 30-35w

40 -42 mV

Sweet clean tones, which move easily into a
super creamy overdrive. So nice it’s what the
amps come with as standard!

2 x Sheldon-EL34 40-45W

30 – 35 mV

Characteristic British rock/blues tones with
crisp highs and plenty of midrange grit and
grind.

2xSheldon- 6L6/5881 40-45W

35 – 45 mV

Sweet chiming clean tones with solid bass and
top end. More detail in the tone and a smooth
overdrive tone.

4 x Sheldon-EL34

45-50W

70 – 80 mV

Even more of that Classic Brit rock tone! But
with more headroom. Like a 100W plexi but at
50w volumes!

4 x Sheldon-6L6/5881

45-50W

70 – 90 mV

More of that great 6L6 tone!
Better headroom, very suited to the clean
blues player but will break up very nicely when
pushed moving into a smooth driven tone!

2xSheldon-6L6

2xSheldon 6V6

35-40W

45 – 55 mV

A best of both worlds combination! The clear
top and bottom of the 6L6’s complementing
the smooth creamy break-up of the 6V6’s
gives probably the best blues tone you will
hear!

2xSheldon - KT88/6550 45-50W

55 – 60 mV

The ultimate in solid bass and crystal clear
highs, late break up but boy when it does!! For
the cleaner style of playing this is probably
one of the best set ups.

Choosing your output configuration has never been easier or more versatile! The TT1 gives
the player a wider choice than previously available in all but a very few amplifiers and puts the
power of choice in the hands of the player or tech.