Valvestate AVT275, AVT150, AVT150H User Manual

From Jim Marshall

I would like to thank you personally for selecting one of our

Valvestate 2000 AVT amplifiers.

Ever since its initial launch in the early 1990’s, the original
Marshall Valvestate technology received worldwide acclaim and set a
new standard in affordable quality amplification. However, my
dedicated team of designers are constantly looking for methods to
make our amplifiers sound even better. As they are all guitar players
themselves this process has become a passion within the design
department.

As the name Advanced Valvestate Technology (AVT) suggests,
your new amplifier benefits from their research and utilises their
latest circuit innovations, all of which are totally unique to Marshall.
By emulating the feel and response of an all-valve amplifier even
more closely, the new AVT range perform brilliantly and represent
yet another major step forward in guitar sound technology.

I suggest that you read this manual thoroughly before operating
your new amplifier and keep it in a safe place for future reference.
This will help you to derive maximum enjoyment from our Advanced
Valvestate Technology.

Wishing you every success.

Yours Sincerely,

ENGLISH

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WARNING! - Important safety instructions

!

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A PLEASE read this instruction manual carefully before switching on.
B ALWAYS use the supplied mains lead, if a replacement is required please contact your

authorised Marshall Dealer.

C NEVER attempt to by-pass the fuses or fit ones of the incorrect value.

D DO NOT attempt to remove the amplifier chassis, there are no user serviceable parts.

E Refer all servicing to qualified service personnel including replacement of fuses and

valves. Servicing is required when the apparatus has been damaged in any way, such as

the power supply cord or plug is damaged, liquid has been spilled or objects have fallen into
the apparatus, the apparatus has been exposed to rain or moisture, does not operate
normally or has been dropped.

F NEVER use an amplifier in damp or wet conditions.
G ALWAYS unplug this apparatus during lightning storms or when unused for long periods of time.
H Protect the power cord from being walked on or pinched particularly at plugs, convenience

receptacles and at the point where they exit from the apparatus.

I DO NOT switch the amplifier on without the loudspeaker connected.

J ENSURE that any extension cabinets used are of the correct impedance.

➲

Note: This equipment has been tested and found to comply with the requirements of the EMC

directive (Environments E1, E2 and E3) and the Low Voltage directive in the E.U.

EUROPE ONLY - Note: The Peak Inrush current for the AVT150, AVT150H & AVT275 is 32 amps.

WARNING: THIS APPARATUS MUST BE EARTHED!

This equipment has been tested and found to comply with the limits for a Class B digital device,
pursuant to part 15 of the FCC rules.

These limits are designed to provide reasonable protection against harmful interference in a
residential installation. This equipment generates, uses and can radiate radio frequency energy
and, if not installed and used in accordance with the instructions, may cause harmful interference to
radio communications. However, there is no guarantee that interference will not occur in a
particular installation. If this equipment does cause harmful interference to radio or television
reception, which can be determined by turning the equipment off and on, the user is encouraged to
try to correct the interference by one or more of the following measures:

◆

Reorient or relocate the receiving antenna.

◆

Increase the separation between the equipment and the receiver.

◆

Connect the equipment into an outlet on a circuit different from that to which the receiver is
connected.

◆

Consult the dealer or an experienced radio/TV technician for help.

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WARNING! - Important safety instructions (cont.)

➲

Caution: Any changes or modifications not expressly approved by the party responsible for

compliance may void the user’s authority to operate the equipment.

➲

Note: It is recommended that all audio cables used to connect to the AVT150 Combo, AVT150H
Head or AVT275 are of a high quality screened type. These should not exceed 10 metres in
length. Always use a Marshall approved speaker lead with the AVT150H Head and extension
cabinets.

➲

WARNING: Do not obstruct ventilation grilles and always ensure free movement of air around
the amplifier!

USA ONLY - DO NOT defeat the purpose of the polarised or grounding type plug. A

polarised plug has two blades with one wider than the other. A grounding type plug has two
blades and a third grounding prong. The wide blade or the third prong is provided for your safety.
When the provided plug does not fit into your outlet, consult an electrician for replacement of the
obsolete outlet.

FOLLOW ALL INSTRUCTIONS AND HEED ALL WARNINGS

KEEP THESE INSTRUCTIONS !

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Introduction

What is AVT?

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Advanced Valvestate Technology, or AVT for short, is a major step forward in hybrid amplifier
design which is exclusive to our new Valvestate 2000 (VS2000) Series of amplifiers. It has evolved
from the original, critically acclaimed Marshall Valvestate technology, but is improved so that it
emulates even more closely the feel and response of the classic Marshall all-valve power
stage...without using valves.

It is not only the power stage that has been significantly improved in the VS2000 Series either.
Much careful attention to detail and many hours of development have also gone into the preamp
section too. As a result, each AVT channel offers the widest possible range of control and shape to
your sound, with an ECC83 (a.k.a.12AX7) preamp valve adding to the all-important tone and feel of
these latest Marshall creations.

Valve Drive Preamp

As just stated, each amp in the VS2000 range boasts a preamp stage equipped with an ECC83
Dual Triode valve. Drawing on our vast experience in this field, we have gone to great lengths to
ensure that this precious device delivers maximum sonic benefit at all settings and volume levels.
As a result, the clean sounds ring with the ‘bell-like’harmonics that only a valve preamp can deliver
and the break-up is never harsh or unnatural sounding. Whenever an AVT Overdrive channel is
selected the ECC83’s dual triode is saturated to its limit, providing the dynamics and feel worthy of a
place in the Marshall hall of fame.

Power Amp Delivery

The same sort of toneful care and attention was also focused on the all-important power stages
of the AVT series too. Our goal was to ensure that each one would create the warm, musical feel
and 3-dimensional sounds that have made our all-valve power amps world renowned. In addition,
these VS2000 products were designed to deliver the goods in the often hostile and unpredictable
environment of the live performance stage - which is why all the AVT power amps, from the AVT50
upwards, are fan cooled for optimum reliability.

'Extended Bass Response' Loudspeakers

Knowing how important the relationship between the amplifier and speaker is, this is another
area where we spent a great deal of time and effort when developing the VS2000 Series. By
working extremely closely with our long-term colleagues at Celestion Loudspeakers, we have
successfully developed a range of speakers which, through radical design, re-define the state-of-the­art in rock guitar reproduction. In a nutshell, they allow the compact closed back cabinets used in
the AVT range, to maintain the bottom end delivery normally only associated with a full 4 x12 cabinet set­up.

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Introduction (cont.)

DFX Onboard

At Marshall our aim is to create products that offer our fellow guitarists true inspiration in the
practice and performance of their art. When integrating DFX (Digital Effects) into the tonal topology
of AVT, the greatest care was taken to ensure that the highest level of signal integrity was
maintained. Through careful shaping and mixing of the ‘wet’ (processed) and ‘dry’ (unprocessed)
signals, we have ensured that the onboard effects enhance your tone while adding none of the
nasty, artificial ‘grain’ often associated with DFX. Different effect types can be assigned to the Clean
and Overdrive channels and can, of course, be turned on and off via the sturdy 6-way LED foot
controller supplied with your amp.

We are so proud and enthused by the end results of our labour that we feel fully justified in
hailing Advanced Valvestate Technology as a major breakthrough in hybrid guitar amplifier design.
We are convinced that you will derive as much pleasure from playing them as we did while
designing them. Enjoy!

AVT150/AVT150H & AVT275 Front Panel Features

Note:

I. The Preamp Section

Your AVT amp boasts no fewer than four
channels: Acoustic Simulator, Clean, Overdrive 1
and Overdrive 2. The preamp section is where
the gain, tone and relative volume of these four
channels is determined.

1 Input Jack Socket

This is where you plug your guitar into the
amp. You must always use a screened
(shielded) guitar cable and never use an
unscreened (unshielded) speaker cable. Also,
this cable should be one of good quality. If you
are in any doubt regarding this, your Marshall
dealer will be more than happy to help and
advise you.

The amp’s Master Presence control (21)

affords you further adjustment of the high end.

4 Body Switch

This changes the ‘body resonance’
simulation of the channel from that of a regular
sized, steel-string acoustic (switch ‘out’) to that
of a large bodied, ‘Jumbo’ acoustic (switch ‘in’).

5 Volume Control

This dictates how loud the Acoustic
Simulator Channel will be.

6 Clean Channel Selector Switch

This allows selection of the Clean channel
via the front panel.

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2 Acoustic Simulator Channel

Selector Switch

Allows selection of the Acoustic Simulator

channel via the front panel.

3 Top Control

This control takes the channel’s sound
from a mellow, acoustic tone (similar to a
microphone placed towards the neck of the
instrument) all the way to a bright, piezo-like
acoustic sound and all points in-between.

7 Clean Channel Gain Control

This rotary control regulates the drive into
the two cascaded valve stages of the preamp.
Lower settings will give you a wide range of
well defined, warm clean tones.

At higher Gain settings you will pass
through natural, valve-induced compression
and into an increased level of desirable ‘break­up’ (a.k.a. ‘crunch’) which is perfect for subtly
overdriven blues/rock.

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