Oldfield Amplifiers Marquis 36 User manual

Oldfield Amplifiers Owners Guide
Marquis 36 - 6736

Thank You
Welcome to the Oldfield family and thank you for putting your trust in
Oldfield Amplifiers. We value that trust as much as we think you will
enjoy your new Oldfield amplifier.
Your new Oldfield amplifier is built to provide you with the best tonal
experience and durability available in a guitar amplifier. As with all
Oldfield’s, It is hand built with you, the player, as the central focus of
our efforts. By using the highest grade components, point-to- point
vacuum tube circuitry and fine craftsmanship, your amplifier will
inspire many hours of musical satisfaction and lasting enjoyment.

Table Of Contents
Important Safety Instructions.............................................................4~5
Overview................................................................................................6
Front Panel Controls And Features.......................................................7
Rear Panel Controls And Features………………………………….……8
Tube Layout…………………………………….……………………………9
Warranty…………………………………………………………..….…….10

Important Safety Instructions
ΔFor your safety read, retain, and follow all instructions. Heed all warnings.
ΔOnly connect the power supply cord to an earth-grounded AC receptacle. "This amplifier is
designed to operate on standard North American 115V AC and should only be plugged in to a
receptacle meeting those specifications.
ΔWARNING: To prevent damage, fire or shock hazard, do not expose this unit to rain or moisture.
ΔUnplug the power supply cord before cleaning the unit exterior (use a damp cloth only). Wait until
the unit is completely dry before reconnecting it to power.
ΔMaintain at least 6 inches (15.25 cm) of unobstructed air space behind the unit to allow for proper
ventilation and cooling of the unit.
ΔThis product should be located away from heat sources such as radiators, heat registers, or other
products that produce heat.
ΔThis product may be equipped with a polarized plug (one blade wider than the other) or a three-
prong grounded plug. This is a safety feature. If you are unable to insert the plug into the outlet,
contact an electrician to replace your obsolete outlet. Do not defeat the safety purpose of this plug.
ΔProtect the power supply cord from being pinched or abraded.
ΔThis product should only be used with a cart or stand that is recommended by the manufacturer.
ΔThe power supply cord of this product should be unplugged from the outlet when left unused for a
long period of time, or during electrical storms.
ΔThis product should be serviced by qualified service personnel when: the power supply cord or the
plug has been damaged; or objects have fallen, or liquid has been spilled onto the product; or the
product has been exposed to rain; or the product does not appear to operate normally or exhibits a
marked change in performance; or the product has been dropped, or the enclosure damaged.
ΔDo not drip or splash liquids, nor place liquid filled containers on the unit.
ΔCAUTION: No user serviceable parts inside, refer servicing to qualified personnel only. "Do not
expose the circuit of the amplifier under any circumstances.

ΔCAUTION: By nature vacuum tubes get very hot during operation. "Do not touch vacuum tubes
until they have sufficiently cooled.
ΔOldfield amplifiers are capable of producing very high sound pressure levels which may cause
temporary or permanent hearing damage. Use care when setting and adjusting volume levels during
use.
ΔFailure to comply with any of these safety precautions could result in damage to the amplifier and in
worst cases bodily harm. "Non-compliance with any safety precaution may void any stated warranties.

Overview
Congratulations on your purchase of a new Oldfield Marquis 36 amplifier. The Marquis 36 gets it
roots from the legends of the British rock revolution and is well suited for Americana, Blues, Country
and Rock players.
This amplifier is all tube and hand-wired using the best quality components available for guitar
amplification. It is built to last a lifetime and give the owner countless hours of enjoyment whether
on stage, in the studio, or in the home.
The Marquis 36 has two very distinctly voiced channels. Channel One is the cleaner of the two
channels with slightly more headroom. It’s very simple with just a volume control and tone control.
Channel Two features a preamp gain control, full tone stack and master volume. The Edge Control
and HFRO Control are global to both channels.
Feature summary:
Two channels
36 or 15 watts output power into 8Ω
All tube, hand-wired circuitry
(4) EL84 Power Section
(4) 12AX7 Preamp Section
5AR4 Tube / Solid State Selectable Rectifier
Full Power / Half Power Option
Fully Bypassed Effects Loop (Optional)
Finger–jointed Cabinet

Front Panel: Controls And Features
(Reference the front panel viewing left to right)
1. Manual Channel Selector: This switch is used to select either Channel One or Channel Two of
the Marquis 36. "(Note: The switch must be in the Channel Two position when operating the amplifier
with the footswitch.)
2. Channel Indicator Light: This light is on when the amplifier is operating in Channel Two mode.
3. Channel 1 Volume: Controls the volume of Channel One. Rotating the control clockwise will make
the Channel One volume louder and increase overall gain and harmonics.
4. Channel One Tone: Rotating the Top Cut control clockwise will “roll off” the high end of Channel
One. "This control only affects Channel One.
5. Channel Two Volume: Controls the gain of Channel Two. Rotating the control clockwise will
make the Channel Two volume louder and increase overall gain and harmonics.
6. Treble: Rotating the control clockwise will increase the high end frequency output of Channel Two
only.
7. Middle: Rotating the control clockwise will increase the mid frequency output of Channel Two only.
8. Bass: Rotating the control clockwise will increase the low end frequency output of Channel Two
only.
9. Master: Rotating the control clockwise will increase the overall volume of Channel Two only.
10. Edge: Rotating the control clockwise will gradually decrease the amount of negative feedback
applied to the amplifier’s phase inverter yielding a “edgy” type of distortion. With the control at max
the NFB loop is completely eliminated from the circuit.
** Not Shown ** HFRO: The High Frequency Roll Off control is a high frequency cut for the power
section. This control is useful when running the Edge control at high values to mitigate any fizziness
that might occur with those settings
11. Indicator Light: On when the mains switch is on.
12. Standby: Move to the up position for play and down to put the amplifier in standby mode. "
13. Mains: Move to the up position to power up the amplifier and down to shut the amplifier
completely off.

Rear Panel: Controls And Features
(Reference the rear panel viewing left to right)
1. Power Cord: Connect to electrical main supply. "Your amplifier is designed to operate on 120v AC.
2. Fuse: Replace only with a 3A slo-blo fuse. "Never install a larger fuse than specified. "Failure to
install the properly rated fuse could result in damage to the amplifier. "Fuses provide a critical
safeguard for the amplifier and a blown fuse could be an indication of a much bigger problem either
with the amplifier or the power source. "See a service technician if the amplifier is repeatedly blowing
fuses.
3. Power Level: The power level switch will allow you amplifier to operate at 15W (Half Power) or
36W (Full Power).
4. Rectifier Selection Switch: Your amplifier has the ability to operate on either a tube rectifier or
from a solid state rectifier and the Rectifier Selection Switch determines the mode of operation. The
tube rectifier will be a bit warmer with a softer feel while the solid state will provide the player with a
bit more volume and edge. "The amp must be in Standby mode before changing the position of this
switch.
5. Main And External Speaker Jacks: Connect a speaker to either of these jacks. "Both jacks can
be used at the same time to drive multiple cabinets. Do connect a combined speaker load less than
4ohms or greater than 16ohms. IMPORTANT: A speaker load must be connected to the amplifier at
all times during amplifier operation. "Failure to do so will result in output transformer failure very
quickly and will not be covered under warranty. "It is a good practice to get in the habit of listening for
normal amp noise as soon as the standby switch is moved into the play position. "If no noise is heard
the amp should be turned off immediately and speaker connections checked.
6. SPEAKER IMPEDENCE SELCTOR: Position the selector switch to match the amplifier speaker
load.
7, 8 and 9. EFFECTS LOOP: Send / Receive / Bypass switch for the effects loop.
10. Footswitch Jack: Connect the channel switching footswitch to this jack. "

Tube Layout
RECTIFIER TUBE: 5R4. "Replace only with high quality 5R4 (or compatible) tube.
POWER TUBES: EL84 (x4). "Replace only with a high quality matched quad of EL84 tubes. "The
Marquis 36 is a Class A, cathode biased amplifier and therefore does not need to be re-biased when
changing output tubes.
PHASE INVERTER TUBE: Replace with any high quality 12AX7 tube.
CATHODE FOLLOWER TUBE: Replace with any high quality 12AX7 tube.
PER-AMP GAIN TUBE Channel Two: Replace with any high quality 12AX7 tube.
PER-AMP GAIN TUBE Channel One: Replace with any high quality 12AX7 tube.

Warranty
The following warranties apply to the original owner of the amplifier. "All warranty work must be
performed by Oldfield or an authorized technician for the warranty to be in effect. "Warranties do not
cover normal wear and tear or abuse. Failure to comply with the safety precautions outlined earlier in
the owner’s manual will void all warranties.
Rectifier and Power Tubes: Guaranteed for thirty days after date of purchase. "If a failure occurs
Oldfield will replace any rectifier or power tube during this period free of charge
Preamp Tubes: Guaranteed for ninety days after date of purchase. "If a failure occurs Oldfield will
replace any preamp tube during this period free of charge.
Power Transformer, Output Transformer And Choke: These items are guaranteed for one year after
date of purchase against manufacturer’s defects. "If a failure occurs due a defect in manufacturing
Oldfield will replace any of these items during this period free of charge. "Warranties on these items
are void if the owner uses any type of power soak or attenuator in conjunction with the operation of
the amplifier or fails to connect a speaker load to the amplifier while in operation.
Defects Due To Workmanship: Oldfield guarantees the amplifier to be free from workmanship defects
for five years.
Circuit Components: Any failed circuit component will be replaced at Oldfield’s discretion for a period
of five years after the purchase date. "
In every case Oldfield guarantees to work with the customer to remedy any situation in a timely
manner and to the satisfaction of the amplifier owner.