Marshall Amplification JTM-1H, Owner'S Manual

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Front panel
IMPORTANT: Read before powering-up
Before powering-up your Marshall JTM-1
amplifi er, you must ensure that an appropriate
speaker cabinet is connected to the
corresponding impedance matched loudspeaker
jack on the rear panel. Failure to do so could
result in serious damage being caused to your
amplifi er. Always use an unshielded loudspeaker
cable to connect an amplifi er to a loudspeaker
cabinet, never use a screened (shielded) guitar
cable. After use, always allow the amp to cool
down before moving.
NOTE: the internal speaker in the JTM-1C is 16 Ω
IMPORTANT NOTE:
Please refer to the ‘Warning’ plate on underside
or back of the product.
1. Power Switch
This is the On/Off switch for the mains electric
power to the amplifi er.
NOTE: Please ensure the amplifi er is switched
off and unplugged from the mains electricity
supply whenever it is moved!
2. Mains Indicator
This amber indicator will light up whenever the
amp is plugged into the mains and the Power
Switch (1) is on.
NOTE: Please allow a minute or so for the amp
to ‘warm-up’ after switching on. This is normal
with valve amplifi ers as valves need to reach
their ‘working temperature’ to operate properly.
3. Tone
This control determines the amount of high
frequency (top-end or treble) that is present.
The tone control differs from most other single
tone knobs in that it boosts as well as cuts. to set
the control at 12 o'clock and then cut or boost
according to taste.
4. Loudness
This control sets the overall output volume of the
amplifi er. At lower volume levels, the tone is also
a little brighter. As the loudness is increased, the
amplifi er will start to overdrive.
Tonal Tip: The bassy nature of the amplifi er
means that with many guitars, the sound most
typical of the era is with the Loudness at less
than maximum. In the ’60s it was very common
to use a treble booster or fuzz box to get more
overdrive without losing defi nition.
5. Input Jack Socket
This is where you plug your guitar into the amp.
You must use a screened (shielded) guitar cable.
Never use an unscreened (unshielded) speaker
cable. The input to any guitar amplifi er is a very
sensitive part of the signal path and is very
sensitive to electrical interference, hence the
need for a screened guitar cable. Your screened
cable should be of good quality. If you are in any
doubt regarding this, your Marshall dealer will be
more than happy to help and advise you.
Rear panel
WARNING: Although your JTM-1 amplifi er has
two extension speaker outputs, never attempt
to connect cabinets to both extension speaker
outputs simultaneously. Only use one speaker
output at a time.
1. Extension Speaker 8 Ω
This is the output that connects to an 8 Ω
extension cabinet.
2. Extension Speaker 16 Ω
This is the output that connects to a 16 Ω
extension cabinet.
3. Low power switch
This switch activates the low power mode. The
amplifi er is connected to an internal dummy
load and a reduced level is fed to either internal
speaker (JTM-1 combo) or external load (both
head and combo). This level has been selected
for personal practice.
NOTE: With this button pressed, the amplifi er
may be operated without a speaker connected
without causing any damage.
4. Mains Input
Your amplifi er is provided with a detachable
mains (power) lead, which is connected here.
The specifi c mains input voltage rating that your
amplifi er has been built for is indicated on the
back panel. Before connecting for the fi rst time,
please ensure that your amplifi er is compatible
with your electricity supply. If you have any doubt,
please ask the advice of a qualifi ed technician.
Your Marshall dealer will help you in this respect.
The correct value of mains fuse located in the
small drawer at the bottom of the mains socket is
specifi ed on the rear panel of the amplifi er. The
drawer contains a space for a spare fuse.
NEVER attempt to bypass the fuse or fi t one of
the incorrect value!
NOTE: It is wise to carry spare fuses at all times.
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JTM-1H and JTM-1C Technical Specifi cations
JTM-1H JTM-1C
Power (RMS) 1W 1W
Valves 1 x ECC82 + 2 x ECC83 1 x ECC82 + 2 x ECC83
Dimensions (mm) H, W, D 180 x 380 x 195 360 x 380 x 220
Weight (kgs) 5.2 9.4