1.
Always make sure the speaker is plugged in properly
before turning on the amplifier. Failure to do so may
cause expensive or even catastrophic results.
2.
Turn on the main power switch and wait at least 30
seconds before turning on the standby switch to
extend your tubes` lives. If your amp uses 6550 type
output tubes, wait about 60 seconds before switching
on the stand by switch.
3.
Use a grounded AC outlet and don`t defeat the ground
pin on the three pronged AC plug on the end of your
power cord. Better hardware stores sell a device for
testing the integrity of the AC receptacles to see if
the building`s ground wiring is connected properly.
This is a wise investment in your safety and future.
If the testing device indicates a faulty or missing
ground path, you may be in danger of severe
electrical shock.
4.
Have your power output tubes changed (6V6, 6L6, 6BQ5,
6550, 6CA7, EL34, EL84 etc.) about once a year, or
more often if you play every day for roughly six or
eight hours, or if you notice a dullness in your
sound. Always purchase matched pairs, or quads, of
output tubes; they will sound and work much better
than unmatched output tubes. Even if you only need a
pair of matched output tubes, it is very wise to buy
a matched quadruplet set so you will have a pair that
is ready to use without a big change in tone . If you
see glowing red plates in your output tubes, STOP!
You either have failed tubes or circuitry trouble,
and failure to shut the amp off usually results in
major blown parts (£££s). The pre-amplifier tubes,
the 12AX7`s and 12AT7 smaller type tubes might last
for several changes of output tubes, but this is not
a rule. If you hear jingles, rattles, pops, squeals
or if the gain or attack decreases, it may be time to
have these tubes changed out.
5.
Transport your amp on a padded surface. Amps
transported on the bare metal floor of a van or
unpadded boot of a car may have the elements in the
tubes shaken loose and cause microphonic rattles or
worse, short out when next powered up at a gig. Treat
the amp gently and it will last longer. Consider the
purchase of a professional flight case if you plan to
transport your amp frequently. If you are going to
place your amp on a plane, a professional flight case
is a must.
6.
Carry a spare fuse or two with you and tape them to
the inside of the amp cabinet. Always unplug the
amplifier from the power source before changing any
fuses. Follow the amplifer manufacturers
recommendations about fuse changing. Never, ever use
a fuse of a higher rating than called for, or you may
wind up with a (£££s) blown power or output
transformer.
7.
Do not plug your amp into an AC outlet where heavy
appliances or industrial equipment are also plugged
in, such as refrigerators, freezers, heaters. Their
off and on transients may cause severe voltage spikes
on the power line which could take out weak
components. Your amp will not like the brownout
condition a 15 amp heater will cause if plugged in
together.
8.
If your amp has an impedance selector, such as
Marshall, HiWatt, some Ampegs, etc., place the amp in
standby before changing the impedance. Also, be sure
to select the correct impedance for the type and
number of speakers being used.
9.
To determine the impedance of the speakers used,
follow these general guidelines; two 16 ohm speakers
in parallel equal 8 ohms; Two 8 ohm speakers in
parallel equal 4 ohms and two 4 ohm speakers in
parallel equal 2 ohms. And 2 ohms is about as low an
impedance as any amp can withstand. Many solid state
amps will fry with a 2 ohm load. If there is an
impedance stated near the amplifier speaker output
jack, do not use a speaker combination lower than
this stated value.
10.
Use a thick wired cord for speaker hookup (the orange
'lawn mower' cable is ideal). Don`t use thin coaxial
guitar cables as speaker wire if possible. This is
specially true for bass, where damping factor, tone
and watts could be easily lost. However, if your are
experiencing radio or TV interference, a shielded
guitar cable might help out with this problem, as the
culprit interfering radio frequency energy could
enter your amp through a speaker cable, as well as
through the input cables. Additionally, shielded
coaxial cables used in the speaker path might cause
some amplifiers to break into uncontrollable and
dangerous oscillations. Caution is advised here. If
the amp doesn't sound right or if it behaves oddly
after installation of a shielded coaxial speaker
cable, go back to using the zip cord type.
11.
If you hear the amp cutting in and out,
reduce the amp volume then wiggle the speaker cord.
If this influences the cutting in and out, STOP! An
intermittently open or shorted speaker connection or
lead might blow up your amplifier. This one is very
important.
12.
Keep all cable ends clean. Dirty input jacks cause
intermittent crackles and hums sometimes attributed
to more serious problems.
13.
Don`t unplug your guitar from the guitar end of the
input cable while the amp is powered up. The loud hum
you will hear could be the death knell of some
component or speaker if the sun is not shining well
on you that day. Some otherwise well informed people
think this is an old wives tale, but if you have
several hundred watts available, the results could be
catastrophic. If you believe in trial by fire, then
this one`s for you.
14.
After powering up your tube amp, look at the output
tubes. If the tubes' plates are glowing red hot,
STOP! You could be in big trouble if you continue to
operate with tubes running away, as red hot plates
are called. This symptom takes moments to show up and
just a few more moments to destroy the output
transformer or other parts. The problem could be as
simple as worn out tubes, or you could have other
trouble, such as bias supply failure. A new set of
output tubes plugged into a seriously malfunctioning
amplifier can be ruined in a very, very short time.
When in doubt, have your amp tested by a competent
technician.
15.
NEVER PLAY ON A WET OR DAMP CONCRETE FLOOR OR WET
WOODEN STAGE! (That's the support bands job!).
If a shock potential exists, you will be bitten
badly, especially if you wear leather bottomed shoes.
Wet or damp leather is a fairly good conductor of
electricity, and hand to foot shocks can be quite
fatal. Don't play in the rain. Beyond the obvious
shock potential, your amp and particularly your
speakers may be ruined. If using an extension AC cord
outdoors, be absolutely sure you are plugged into a
grounded outlet and that all the ground pins on AC
plugs are intact or else.....
16.
Never touch the grounds (input jacks) of two
amplifiers at the same time. One may be properly
grounded and the other amplifier may have any number
of dangerous volts present waiting to shock you. Hand
to hand shocks are the most dangerous type. Avoid
them like the plague.
17.
Use moderate sound volume levels. Sustained high
levels of amplified sound (above 80 D.B. S.P.L.) can
cause permanent and irreversible hearing loss. You
may want to purchase a sound pressure level meter
(and learn how to use it properly by carefully
reading its instruction manual), to protect your very
precious hearing capabilities.
18.
Give the amp plenty of ventilation. A fan blowing on
the output section of the amp will keep things cooler
and generally increase the service life of the
electronic components in the amp greatly. An easy way
of accomplishing the cooling process is to purchase a
small table fan at a discount store and place the fan
behind the amp blowing into it. The cooler your amp
runs, the longer it will run. Your capacitors will
especially love you if you keep them cool. Never
place the amp with its back against a wall. This will
severely limit the natural ventilation the
manufacturer has hopefully built in.
19.
Do not move the amplifier immediately after
switching it off. Let the amp cool down for a few
minutes before moving or transporting it. It is also
a very good idea to switch off the standby switch
first before turning off the mains AC power switch.
This extends tube life.
20.
Do not take your amplifier apart. Do Not remove the
chassis (the metal box containing all the electronic
components) from the cabinet. There are no user
serviceable parts inside your amplifier. There are
capacitors in amps which store 500 deadly volts long
after you switch it off. Contact with these lethal
voltages will lead to only one outcome. You could be
playing harp with Jimi immediately upon contact with
many parts in your amp. Some amps have bleeder
resistors in them to automatically discharge the caps
within a few minutes of switching off the amp, but
many amps do not have this feature (especially older
amps like tweeds and most black tolex Deluxes).
BEWARE! DON`T EVER GO INSIDE YOUR AMPLIFIER! Leave
all amplifier work up to your trusted technician. He
knows how not to get killed by the 500 or so volts in
your amplifier. (Ampeg SVT's top out above 650 volts
at about three amps capability).
21.
A little knowledge can be a dangerous thing. What may
start out as a simple problem can turn into an
expensive repair when you have a well meaning friend
"who knows something about amplifiers" try
to fix your amp for you inexpensively. I can attest
to this situation personally, as I have repaired
several amps which started out with a simple problem,
and which turned into a catastrophe when some well
meaning novice let his meter probe slip off the
desired test point and caused a smoky short blowing
several expensive tubes and other parts. Bring your
troubled amp to a qualified technician only. If you
are new to an area and do not know who`s good and
who`s not, either ask fellow musicians or call a
music store and ask for a referral.
22.
Use common sense at all times. Follow your first
mind. I have helped many musicians who said something
like, " I thought that hookup might blow my amp
up (speakers, tubes, transformer etc.). I wish I had
done what I thought was right instead of blowing it
up"
23.
Never, ever, plug the speaker output of one amp into
the guitar or line level input of another amp. There
is a way to do this without harm, but you need a
special interface. This can be a very expensive
mistake if not avoided. If your amp has a line output
jack, this is a safe signal level to plug into
another amplifier's line input. The line output of
some amps is fairly large (a volt or more) and may
distort the guitar level input of your amplifier. Try
using the second input jack on your input channel
which is typically 6 db less sensitive, and
therefore, less likely to distort the preamplifier
stages when a large input signal is presented.
24.
Never try to parallel the output of one amp with the
output of another amp. Never try to connect two amps
to the same speaker. (These two "nevers"
are exactly the same). This is the best way of
generating the most smoke and most expensive repairs
I know of.
25.
Amplifiers which have been sitting unused for many
months may have their power supply electrolytics
deformed to a lower voltage than required for proper
operation. Bringing the amplifier slowly up to 120
volts with a variac is a good idea. (Your amp tech
should have a variac.) Amplifiers which have been
unused for years usually have dried out
electrolytics. Powering up one of these amps
frequently has one outcome: smoke. Electrolytic
capacitors have a useful life of about ten years.
(Although many last much longer, some have much
shorter lives.) Any old tube amp with its original
electrolytic capacitors should have those power
supply caps changed out by your tech promptly if you
intend to plug the amp in and use it. If you are a
collector of amplifiers and are never going to plug
the amp in and use it, then you may forego this vital
maintenance. While collectors want to see all
original components in an old amplifier, players
should have the proper maintenance performed on an
old amp before any appreciable use is given to it.
This is because old electrolytics may seem to be
performing sufficiently, but may be leaking current
and imitating a resistor. The current may not be
enough to blow the fuse, but could be enough to
overheat and burn up the old, often very hard to find
(=£££s) power transformer.
Remember: "Too
old to rock---Too young to die!"
