Komet Aero 33 User manual

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KometAero33 Owner’s Manual
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Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

PRECAUTIONS
TUBES ARE HOT!Make sure you allow the tubes in your amplifier to cool down before
handling them. They are also made of glass and can easily break. Wear safety gloves and goggles
when handling audio tubes.
DO NOT OPEN UP THE AMPLIFIER!There are no user serviceable parts inside. There are
lethal voltages present even when unplugged.
NEVER: replace the Mains or H.T. fuse with a higher rated fuse. This will most certainly cause
severe damage to your amplifier.
NEVER: use a shielded guitar or instrument cable as a speaker cable connection.
NEVER: operate any amp without a speaker load connected to the output jack(s).
ALWAYS:make certain that your AC power cable is unplugged when replacing any fuse.
ALWAYS: operate your Kometamplifier with the correct tube types listed in this owner’s
manual.
ALWAYS:use a three pronged, grounded AC power cable and always plug into a properly
grounded outlet. Failure to do so may result in injury or death.
ALWAYS UN-PLUG YOUR AMPLIFER WHEN YOU ARE DONE! This is to protect your
amplifier from surges in electrical power, or transient voltage. The standard American home AC
voltage is 120 Volts. Anything over this amount is considered transient and can damage
electronic devices that are plugged into an AC outlet. Though power surges are brief and
measured in nanoseconds, they can cause considerable or permanent damage to electronic
equipment. Electrical surges can damage electrical equipment by burning or fusing internal wires
or by the gradual degradation of a device’s internal components. The best way to prevent
damage is to unplug your amplifier when not in use.
NOTE:Devices such as refrigerators and air conditioners require large amounts of energy to
switch motors and compressors on and off. Such devices can create surges in power that disrupt
the steady flow of line voltage. Lightning, faulty wiring, downed power lines and faulty
equipment at the power source (utility company) can all cause power surges as well.
ALWAYS:try to keep your amplifier and /or speaker cabinet in a climate controlled setting.
Failure to do so can be problematic. The tolex on your amplifier head box cabinet can shift and
shrink in the Summer, especially if you leave your amplifier for an extended amount of time in a
sun heated vehicle, trunk, trailer, or an extremely hot and humid, non-airconditioned
environment. This is due to the glue used to apply the tolex to the wooden head box cabinet. The
glue can become slightly molten from excessive heat, which can make the tolex movable, expand
and then shrink when cooled. Excessive heat can only cause this tolex situation and this is not
covered under your Kometwarranty.
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

IMPORTANT SAFETY INSTRUCTIONS
1. Read these instructions.
2. Keep these instructions.
3. Heed all warnings.
4. Follow all instructions.
5. Clean only with dry a cloth.
6. Do not block any ventilation openings. Install in accordance with the manufacturer’
instructions.
7. Do not install near any heat sources, such as radiators, heat registers, stoves, or other
apparatus (including amplifiers) that produce heat.
8. Protect the power cord from being walked on or pinched, particularly at plugs,
convenience receptacles, and the point where they exit from the apparatus.
9. Only use attachments/accessories specified by the manufacturer
10. Unplug this apparatus during lightning storms or when not used for long periods of time.
11. Refer all servicing to qualified personnel. Servicing is required when the apparatus has
been damaged in any way, such as a 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.
12. CAUTION: To disconnect the unit completely from the Mains, unplug the unit. Turning
the power switch off does not completely disconnect the unit from the Mains.
13. Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized 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 and the third prong are provided for your safety. If the
provided plug does not fit into your outlet, consult an electrician for replacement of the
obsolete outlet.
14. The unit shall not be exposed to dripping or splashing of liquids, and that no objects filled
with liquids such as vases shall be placed on the unit.
15. WARNING:This is a Class 1 apparatus. This unit should be connected to a MAINS socket
outlet with a protective earthing connection.
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

EU ENVIORNMENTAL DIRECTIVES
RoHS This product is compliant with the EU Directive 2011/65/EU for the Restriction of
the use of Certain Hazardous Substances in Electrical and Electronic Equipment. No lead
(Pb), cadmium (Cd), mercury (Hg), hexavalent chromium (Cr+6), PBB or PBDE is
intentionally added to this device. Any traces of impurities of these substances contained
in the parts are below the RoHS specified threshold levels.
REACh This product is compliant with the European Union Directive EC1907/206 for
the Registration, Evaluation, Authorization, and Restriction of chemicals (REACh) and
contains none or less than 0.1% of the chemicals listed as hazardous chemicals in the
REACh regulation.
WEEE This symbol on the product or its packaging indicates that this product must
not be disposed of with other waste. Instead, it is your responsibility to dispose of your
waste equipment by handing it over to a designated collection point for the recycling
of waste electrical and electronic equipment. The separate collection and recycling of
your waste equipment at the time of disposal will help conserve natural resources and
ensure that it is recycled in a manner that protects human health and the environment.
For more information about where you can drop off your waste equipment for
recycling, please contact your local city recycling office or the dealer from whom you
purchased the product.
CE This product complies with the European Union Council Directives and Standards
relating to electromagnetic compatibility EMC Directive (2006/95/EC) and the Low
Voltage Directive (2004/10).
Copyright 1999-2017 KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

THANK YOU FOR PURCHASING THE KOMETAERO 33 AMPLIFIER
The KometAero33 is a straightforward and easy to operate amplifier. The goal of this manual
is to help you "get acquainted "with your Kometamplifier, and how to make use of its many
capable sounds.
FRONT CONTROL PANEL LAYOUT (left to right):
1. Power Switch: engages the wall AC/ power to the amplifier.
2. Standby Switch: allow the amplifier to warm up for 60 seconds before engaging the
standby switch to the play position. This action will allow for all of the tubes to heat up
to the proper voltage required for operation and will help prolong their lifespan.
3. Pilot Light:illuminates when power switch is placed in the "On" position. The pilot
light is a type #47 (6.3 Volt)light bulb. (See troubleshooting section for bulb replacement
information).
4. Hi-Cut: this control allows shaping of the treble response in the power amp. For players
who prefer a darker tone, the only option with most amplifiers, is to roll down the treble
control. The treble control is passive (reduces a portion of the signal), so the result is a loss
of gain, and "muddy"distortion. The Hi-Cut feature allows you to set the preamp EQ for
the right balance by "darkening" or "brightening" the overall tone without changing the
basic EQ setting.
5. Presence Control: affects the highest frequencies in the output stage. It is normal to
hear a slight "scratchy" sound when engaging the Presence control. This is due to this
amplifier’s particular circuit design.
6. Bass Control: controls the low end range bass frequencies.
7. Midrange Control: controls midrange frequencies.
8. Treble Control: controls high end range treble frequencies.
9. Volume Control: controls overall volume and gain of the amplifier.
10. Bright Switch:three way selector switch. Middle position is off, Down position -
slightly bright, Up position -most bright.
11. Input Jack: accepts standard ¼ inch plug. Input impedance is 1 Megohm.
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from Komet Amplification.

BACK CONTROL PANEL LAYOUT (left to right):
1. AC Input: this IEC receptacle accepts a standard DIN AC 16 gauge, three conductor
power cable. All Kometamplifiers can be internally modified to operate on either 120V
or 240V only. Please inquire with KometAmplification for AC conversion information.
2. Mains Fuse:3Amp "slow blow" fuse (a.k.a. MDL 3A - size: ¼ inch by 1 and 1/4 inch) is
used on 120V model, a 2Amp "slow-blow" fuse on the 240V model. CAUTION:
ALWAYS MAKE SURE YOUR AMPLIFIER AC CABLE IS UN-PLUGGED BEFORE
REPLACING A FUSE.
3. H.T. (High Tension) "fast acting"fuse: 1/2 Amp or 500mA (a.k.a. AGC 500 mA - size: ¼
inch by 1 and ¼ inch). Should the H.T. fuse repeatedly fail in your Kometamplifier,
replace the fuse and replace the EL84/6BQ5 power tubes with a new quartet with the
correct IP (plate current draw) rating (see bias section). Your amp may need servicing by an
authorized technician if the problem persists. CAUTION:NEVER REPLACE ANY
FUSE WITH A HIGHER RATED FUSE. This will most certainly cause severe damage
to your amplifier.
4. Output Impedance Selector:set this selector according to the appropriate speaker
impedance you are using. 4, 8, and 16 Ohm settings are available.
5. Output Jacks: two, standard ¼ inch speaker jacks, wired parallel, which will
accommodate any quality standard speaker cable. Note:never use a shielded guitar cable
as a speaker cable. You can severely damage an amplifier.
6. Tube Chart: displays the placement of the power and pre amp tubes (V1 to V7).
7. Fast / Gradual:switch enables the musician to alter the response characteristics of the
amplifier to suit their playing style. A simple flip of the switch lets you choose between
two different responses to your picking dynamics and guitar’s volume control settings.
This is not an extra gain stage or gain boost circuit. Instead it functions by magnifying
subtle changes in pick or finger attack along with subtle changes in guitar volume. The
Gradual setting of the circuit allows a clean player to run the full range of dynamics
without breaking into unwanted distortion. You can play on the edge of distortion easily
going from clean to blues overdrive using pick attack as the controlling factor. An over
the top player can go from clean to scorch using the Fast setting. The slightest change in
pick attack or guitar volume setting will translate to huge changes in dynamics and
power. To sum it up, this function lets you choose the response and feel you want and
makes your amplifier capable of playing every style of music desired.
Note: you will hear a "thump" coming from the speakers when the Fast / Gradual switch is
engaged in the "Play" position. This is normal, part of the circuit design, and is not indicative of a
problem with your amplifier. We recommend that you engage the "Stand By" switch before
changing the Fast / Gradual switch setting to avoid this sound. (continued)
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from Komet Amplification.

Note:when using effects pedals with your Kometamplifier, you may want to experiment with
the two different settings of the Fast / Gradual switch to see which one works best with your
particular pedal(s)of choice.
Note: please be aware that the tone controls on all Kometamplifier models are passive, but
very powerful. If you come across a set of parameters, which does not work well with your
guitar/ speaker combination, simply change the settings, and avoid that particular setup in the
future.
TUBE CHOICES FOR THE AERO33
PRECAUTION:always allow the power and pre amp tubes to cool down before handling. They
are made of glass and can easily break when mishandled. Wear safety goggles and heat
protective gloves when handling hot tubes. Never remove or replace the power or pre amp tubes
while an amplifier is on.
The Aero33 was designed and voiced to utilize current production tubes to their maximum
potential. The current stock power tubes (V4,V5,V6 and V7) are a matched set of SovtekEL84 /
6BQ5s. This is a widely available and reliable power tube. The Mullard re-issue EL84/6BQ5 by
Sovtekis an excellent replacement upgrade.
We prefer the Sovtek12AX7 LPS for the V1 (input stage), V2 and V3 (the phase inverter position)
positions. The LPS is an excellent sounding 12AX7 and are used in all Kometamplifier models.
The re-issue SovtekMullard 12AX7 is another excellent 12AX7 option. With this factory stock
tube compliment, the Aero33 sounds powerful, complex and detailed. The distortion is balanced
and harmonically rich.
Please note: you may find that some pre amp tubes, whether newly manufactured, used, or even
n.o.s., may be too "microphonic"for the first gain stage (V1)of a Kometamplifier. A
microphonic preamp tube is a condition in which a tube will absorb mechanical vibration and
amplify it into the audible range. In this scenario, a tube can "feed-back", or give off a loud, high
pitched squealing noise.
Feed-back can occur intermittently, even without an instrument plugged into the input of the
amp. This does not mean that the tube(s)are completely unusable. One possible solution you can
experiment with is moving the microphonic tube to the V2 phase inverter socket where
microphonics are not as noticeable. The microphonic 12AX7 may be quieter in the V2 position as
opposed to the V1 position.
Please note: a small amount of "hiss"is normal for high gain amplifiers. An excessive amount
of hiss, especially when the volume control of the amplifier is all the way down and with no
instrument plugged in the amplifier’s input, usually denotes a bad pre amp tube. Some n.o.s.
audio tube suppliers offer "select"or hand picked pre amp tubes, which are superior in all aspects
of quality, especially when it comes to being quiet and non-microphonic.
(continued)
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

Please note: your amplifier produces heat. Prolonged gigs, outdoor or non-climate controlled
venues, only multiply that factor. We suggest after extended play - that you allow for a sufficient
amount of time to pass - so as to let your amplifier cool down prior to moving or loading. This
will help protect and extend the lifespan of the audio tubes and internal components from
excessive vibration or damage.
Please pay close attention when extracting and installing the power and pre amp tubes. The pins
must align perfectly into the tube’s socket. Bent tube pins, especially when forced into a tube
socket, can cause serious damage to an amplifier’s tube socket pin inserts. This results 99% of
the time with the tube socket needing replacement. To avoid this contingency, we recommend
that you purchase a miniature pinned, nine hole, pre amp tube pin straightener. These can be
found on line from many vintage tube retailers. This easy to use device guarantees that your pre
amp tube and EL84 power tube pins will be straight and aligned for socket insertion. Please note:
KometAmplification’s warranty will not cover damage done to a tube socket’s insertion pins
from forced or accidental mis-alignment / and or bent / crimped insertion pins.
TUBE REPLACEMENT
A noticeable deterioration in your amplifier’s overall sound is an indication of an imminent tube
replacement. You may notice symptoms such as "muddy"or "saggy"power chords, a loss of
tightness or "punch", a weak sounding treble and bass, and loss of certain sonic frequencies or
note "bloom". We suggest that you first start by replacing your power tubes. Pre amp tubes can
last a very long time, and do not necessarily need to be replaced as often as the power tubes.
However, we do recommend that you have both the pre amp and power tubes properly tested by
a technician between servicing.
BIASING THE AERO33
The Aero33 is a cathode biased amplifier. An internal resistor sets the amplifier’s power tube
bias. A bias adjustment should not be necessary. To guarantee your amplifier will operate
properly in conjunction with the supplied voltages and the current draw of the Aero33, we
recommend that when you replace your power tubes, that you purchase a matched set of
EL84/6BQ5slabeled by the manufacturer with a low IP number (or a low plate voltage / current
draw number) or grade and labeled as well with a transconductance (Gm) matching numbers.
Having matched power tubes ensures that all of the power tubes will operate and react equally
within the amplifier. Matched power tubes will also guarantee better harmonics, sonic
performance and extended tube life. Most reliable and reputable audio tube vendors and n.o.s.
tube dealers sell their power tubes in matched, output power or plate current draw, numerically
rated sets. You should be able to request a certain IP (plate voltage /current draw) grade or range
from your tube vendor.
(continued)
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

Some tube vendors refer to their power tubes for their "break up" characteristics by labeling their
sets with terms like: "soft", "medium"or "hard". Usually, power tubes labeled "soft"are of the
low / lower plate current drawing type. Many vacuum tube vendors use their own numeric
measurement system. Some examples: the SovtekEL84 grade for the Aero33 is an IP
number range from # 12 through # 15. The original Groove Tuberating scale for the Aero33
would be a grade #1through # 3.
WARNING: Never remove any of the four EL84/6BQ5 power tubes in order to attempt cutting
the power of the amplifier in half. The Aero33's EL84 power tube circuitry shares only one
cathode resistor. Removal of one or more of the power tubes will cause the other EL84s to
catastrophically malfunction and fail. Note: the 12AX7 pre amp tubes in your amplifier are
internally self biased and need no adjustment.
Under-biased Power Tubes:
EL84/6BQ5 power tubes that are under biased, (or drawing too much current), will usually create
the following symptom: a low, background "hum" sound coming from the amp, which may get
louder as time passes. You should inspect the plates of the power tubes (the flat grey colored,
metallic, square section inside the center of the power tube/s). Make sure your amplifier is on. Do not
confuse the yellow / orange filament glow on the top and bottom of the power tubes for the
center plates.
If the plates in the center of the tube are glowing a dull "red"or are "cherry colored"from the
center, (see reference photo on next page), then the power tubes are under biased and must be
replaced with a lower (IP)plate voltage / current drawing - set. If not replaced, they will fail
and "short out"in short order, and the H.T. fuse will blow. Another sign of under-biased power
tubes - the descriptive, colored lettering/labeling on the tube(s) has turned a bright, frosted white
color, or occasionally - completely burned off
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

SPEAKERS FOR THE AERO33
The Aero33 is a big sounding amp. It is voiced for a sparkling clean sound at low volumes, and
a smooth, dynamic - harmonic overdrive and strong midrange punch. In our opinion, these
characteristics are best complimented with a closed back, (preferably vintage) 4 X 12 speaker
cabinet. Our favorite reference speakers for Kometamplifiers in general are original coned,
vintage 12 inch Celestionspeakers from the 1960’s. You may come to a different conclusion,
depending on your playing style and preferences.
A 2 X 12 cabinet, (open or closed back), is another excellent choice, but care should be taken to
select speakers that can handle the power, low end, and attack. The KometAmplification
speaker cabinet lineup is another excellent option. Please see our website www.kometamps.com
for full speaker cabinet information. Whichever cabinet you do use, make sure you set the
impedance selector correctly. If you use two cabinets, keep in mind that the outputs are in
parallel. This means that if you are operating the amplifier on two, 16 Ohm cabinets, you must
set the amplifier’s impedance selector to the 8 Ohm setting. If you operating on two, 8 Ohm
cabinets, set the selector to 4 Ohms. We do not recommend using two, 4 Ohm cabinets. Speaker
wiring diagrams are located at the end of this owner’s manual.
An Important Note on Speaker Cables, Cabinets and Speakers: It is crucial that you always
maintain a solid, un-interrupted signal between your amplifier and speaker cabinet. Sub-standard
speaker cables as well as sub-standard cabinet wiring can become problematic, intermittent and
fail over time. This can possibly causing damage to your amplifier and speakers. We recommend
that you use quality brand speaker cables (16 to 18 gauge is sufficient) made with quality male
input plugs. The speaker cable plugs should be soldered directly on to the internal speaker cable
wires. Using a quality made speaker cable will ensure a tight fit from the amplifier’s speaker
jacks to the speaker cabinet.
Your speaker cabinet should be equipped with a quality brand input jack. We prefer and use the
Switchcraft#11 mono input on our cabinets, amplifiers and vintage repairs. Many vintage
speaker cabinets from the 1960’s to 1970’s used the Switchcraft#11 jack. It is reliable, solid
and time tested. Many modern made brand speaker cabinets use the #11, but not all. Some
manufacturers have their speaker jacks panel mounted on the back of their cabinets which
incorporate an internal circuit board on which the jacks are soldered. This type of system is not
designed for a type #11 jack, and conversion to the #11 can be very tedious. All electrical work
should be performed by a professional and knowledgeable technician.
We also strongly urge you to inspect and make sure that all of your internal speaker cabinet wire
leads are soldered at the speaker jack and soldered at the speaker terminals. We do not
recommend using the "slide on"type gripping speaker wire terminals. These grip type terminals
loosen over time causing an interruption or failure of the signal. These recommendations help
guarantee a solid, un-interrupted signal from the amplifier to the speakers at all times.
Please note:KometAmplification recommends using resistive load attenuation devices in
conjunction with any Kometamplifier and speaker cabinet. Please see our website
www.kometamps.com for further information on the KometAirbrakeattenuator. The owner’s
manual for the Komet Airbrakeis located at the end of this manual.
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

TROUBLESHOOTING
When troubleshooting a problem, we recommend that you remove all effects pedals and only go
direct with your guitar and guitar cable into the amplifier. Also, remove any attenuation device
from your amplifier to speaker cabinet signal chain. This way you can easily and quickly rule out
(or discover) if your amplifier is the source of the problem.
Pilot Light Not On:
Check to see if the amplifier’s AC cable is plugged in at wall and plugged in at the IEC
connection on the back panel of the amp. Make sure the DIN AC cable plug is securely inserted
into the IEC AC input connection, and pushed in all the way.
Check the type 47 pilot light bulb. It may be burned out. For bulb replacement, gently turn the
jewel lens cap counterclockwise and remove. Using the tips of your fingers, gently push and turn
the exposed bulb counterclockwise, extract bulb and replace. Note: your amplifier will continue
to operate with no problem with a shorted bulb or with no bulb at all.
Check the 3amp "slow blow" AC supply "Mains"fuse to see if it is blown. Replace the blown
fuse with a new 3amp "slow blow"(a.k.a. MDL 3A 250V) or a 2 amp "slow blow"for a 240V
model. ALWAYS - make certain that your AC power cable is unplugged when replacing any
fuse.
Mains Fuse -"blowing":
Unplug amplifier from the wall AC. Remove the power tubes (see precautions section). Install a
new 3 Amp "slow blow"fuse 2 Amp "slow blow" 240V).Plug into the wall AC and turn the amp
on (with no power tubes in the sockets).
Should the mains fuse continue to "blow", (with no power tubes installed) then your amp will
need to be serviced. If the fuse does not "blow", and the amp lights up, turn amp off, and install a
new set of matched EL84 power tubes. Turn the amp back on. If the fuse does not blow, play
the amp and monitor.
Amp Lights Up - No Sound:
Check the speaker connection at back of amp and at the input of the speaker cabinet. Bypass all
pedals and effects and plug your guitar into only the amplifier. Check the guitar cable and / or
try another guitar.
Check the power and the pre amp tubes and make sure that they are installed correctly and that
the filaments within each tube are lit. Note:sometimes audio tubes can look operational - (with
the filaments lit) - but be defective in not passing signal. This is rare, but can occur.
Check / test / replace - the H.T.fuse for continuity with a digital Ohm meter. It may be blown.
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

Amp is making a "Humming","Hissing","Feedback"or "Crackling"-sound:
This is most likely a bad pre amp tube. Pre amp tubes can develop problems over their life span.
They may be operating flawlessly, and they may also test fine on a tube tester, but for what
appears like for no reason, can suddenly begin to make a "hissing" or a "crackling" sound. They
can begin to feedback or have microphonic or "ringing" symptoms, or develop filament
"humming" - which is a low background hum, often mistaken for a problematic filter cap.
Filament "humming" is much more common with new, modern available pre amp tubes.
Unfortunately, you will most likely have to replace one of more of your pre amp tubes with any
of these problems.
Fluorescent and neon lights, rheostat wall dimmers, and some appliances may cause your amp to
contain a "hum" or "buzz"sound. An internally shorted guitar cable or using a speaker cable for
a guitar cable can also create a "buzz" sound through your amp.
Over time, the input jack may occasionally make a "crackle"sound when you extract your
instrument cable from the front panel of your amp. This is usually due to a dust / contaminate
build up on the input jack’s ground shunt. This would require that the inside of the input jack be
cleaned professionally. We recommend using DeoxIT®Gold G5.
Amp sounds "spongy"or "sputtering":
A "spongy" or "sputtering"- weak response from your amp can be one of two things. Under
normal operating conditions, this symptomatic sound can be the result of "weak"power tubes,
i.e. power tubes that have reached their operational lifespan. You may also notice this symptom
when the volume control and saturation control are completely "dimed" out 100%, even with
new power tubes. This is a result of both the power tubes and output transformer reaching
complete saturation and is part of the circuit design. Backing off each control a small degree will
re-align the signal path.
TUBE REPLACEMENT FOR THE AERO33
Unscrew (in small increments) the two, back panel insertion screws. Remove the back panel
evenly with two hands. Use the reverse instructions when installing the Aero33 head back
panel. You will find the tube placement chart on the back panel of you amp. There are six tube
sockets in total. These sockets are miniature nine pin pre amp tube socket types.
Follow the placement of the four tubes by referring to the tube chart. Make sure the amplifier’s
tubes have cooled down sufficiently before handling the amplifier’s tubes. V1,V2 and V3 are the
12AX7 pre amp tubes. V4 through V7 are the EL84/6BQ5 power tubes.
Gently install each tube in the correct corresponding tube socket. Please note each tube‘s pin
configuration must be properly and perfectly aligned with the tube socket for installation. Do not
force a tube into its socket. If correctly aligned, it should easily install into the socket.
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

SERVICING
We are very confident that your Kometamplifier is one of the most reliable amplifiers ever
built. A combined experience of many decades of amp design and service has been applied to the
construction all Kometamplifier models. We have been inside thousands of amps and we have
seen every kind of problem that can occur. Great care has been taken to anticipate and prevent
such problems in your Kometamplifier. Every part and component in this amplifier has been
carefully chosen for its specific performance. Some parts are proprietary or hard to find. We do
not recommend replacing any of the internal components with generic parts from different
manufacturers.
We also recommend that you bring your Kometamplifier to only a qualified service technician,
especially if you should feel un-comfortable changing / installing audio tubes. Should your
Kometamplifier ever need servicing or repair, please make arrangements with us to have your
amp shipped back to KometAmplification for factory service.
CLEANING
We recommend cleaning your head box / tolex with a slightly damp, warm cloth towel. Please
be very careful when cleaning the front panel of your Aero33 head box. The points of the plexi
glass triangle Kometlogo could possibly catch on a cleaning cloth. We recommend that you
clean the triangle Kometlogo starting from the center of the logo - to the outer edges of the
amp. Repeat procedure always from the center. Avoid using T-shirts or cloths that contain
graphics or embroidery. They may scratch some surfaces of your amp. We prefer using a micro-
fiber cleaning cloth for the logo, control panels and metal surfaces.
SPECIFICATIONS
• Dimensions: 22.5" x 9" x 9"
• Weight: 32 lbs.
• Power: 33 Watts RMS (33 clean watts measured before distortion)
• Tubes:3 - 12AX7, 4 - EL84 / 6BQ5
• Mains Fuse:3 Amp “slow blow“ a.k.a. MDL 3A - rated at 250V (2 Amp for 240V operation)
•H.T.Fuse:1/2 Amp “fast acting“ a.k.a. AGC 500 mA - rated at 250V
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

A FINAL WORD
Your Kometamplifier was designed to be played and enjoyed. By virtue of its unmatched
quality, it will free you from thinking about your equipment and concentrate on the very thing
that matters: your music. The Aero33 's responsiveness, musicality and immediacy - places you
in charge of your sound. It can handle a small club performance situation with ease and is voiced
to cut through the band mix.
Give yourself and your new amp a little time to get to know each other. No matter how good it
sounds right out of the box, your amp will break in and improve tremendously after being played
over time. The harmonic complexity will continue to improve; the tone will sweeten up and
become even more fluid and resonant. Have fun!
Thank you for purchasing our product.
Michael Kennedy
Holger Notzel
Co-owners
KometAmplification
CONTACT
KometAmplification
1865 Dallas Drive
Baton Rouge, LA 70806-1454
[phone]
Email: [email protected]
Website: www.kometamps.com
Facebook: https://www.facebook.com/pages/Komet-Amplification/739410886107995
Tumbler: http://kometamplification.tumblr.com/
Twitter: https://twitter.com/kometamps
KometWarranty information located at end of owner’s manual.
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

KometSpeaker Wiring Diagrams
Single 12” 16 Ohm Speaker
2 X 12” 8 Ohm Speakers in series for 16 Ohms
4 X 12” 16 Ohm Speakers in series / parallel for 16 Ohms
Note: KometAmplification recommends using a 16 Ohm load with their amplifiers for the best sonic results.
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

KometAirbrakeManual
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

The KometAirbrakeUsers Manual
The KometAirbrakeis a resistive load power attenuator, which connects between an
amplifier’s speaker output jack and a speaker cabinet. It allows the user to "turn up"the
amplifier’s volume, utilizing the amplifier’s harmonically rich output stage distortion, while
reducing the signal sent to the speakers. This lowers the amplifier’s overall sound pressure
level and is useful when high volume is not required.
All power attenuators by design reduce the interaction between an amplifier’s output stage and
the speakers, which is a critical part of the sound and feel of a tube amp. An attenuator can
change the human ear’s perception of the frequency spectrum by reducing the sound pressure
level. Accordingly, there is no power attenuator that does not change the overall sound of an
amplifier.
The KometAirbrakesounds very natural and "transparent"at reasonable levels of attenuation.
It allows the user to bring the level of a 50 / 60 Watt Kometamplifier down to that of a
"cranked" 20 to 25 - watt amplifier, all the while retaining its distinct voice and dynamics. It is
therefore best suited to match Kometamplifiers to a smaller room, or in a quieter playing
setting. 
Features of the KometAirbrake:
- operates on 8 or 16 speaker loads only.
- designed for a maximum power handling capability of 100 Watts.
- five graduated attenuation settings via a six position rotary switch.
- 3dB drop in first step of attenuation, approx. 1.7dB each step after.
- the first (12 o’clock) position of the six position rotary switch is a true bypass
setting (under no attenuation).
- one input, two parallel output jacks.
- line level signal out control.
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

Using the KometAirbrakePower Attenuator:
You will need two, quality constructed, standard speaker cables. At the bottom of the
KometAirbrake, below the Kometlogo, you will find three input jacks arranged in a triangle
formation. The top input jack (of the triangle formation) is the Airbrake’sinput.
Connect one speaker cable from one of the amplifier’s speaker outputs into the top input of
the KometAirbrake. Note: (see last page for descriptive layout).
The bottom two jacks of the triangle formation are the two parallel outputs. Connect the second
cable from one of the two KometAirbrakeoutputs into the speaker cabinet input. If you only
use one speaker cabinet, you may plug it into either one of the two, bottom output jacks on the
KometAirbrake. Note: (see last page for descriptive layout).
Set the amplifier’s impedance selector according to the impedance of the cabinet used.
Remember to always use dedicated speaker cables of a sufficient gauge (we prefer 18 gauge) for
both connections. WARNING: Never use instrument (guitar) cable as a speaker connection. By
doing so will cause damage to the amplifier.
If you plug two speaker cabinets into the KometAirbrake’sparallel output jacks, make sure
both cabinets or both speaker loads are rated at 16. Keep in mind that the combined load of
both cabinets or both speaker loads will be 8. Set your amplifier’s impedance selector
accordingly to 8.
Do not use two, 8 speaker cabinets. The combined load will be 4, which is below the Komet
Airbrake8/16 Ohm operating range. For the same reason, do not use two 4cabinets. Never
combine two cabinets of different impedance ratings (for example an 8cab and a 16cab).
The line level signal out control is the cream colored knob located at the top of the
KometAirbrake. The line level output jack is located to the right of the cream colored control
knob. The line level signal out feature allows the user to send the un-attenuated signal from the
amplifier under attenuation, into another amplifier, say one with reverb or tremolo, or send a
signal to a recording or mixing console, or can be used to send the signal to a wet/dry rig. Make
sure you use a quality constructed shielded instrument / guitar cable for this signal sending
portion of the device.
If you use the line level signal out control to send a signal to a P.A. (public address) system, make
absolutely sure that the level control is set and not disturbed while in use. You could possibly
damage the P.A. system if the volume level/control knob were to be drastically raised or quickly
"turned up" while in use.
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

Important:
We recommend that if you intend on using your KometAirbrakein conjunction with much
older, vintage amplifiers, that you set your vintage amplifier’s impedance selector to 8for the
first step of attenuation (or the first click of the rotary switch), regardless of an actual 16 Ohm
impedance of the speakers or cabinet used. If your amp and speaker load is 8 set the
impedance selector to 4in the first step of attenuation. This precaution will lower the current
flowing within the output tubes under full power. We also recommend this same action with
EL84/6BQ5 powered amplifiers. Set the impedance selector of your vintage amplifier according
to the speaker impedance being used in any other step of attenuation past the first click.
We recommend that you do not use the KometAirbrakewith a 100 Watt plus rated amplifier
for very long, extended periods at very high volume levels (or with the volume controls “dimed
out”). This is because the KometAirbrakeis a 100 Watt rated device. Any 100W amplifier can
surpass its 100W RMS rating when cranked way up. This could possibly over-heat the attenuator
causing damage to one or more of the load resistors.
Note: The KometAirbrakewill increase it’s ability to handle an amplifier’s wattage as the
attenuation level increases. The maximum load capability for the KometAirbrake is 200 Watts
under full attenuation. You should not have a problem using the KometAirbrake with a 100W
amplifier, but it is always best to operate your 100W amplifier and attenuator within reason.
Note: we do not recommend adjusting the Ohm settings via the adjustable lugs located on one of
the resistors within the unit. They are factory set.
Final note:
The KometAirbrakepower attenuator reduces volume by converting the amp’s excessive
power into heat. The device will get very warm, even hot, during use. Please make sure you
place the unit it in a well ventilated area and never have it covered up. The KometAirbrake
was designed for optimum performance with Kometand Trainwreckamplifiers. The
KometAirbrakewill work equally well with most other manufacturer’s amplifiers, but
KometAmplification only guarantees safe operation with Kometand Trainwreckamplifiers.
A Special Note on Speaker Cabinets and Speakers: we recommend that you use quality
speaker cable with quality brand male plugs. This is to guarantee a tight fit to the speaker jacks
and cabinet. We prefer the Switchcraft#11 mono input. We also recommend that your speaker
cabinet wire leads are directly soldered to the to the speaker terminals instead of using the "slide
on"gripping terminals. (See special note in the Speaker Cabinet section of this manual).
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.

The KometAirbrakeLayout
Copyright 1999-2017, KometAmplification. Group, L.L.C. May not be reproduced in any form without express written consent from KometAmplification.