Fuchs Audio Technology Mantis Series User manual

MANTIS SERIES AMPLIFIERS
Operations Manual
For
Mantis 89 / Mantis Jr models
Fuchs Audio Technology®
407 Getty Ave, Clifton, NJ 07015
[phone] (fax) 973-772-4460
Website: www.fuchsaudiotechnology.com
Email: [e-mail]
 2000-2021 Fuchs Audio Technology. All
rights reserved.
12-01-2021-AMF Rev-1.1


A Note from Andy,
First of all, Thank You for purchasing a Fuchs Audio Technologyamplifier!
Due to player demand and customer feedback, Fuchs® developed the popular Casino
series amps into a new series of amps, the Fuchs ® Mantis 89®. The Mantis 89 is built to
deliver killer British M-style tones at a terrific price with high end features and tone that
exceeds your expectations. And like all Fuchs® amps and pedals, each Mantis 89®
amplifier is precision crafted by the team at Fuchs Audio to the same high standards of
excellence found in all Fuchs® products, regardless of price. With over two decades
experience in the service, manufacturing, and design of tube audio/music equipment,
we at Fuchs Audio are extremely proud of the quality and tremendous musicality of this
new series.
Please read this manual carefully. Although these amps were created to be simple
amplifiers to learn and operate, they will perform to its maximum by your full
understanding of thecontents of this manual.
Feel free to call or e-mail us (we love emails!) with comments & questions about your
amp, or just to find out what’s new here at Fuchs Audio.
Lastly, I recommend checking out our website: www.fuchsaudio.com, for
product/userupdates, cool links and other info benefiting our customers.
Welcome to the Fuchs family,
Andy Fuchs
President
Fuchs Audio Technology LLC 
Fuchs Audio Technology
407 Getty Ave, Clifton, NJ 07011
[phone] (fax) 973-772-4460
Website: www.fuchsaudiotechnology.com
Email: [e-mail]
(“Fuchs Audio Technology” & all product names are registered trademarks of Fuchs Audio Technology)


Table of Contents (by section)
1) Introduction to the Fuchs Audio Casino series amplifiers
2) Please Read before powering up your amp
3) Diagrams- FRONT/REAR panels, Tube bias diagram
4) Front Panel Controls, Inputs & Functions
5) Rear Panel Controls, Inputs/Outputs
6) Biasing The Amplifier Power Tubes, Warnings and Technical Information
7) Warranty/repair information & mail-in warranty form
 2000-2021 Fuchs Audio Technology. All rights reserved.

1. INTRODUCTION TO THE FUCHS AUDIO MANTIS 89® SERIES™ AMPLIFIERS
Having become one of Fuchs Audio Technology’s bestselling amplifiers, the Mantis 89®
Series series ™ brings the premium build quality and breathtaking tones people expect
of Fuchs products into an affordable price range. The Mantis 89® Series are based on a
three 12AX7 preamp stage, and each model has its own unique power stage. Unlike other
amps in this price range, the Mantis 89® Series features two channels, a gain boost, and
a feature set unlike any other boutique “M-style” amp in this price range. They feature a
full complement of extremely flexible tone controls. A surprising amount of clean
headroom is available before the output stage begins distorting with a sweet British rock
edge.
The Mantis 89® Series boasts all the most sought-after Fuchs® amplifier features,
including an aircraft grade aluminum chassis, our proven PC board and hand wired
construction and top-grade transformers. On these models the preamp tubes and power
supply circuitry are on the PC board, while the power tubes and transformers are
mounted on the chassis for stability, performance, and easy service. A detachable power
cord is standard. And through Fuchs® single point grounding, the amp is quiet and free of
hum at all operating levels.
A single instrument input and 3 speaker outputs for 4-8-16 ohms are provided. An effects
patch jack is provided as is a dual footswitch jack for channel and gain boost via a dual LED
footswitch.
Features:
♦¾” solid premium plywood cabinet with durable Tolex covering.
♦Anodized aluminum chassis with long lasting silk-screened panel
labeling
♦Heavy duty Cliff brand jacks. Solid metal-shaft Alpha potentiometers.
♦Ultra-long-life fuse-lamp pilot lamp and heavy-duty AC power and standby
switches.
♦Simple user adjustable fixed output tube bias.
Specifications:
Amplifier Model
Output Wattage/Tube Complement
Input
Impedance
Weight & Dimensions
Mantis 89® 20-watt
head
20 watts into 4-8-16 ohms, 2x6V6 power
tubes
1Meg.
24 lb
18 7/8 * 11 3/8 * 9 3/4
Mantis 89® 1x12
Combo
20 watts into 4-8-16 ohms, 2x6V6 power
tubes
1Meg.
35 lb,
24 3/8 * 11 ¾ *22 7/8
Mantis 89 50® Head
50 watts into 4-8-16 ohms, 2 x 6L6 power
tubes
1Meg.
29 lb,
18 7/8 * 11 3/8 * 9 3/4
Mantis 89 50® 1x12
Combo
50 watts into 4-8-16 ohms, 2 x 6L6 power
tubes
1Meg.
40 lb,
24 3/8 * 11 ¾ *22 7/8
Mantis 89 100®
Head
100 watts into 4-8-16 ohms s, 4 x 6L6
power tubes
1Meg.
32 lb
18 7/8 * 11 3/8 * 9 3/4
Mantis 89 100®
1x12 Combo
100 watts into 4-8-16 ohms, 4 x 6L6
power tubes
1Meg.
44 lb,
24 3/8 * 11 ¾ *22 7/8

2. PLEASE READ BEFORE POWERING UP YOUR AMPLIFIER.
NOTE: Please see Panel Diagrams in Section 3 for assistance.
1) Inspect to make sure power & pre-amp tubes are intact & snuggly seated in their
sockets.
2) Make certain a speaker (load) is plugged into speaker input jack on the back of
the amplifier. Failure to have a speaker connected to the amp will result in
damage to the output tubes or output transformer ! Your amp is supplied with
4,8 and 16 ohm speaker output jacks, select the one which matches your
speaker(s) impedance.
3) Reduce Front panel GAIN controls to moderate level.
4) Install instrument cable from guitar into front panel INPUT
5) Be sure both POWER switch (front panel) is in DOWN (0ff) position and standby
is in off (down) position.
6) Install power cord to amplifier (AC POWER IN) and to appropriate AC power
source.
7) POWER UP amplifier by: 1) flipping POWER switch UP. Allow at least 30 seconds
to 1 minute for tubes to heat up. Then switch amp to operate mode via standby
switch.
8) The Amplifier is now fully on and ready to use. Feel free to adjust all controls as
you see fit.
9) Provide adequate and unimpeded ventilation.
10) Do not expose the unit to drips or splashes.
11) Do not to place liquids on the unit.
12) Properly ground the unit (i.e. make sure the outlet used is grounded, and ground
is not defeated between the outlet and unit).

3. DIAGRAMS OF FRONT & REAR PANELS, TUBE BIAS DIAGRAM
Front Panel
Rear Panel
Tube Bias Diagram

PREAMP TUBES AND THEIR FUNCTIONS:
V-1 12AX7 (nearest to input jack). Main input preamp, first clean and overdrive preamp
(premium tube recommended)
V-2 12AX7 (middle tube) Gain stage/ tone stack
V-3 V-3 12AX7 Phase inverter/driver tube
4. FRONT PANEL CONTROLS, INPUTS & THEIR FUNCTIONS
Input Jack:
Input jack is a 1/4" phone plug, designed for 1-Meg impedance, guitar-level signal. This
input will readily accept pedals/effects without any loss in performance. Pedals/effects
input is also inserted to this input in series with your guitar.
Gain Control:
The 800 gain control sets the overall gain/volume for the amplifier in the clean
(channel-1) mode. Adjust to volume /tone taste. This is the lower gain channel. This
channel with gain boost ON, brings it to the level of the 900 channel without boost.
900 Gain Control:
The 900 gain control sets the overall gain for the amplifier in the 900 channel. Adjust
to volume /tone taste. This channel is about 10 db more gain (without boost) as the
800 channel. This channel with boost, takes the amp over the top with shred level gain.
High Control:
Adjust the high control to taste, it controls adjusts the high frequency spectrum of your
amplifier.
Mid Control:
Adjust the Mid control to taste, it controls adjusts the mid frequency spectrum of your
amplifier.

Low Control:
Adjust the Low control to taste, it adjusts the low frequency spectrum of your amplifier.
800 Master:
The 800-Master sets the volume for the 800 channel. This control pulls out to switch to
the 900 channel manually. The footswitch is disengaged when the control is pulled.
900-Master:
The 900-Master controls the volume of the amp in channel-2 (high gain) mode. The input
gain sets the amount of distortion, and the master sets thevolume at which this channel
operates.
Thrust Control:
The thrust control works on the power amp section on the low end and raises low end
gain and provides a bass boost and a looser overall feel and affects both channels.
Accent Control:
The accent control adds highs to the power amp section, altering the overall bite of the amp and
presence of the power stage on both channels.
5. REAR PANEL CONTROLS, INPUTS/OUTPUTS
AC power cord input:
Using a standard IEC power cord. Connect to AC POWER IN on the amplifier and to AC
power source. Please note the voltage on the chassis, and make sure you are supplying
the correct AC voltage to the unit. Damage from incorrect voltages is not covered by
warranty.
AC power Fuse:
This fuse protects the amplifier if any malfunction occurs. Use ONLY the stock fuse
rating as supplied by factory and shown on the rear panel for the voltage and current in
your location.
Speaker outputs:
4, 8, 16-ohm outputs. Use the same impedance as the speaker you are using for
maximum power and performance and use only one speaker output at a time.

Standby/Play switch:
Up is play mode. When amp is not being used, but being warmed up, place amp into
standby mode.
Effects Loop Patch jack:
This is a stereo ¼”. The tip is the return to the power amp. The ring is the send from the
preamp. This may be used with an outboard effect loop like the Plush Tube FX loop, or
various other aftermarket devices for this purpose. Depending on the outboard unit
youare using, an effects loop device may not be needed. You can try any unit you like
and see if the tone and performance is acceptable to you without damage to the unit.
6. BIASING THE AMPLIFIER POWER TUBES, WARNINGS AND TECHNICAL INFO
The circuit board is shown in Section 4 of the manual should be viewed as having
the chassis sitting on its transformers, and front panel facing the user.
Biasing Information for Various Models:
Refer to diagram above for location of bias trimmers and test points
20-watt : Set for .02 volts on each test point (20-Ma per tube Class-AB-1)
50- watt : Set for .036 volts on each test point (36 ma per tube Class AB-1)
100-watt : Set for .036 volts on each test point (36 ma per tube Class AB-1)
Bias is tested at the respective test point for each tube and set by the (ten turn)
trimmer for each power tube. There may be interaction between the tubes, so
adjusting in order and returning to the first tube and so forth, until all tubes are at the
same bias level.
!!! WARNING – ELECTRICAL SHOCK HAZARD!!!
THERE ARE EXPOSED POTENTIALLY DEADLY HIGH-VOLTAGES IN THIS AMPLIFIER,
EVEN WITH THE AMPLIFIER SHUT-OFF!
If you are not familiar with servicing tube amplifiers and/or high voltages, do not attempt to
remove the chassis from its cabinet or to attempt to service this amplifier. Do not attempt to
service, repair or conduct tube biasing on your amplifier unless you are qualified to do so.
Refer servicing to the factory or to someone with experience servicing these types of amplifiers.
DISCLAIMER: Fuchs Audio Technology, LLC®, its subsidiaries, affiliates and/or agents shall have
no responsibility for, nor shall they be held liable for any harm of any kind to any person/s or
property (including damage to this amplifier) as a result of improper and/or unauthorized
service, repair or internal adjustments made to this amplifier.

FCC COMPLIANCE STATEMENT: This equipment has been tested and
found to comply with the limits of 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 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.