FUCHS Clean Machine II User manual
Clean Machine II
Instrument Amplifier
V 2.0
Operations Manual
For Clean Machine II Models (heads and combo)
CM-100/50 CM-50/25
Fuchs Audio Technology
407 Getty Avenue 2nd Floor
Clifton, N.J. 07015
(973) 772-4420
Website: www.fuchsaudiotechnology.com
Email: [email protected]
Clean Machine-Manual Rev. 1.0 12-2008-AMF
A Note from Andy,
First of all, thank you for purchasing a Fuchs Clean Machine II
amplifier!
As a guitar player I designed the Clean Machine series of amplifiers to
be sensitive and responsive instruments for musicians to create music.
Each Fuchs product is precision handmade by myself and the staff at
Fuchs Audio, built to extremely high standards of excellence using the
highest quality components. 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 all our products, and know you’ll feel the same way.
Please read this manual carefully. Doing so will allow you full
understanding of your amplifier and operation, thus quickly providing
you the tones & performance you want. Your Clean Machine II can
only perform to its fullest glory by your full understanding of all its
features.
Feel free to call or e-mail us with comments & questions about your
amp, or just to find out what’s new here at Fuchs Audio.
Lastly, I recommend checking out our web site:
www.fuchsaudiotechnology.com, or www.fuchsaudiodirect.com for
product/user updates, cool links and other info benefiting our
customers.
Sincerely,
Andy
Andy Fuchs
President
Fuchs Audio Technology
Fuchs Audio Technology407 Getty Aev Second Floor West
www.fuchsaudiotechnology.com [email protected]m
(“Fuchs Audio Technology” & “Clean Machine” are registered trademarks of Fuchs Audio Technology)
Clean Machine-II Manual Rev. 1.0 05-2023-AMF
Clean Machine
Instrument Amplifiers
Table of Contents (by section)
1) Introduction to Fuchs Audio Technology Amplifiers
2) Please Read before powering up your AMP!
3) Diagrams- FRONT/REAR panel controls & Footswitches
4) Front panel Controls & their functions
5) (A) Rear Panel controls, inputs/outputs, (B) Effects Loop
6) Footswitches (standard, Artist, Artist Plus)
7) Biasing your power tubes & other technical info.
8) Warranty/repair information & mail-in warranty form
© 2000-2023 Fuchs Audio Technology. All rights reserved.
Clean Machine-II Manual Rev. 1.0 05-2023-AMF
1 Introduction to Fuchs Audio Technology Amplifiers
What makes our products unique?
The recent proliferation of "Boutique” amplifiers, allow guitarists to recognized
what audiophiles have known for years, properly designed tube circuits can offer the
finest musicality, detail, and sensitivity to playing subtleties of any type amplifier.
Anyone who’s enjoyed the sweet, responsive character of a well-built tube amplifier
realizes you can't model or computer simulate the “organic” qualities, no matter how
hard you try. It's like enjoying fresh food or food that's been frozen. Something gets
lost in the translation.
We feel our designs go a few steps beyond those of other manufacturers!
In addition to refining our circuit designs and operating points with computer
"Spice" modeling, we also spend countless hours tuning our circuits through careful
parts selection and refining the internal layout of our products. Details like single-
point star grounding of all internal circuits, premium audiophile grade power and
output transformers, high speed switching diode power supplies, regulated and
buffered DC power supplies for both filaments and high voltage sources, are key
elements to producing an amp that has truly unique sonic advantages. All completed
amps are compared to reference samples on both test equipment by live players
before they may be shipped.
Our attention to the power supply and grounding results in an amp with extremely
high gain capabilities, but with a super low noise floor. This reduction in noise and
increases in overall circuit clarity makes the selection of components an even more
critical element to achieving good tone. While we use many time-honored component
brands and features like “Orange Drop” Capacitors and/or carbon/metal film
resistors, we also use Audiophile grade “Wonder Caps” and unique circuit
refinements in many parts of our amplifiers as well.
It's a well-known fact that chassis materials can change the tone of the circuits
built into them. We use an aircraft grade T-6 aluminum chassis, which is 1/6" thick,
bent at its edges for strength, and when the front and rear panels are attached,
forms a strong yet lightweight chassis. Aluminum also provides an excellent heat
sink for excess tube, transformer, or regulator heat. Although we install fans in all
models, our amps would dissipate plenty of heat even without a fan. The front and
rear panels are attached to the chassis pan with pem-nuts, a 1/8 thick assembly
formed at both the front and rear of the chassis for rigidity.
A combination of modern and traditional wiring methods
Internal construction in all models is based around a central circuit board, which
supports most of the power supply and the amplifiers FX loop, driver and bias
circuitry. The balance of the amp is hand wired, with particular attention paid to the
preamp section and low-level circuits. All tube sockets are chassis mounted for
strength and ease of replacement; in the unlikely event a socket fails. This also
keeps tube heat away from the other internal components in the amps.
Our amplifier power supply starts with a high voltage supply, which is rectified
using high-speed switching diodes, combining the sonic attributes of a tube rectifier,
with the efficiency of solid-state diodes. These produce greater voltages, a more rigid
supply that doesn't 'bend' under the stress of loud playing, and they also produce
zero heat. This DC supply is highly filtered, contributing to an amplifier that has a
strong voice yet remains loud & clear up to its limits.
Our output stage(s) feature separate bias for each power tube. Although we use
premium “matched set” tubes as standard equipment, by individually setting bias,
we can obtain maximum power before clipping, extending tube life with better tone.
Our power amp driver circuit uses an AC balance trim control, which adjusts the
signal balance to the power stage, keeping it linear, producing a clean, strong tone.
When driven to clipping, overloading is ultra- smooth, compressing in a sweet way,
not at all aggressive or harsh.
Clean Machine-II Manual Rev. 1.0 05-2023-AMF
Premium Transformers
Our power and output transformers are designed for highest self-regulation as well
as conservative operation, assuring lowest heat and highest reliability. Our output
transformers are premium grade audiophile quality. We use custom built power and
output transformers, as well as custom wound chokes. All amplifiers feature 4, 8 and
16 ohms outputs, grain oriented steel cores, with heavy-duty mounting bells and
hardware for maximum roadworthiness.
Buffered FX Loop
Our buffered FX loop features both series and parallel operation. It uses a
conventional high-current biased cathode follower, which provides a low-impedance
signal source, which is level adjustable and can drive from a pedal level to a rack
mount unit cleanly. Two simple switches set series/parallel operation, signal levels
from 0db to –20db, easily matching any and all effects, tube or solid state.
Studio Grade Reverb
Our reverb sections features a Spin Technology 16-bit digital reverb design. By
treating the reverb mix and the reverb itself, we have produced a quiet, dynamic and
musical reverb that sounds as warm and detailed as a tube reverb, plus the reliability
of digital and NON mechanical reverb pans. The reverb is not only equipped with
level and decay controls, but low and high frequency controls to adjust the voice of
the reverb to taste. This reverb is interfaced through the FX loop, adding warmth to
the overall sound. Additional signal clarity is achieved by eliminating the common
reverb mixer network used by most other manufacturers.
Our Preamp Circuits
Our preamp circuits form the heart-and-soul of our amplifier tone. Any subtleties
lost or masked by preamp stages are truly lost forever. By operating our low-level
circuits on a regulated and passively buffered high voltage supply, using a regulated
DC supply, we completely eliminate the effects of conventional power supply filtering
and decoupling. Audio signals can (and do) appear on power supply sources. Despite
large filter capacitors these audio signals do not belong on the pure DC that a tube
circuit needs to perform properly. This subtle coupling of signals from adjacent
stages can produce a masking of inner detail and potential instability in other high
gain circuits. A careful selection of passive parts (resistors and capacitors), as well as
the active parts (tubes and/or solid state parts), results in the unique sonic signature
our amps are becoming known for. We also use regulated DC filament power
supplies, for lowest practical noise floor.
Internal Construction
We proudly can say our products are built better than ever. Our circuit boards are
now two-sided extra thick boards, with heavy copper plating and a full solder mask.
Our internal layout has been refined to minimize wire runs, lowering the noise floor
to the circuit’s practical limits. We still chassis mount our tube sockets for maximum
strength, durability and serviceability. We hand select our tubes for lowest noise and
optimal tone. Most models include a DC fan for low chassis temperatures and
extended tube life. All passive parts are carefully chosen for both reliability and sonic
attributes. Each and every Fuchs amplifier undergoes 20-40 hours of “burn-in”
before leaving our shop. This ensures every Fuchs amp is built for the long haul.
© 2000-2023 Fuchs Audio Technology. All rights reserved.
Clean Machine-II Manual Rev. 1.0 05-2023-AMF
2 Please read before powering up your Clean Machine
Please see Panel Diagrams in next 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 the correct speaker input jack
on the back of the amplifier (4 or 8 ohm). Failure to have a speaker
connected to the amp will result in damage to the output tubes! Your ODS is
supplied with multiple speaker inputs for various impedances, select the one
closest to your speaker(s) impedance.
3) Reduce Front PANEL controls (MASTER, GAIN, INPUT, and OUTPUT) to
moderate levels (approx at 7-9 o’clock positions).
4) (optional) Install cable into footswitch (either standard or Artist) and then
connect into rear panel input marked FOOTSWITCH. (Standard uses ¼”
phone jack, Artist/Artist Plus uses 5-pin Cat-5 Connector.
5) Install instrument cable from guitar into front panel INPUT
6) Be sure both POWER and STANDBY switches (rear panel) are in DOWN
position.
7) Install power cord to amplifier (AC POWER IN) and to AC power source.
8) POWER UP amplifier by: 1) flipping POWER switch UP. WAIT at least 1 minute
for tubes to heat up. 2) Flip STANDBY switch UP, amplifier will now operate.
9) The Amplifier is now fully on and ready to use. Feel free to adjust all controls
as you see fit.
TO PUT AMP IN STANDBY MODE- Simply flip the STANDBY switch DOWN.
TO PUT AMP IN PLAY MODE- Simply flip the STANDBY switch UP.
TO TURN AMP OFF Flip the STANDBY switch DOWN. We then recommend (as
a kindness to the output tubes) waiting at least 1 minute before flipping POWER
switch DOWN hence fully shutting the amp down.
Clean Machine-II Manual Rev. 1.0 05-2023-AMF
3 Diagrams of FRONT & REAR Panels and FOOTSWITCHES
Rear Panel
Effects Loop
Clean Machine-II Manual Rev. 1.0 05-2023-AMF
4Front Panel Controls and Their Functions
Input Jack(s):
Input jack(s), are 1/4" phone plugs, designed for 1-Meg impedance, guitar-level
signal. This input will readily accept pedals/effects without any loss in performance.
The design of the Clean Machine amplifier is quite flexible, so we first suggest
exploring its performance without any effects or pedals initially.
Gain Control:
The gain control sets the overall gain for the amplifier. There is no master volume.
Depending on the guitar, pickups and whether you are using pedals or not, this
control may be set anywhere on its rotation. Although this amp is called the Clean
Machine, it can be driven into overload at high volumes. It is capable of clean output
up to clipping, and usually produces more than its listed power. This control pulls for
gain boost (internally adjustable), and operated on the footswitch as Gain-1.
Brite Switch:
The Brite switch operates with the gain control/and is active over about ½ of the
input gain control range. From ‘0’ to about midway, it provides a boost to highs, and
the effect of the switch decreases beyond the halfway point on the gain control
rotation. Center is OFF, and the up position places the boost lower into the
midrange, while the down position is more subtle and higher in frequency
Deep Switch:
The deep switch shifts the overall tonality of the amplifier, increasing the low
Frequencies. This is often useful for single-coil guitars, which sometimes need
A low-frequency boost, or for jazz players who prefer the added warmth.
EQ Switch:
The EQ switch alters the operation of the tone controls. The upper position is
Will be the highest gain, and a brighter equalization. In the downward
Setting, the tone is a more neutral/linear tone. All tone controls work in both
Modes, however their range and depth of operation is changed. The center position is
tone stack bypass (also active by footswitch as gain-2)
High Control:
The High control serves 2 functions: (IN)-it adjusts high frequency spectrum. (OUT)
the High control engages the mid-boost. This shifts the range of the high control
downward, to include more midrange. All tone controls still operate, however the
tone will be fatter. This boost is activated on the footswitch as mid-boost.
Mid Control:
The Mid control serves 2 functions: (IN) Acts to adjust mid frequencies. (OUT)
changes the frequency of the mid boost. This warms the overall midrange tone and
this can also fatten sound for Single coil pickups. Pulling the mid control moves the
mid boost downward further toward the low end frequencies.
Low Control:
This control adjusts the low spectrum of the amp. Pulling it alters the pivot
(frequency) point of both the mid and low controls for greater tonal range.
Clean Machine-II Manual Rev. 1.0 05-2023-AMF
The Reverb Controls:
The reverb controls allow the widest range of reverb adjustment on any amp or
outboard reverb unit made today. These four controls will allow you to tailor both the
input level and dwell (decay), as well as low and high frequency tailoring of the
reverb output. The reverb while digital (using the Spin Technology chip), is fed on
both the input and output by a 12AX7 tube, which gives it warmth and analogue
smoothness. It produces tones ranging from subtle and warm to a bright extreme
surf style, and anything in between. It is best to start with the controls in the 12.00
position, and adjust from that point to your personal taste.
There are no “correct” Reverb settings, finding the desired tone setting depends on
the guitars/pickups used, as well as your own personal tastes.
Accent Control:
The accent control works within the power amp section, reducing negative feedback
at higher frequencies. It adds an edge to the overall amplifier tone. It's excellent for
cutting through in a band or a recording mix. It can also allow greater ability to
selectively make notes feed back and "sing".
NOTE: There are no internal trimmer pots, other than output tube bias and AC
balance controls for the power amplifier stage. There are no internal tone altering
controls in a Clean Machine II. These internal controls are best left to professional
technicians, who have the proper measuring equipment to set them properly. There
are hazardous voltages present in any tube amplifier, even after it has been shut off
for some period of time. Please exercise extreme caution when the chassis is
exposed out of the cabinet !
Clean Machine-II Manual Rev. 1.0 05-2023-AMF
5 (A)-REAR Panel Controls, inputs/outputs, (B)-Effects Loop
(A)-REAR panel Controls/input/output jacks
AC power cord input:
Using the supplied power cord. Connect AC POWER IN on amplifier and to AC power
source. Please confirm your line voltage matches that of the amplifier!!!
AC power Fuse:
This fuse protects the amplifier if any malfunction occurs. Use ONLY stock fuse rating
as supplied by factory.
Power On/OFF switch:
Up is ON, DOWN is OFF
Standby switch:
UP is ON, DOWN places the amplifier in STANDBY
Speaker input(s): (You must have a speaker load inputted to the ODS before powering on).
Connect using a ¼” phone plug to either an outboard speaker cabinet. Multiple
speaker inputs are installed on your ODS (4, 8, 16 ohm). Connect speaker to input
jack that most closely matches your speaker(s) impedance. When using an external
speaker with a combo, a Y-connector is required to split the respective output jack.
Contact the factory for assistance, if required.
Series/Parallel Pull Switch:
When in Series Mode-the amplifier must have effects connected to the loop, or amp
will not produce sound. When in Parallel-Mode amplifier will always produce sound.
Parallel mixes effect signal with drive signal, which then remains in amplifier. Normal
position (when not using loop) is control IN.
Return Trim Pull Switch:
Sets sensitivity & adjusts sensitivity of return input of the effects loop. This allows
tailoring of signal of effect or rack device. If using an effect which requires more
return sensitivity, pull this control out. Normal position is IN.
Return adjustment control:
This allows overall volume adjustment of amp (to set unity gain), thus retaining
same volume with or without effect). This control sets the level coming back from
your effects, also a secondary means of adjusting return of effect signal. The series
parallel switch controls whether the loop is “open” (series) or “closed” (parallel).
Return Input jack:
Connects to OUTPUT FROM your EFFECTS
Send Input jack:
Connects to INPUT TO your EFFECTS.
Send adjustment control:
Adjusts signal level going to effect. Adjust send control so that effect receives
maximum amount of signal before distorting.
Clean Machine-Manual Rev. 1.0 12-2008-AMF
(B)-Effects Loop
Using the Loop:
When inserting a device like an equalizer, or perhaps a Sonic Maximizer (or similar
processor), the loop should be set in series mode. The mix controls on the outboard
device can be used to control all effects and the balance between clean and dirty
effects. The loop is intended to interface external devices, and is intended to
maintain unity gain (same level as when loop is not used), and should be adjusted as
such.
Side-Chaining Effects:
For maximum signal purity and sound quality, when using effects like digital reverbs
and/or effects like an echo or tape delay, the loop can be used in parallel mode. In
this case, the effects should be run fully “wet” (no non-processed signals sent
through the effect). The send and returns of the loop are set for proper balance of
clean/effect and the controls on the effect can be used to trim the tone. This
method assures the clean (dry) non processed signal will remain in the amplifier, and
not be degraded by the outboard effect. In some cases, phase cancellation may
result. In this case, the effect should be adjusted for correcting the output phase (if
possible) or the effect must be used in series mode only. Phase cancellation is
marked by losses in bass or a thin “sucked out” quality, when effects are engaged.
Amplifier Block Diagram:
Clean Machine-Manual Rev. 1.0 12-2008-AMF
FOOTSWITCHES:
Your Clean Machine is provided with either: a 1- button standard, 2-Button
enhanced, or a 4 button “Artist” footswitch depending on your purchase selection.
Standard 1 or 2-Way footswitch:
Connects via ¼” phone cable (supplied) to rear panel input. Single button controls
reverb. In a two button footswitch customer may order reverb, mid boost, gain
boost, effects loop bypass or global mute functions.
Clean Machine-II Manual Rev. 1.0 05-2023-AMF
7 Biasing power tubes and other technical info
Biasing and Internal Adjustments:
Part of chassis and circuit board is shown below with the chassis sitting on its
transformers, and front panel facing you. There are exposed high-voltages in this
chassis, even with the amplifier shut-off! If you are not familiar with tube
amplifiers and/or high voltages, do not attempt to remove the chassis from its
cabinet or to attempt to service this amplifier. Refer servicing to the factory or to
someone with experience servicing these types of amplifiers.
High Internal voltages inside this amplifier can cause harm or Death!
AC Balance:
This is factory set for linear clipping at maximum power output, and is set with an
oscilloscope for proper adjustment.
Bias Controls:
The tube (in the 75) or each pair of tubes in the 100 and 150-W models is factory set
for proper bias. measured on the one-ohm cathode resistor connected to each power
tube pin 8. This should be set with the amp cold, then reset after the amp has run
for about an hour. Use a reliable digital volt meter for these settings. The 75 and 150
(using 6550 tubes) are set to .040 volts (40 millivolts dc = 40 ma) per tube, and the
100 (using 6L6’s) should be set to .036 volts (36 millivolts dc= 36 MA).
DISCLAIMER: There are exposed Internal high-voltages in this amplifier. Do not
attempt to service, repair or conduct tube biasing unless you are qualified to do so.
Please contact Fuchs Audio beforehand with questions in this regard. Fuchs Audio
takes no responsibility or shall be held liable for any personal harm caused or
damage to this amplifier as a result of unauthorized service, repair or internal
adjustments made to this amplifier.
Clean Machine-II Manual Rev. 1.0 05-2023-AMF
8 Warranty Information
The Fuchs Audio Technology-ODS Warranty
Fuchs Audio Technologyguarantees our products to be free from defective
workmanship or material failure for a period of three years from date of new purchase to
the original purchaser. This does not apply to Fuchs amplifiers that have been tampered
with, damaged by shipping carriers, reverse engineered, or modified. This warranty is
void if the amplifier is used with power attenuator type devices (Power Soaks, Air
Brakes, Hot Plates etc.). Your warranty form/information must be returned to Fuchs
Audio Technologywithin 30 days of purchase, or your warranty will not be in effect.
Fuchs Audio Technologyreserves the right to suspend or terminate the above
warranty at our sole discretion, should damage from any of the above limitations and or
exclusions be detected upon examination.
Keep the information on this page for your records.
Please mail-in warranty form on next page
FUCHS MODEL ______________________
SERIAL NUMBER ______________________
OPTIONS INCLUDED ______________________
________________
________________
________________
Fuchs Audio Technology 407 Getty Ave, Clifton NJ, 07015
Clean Machine-II Manual Rev. 1.0 05-2023-AMF
WARRANTY REGISTRATION FORM
This completed form must be returned to Fuchs Audio Technology within 30
days of purchase along with a copy of your receipt from your authorized
dealer.
Please fill in all requested information on this form so we may register you for future
warranty repairs or future upgrades, should they become available.
Purchasers Name ___________________________________________________
Address___________________________________________________________
City ____________________ State _____ Zip __________ Country___________
Phone Number _____________________________________________________
E-Mail address _____________________________________________________
Model ____________________________________________________________
Serial Number _____________________________________________________
Date of Purchase ___________________________________________________
Dealer Name ______________________________________________________
Comments:
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
Please return this form to:
Fuchs Audio Technology407 Getty Avenue, Clifton NJ, 07015
Clean Machine-II Manual Rev. 1.0 05-2023-AMF
This manual suits for next models
2
Table of contents
