Fuchs Audio Technology Clean Machine CM-75, Clean Machine CM-100, Clean Machine CM-150 Operation Manual

Clean Machine



Instrument Amp lifier

V 2.0

Operations Manual

For Clean Machine Models (heads and combo)

CM-75
CM-100
CM-150
Fuchs Audio Technology

407 Getty Avenue 2nd Floor

Clifton, N.J. 07015

[phone]

Website: www.fuchsaudiotechnology.com

Email: [e-mail]

Clean Machine-Manual Rev. 1.1 08-2011



A Note from Andy,

First of all, thank you for purchasing a Fuchs Clean Machine 
amplifier!

As a guitar player I designed the Clean Machine series of amplifi ers to
be fabulous 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 t one s & p e rformance you want . Your Clean Machine can onl y
perform t o i ts fullest glory by your full under s ta nding of all its features.

Feel free to call or e-mail us (we prefer emails!) with comments &
questi ons 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, for product/user updates, cool links

and other info benefiting our customers.

Sincerely,

Andy

Andy Fuchs
President

Fuchs Audi o Technology

Fuchs Audio Technology 7 3 C ollins Av e n ue , Bloom field, NJ, 07003

(973)-893-0225 www.fuchsaudiotechnology.com [e-mail]

(“Fuchs Audio Technology” & “Clean Machine” are registe re d trademarks of F uchs A udio Technology)

Clean Machine-Manual Rev. 1.1 08-2011



Clean Machine

Instrument Amplifiers

Table of Contents (by sec tio n)

1) Introduction to Fuchs Audio Technology Amplifiers

2) Please Read before powering up your AMP!

3) Diagrams- FRONT/REAR panel controls & F ootswitches

4) Front panel Cont rols & their functions

5) (A) Rear Panel controls, inputs/outputs, (B) Effects Loop

6) F ootswit ches (standard, Artist, Artist Plus)

7) Biasing your power tubes & othe r te c hnical info.

8) Warranty/repair information & mail-in warranty form

(Please note: Many of ou r Clean Machine amplifiers are custom-made, so not all

features appear on all models. This operation manual will indicate features your

particular model may or may not have. (Such as: 50/100 power switch, Artist

footswitch or other opti ons.)

 2000-2008 Fuchs A ud io Te chnology. All rights rese rv e d.

Clean Machine-Manual Rev. 1.1 08-2011

1 Introduction to Fuchs Audio Technology Amplifiers

What makes our products uni q ue?

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 enj oying fresh food or food that's been frozen. Something gets
lost in the translation.

We feel our desi gns go a few step s beyond t hos e of other manufacturers!

In addition to r ef ining our circuit designs and oper a ting points wit h 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 single­point star grounding of all internal circuits, premium audiophile grade power and
output transfo rm ers, high speed switching diode power supplies, regulated and
buffered DC power supplies for both filaments and high voltage sources, are key
element s to producing an amp tha t has truly uniqu e sonic advantage s. 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 result in an amp with extremely
high gain capability, but with a super low noise floor. This reduction in noise and
increases in overall circuit clarity makes the se lection of components an even more
critic a l element to achie ving good tone. Whil e we use many time honor ed 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 a mplifiers as wel l.

It's a we ll-known fact that chassis materials can change the tone of the circuits
built into them. We use an aircraft grade T-6 alum inum 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 m odern and tra d i tional wiring methods
Internal cons truction in all models is based arou nd a central circu it board, which
supports most of the power su p ply and the amplifiers FX loop, driver and bias
circuitry. The balance of the amp is hand wired, with particular attentio n paid to the
preamp section and low-level circuits. All tube so ckets are chass is mo u nted 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
zero heat. This DC supply is highly filtered, using over 200 ufd of power supply
filtering, 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 balanc e to the power stag e , keeping it lin e a r, produci ng a clean, s trong to ne .
When driven to clipping, overloading is ultra- smooth, compressing in a sweet way,
not at all aggressive or ha rs h.

'bend' under the stress of loud playing, and they also produce

Clean Machine-Manual Rev. 1.1 08-2011

Premium Transformers
Our power transformers are designed for highest self-regulation as well as
conservative operation, assuring lowest heat and highest reliability. Our output
transformers (depending on the model) are premium grade audiophile quality. We
use custom built power and output transformers, as well as custom wound chokes by
Mercury Magnetics. All amplifiers feature 4 and 8 ohm outputs, grain oriented steel
cores, with heavy-duty mounting bells and hardware for maximum roadworthiness.
Buffered FX L oop
Our buffered FX loop features both series and parallel operation. It uses a
conve nt io nal 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 feature a solid-state current driven design. By treating the
reverb transducer as a current driven device (rather than a voltage driven device like
most other designers do), we have produced a quiet, dynamic reverb that sounds as
warm and detailed as a tube unit, p lus the reliability of solid-state ci rcuitry. This
saves on both space, and heat generation within the amp. Our 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 adja cent
stages c an produce a masking of inner detail and potential inst a bility in other hig h
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 inte rnal layout has been r efined to minimize wi re runs, lowering the noise floor
to the circuit’s practical limits. We still chassis mount our tube sockets for maximum
strength, dura bili ty a nd s er viceability. We hand select our t ub e s for lowe st noise a nd
optimal tone. Most mode ls include a DC fan for low chassis temp eratures and
extended tube life. All passive p arts are carefully chosen for both rel iability 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.

 2000-2008 Fuchs Audio Technology. All rights reserved.

Clean Machine-Manual Rev. 1.1 08-2011

2 Please read before powering up your Clean Machine

Please see Panel Diagra m s in next secti on 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! You r ODS is
supplied with multiple speaker inputs for various impedances, select the one
closest to your speake r (s) imp ed an ce.

3) Reduce Front PANEL controls (MASTER, GAIN, INPUT, and OUTPUT) to
moderate levels (appro x 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 Connect or.

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.

10) Provide adequate and unimpeded ventilation.

11) Do not expose the unit to drips or splashes.

12) Do not to pla c e li q u id s on the un it.

13) Properly ground the unit (i.e. make sure the outlet used is grounded, and
ground is not defeated between the outlet and unit).

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 F l ip the STAN DBY switch DOWN . We t hen reco mme nd (a s

a kindness to the output tubes) waiting at least 1 minute before flipping POWER
switch D OWN hence fully shutting the amp down.

Clean Machine-Manual Rev. 1.1 08-2011

3 Diagrams of FRONT & REAR Panels and FOOTSWITCHES

Front Panel

Rear Panel

Effects Loop

Standard Footswitch (2-way) Artist Footswitch (4-way)

(Please note that external appearances of footswitches may vary depending on production

date. All functions remain the same regardless)

Clean Machine-Manual Rev. 1.1 08-2011

4 Front 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 n o 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.

Brite Switch:

The Brite switch operates with the gain cont rol/and is active over about ½ of the
input gain control range. Fr om ‘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.

Deep Switch:

The deep switch shifts th e overall tonality of the amplifier , increasing the low
Frequencies. This is often useful for single-coil guitars, which sometimes need
A low-freque ncy boost, or for jaz z players who prefe r the added warmth .

EQ Switch:

The EQ switch alters the ope ration 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 mo r e neutra l/linear tone. All tone controls work in both
Modes, however their range and depth of operation is changed.

High Control:

The High control serves 2 functions: (IN)-it adjusts high frequency spectrum. (OUT)
the High control engages the mid-boost. T h is shifts the rang e of the high cont r o l
downward, t o include more midrang e. All tone contr ols still operate, however the
tone will be fatter.

Mid Control:

The Mid control serv es 2 fu nc tio ns: (IN ) Ac ts to a dj ust mid freq u en cie s. (OUT)
changes the frequency of the mid boost. This warms the overall midrange tone and
this can also fatten sound for Single coil pickups.

Low Control :

This control adjusts the low spectrum of the amp. Pulling it alters the p ivot
(frequency) point of both the mid and low controls for greater tonal range.

Clean Machine-Manual Rev. 1.1 08-2011

The Reverb Co ntrols: (Input t one, Input Dwel l , Output level, Output tone)

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 tone, and the output level and tone for reverb 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 Cle an Mach i ne . These co n tr o ls are best left to pro fess io nal technicians,
who have the proper measuring equipment to set them properly. There ar e
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-Manual Rev. 1.1 08-2011

5 (A)-REAR Panel Controls, inputs/outputs, (B)-Effects Loop

(A)-REAR panel Controls/input/outpu t jacks

AC power cord input:

Using the supplied power cord. Connect AC POWER IN on amplifier and t o 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 swi tch:
Up is ON, DOWN is OFF

Standby switch:
UP is ON, DOWN places the amplifier in STANDBY

Speaker inpu t (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 installe d on your ODS (4, 8, 16 ohm). Connect speaker to inpu t
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 prod uce sound. When in Parallel-Mode
Parallel mixes effect signal with drive signal, which then remains in amplifier. Normal
positi on (when not using loop) is control I N.

Return Trim Pull Switch:

Sets sensitivity & adjust s sensitivit y of return input of the effects loop. This allows
tailor ing of signal of ef fect or rack device. If using an effect whi ch requ ires more
return sensitivity, pull this control out. Normal position is IN.

Return adjustment control :

This allows overall volu me adjustment of amp (to set unity gain), thus retaining
same volume with or without effect). This contr o l sets the leve l co mi ng back from
your effects, also a secondary means of adjusting return of effect signal. The serie s
parallel switch controls whether the loop is “open” (series) or “closed” (parallel).

Return Input ja ck:
Connects to OUTPUT FROM your EFFECT S

Send Input jack:
Connects to INPUT TO your EFFECTS.

Send adjustment control:

Adjus ts s ignal le vel going to e ff ect. Adj ust send co ntr ol so tha t effect re c eives
maximum amount of signal bef ore distorting .

Clean Machine-Manual Rev. 1.1 08-2011

amplifier will always produce sound.

(B)-Effects Loop

Using the Loop:

When inserting a device like an equalizer, or perhaps a Sonic Maximizer (or similar
processor), the loop sh ould be set in series mode. T he mix controls on th e 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 paralle l mode. In
this case, the effects should be run fully “wet” (no non-proce ssed sig nal s 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. 1.1 08-2011

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, g a in
boost, effects loop bypa ss or global mute functions.

“Artist” 4-Way footswitch:

Connects via 5-pin “CAT-5” cable (supplied) to rear panel input. This footswitch
allows remote control of 4 functions: mid-boost, gain-boost, Mute (o r effects bypass)
and reverb mute. The artist fo otswitch requ ires: HIGH con trol be pushed IN (of f) for
the footswitch to operate the midboost function. When an LED on the footswitch is
lit, that function is ON, except REVERB

(Reverb is muted when LED is lit). The

amp/controls function normally without Artist footswit ch connected.

Clean Machine-Manual Rev. 1.1 08-2011

7 Biasing power tubes and other technical info

Biasing and Internal Adjustm ents:

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 amplif ier. Refer s er vicing to t he fa ctory or to
someone with experience servicing these types of amplifiers.

High Internal v oltages inside thi s amplifier can cause harm or D eat h!

AC Balance:

This is factory set for linear clipping at maximum power output, and is set with an
oscilloscope for proper adjustment.

Bias Control s:

The tube (in the 75) or each pair of tubes in the 100 and 150-W mo de ls 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. Th e 75 and 150
(using 6550 tubes) are set to .040 volts (40 millivolts dc = 40 ma) per tub e , an d the
100 (using 6L6’s) should b e 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 thi s amplifier as a result of unauthoriz ed service, r epair or internal

adjustments made to this am plifier

Clean Machine-Manual Rev. 1.1 08-2011

.



8 Warranty Information

The Fuchs Audio Technology-ODS Warranty

Fuchs Audi o Tec hnology guarantees our products to be free from defective

workmanship or mat er i al fai lur e for a perio d of on e year fr om dat e of new purchase to

the origin al pur chaser. 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 Technology within 30 days of purchase, or your warranty will not be in effect.

Fuchs Audi o Tec hnology reserves 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 ex am ination .

Keep the in formation on this pa g e for your records.

Please mail-in warranty form on next page

FUCHS MODEL ______________________
SERIAL NUMBER ______________________
OPTIONS INC LUDED ______________________

________________

________________
________________

PRODUCTION DATE ____/____/____
TESTED BY ______________ Fuchs Audio Amplificati o n

Fuchs Audio Technology  407 Getty Ave, Clifton NJ, 07015

(973)-772-4220 www.fuchsaudiotechnology.com [e-mail]

Clean Machine-Manual Rev. 1.1 08-2011



WARRANTY REGISTRATION FORM

This completed form must be returned to Fuchs Audio Technol og y w i t hin 30

days of purchase along wit h a copy of your recei pt from your authorized

Please fill in all requested information on this form so we may regi ster you for future
warranty repairs or future upgrades, should they become available.

Purchasers Na me _____________________________ ______________________
Address___________________________________________________________
City ________ ____________ State _____ Zip __________ Count ry___________
Phone Number _____________________________________________________
E-Mail a ddress _______________________________________________ ______
Model ____________________________________________________________
Serial Number _____________________________________________________
Date o f Purchase _______________ ______________________ ______________
Dealer Name ______________________________________________________
Comments:
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________

Please re t urn this for m to:

Fuchs Audio Technology 407 Getty Avenue, Clifton NJ, 07015

[phone] www.fuchsaudiotechnology.com [e-mail]

dealer.

Clean Machine-Manual Rev. 1.1 08-2011