The Ultimate Guitar Rig Building Guide

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    control without l imits!

    Prostage S.L. Apdo 57 ES-07560 Cala Millor

    [email protected] www.prostage.eu

    The ultimate Guitar Rig Building Guide

    Humfree wiring of guitar systemsand avoiding other noises

    1stEdition | Published on 20thMay 2014

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    Page 2

    Table of Contents

    1. Introduction 3

    2. Noise 4

    3. Hum Caused by Ground Loops 63.1 Earth | Chassis | Cable Shield 63.2 Star-shaped Wiring 63.3 Triangle | Ring Wiring 73.4 Two Amplifiers 73.5 Isolating Transformers to Prevent Ground Loops 83.6 Switched Grounds 93.7 Ground Loops over Effect Loops 103.8 19-inch Racks: Ground Connection via the Rack Rail 123.9 Wireless Receiver 123.10 Potential | Potential Compensation 133.11 Galvanic Isolation 13

    4. Hum by Interferences 14

    4.1 Interferences via the Pickups | Environment 144.2 Interferences from Nearby Power Supplies | Transformers 144.3 Interference by Parallel Cable Runs 144.4 Interference over the Local Power Grid 14

    5. Hum Caused by Faulty Equipment 16

    5.1 Missing Shield | Missing Ground 165.2 Faulty Power Supply 165.3 Faulty Tubes 16

    6. Other Noise Types 17

    6.1 Hiss 176.2 Whistling Sound | Switching Mode Power Supplies 176.3 Scratching 176.4 Transparency | Volume Loss 186.5 Clicking | Popping Noise 186.6 Clinking | Ringing, Combined with Some Kind of Feedback (Microphony) 186.7 Crackling | Sizzle 196.8 Rising and Falling Sound 19

    7. Important to Know 20

    7.1 Impedance 207.2 Capacity 20

    7.3 Balanced Signals (Microphone Cables) 217.4 The Pseudo-Balanced Trick 217.5 Serial | Parallel Effects Loops 227.6 Latency 22

    8. My Dream Guitar Rig 23

    8.1 The Order of the Effects 238.2 Typical Configuration of the "Dream Guitar Rig" 248.3 All You Need to Consider Building a Guitar Rack 26

    9. Trouble Shooting 29

    9.1 Help! It's Buzzing - What to Do 29

    9.2 Important Warnings 299.3 Step by Step Instructions for Trouble Shooting 30

    10. A Few Words About Prostage and the Author of this Guitar Rig Building Guide 32

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    Page 3

    1. Introduction

    Dear guitarist, guitar technician, Prostage customer

    Big refrigerator sized racks were absolutely in style in the 80's. Nowadays, pedalboards are most popular. But a

    rack still offers many advantages over a pedalboard:

    Greater reliability: the devices are protected from flying beer cans and water bottles. Furthermore, no one canstumble over the connectors or devices.

    Better sound quality: You have less sound losses due to shorter cable runs.

    Stompboxes can be installed in the rack. If youre using the Prostage XDS loop system or a self-built drawer, you

    have convenient access to the effects in the open drawer during the show. You don't need to kneel in front of

    your audience to adjust something. Also, WahWah and volume pedals can be controlled remotely. You can find

    more information about this on the last page.

    Faster set-up before the gig, because the rack-system is wired ready for use and - apart from the speaker cables -

    you only have to run a single MIDI cable to the front of the stage.

    Professional bands that tour a lot therefore continue to rely on rack systems. The Ultimate Guitar Rig Building

    Guide will help you build your system free from noise. Building a guitar rig free of hum and properly wired is noteasy. Hum can have many different causes. Therefore, it is important to know the causes and solutions.

    Many statements are applicable, of course, also on guitar rigs that do not use a rack. The information is kept largely

    unbiased of products and will explain the system structure in general.

    This guide is divided into two parts: In the "theoretical part" (chapters 2-7) youll learn how hum and other noise

    occur and what is their cause. This knowledge is important in order to understand and implement the approaches

    described in the "practical part" (chapter 8 & 9). Part of the theory is a bit technical due to the nature of the

    subject. It is not imperative that you understand the technical details 100 %. But you have to know and understand

    the consequences that arise from the facts.

    We are sure that this extensive guide will save you some headaches in your rig building adventure. If you,nevertheless, cannot solve your problem, please write us an email to [email protected]. We will be glad to help

    you.

    mailto:info%40prostage.eumailto:info%40prostage.eu
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    Send Return

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    --- Theoretical Part ---

    2. Noise

    Where there is electricity, there is also noise. This is a physical fact and cannot be wiped out even with the best

    guide. If there is no noise, there is no power too. Our aim is to keep this noise as low as possible, ideally below the

    hearing threshold. There are three key factors:

    Arrangement, placement of each device

    Correct wiring of the guitar system

    Quality of the equipment used, respectively the components used

    As your guitar signal passes from the pickup all the way to the speakers, there are many places where it can capture

    hum and noise. The closer this happens to the guitar in the overall signal path, the worse it will be, because the

    noise will be further amplified by each following device. Thus, the effect units and cables in front of the guitar amp

    play a more important role than those in the send / return. The following diagram illustrates this:

    Gain

    Guita

    rsign

    al

    PreampLoudness

    Volume

    Poweramp

    Hum/No

    isebe

    foreA

    mp

    Hum

    /Nois

    efrom

    Effec

    tsLoo

    p

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    Gain

    Output Volume

    Page 5

    Particular attention in this context is given to distortion pedals. The distortion which we all love is produced by a

    component (e.g. the tube) when it is overdriven. Therefore it is driven into saturation.

    The component should actually amplify louder than it can effectively do. Therefore, the signal will now not get any

    louder, but the peaks are cut off. The higher the gain, the stronger the component is overdriven, the stronger the

    signal peaks are clipped and the greater is the distortion. The distortion therefore comes along with a compression

    effect.

    Quiet signal components, for example our noise, are further amplified because they do not reach the limit of thecomponent. Therefore, with increasing gain the noise is coming closer to the actual guitar signal. In the extreme

    case, both signals are even identically loud!

    Guita

    rsign

    al

    Saturation (Distortion)

    Hum

    /Nois

    e

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    3. Hum Caused by Ground Loops

    Ground loops are certainly the most common reasons responsible for the hum. To understand and to get rid of

    ground loops, it is important to distinguish between "earth", "chassis" and "cable shield". But in a way, "earth",

    "chassis" and "cable shield" are the same, because they are somehow connected. And the term "Somehow" is

    exactly the problem. To avoid ground loops, we need to know where "earth", "chassis" and "cable shield" are

    connected. When wiring a guitar rig we must be aware where we want them to merge.This is due to the "potential" or the "potential compensation". The explanation comes at the end of this chapter.

    First we will take a look on how ground loops are created at all.

    3.1 Earth | Chassis | Cable Shield

    Earth:(also called "ground"): The earth is, as the name suggests, the connection to the earth. This is the zero

    potential. In power cables, the connection to earth is called "grounding conductor".

    Chassis:If the chassis (housing) of a device is made of metal and the device is operated with mains voltage (120 /

    240V), the housing must be grounded (connected to earth inside the device) for safety reasons.

    Cable shield: The shield is used to keep electromagnetic fields from the audio signal. Within guitar cables, this is

    the outer, mostly braided conductor. In order that the cable shield can fulfill its function, it must be connected on

    one (!) end to earth.

    In guitar cables, the shield is also used for the negative pole (unbalanced signal). Therefore, the shield must always

    be connected at both ends. With microphone cables (balanced signal), the shield can be connected on one side

    only under certain circumstances. For more details, please refer to chapter 7.3

    Conclusion: Earth, Chassis and Cable Shield are always connected somewhere. To prevent hum by

    ground loops, it is important to know where they are connected.

    3.2 Star-shaped Wiring

    Basically, the connection of "Earth", "Chassis" and "Cable Shield" must be structured like a star:

    Earth

    Cable shield

    Instrument

    Chassis

    Chassis

    Chassis

    Central / common ground point(Zero-potential )

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    3.3 Triangle | Ring Wiring

    If the star-shaped structure is not strictly observed and instead wiring is made in a triangle, the classic Ground Loop

    occurs. The problem is that the instrument is connected via two different paths to ground and the current can

    therefore flow through two different ways, respectively, the current can flow in a circle.

    Earth

    Cable shieldCable shield

    Instrument

    Chassis Chassis

    Central / common ground point

    (Zero-potential )

    3.4 Two Amplifiers

    A typical example of such a triangle wiring is the use of two amplifiers. The following diagram shows a typicalground loop:

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    Iso

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    Explanation of the Diagram on the Previous Page:

    In a guitar amp, the earth from the power cable and the shield of the guitar cable are connected to the chassis.

    In our example, the shield of the guitar cable therefore is connected to ground once thru the amplifier on the left

    and once thru the amplifier on the right. It does not matter whether the guitar signal is split by a Y-cable, or if the

    second amplifier is connected to the first amplifier.

    Due to the cable resistances, the potential for the two amplifiers are quite minimally different (we are talking about

    milivolts). Therefore, along the line marked in red, a small current begins to flow in the circle. This is the GroundLoop! The detailed explanation can be found in chapter 3.10.

    The Ground Loop is audible as hum because this current flows with the mains frequency (50Hz in Europe, 60Hz

    in America). In addition, the harmonics (100 Hz, 150 Hz, 200 Hz, .... respectively 120 Hz, 180 Hz, 240 Hz, .... ) are

    also generated.

    3.5 Isolating Transformers to Prevent Ground Loops

    In order to prevent the ground loop, the connection of the cable shield from one to the other amplifier must be

    separated with an isolating transformer. Inside an isolating transformer, there is no electric connection between

    input and output. The signal is transmitted magnetically instead. Transformers specifically made for guitars mustbe used (e.g. Lehle P-Split) so that the guitar signal is transmitted unaltered. Isolating transformers for studio

    applications are not suited for guitars (see chapter 7.1impedance).

    IMPORTANT:

    Never cut the ground from the amplifiers power cord! Indeed this can solve the ground loop problem, but it is

    dangerous to life!

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    3.6 Switched Grounds

    If only one or the other amplifier shall be used at the same time, you can switch between the two amplifiers using

    an A/B switcher. There are A/B switchers that do not only switch the guitar signal, but also the shield / ground.

    Using such a switch, the triangle (ring) connection is suspended. This means, the ground of the guitar is connected

    either to amplifier A or B, but never to both. This also allows to suppress the hum.

    The disadvantage of this solution is that when switching the ground, the potential of the guitar is moved, which

    usually leads to unsightly switching noise (clicking). "Moving across" the potential is definitely not a neat solutionand I would recommend to not do it whenever possible. In very complex guitar rigs, it may possibly be unavoidable

    in certain cases to switch the ground too. But I would never use a looper which switches the ground by default.

    More information about potential can be found in chapter 3.10.

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    3.7 Ground Loops over Effect Loops

    A typical case for ground loops is also when inserting effects in the send / return of the amplifier and the whole is

    connected to the pedalboard with long cables.

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    PSU

    **

    Page 11

    The very strong hum you catch, when you use some effects before the amp and some in the effects loop (Send/

    Return) of the amplifier and they are fed with the same, galvanically not isolated power supply or if the ground of

    the pedals otherwise are connected together, e.g. by jack plugs that touch each other. Effects before the amplifier

    and those in the effects loop must not have a common ground connection and must always be fed separately!

    * Note:

    The use of power distribution cables (special cables for simultaneous powering of several stompboxes) alreadycreates a ground loop between the individual effect pedals. Since the cable run and therefore the circuit in which

    the current can flow are very short, there is no significant potential difference and no audible hum will occur.

    Therefore, this ground loops can usually be ignored. In certain cases, however, this very short loop may lead to

    problems.

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    3.8 19-inch Racks: Ground Connection via the Rack Rail

    Within 19-inch racks you have to keep in mind that the chassis of the individual devices are connected together via

    the rail and therefore a ground connection is formed. Even if a 19-inch device does not have a grounding plug (or

    if it is pinched off), the chassis is still connected to the other devices via the rail. If the audio ground is connected

    to the chassis inside the unit, we have again a hidden potentially source of the hum.

    Since the housings usually are painted, it may even happen that the device did not have real contact with the rack

    rail yesterday. But today, after transport (vibration), it has. Yesterday, everything was fine but today there's hum.Therefore, proper building of a humfree guitar rig already begins by bolting in the units!

    To fit a device isolated from the rack rail and therefore isolated from the other devices in the rack, one can use so-

    called "Humfrees". These are special, isolated rack screws with plastic washers. Important when using Humfrees

    is, that the housing is additionally isolated from the devices above and below using plastic spacers or stable plastic

    film. Especially protruding screws are otherwise again a source of error. Therefore, the unit must be mounted so

    that its chassis does not make contact anywhere to any another device or the rack rail. The isolated mounting

    serves its purpose only if the equipment is not grounded via the power cord.

    3.9 Wireless Receiver

    Another ground loop trap are wireless receivers that have a metal housing or a 3-pin power plug. Unfortunately,

    within these devices, the audio ground (shield of the guitar cable) is usually connected to the chassis ex-works. The

    guitar cable is therefore connected to ground in front of the amplifier, and as a result there again is the dreaded

    triangle connection.

    There are several solutions for this problem:

    Professional devices have a ground lift switch, which allows you to interrupt the connection between the audio

    ground and the chassis/earth. In wireless receivers, that is rather not the case. But often, a cable can just be

    pinched off inside the unit, and the problem is solved. This should always be done by a trained technician. But

    sometimes, the devices are designed so that a separation of audio ground and chassis inside the unit is not very

    feasible.

    If the receiver has a balanced output (XLR), you can apply the pseudo-symmetry trick (see chapter 7.4).

    If the receiver does not offer the first two variants, you have to use an isolating transformer.

    As a final alternative, you can mount the device with "Humfrees". See chapter 3.8.

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    Page 13

    Earth

    Earth

    Cable 1

    Cable 1

    Cable 2

    Cable 2

    Central / common groundpoint (Zero-Potential )

    Central / common groundpoint (Zero-Potential )

    Potential shift

    Once the two ends of the cables are connected together again, a potential balancing occurs. Therefore, a small

    current starts to flow, which is driven by the mains frequency. Here it is, the hum! What we hear is the basicfrequency of the power grid (50Hz in Europe, 60 Hz in America) and their harmonics with progressively reduced

    volume.

    Important:

    The longer the power cords and guitar cables are, the greater is the potential difference and the greater is the hum.

    On very short cables, typically in a rack's internal wiring, this potential shift can be usually ignored. A guitar rack

    with very short cables can be seen as a large ground node with a single potential. But for all the cables leading out

    from the rack, the potential shift must be taken into account.

    3.11 Galvanic Isolation

    Galvanic separation means that an electric signal is transmitted without electric contacts. This is done with

    transformers. The signal is transmitted magnetically. The ground line at the entrance of the transformer mayhave a different potential than the ground line at the output of the transformer. The two ground lines are not

    directly connected. Using a transformer, a floating (galvanically isolated) transmission is possible. In our guitar rack,

    galvanic isolation is used in two locations:

    As a transmission transformer for audio signals to suppress ground loops (e.g. Lehle P- Split).

    Within power supplies with multiple outlets for effect pedals. With these devices, you should always make sure

    that the outputs are isolated. An isolated power supply or a power supply with isolated outputs means that the

    outputs are galvanically isolated. Each output has a separate winding on the transformer and its own voltage

    regulation and filtering. In addition, these power supplies should have a toroidal transformer (explanation in

    chapter 4.2). These devices are, of course, more expensive than a simple power supply with multiple parallel

    output jacks.

    With such a power supply, it is also possible to simultaneously supply effect units in front of the amp and thosein the effect loop of the amplifier.

    3.10 Potential | Potential Compensation

    Why, however, is it humming when we wire devices in the triangle? Each cable has an electrical resistance, even

    if it's the best quality. This means that the voltage at the beginning of the cable does not completely arrive at the

    other end. This shifts the potential, or in other words: the potential at the end of the cable is no longer the same

    as at the beginning. The potential shifts slightly from the zero potential and differently in each and every cable. In

    two parallel routed cables, the potential shifts not just in parallel. The potential at the end of the cables are shifted

    against each other:

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    4. Hum by Interferences

    Hum can also be introduced by Interferences. Lighting systems, power transformers, computer monitors, fluorescent

    lights, electromagnetic interference from the building wiring, nearby high-voltage lines and many other sources

    emit electromagnetic fields, which we can capture with our guitar rig in different ways.

    4.1 Interferences via the Pickups | Environment

    Pickups, especially single-coils, are very sensitive and act as antennas for noise. This is especially a concern because

    the signal of the pickup will be 100 times, or even 1000 times, amplified afterwards. The electromagnetic

    interference fields are different at each position in the room. In the studio, you can search the position where the

    pickups captures the least amount of hum. Often it also helps if you just turn to one side a little bit.

    When moving around the room, you can find out relatively easy where the interference may have come from and

    then maybe place the interference source differently or simply switch it off when not in use. Particularly obvious

    sources of interference such as fluorescent lights should just be turned off (and replaced with a candle ;).

    Your own guitar amplifier is also a source that emits interference. This is explained in the next section.

    4.2 Interferences from Nearby Power Supplies | Transformers

    Transformers, especially the large power transformers of guitar amps or tube amplifiers, emit strong magnetic

    fields. The electromagnetic interference field decreases with increasing distance from the transformer. Toroidal

    transformers have, based on their design, a much, much lower electromagnetic interference field than normal

    (square) transformers. Especially with power supplies for multiple stompboxes, it is highly recommended that you

    choose one with a toroidal transformer.

    Effect devices and other devices that are located near a transformer can capture the interference. Therefore we

    hear the mains frequency as hum. If you stand too close to the amp with your guitar, the pickups catch this

    magnetic interference field. Particularly sensitive, for example, is also the Prostage Remote WahWah, since it uses

    a Fasel coil for the effect. The Fasel coil acts as an antenna for this interference.

    Therefore, to minimize hum captured by transformers, the distance between the transformer and the device

    that captures the hum, must be increased. Furthermore, the interference of (square) power transformers have a

    direction. Therefore, it can often help, to just rotate the device that captures the hum by 90 in place.

    4.3 Interference by Parallel Cable Runs

    Guitar cables should never run in parallel to power cables. Otherwise, the mains frequency from the power cable

    crosstalks to the guitar cable. An "All-In-One" multi-core cable with guitar and power cords from the rack to the

    front edge of the stage is generally a very bad idea.

    4.4 Interference over the Local Power Grid

    Noise may come into the guitar rig via the local power grid. A typical problem are dimmers of lighting systems.

    Dimmers chop up the power so that only a portion of the voltage goes to the lamp and therefore it lightens

    less. This chopping of the voltage has an impact on the local power grid and can be noticeable in your amp with

    unpleasant noise.

    Nowadays also signals, for example, internet connections, are modulated over the mains voltage. In general, you

    will never get a "clean" power from the power grid.

    This problem can be alleviated by a line filter. There are power strips with a built-in mains filter available for 50 to

    60 USD. Simple 1U rack power conditioners also work with such filters. A good quality power strip with a line filterdoes the same job as an expensive 1U 19-inch power conditioner will do.

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    In addition to power conditioners with a simple line filter, there are also AC voltage regulators. These devices do

    more than a simple line filter. They use a large transformer which not only regulates voltage fluctuations, but also

    helps to filter high-frequency noises from the power grid.

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    5. Hum Caused by Faulty Equipment

    It may also be that a device hums without any external influences. On the one hand, this may be because the

    grounding has not been correctly designed inside the device itself or the shield is missing at all. On the other hand,

    it my be due to a faulty or poorly designed power supply or a defective component.

    5.1 Missing Shield | Missing Ground

    If the grounding is not installed correctly in a device or if the grounding is missing at all, the unit hums. For guitars,

    this happens a lot of times. Note that very few guitars are adequately shielded and properly grounded ex-works.

    Even expensive ones may lack this. If the noise actually gets louder when you touch the strings, it is likely that

    the strings are not well grounded or that the hot and ground wires to the jack are reversed. Make sure that the

    electronics are completely shielded inside the guitar, the strings are properly grounded and the jack connector is

    properly connected. The strings are grounded in general by the bridge which has to be connected to the ground.

    5.2 Faulty Power Supply

    Devices that are operated with mains voltage, therefore alternating current (AC), must transform the voltage firstand then rectify it. After rectification, the voltage needs to be regulated and filtered in order to get the clean DC

    voltage (DC) which the device requires. Now, if this filtering is not made properly (e.g. by the use of undersized or

    inappropriate, cheap components), part of the mains frequency (50 Hz in Europe / 60Hz in America) remains in

    place and the unit is buzzing. Particularly audio devices are very sensitive to dirty rectified power supplies.

    This filtering, or voltage smoothing, is realized with the so-called electrolytic capacitors. These components dry

    out over the years, therefore they are losing their effect. Therefore, especially old tube amplifiers tend to hum. The

    only solution is to exchange the old electrolytic capacitors, even if the amp therefore no longer is original. But it

    will sound better in any case. Have the unit serviced by a qualified technician.

    5.3 Faulty Tubes

    Tubes wear out and must be replaced from time to time. Also a new tube can sometimes have a manufacturing

    defect and therefore is not working correctly. Tubes have a heating. The filaments are fed usually with alternating

    current, similar to an old, traditional light bulb. In a defective tube, the heating current can crosstalk to the audio

    signal. Power tubes need to be calibrated after the exchange. Have the amp serviced by a qualified technician.

    Some tube amplifiers have a hum compensation circuit, which is adjustable via a potentiometer. If this is the case,

    the hum can lead from a incorrectly adjusted or defective potentiometer.

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    6. Other Noise Types

    6.1 Hiss

    Hiss noise results from the fact that in every electronic component some electrons whirl around uncontrolled. How

    strong the noise in a device is, depends on two factors:

    The quality of the components used

    The electrical design of the device, therefore how the components affect each othe

    If we connect two devices in our signal chain, the components of the two devices affect each other too.

    Consequently, the interaction of multiple devices has an effect on the hiss. Also, impedance plays a part (see

    chapter 7.1). When devices are connected together with unsuitable impedance, this increases the hiss noise.

    You can minimize the hiss by using only high-quality equipment. Whenever possible, avoid using devices which

    generate unacceptably loud hissing. Pay particular attention to devices which are placed in the signal chain before

    the distortion pedals. Under certain circumstances, a change in the effect order can reduce lot of the hiss. At least,

    put very noisy devices in the signal chain after the high-gain devices, such as distortion pedals.

    6.2 Whistling Sound | Switching Mode Power Supplies

    Whistling sounds usually come from a so-called switch-mode power supply. These are power supplies that do not

    have a power transformer, but crop the current. This occurs at a high frequency, and this can result in an audible

    whistling. Switch-mode power supplies are suitable for audio applications to only a limited extent and only if

    they are high-quality power supplies with very good filtration. Stay away from cheap power supplies from the

    supermarket!

    Switch-mode power supplies can be recognized by their very lightweight and small construction. A typical

    example of such power supplies are cell phone chargers. In certain cases, however, these power supplies can also

    solve problems. Since they do not have a classical mains transformer, they also do not send out mains frequency

    interferences as described in chapter 4.2. If a normal power supply (wall wart) causes a hum, you can replace the

    power supply by a switch-mode power supply and the hum is gone.

    6.3 Scratching

    Scratching when adjusting controls

    A scratching noise indicates that the pots are worn or dirty. In particular, high humidity is detrimental to the

    pots: The contact surfaces oxidize. A slight scratching can be usually eliminated with contact cleaner spray. Heavy

    scratching pots need to be replaced.

    In guitars and stompboxes you can possibly do it yourself. Amplifiers or other mains opperated devices must be

    serviced by a qualified technician.

    Scratching when moving an expression pedal

    You have connected your MIDI-capable guitar amplifier, a multi-effect device and a MIDI foot controller with

    expression pedal in a MIDI chain. Once you move the expression pedal with which you want to control an effect,

    you hear a scratching noise? This is because the MIDI commands crosstalks into the guitar signal. The expression

    pedal continuously transmits data as long as it is moved, that is, several hundred instructions per second. That's

    where the scratching comes from. Program Changes are not audible since only a single, very short command will

    be sent.

    Most likely, the MIDI signal crosstalks in the guitar amplifier. You can solve this problem by inserting a MIDI adapter

    in between, which filters out the commands from the expression pedal in front of the guitar amplifier (the amplifierrequires only the program change commands). For example, the Prostage XTMpro adapter offers two independent

    MIDI Outs. You connect MIDI Out A to the guitar amplifier and adjust the MIDI True settings so that only Program

    Changes are sent to the amplifier. You connect the effect unit to MIDI Out B and send out all MIDI commands on

    this output.

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    6.4 Transparency | Volume Loss

    If you notice that your signal suddenly loses its transparency or volume when switching between different effects,

    it is most likely due to the different input impedance of the effects device you have switched to. More about

    "impedance" can be found in chapter 7.1.

    Transparency losses are also related to the capacity of the guitar cable. See chapter 7.2.

    6.5 Clicking | Popping Noise

    Popping noises can arise from relays when switching amp channels or effect loops. Popping noises can also be

    caused by a discharging capacitor.

    Soft popping when switching pickups

    This usually happens only when there is a preamp in the guitar and is caused by a voltage building up in a capacitor

    somewhere in the circuit. A resistor from each terminal of the pickup selector-switch to ground can help. Another

    technique is to place very large resistors (approx. 470kOhm) between the switch terminals. But note that both

    options will alter your tone.

    Soft popping when touching strings or other metal parts on the guitar

    Through the contact of your body with the guitar, a capacitor is discharged. If there is an isolation capacitor

    between the signal ground and the bridge, you may need to place a 220k Ohm resistor across it.

    Loud popping when switching Loops

    A very soft popping noise when switching loops is normal. But if it pops very loudly, it is highly likely that there is

    a potential problem. This is also known as "DC-Offset". Because the device which is inserted or disconnected is

    on a different potential, the potential is compensated when switching, and this produces the pop. To avoid this

    problem, make sure that all units have a reference to the common ground point, even if the loop is turned off.

    Within loopers that switch the ground too, a separate ground connection must be established in certain cases. DC

    offset problems can also be solved with a capacitor in the signal path. There are ready-to-use adapters for this,such as the Lehle DC Filter.

    6.6 Clinking | Ringing, Combined with Some Kind of Feedback (Microphony)

    A ringing sound going into feedback squeal too easily, can be caused either by the guitar or amp. Try the amp with

    different guitars to determine where the problem is coming from.

    Microphonic guitars

    Ringing may be caused by microphonic pickups, poorly mounted pickups or the tremolo springs. Make sure that the

    springs to adjust the pickup height and the tremolo springs can not resonate. The springs can e.g. be attenuatedby a plastic hose slipped over the springs.

    Microphonic amplifiers

    Ringing in the amplifier is caused most probably by a microphonic tube. Usually, it is a preamp tube, but it can

    happen with power amp tubes too. This is fairly common with combo amps that have the tubes hanging behind

    the speaker.

    Tubes are electro-mechanical components, which absorb the mechanical vibrations and therefore give it to the

    audio signal. These vibrations are absorbed primarily by the vibrations of the housing. A microphonic tube can

    relatively easily be identified by tapping onto the chassis of the amplifier or softly knocking directly onto a tube. If

    a tube begins to be microphonic, this is usually a sign that it would soon fail completely.

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    6.7 Crackling | Sizzle

    Crackling only when playing.

    Crackling while playing is due to static build-up on the pick guard. The charges are caused by your movement or

    friction between your body and the guitar. To counteract this, wear short sleeves or a shirt of a different material.

    Alternatively, cover the entire back of the pick guard with aluminum foil, which must be connected to the ground

    of the guitar.

    The guitar amplifier crackles even without a connected guitar

    If the amp crackles and sizzles on its own, it has a serious problem. Probably a tube will be failing soon, or the

    power supply breaks through. Turn off the power immediately and have the amp serviced by a qualified technician.

    Otherwise, more serious and expensive damage may result.

    6.8 Rising and Falling Sound

    This noise sounds a bit like waves rolling onto a beach and also arises even if no guitar is connected to the amplifier.

    In general, only tube amplifiers are affected. This noise heralds a serious problem that is likely to get worse very

    quickly. Usually, it means that the tubes and/or the associated resistors are failing. Stop using the amp immediatelyand have it serviced by a qualified technician.

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    Page 20

    7. Important to Know

    For successful wiring a guitar rack, a few other important aspects need to be considered:

    7.1 Impedance

    The impedance describes the electrical resistance of an audio connection. The resistance at the input is calledinput impedance, the resistance at the output is called output impedance.

    If you connect your guitar to a stompbox, the guitar pickup has to drive the input of the stompbox. The lower the

    input impedance, the more the pickup must work, respectively, the stronger the pickup is loaded. Therefore, the

    guitar signal is attenuated and loses volume and transparency. For a high-quality signal transmission, the input

    impedance of the "signal consumer" (e.g. the stompbox) must be much higher compared to the output impedance

    of the signal supplier (e.g. the guitar).

    Since guitar pickups have a relatively high output impedance and deliver only a low signal, the input impedance

    on guitar amps must be very high. Usually it is 1 mega-ohm. In HiFi or studio equipment, the input impedance is

    much lower (the advantage of a lower impedance is that the device is less noisy). Hence, if a guitar is connected

    to a studio device, the signal is attenuated by the input impedance, which is too low. The guitar sound losestransparency.

    Unfortunately, there is no mandatory standard for the impedance within the bunch of stompboxes. Some devices

    are optimized for guitars (with a very high input impedance). Other effect units comply to the studio standards.

    And there are also units somewhere in between.

    But in general, ground effects are more suitable for use in front of the amplifier (high impedance), while 19-inch

    devices are usually inserted in the effects loop of the amplifier (low impedance).

    If several stompboxes are connected to a looper, the guitar might be routed once to a device with a high input

    impedance, and in another loop configuration the signal from the guitar encounters a low input impedance.

    Therefore, the signal loses volume and transparency as mentioned above.

    To solve this problem, the Prostage Booster | Impedance Matcher can be set between the guitar and the devices.

    The booster has a very high input impedance, optimized for guitars, and a very low output impedance. Therefore,

    stompboxes and studio effects devices can be connected to the booster.

    The impedance matching can be carried out in two places:

    As the first device right after the guitar. The booster is, therefore, placed firmly in the signal path and works as a

    line driver | buffer amp. The impedance matching is for the subsequent effect device. When using a looper, this

    means that the impedance matching is for the first stompbox activated by a loop (chapter 3.8).

    Directly in series before a certain stompbox with a too low input impedance. Like this, the booster is only in the

    signal path when the effect is switched on

    7.2 Capacity

    Each electric component, particularly the guitar cable, has a capacity. The longer the cable is, the higher the

    capacity. The capacity is a resistance which depends on the frequency of the signal. The higher the frequency, the

    lower the resistance. In cables, the capacity is between the signal conductor and the shield, or ground respectively.

    Thus, the higher the frequency, the smaller the resistance between the signal conductor and the ground. As a

    consequence, the signal loses trebles.

    Therefore, it is extremely important that you use high-quality cables and that the cable runs are as short as possible.

    If you are looking for the perfect sound, you will not use a pedal board front edge of the stage, but connect your

    guitar directly to the amp using a cable as short as possible. Effect units are connected directly next to the amp or

    in the guitar rack with the shortest possible cables.

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    7.5 Serial | Parallel Effects Loops

    In serial effects loops, the entire guitar signal is sent through the effect unit(s). The proportion between the original

    signal and the effect signal is mixed in the effect unit. A poor-quality effects unit affects the entire sound, including

    the unprocessed part (dry) .

    In parallel effects loops, the signal is split. On the one hand, the signal is sent to the effect unit via the effects send

    jack. But the signal is sent internally also directly to the power amplifier. By the Dry / Wet knob you can now adjust

    how much effects signal (wet) is added to the original signal (dry). The advantage of parallel effects loops is thatthe original signal reaches the final stage completely unaffected. If you want to insert several effects devices, it is

    also advisable to use a line mixer. With a simple line mixer such as the Lehle Parallel, an amp that only has a serial

    effects loop, can be supplemented with a parallel effects loop.

    It is very important for parallel effects loops that the effects unit sends back only the effect signal and no(!) original

    signal! Therefore, the effect mix must be programmed in the effects unit to 100% wet. Some effects units also

    offer a so-called "Kill Dry" feature that needs to be turned on when used in a parallel loop. If you don't do this,

    you have the original signal twice (once over the effects unit and once directly in the amp), which leads to unsightly

    comb filter artifacts when using digital effects devices due to their latency (see next section).

    7.6 Latency

    Digital effect units (and also digital mixers) first convert the guitar signal from analog to digita. Then they have

    to think and calculate a little bit, and at the end, the signal is again converted from digital to analog. This takes a

    few milliseconds and the signal is delayed. This delay is known as latency. The latency is so short that you will not

    notice it while playing.

    However, if you mix a digitally processed signal with an unprocessed (analog) signal, a comb filter effect is formed,

    because these two, actually identical signals are slightly offset in time. Thereby, certain frequencies in the signal are

    boosted, others are canceled. The signal sounds therefore very unnatural, like a bad chorus.

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    Send Return

    Fuzz

    Buffer

    Line Driver

    Wah Wah

    Compressor

    Pitch

    Shift

    Delay

    Distortion

    Modulation

    Reverb

    Overdrive

    Page 23

    --- PRACTICAL PART ---

    8. My Dream Guitar Rig

    8.1 The Order of the Effects

    The order the effects are connected is a matter of taste, but also has an influence on the noise and losses. Thechart below should be understood as a starting point for the correct order. But it does not have to be done exactly

    the same way. In front of distortion pedals, only low-noise effects units should be used in any case. Therefore, it

    may also be useful to place the WahWah after the distortion. Effect loops in guitar amplifiers have very different

    level conditions and usually also other impedances as the input of the amplifier. Therefore you have to consider

    the following:

    Stompboxes are basically designed for use in front of the amp and are only suitable in certain cases for use in the

    effects loop of the amplifier. Just try whether it sounds good or not.

    19-inches effect units without dedicated guitar input are not suitable for use in front of the amplifier and should

    always be used in the send / return.

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    to the Guitar Rig

    foot controller X10

    127

    foot controller X07

    Page 24

    A buffer or buffered bypass pedal (which buffers your signal even when the effect is turned off) at a strategic

    point in your signal chain can help maintain your core tone when running through lots of pedals and cables.

    A buffer at the beginning of your effects chain helps to compensate losses due to the long guitar cable and

    converts your guitar signal to a lower impedance which will enhance driving the following effects pedals.

    Fuzz pedals want to be connected directly to the pickup of the guitar. Therefore, a fuzz has to be the first device

    in the signal chain, even before any Buffer | Line Driver.

    Modulation effects can also be before the amp, depending on your taste. But Delay and Reverb should alwayscome after the distortion. Therefore, if you are using the distortion of your amp, delay and reverb belong

    basically into the effects loop.

    A volume pedal can be used in very different places, depending on its purpose.

    - At the very beginning of the chain, the pedal causes the same as the volume pot of your guitar.

    - In front of the return of the amp, it regulates the total volume in case of a serial loop, or the amount of effect

    in a parallel effects loop.

    8.2 Typical Configuration of the "Dream Guitar Rig"

    The following design shows a typical example of the ultimate guitar rig. It is laid out as a Dry / Wet system. That

    is, on the left cabinet is the dry guitar signal which only contains the basic effects (WahWah and distortion). Allother effects, especially reverb and delay, are only on the right (wet) cabinet. This is a very established principle.

    Further, the stompboxes are incorporated directly into the rack and are switched through a looper. The WahWah

    and the volume pedal / remote volume (VCA) are remotely controlled with expression pedals. Herein the cable run

    of the guitar signal is reduced to a minimum. The volume pedal (VCA) is used to control the overall level of the

    Wet cabinet in this example.

    The delay time of the multi-effect device can be taped with a switch on the foot controller, and the amount of

    effect is controlled with an expression pedal. Of course, the returns of the multi-effects could also be connected in

    stereo and distributed to two speakers. That would then be a wet-dry-wet system where the "Dry"-cabinet usually

    is placed in the middle.

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    outin

    midi

    in out/thru

    midi

    out Ain out B send 1 insend 2send 3send 4return 4out return 3 return 2 return 1

    18VDC250mA

    ground 12VDC500mA

    9VDC500mA

    9VDC500mA

    SAG

    outin

    midi

    in out/thru

    Buffer | Line Driver

    Guitar Input

    midi

    out A

    Foot Controller

    Prostage XDS Loop System

    Muliti FX unit 1

    Muliti FX unit 2

    Remote Volume (VCA)

    InputLine Mixer

    MIDI In Thru

    MIDI In ThruInput Output

    Input Output

    Splitter withisolated outputs

    Send Return

    Guitar Amplifier Power Amp

    Input

    Dry cabinet Wet cabinet

    Remote WahWah

    Page 25

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    Page 26

    8.3 All You Need to Consider Building a Guitar Rack

    If you consistently implement the information in the theory section, chances are very high that your guitar rig is not

    buzzing. Here is a summary with additional hints on how to use all the theory in the practice:

    1. Don't start building your rig three days before you go on tour. A guitar rig is something that takes a lot of planning

    up front and a lot of debugging before the rig is ready to go.

    2. The arrangement of the units in the rack can play a crucial role. E.g. don't place sensitive analog effects units

    directly above the power amp. Above the amp, there should anyways be 1U be left blank to get more distance

    to the power transformer (to reduce the risk of interferences). For the other reason that the amplifier gets

    enough air and there is no heat build-up inside the rack.

    3. If you're using a guitar head that you want to put directly on top of the rack, then use as the top unit in the rack

    something that is not sensitive to interferences, e.g. the rack drawer with your cables or the power distribution.

    4. Before getting started with the wiring, you need to know where the central grounding point is, thus from

    where all the ground connections start from. This is usually the guitar amp, but it can also be the 19-inch rack

    (rack rail).

    5. Before installing into the rack, check every 19-inch device by using an ohm meter, whether the audio ground

    is connected to the housing or the ground pin of the power plug respectively. The device which acts as the

    central grounding point (zero potential) for your rig must have the audio-ground connected to earth. Typically,this is the guitar amplifier or the preamp respectively.

    All other (peripheral) devices, e.g. effect units, should not have connected the audio ground to the chassis.

    Otherwise wiring this unit creates a ground loop. Some devices have a ground lift switch, with which you can

    determine whether the audio ground is connected to the chassis or not. If this is not the case, the connection

    can possibly be separated inside the device with few steps. Refer to a qualified technician.

    If a device does not let you separate the connection between audio ground and the chassis/earth, give these

    devices special attention when wiring your rig. Due to the short cable runs in the rack, usually no audible hum

    arises. But if the unit causes hum, you can find solutions to this problem in chapter 3.5, chapter 3.8and

    chapter 7.4. A further solutions is described below in point no. 12.

    6. If you want to install stompbox effects in a 19" drawer, use a drawer with a built-in looper. Otherwise, when

    using a separate, external looper, the cable runs are too long.

    7. Basically, all power cords, switching and MIDI cables should be routed on one side of the rack, the audio

    cables on the opposite side of the rack. Run the power cords on the same side on which the majority of the

    equipment has the power connections. Do not install power cords and audio cables in parallel to each other.

    Where unavoidable, power and audio cables may cross in an angle of 90.

    8. All devices of your guitar rig must be connected to the same power source. Use a power distribution (power strip

    or 19-inch unit) with integrated line filter. (If units are fed by different power sources, signal routing must be

    balanced.)

    9. The first unit after the guitar, which is supplied with main voltage, must always be grounded to earth!! Usually,

    this is the guitar amp, but it can also be an effects unit in front of the amp.

    10. The structure of the ground connections (earth / chassis / cable shield) must always be star-shaped.

    11. If a triangle cabling is unavoidable, this means a closed ring connection is build, then this ring has to be isolated

    with a transformer (e.g. Lehle P-Split). Alternatively, the signal may also be transmitted balanced, but without(!)

    ground connection. This means, Pin 1 of the XLR connection must be connected on one end only (This is ideally

    reached through the proper position of a ground lift switch on the device)

    12. If a device already has a reference to the common ground point, e.g. over the rack rail or power cord, a hum

    may be avoided by custom jack cables where the shield is connected on one side only (ground lifted).

    Further, when a device is connected in the effects loop or using a stereo device, a hum may possibly be avoided

    by using only one cable with ground connected at both ends (e.g. input left). All other connectors of the device

    are wired using cables with single-ended ground. Here, you have to try a little to find what works best.

    Plug the grounded (normal) end of the cable consistently to the Output / Send, and the lifted cable end intothe Input / Return. Warning: single-ended jack cables work only at very short cable runs. For long cable runs,

    they have the opposite effect. So be careful when using this cables, they may only be used very sparingly if

    really needed.

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    13. It is very important that you mark the lifted side of every cable, for example, by a colored heat shrink tubing or a

    different colored connector housing. Inside the rack it must be clearly visible at any times where grounds have

    been lifted.

    14. The protective conductor of individual devices, so the grounding pin of the power cord, must not be lifted for

    safety reasons. Thus, always build your system in a way that no grounds must be lifted at mains cables.

    Never disconnect the Earth off the guitar amp!! DANGER TO LIFE !!

    15. You should test your rig after each component (looper, effects unit, mixer, etc.) connected to the signal path.

    If you add something and you suddenly are losing signal or you hear some hum, you know almost certainly

    that the last thing you added is the culprit. It is possible that the device itself is defective, or responds to

    interferences. But much more likely is that you have just wired a ground loop that needs to be fixed.

    16. Well-known rig builders recommend unisonous Mogami cables and Neutrik or Switchcraft connectors. Soldered

    connectors are generally preferable to screwed or pressed connections. Test every cable before installation

    with an ohmmeter to make sure that the connections are good and there are no shorts. This applies to both,purchased and self-made cables.

    17. Shorten the power cords as well as the audio cables exactly to the length that they must have. Do not wind long

    cables to coils.

    18. Label the connectors on both ends of each cable. Once your rig is built, it will be difficult to trace a cable from

    one end to the other. If everything is labeled properly, it will be much easier to make changes later or to find

    an error.

    19. Attach the cables to the rack so they do not fly around and the plugs can not fall out during transportation.

    20. The ideal guitar rack does not send an audio signal to the front of the stage, but processes the signal completely

    in the rack. Due to the shorter cable runs, the sound gains in quality. Moreover, such a system is much more

    reliable.

    21. You can fit your stompboxes in the rack, for example, using the Prostage XDS loop system. For the WahWah,

    consider the Prostage Remote WahWah or the Dunlop Rack Cry Baby. Therefore, you can remotely control your

    entire guitar rig using a MIDI foot controller and some expression pedals.

    22. If the signal nevertheless has to be sent to the front edge of the stage, use a loop which is only active when

    the device on the front of the stage is actually used.

    23. Pay attention that pedal power supplies with multiple outputs have galvanically isolated outputs and that they use

    a toroidal transformer.

    24. Effects that are connected in parallel and mixed with the original signal using a Dry/Wet knob or via a line mixer

    must always be programmed so that they output only the effects signal. The unprocessed original signal must

    be muted on the effects unit output (kill dry).

    25. The effects have to be leveled properly. This applies particularly to the 19-inch effect devices. They usually have an

    input and output control.

    26. Final tip: Don't forget to always have a few spare cables with you.

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    Guitar Rig of Zach Petersen, Hot Licks Guitars Hawaii.

    Page 28

    This is how a professional wired guitar rig looks from the rear:

    http://www.hotlicksguitars.com/http://www.hotlicksguitars.com/
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    Page 29

    9. Trouble Shooting

    9.1 Help! It's Buzzing - What to Do

    The fastest and easiest way to eliminate a hum is - to switch off the power! But that is certainly not the solution

    you are looking for. For trouble shooting, you need the following tools:

    A jack plug with a 10k Ohm resistor soldered between tip and shield:

    An ohm meter: Once you have located the hum, you presumably need the ohm meter to test cables or to

    measure where the ground loop goes through. For example, you can check if the housing of the device is

    connected to the audio ground.

    How to test a cable:

    If your ohmmeter has a dial to set the range, set it to the lowest range (usually 200 ohms)

    Check the resistance from the tip of one end to the tip at the other end. It should read a couple of ohms or less,

    the closer to 0 ohms, the better.

    Check the resistance from the sleeve (ground) of one end to the other. Once again, it should be nearly 0 ohms.

    Set your meters range (if applicable) to the highest setting (usually 10M or 20M). Check the tip on one end to

    the ground on the same end. It should read as an open circuit (too high to measure). If the reading bounces

    around, the cable seems to have a to low impedance. This can be caused, among other things, by soldering the

    plugs too hot.

    Its very important when doing this test to not touch the metal parts of the test probes nor the cables themselves

    that will throw off your readings. Also, dont test on a conductive surface like a metal table!

    9.2 >>> IMPORTANT WARNINGS

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    9.3 Step by Step Instructions for Trouble Shooting

    To locate and fix a hum, a systematic approach is very important. First you have to find out which device or which

    connection is causing the problem. Perform the following steps in the given order until the hum is located. Once

    you have found the "bad" device, consult the theory part again. Note that under certain circumstances, only a poor

    connection (such as damaged cables or oxidized connectors) may be the cause of the problem.

    1. As a starting point, setup your guitar rig exactly the way you normally play it live and connect it completely. The

    rig must be connected to a properly grounded outlet. Otherwise, the problem is, at least partially, already withthe power grid connection. When the guitar rig is not properly grounded, no goal-oriented trouble shooting

    can be performed.

    2. Select the preset / the sound where the problem is most evident. If you use a noise gate, turn it off for trouble

    shooting. Please be aware that the noise gate can also be a part of a preset in a multi-effects.

    3. Do not use a wireless system for trouble shooting, but connect your guitar with a cable directly into the amp or

    the first effects unit in your chain.

    If the problem is already solved, see chapter 3.9for the correct use of a wireless receiver.

    4. Turn up the volume pot on the guitar. If the hum gets louder when you touch the guitar strings, the strings

    are most likely not well grounded, or the two wires at the jack socket are reversed. => Refer to chapter 5.1.

    5. Unplug the guitar cable from the guitar. If the noise drops significantly, the problem is with the guitar.Remember that particularly single-coils are very sensitive to interferences => Refer to chapter 4.1.

    If the noise level stayed about the same or even went up slightly, the problem is almost certainly not the guitar.

    6. Unplug the other end of the cable from the amplifier (or from the device to which the guitar is connected to)

    and insert the 10k jack-plug into the input. If the noise level is significantly lower than the connected guitar,

    the problem is the guitar cable.

    Use only high-quality, undamaged guitar cables. The cable should not be longer than strictly necessary and not

    run next to power cables, transformers and other electromagnetic sources.

    If the noise does not significantly decreases, the cable is fine.

    7. If the guitar signal is split, for example, with the use of two amplifiers, or in a dry / wet system, disconnect the

    second signal and test each signal-chain separately. Thus, if the hum is already resolved, you have wired theclassic ground loop. Repeat chapters 3.3 to 3.5.

    8. Disconnect the switching connection (e.g. amp channel switching) one after the other. If this eliminates the

    hum, a ground loop via the switching connectors exists. Ground loops through switching contacts can be

    avoided by the use of a switcher with isolated switching outputs.

    9. If you are using effects before the amp, remove the effects or your pedalboard completely out of the signal

    path (Important: Also remove the power supply to the pedalboard!) and plug the 10k plug right into the amp

    input.

    If the noise level is much lower, the problem lies with the pedal board. Continue with the next step. Otherwise,

    skip to point 12.

    10. Reconnect your pedal board and connect the 10k plug where the guitar usually is connected. If you use the

    effect loop of the amplifier, disconnect the cables from the send and return.

    If the hum is gone now, the problem is caused by a ground connection (ground loop) between the effects

    before the amp and those in the send/return. Usually these ground loops come through the power supply. =>

    Refer to chapter 3.7.

    If the hum persists even without effects in the send/return, go to the next step.

    11. Now, work your way all the way back to the amp by taking one device after the other out of the signal path while

    plugging the 10k jack always into the vacated input. Also disconnect the power supply of the effect. If the

    noise level drops significantly when you remove a certain device, this device or a combination of this device

    with one placed in front of it causes the problem. You can now temporarily power the pedal with a battery to

    see if the hum comes through the power supply.

    If you use a looper, plug the 10k jack into the input of the looper and connect the output directly to the

    amplifier. Remove all other devices connected to the looper (also switching outputs). If the problem still

    appears, the looper itself causes the problem. Otherwise it is due to one or more devices that are connected to

    the looper. Note that under some circumstances, this problem can also be caused by switching contacts (amp

    channel switching).

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    12. Remove the cables from the send & return of the effect loop of the amplifier. If the noise is gone now, the

    problem is with a device in the effect loop. If you have multiple devices looped, reconnect one after the other

    to the amplifier to find out which device is causing the problem. It is also quite possible that more than one

    device causes the hum, or that the hum is produced only by the combination of several devices in the effects

    loop (for example, when using a line mixer).

    13. Disconnect one MIDI cable after the other from the MIDI In side. MIDI is basically a floating, and therefore

    hum-free, signal transmission. Unfortunately, not all manufacturers adhere to the standards. If the problem is

    solved by the removal of a MIDI cable, the MIDI In jack of the corresponding device does not comply to MIDIstandards. The device must be modified by a qualified technician: the connection to ground from the middle

    pin (No.2) of the 5-pin MIDI In connector must be disconnected. This connection must only exist on the MIDI

    Out / Thru, but never at the MIDI In.

    If the "bad" MIDI In jack also runs phantom power for the foot controller, the problem must not necessarily be

    the ground connection of Pin 2, but it may also be due to the phantom power.

    14. If the "naked" amp already hums, that is, the 10k plug is plugged into the input of the amplifier, nothing

    is plugged to the effects loop of the amplifier and no foot switch nor MIDI cables are plugged in, then

    the problem is the amp itself. Certain components of the amplifier wear. Especially tube amplifiers must be

    serviced regularly and the tubes have to be replaced from time to time. In very old devices, also electrolytic

    capacitors may need to be replaced. Have the device serviced by a qualified technician.

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    10. A Few Words About Prostage and the Author of this Guitar Rig Building Guide

    You want a guitar rig with the ultimate sound. We support you in this! Our aim is to ensure loss-free signal

    processing and to provide absolutely reliable and road-ready systems.

    How are we doing this?

    In a Prostage system the guitar signal is processed completely inside the rack. Thus, there are only remote controlunits at the front of the stage. Realtime effects, such as the pure analog Remote WahWah, are controlled with

    an expression pedal. You switch your amp channels and stompboxes using a MIDI foot controller. The effects

    themselves are fitted in the XDS Loop System. This is a 19-inch drawer with an integrated true bypass looper and

    six isolated power supplies for guitar effects. In the rack, the effects are protected from flying beer cans or clumsy

    singers. Further, sound and dynamic losses due to long guitar cable runs belong to the past!

    The Prostage MIDI Foot Controller and Looper | Switcher are interconnected viaStageWire. StageWire was developed

    by Prostage specifically for stage use. This stage-prove MIDI connection provides bidirectional communication of

    multiple devices via just one standard microphone cable from device to device. Further, StageWire also includes

    phantom power for the foot controllers. The Prostage devices are programmed very comfortably using the System

    Manager software for Mac and PC.

    About Prostage

    Prostage was founded in 2001 by me, Lukas Truninger. I am an experienced audio engineer and backliner from

    Switzerland. Beginning in my teenage years, I was increasingly interested in audio electronics and tuned tube amps.

    After completing my apprenticeship as a mechanic, I studied audio engineering at the SAE Institute.

    I have worked with several international touring bands, such as Krokus or the Pepe Lienhard Orchestra (Udo

    Jrgens), during the 1990s and early 2000s. In 2008, I moved the production to the EU, specifically to Spain. Here,

    the Prostage products are further developed and still handcrafted with Swiss thoroughness.

    My experience has now contributed to many construction details of the Prostage devices. Today, Wolf Hoffmann

    from "Accept" and "Flyleaf"'s Jared Hardmann are only two of many guitarists successfully using Prostage productson their extended tours.

    Lukas TruningerProstage SL

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