GT Rack Effect Modules

We have tons more detail about our rack effect modules in the Products section of our site.  Modules are straightforward, and you've probably already figured out much about them.  Here we'll just briefly explain what our modules are and how they work. 


Take a pedal out of its metal (or plastic - yikes!) box, repackage it for rack mounting, and you have one of our modules, right?  Well, no, that's not really all there is to it.  While their rack format is a key feature, it is only one of the major features of our modules. If you'll pardon the pun, many of the main features of our modules are modular.  Modularity is a key design principle we rely upon.  Things can be swapped in, swapped out, repaired, replaced, substituted, duplicated, configured, or otherwise modified and used at multiple levels in our design.  You'll see that as you become familiar with the details of our products.

Modules are "rack versions" of effect pedals


GT modules


Yes, that is the simplest way to view it, but there are numerous differences.  Just like pedals, our rack effect modules come in the usual types such as overdrive, fuzz, delay, boost, flanger, phaser, and distortion, among others.  Just like an Ibanez Tube Screamer is a particular circuit, design, sound, and brand of pedal, the GT Virago is our version of that famous Tube Screamer circuit and many other commercial pedals that are technically very similar.  In most cases you can think of one of our modules as a base circuit with configuration options that can produce one of a family of technically similar pedal circuits.  Everyone knows that copies and clones of effects have been available since immediately after the first effects were introduced to the world back in the 60's.  But you may not be aware that the great majority of all commercially available pedal circuits are considered clones, copies, or derivatives of a few classic effect circuits.  When you look at our Compares To page, you'll see a mapping of many commercial pedals you may know to a much smaller list of GT modules.  That's why.  Our Bluesbuster, Virago, Woodstock, Fuzzbender, and Pi modules are all great example of that.  Those five GT modules can easily be ordered and configured from our options to produce circuits and tones that compare to probably 100 or more different commercial pedals, some of which you may not realize are technically similar - they certainly don't all look, cost, or sound the same.

Rack Effect Module Packaging

Our module packaging comes in two parts.  The first is our rack enclosure.  An enclosure is sort of like the enclosure or metal box of a pedal, except it is larger, designed to standard 19" rack mount specs, and holds multiple modules inside.  The enclosure is 3 standard rack units high, providing 17" of usable horizontal space for modules inside.  The enclosure consists of (4) side rails, (2) front and (2) back rails, (2) side panels, top and bottom panels, and optional adjustable-depth rear supports, along with a quantity of screws, washers, and nuts to hold it all together.  The enclosure takes up about 14.5" - 15" of rack depth, depending on whether the rear supports are in place.  If you don't want to put the enclosure in a rack, you don't have to.  You can add some adhesive rubber feet to the bottom and place it on a flat, level surface.  Multiple enclosures can be stacked that way.  The rack itself is optional.


Empty 3U Enclosure


The second part of the packaging is part of each module.  Each module has a front and rear panel that mount vertically to the front and rear rails.  All the installed module panels together form the front and back of the enclosure.  Each module (with a few exceptions) also has a 2-piece metal PCB support that holds all the boards in the module and is used to mount the module to the front and rear rails of the enclosure.  By the time you get your modules mounted in your enclosure, you have a very sturdy rack-mount "jumbo, configurable, multi-effect" unit.

The controls for each module are mostly on the front panel, along with on/off indicator LEDs, while the connectors for cabling are mostly on the rear panels.  Individual modules are of varying widths, multiples of 1/2", from 1" to 17".  Our Tube Reverb module is our only 17" module, which fills an entire enclosure.  Almost all of our other modules are 1", 1.5", or 2" wide.  Only a few are wider than that.  The number and type of controls and connections usually determine the width of the module - the more controls or connections, the more space needed on the front or rear panels to accommodate them.

The order of the modules in the enclosure doesn't matter at all.  That has nothing to do with their position in your pedal chain or how they are switched.  The order of your chain is determined by how they are cabled together in the back.  There are two special positions in each enclosure.  These are the left and right "wing" positions.  Those are the leftmost and rightmost modules in each enclosure.  The front panels for those modules must be special "wing" panels that include the holes for the rack mounting screws, and help anchor the enclosure to the rack.  As you can imagine, we have many, many different configurations of front panels to match the many possible custom and stock control configurations for all our modules.  To keep the manufacturing costs sane, we don't want to triple that number of configs to provide left wing, center, and right wing versions of all those panels.  So we stock only the most common configs for wing positions, which places some constraints on options for some modules in those locations, especially the left wing position for technical reasons we'll skip in this discussion (see Wing Modules).  Of course, if we really need a new wing config we can get it.  The wing positions are most commonly used for some routing modules for connecting guitars and amps.



Internal Rack Effect Module Parts

Circuit boards are the main pieces inside a module, along with the cabling assemblies that attach jacks, pots, switches, LEDs, or other components to the boards.  The circuit boards mount to the metal PCB support with plastic standoffs.  Internal cable assemblies connect the boards.  Any audio cable assemblies use high-quality shielded cables, of bigger gauge copper wire than is normally found in pedals.  Cables that only carry power, ground, switching, or other non-audio signals may be of unshielded, heavy gauge, copper wire.  The thick metal enclosures, module panels, and PCB supports between module circuits, along with the use of shielded cables, and clean Power result in quiet, low-noise effects.

Most modules, excluding special power, routing, and switching modules, have at least 3 circuit boards for the audio effect, power, and switching.  There may be more than one of each type of board, depending on how the module is configured.  If there are any internal user-adjustable features, they will be on the effect boards.  Most of the configuration options for a module will result in different components being used on the effects boards, but could result in mods to any of the module's boards or any other parts.

If there are lots of controls or connectors, there will be lots of cable assemblies and lots of connectors to the boards.  These are the user-replaceable cable assemblies we've discussed elsewhere.  If you unplug all the cables to a board, you can remove a board by squeezing together the split tops of the standoffs and gently popping the board off them.  Installing a new board in is as simple as aligning the standoffs to the holes in the board, popping them on, and re-cabling them.


Front panel and controls on left, rear panel and connections on right. Metal PCB support connecting the two panels. Effect board toward the left. Switching board near right top. Power board near right bottom. Note connectors on each cable attached to the boards.


Rack Effect Connections

The last thing we'll quickly cover is how everything gets connected together.  Again, except for a few special power, routing, and switching modules, most of our effects modules share another similarity - their back panel connections.  While there are module-specific exceptions, we'll just discuss the "standard" connections here, and assume you are also using our 18V Power module.


Standard rear panel connections




18V Power - Front
18V Power - Rear


We use standard 2.1mm DC power jacks, just like nearly all modern pedals use.  Our 18V Power module provides two channels of power, each providing up to about 2000mA of clean 18V DC power.  To power your modules, just daisy chain them to the two power outputs on the 18V Power module, using standard DC power daisy chains - shielded is always good if you can find them, but it won't likely matter.  2000mA is a lot of power, so you can daisy chain daisy chains to power a very large number of modules.  We have some power-hungry digital and complex analog modules that consume over 100mA, several in the 25-75mA range, and a large number in the under 25mA range.  As you connect modules, the front display on the 18V Power module will show you the resulting power consumption so you'll always know what capacity you have available.  A red LED on the back panel indicates the module is getting power.

We recommend you try to balance the consumption between the two channels, and if you somehow end up consuming most of the capacity, then consider adding another 18V Power module.  In general, you don't want to run electronics near the edge of their operating parameters for long periods of time, just to minimize potential problems.  So the power scheme works mostly like powering pedals on your pedalboard, but without some of the constraints and hassles typically encountered. 


Modules with only the power cables connected. Note both channels of 18V Power module are used.



Audio connections are the same as in your pedal chain.  It works the same way, using the same type of cables.  It's just physically much easier to do it in a rack.  You can use either mono or stereo cables, whatever is a better deal for you.  Make sure to use shielded audio cables to eliminate a common source of pedal noise.  Debates rage about whether expensive, high quality audio cables provide better sound than cheap, shielded cables.  They certainly should for what they cost.  That's up to you.  We'll offer a couple of thoughts for consideration, though.  Use shorter cables when you can, but a few inches here and there won't likely have any audible impact.  An assortment of cable lengths from standard pedal patch cable length up to about 18" will give you options when you need to re-cable your modules in a different order.  You don't want to disassemble and move your modules in the enclosure (which honestly is tedious and takes a bit of time), just because your cables are all too short.  It may be tempting to get the pricey "custom cable kits" that include connectors and cable that you cut to length and assemble yourself.  Maybe we don't assemble them correctly, but they've caused us a lot of problems and we now tend to avoid them.  We don't want to bring pedalboard problems into our rack setups.  If you don't experience that problem, by all means use them.  You can end up with some very neat and tidy cabling that way.


Modules with only the audio cables connected




Three 12-Button Footswitch units connected to three Rack Switch Modules


Rack Switch and a switching cable


The third type of cabling is for switching.  Pedals don't normally have a switching system, just stompswitches.  Footswitch units such as the 12-Button Footswitch are an enclosure housing some circuitry that controls several footswitches.  The footswitches are connected by a cable to a Rack Switch module.  On the back of the Rack Switch module are 12 switching control jacks, corresponding to the footswitches in your footswitch unit.  Each effect module has one (or more) footswitch jacks with a footswitch override switch for each jack.  You cable from a jack on a Rack Switch to the footswitch jack on the module, and the corresponding footswitch on the footswitch unit will then switch that module, just like the stompswitch on a pedal.  The jacks are standard 1/8" jacks, like those used on many portable audio products, like connectors on small headphones used with your phone.  You can use mono or stereo cables, which are widely available at low cost.  A variety of lengths from 6" to 18" is convenient when you want to reconfigure your switching, but length isn't critical.  Sound doesn't go through these cables, but it is still best to use shielded cables to prevent any impact on the audio cables running alongside them.

Sometimes you don't need to switch a module - you want it always on, with the same setting.  That's the purpose of the footswitch override switch.  On one setting the override switch allows your module to be controlled by the signal coming in on the switching cable from your attached Rack Switch and footswitch.  On the other setting, the module is set to an "always on" setting.  When you do that, it is just like using an attached footswitch to turn the module on - on is on.  But that allows you to remove the switching cable, and free up a footswitch on your footswitch unit for some other purpose.  Examples might be using an ABY in a splitter config in your chain - you don't need to switch it if you want both paths on all the time.  Or maybe you have an equalizer or light reverb you want to have on all the time.

There are other switching options available, but that is how it works in its simplest and most common form.


Modules with only the switching cables connected



Modules with all cables connected


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