SurroundTraxx stores a roster of locomotive sound settings in a database called the Roundhouse. This is an extensive library that you can set up and adjust to match your model's prototype or to sound like your favorite horn or whistle, prime mover, or exhaust chuff. Each engine can have a unique sound profile!

Once you have entered your locomotive roster into the Roundhouse, you can use the internal “dispatcher,” which allows up to six trains to operate simultaneously. SurroundTraxx can be set up to pick the first six locomotives detected, or you can assign these slots to the locomotives of your choice (perfect to make sure your favorite engine never goes silent!). These locomotive “slots” used by the dispatcher are called Auto Dispatch (AD) slots.

After the trains have been dispatched, the block detector will identify the trains' locations, the speed they are traveling, and the point where they will cross into new blocks. SurroundTraxx uses this information to move the appropriate sounds to the corresponding sound channel (six are available) on the SurroundTraxx unit. SurroundTraxx uses an intelligent cross-fade algorithm that factors in train speed, direction, and distance between speakers. This reproduces the sound in such a way that it appears as though it is being emitted directly from the train rather than the speakers on the layout.

The multiple trains running on the layout can all be in the same area or spread throughout the layout. SurroundTraxx will still dispatch and reproduce their respective sounds in full audio richness. It truly is a complete layout sound system with multiple trains and operating sessions in mind!

Note: If using single-channel mode (default), the sound will feed through all six channels at once and does not follow the train. In order to set up the other modes of operation, you must use Digitrax® transponding block detection on your layout.

SurroundTraxx can accommodate up to six speakers per system, or five speakers and a subwoofer. The size and quality of these speakers are up to you and should be based on your layout design. However, we have a few helpful guidelines and requirements to help you achieve the best audio experience.

The speakers must be passive 8-ohm speakers rated between 5 and 25 watts. We recommend choosing speakers with a frequency response ranging from 80 to 16,000 hertz. If you plan to use a subwoofer, speakers with a frequency response of 150 to 16,000 hertz are sufficient, as the subwoofer will provide the bass.

SurroundTraxx is designed to operate on DCC layouts. In order to operate SurroundTraxx in transponding mode (multiple trains in multiple sound zones), you must have DCC mobile decoders with transponding installed in your locomotives. Alternatively, you may add separate transponders to any DCC mobile decoder that is already installed. To emphasize this point, when using SurroundTraxx to its full capabilities, you must either use decoders that come equipped with Digitrax transponding or purchase a TL-1 transponder to add to the locomotive. Sound decoders can also be installed in the locomotive, but are not required. Locomotives that aren’t equipped with transponders will still run on the layout, but will not be able to be dispatched or produce any sound through your SurroundTraxx system.

SurroundTraxx requires a Digitrax LocoNet-equipped command station in order to operate in any of its modes. For now, SurroundTraxx cannot be used with other systems.

SurroundTraxx comes with 6’ sections of speaker wire for each sound channel output. If your layout requires more wire, you can add your own wire to the end of the wire harness included with your SurroundTraxx unit.

To achieve the effect of sound traveling through your layout with your train, you must use Digitrax bi-directional block detectors known as BDL-168s. One BDL-168 will operate eight different blocks. Therefore, if your layout has more than eight blocks, you will need more than one BDL-168.

Digitrax RX-4s are required in conjunction with BDL-168s, and you must have one for each block on your layout. For example, if you have 10 blocks you, will need 10 RX-4s for your layout.

The SurroundTraxx User's Guide will guide you through the planning and installation process, from the initial planning stages to the final system configuration.

Installation involves these major steps:

• Plan your layout
• Define your track plan
• Create a schematic
• Divide and wire your layout into blocks
• Define your sound zones
• Identify speaker locations
• Verify the detection is working

By the time you begin planning for sound, you’ve probably already given a lot of thought to the other elements of your layout. Naturally, the extent of planning required varies by the complexity of the layout and its stage of completion when you begin installation of SurroundTraxx. We encourage you to enjoy the planning stages, taking time to consider the multiple factors in play.

If you are adding SurroundTraxx to a layout that is otherwise complete, you may find it helpful to take a test drive in transponder-free mode before finalizing the sound zones.

When deciding how to wire your layout the first factor is choosing which operating mode you would like to implement on your layout. This may change the set up and wiring of your layout. For instance if you wish to use SurroundTraxx in Transponder-free mode then you will wire the layout just as you would for any basic DCC layout. In other words, you wouldn’t need to divide the layout into blocks or add any of the transponding equipment offered by Digitrax. If, on the other hand you wish to use either 6-channel or 5-channel with a subwoofer mode, you will need to take into account two factors in the general wiring of your layout. The first of these factors is how many block detectors you need, and the second is how many sound zones you plan on having.

The table below lists some general size guidelines for a sound zone on your layout. As a reminder a sound zone and a block are not the same thing as a sound zone can encompass multiple blocks within one sound zone. If you intend to use single channel mode you can disregard this table, as the entire layout would be one sound zone.

If you are adding SurroundTraxx to an existing layout, you likely already have a track plan in one form or another. Otherwise, the track plan is your first opportunity to begin planning for sound. The track plan is a scale drawing of your layout, reflecting its geographical realities: each curve, loop, straightaway, etc. It is a helpful tool in identifying challenges and potential tricky spots such as reverse loops and wyes.

The User's Guide shows an example layout to help illustrate the principles employed when planning for SurroundTraxx installation.

For the purpose of SurroundTraxx setup, a detailed electrical schematic is not required, but a basic schematic is an important step in separating the layout into blocks, which is a prerequisite to defining your sound zones.

The schematic will help you assess the factors that affect the block divisions. For example, you wouldn’t want to place a block boundary in the middle of a siding. Instead, the boundary should occur at one end of the siding or the other. Likewise, a wye or yard should usually be confined to a single block. Even if you’re not using block detection with signaling devices, it’s helpful to plan your blocks as if signaling were part of the picture.

A sound zone is the area covered by one speaker. You’ll want to revisit your track plan and schematic with the determined the block boundaries, as these resources together are a great help in defining the sound zones. Remember that the sound zones you define for SurroundTraxx relate to, but don’t necessarily equate to, the detection blocks. In other words, multiple blocks can be in one sound zone. Each SurroundTraxx unit supports up to six sound zones.

Ideally, speakers should be placed as close to the center of your sound zones as possible, as seen in the example below. You may also want to consider the speaker's shape and size when deciding on speaker placement. Some speakers are easier to conceal than others, and this should be a consideration as you shop for speakers.

Ideally, the subwoofer should be mounted under the benchwork or on the floor. This provides optimal low-frequency response without causing vibration within the benchwork and scenery.

When installing speakers, you can conceal them in the benchwork, inside larger buildings or building facades, or behind greenery. You could also mount them on your ceiling or wall. If your layout incorporates mountainous terrain, you can build speaker compartments into hillsides. Wherever you decide to conceal the speakers, plan for easy access later in case of a loose speaker wire, failed speaker, or another maintenance issue. Self-amplified speakers will have onboard volume controls and possibly other controls, so be sure you can access them.

SurroundTraxx comes preloaded with its own sound library built from the quality sound files users have come to expect from SoundTraxx. Containing both diesel and steam prime movers, air horns, whistles, bells, exhaust chuffs, and more, this library gives the user the ability to customize the sounds of their locomotives.

If you aren't sure how to "build" your locomotive from the menu of sounds, start by visiting the section on our website about choosing the right sounds for your model. Selecting the Right Sounds for your Steam Locomotive will give you some insight into matching the available sounds to your steam engine. Selecting the Right Sound for your Diesel Locomotive will likewise point you in the right direction for your diesel models, beginning with matching the prime mover to the model. For those who want to further match the sounds to their prototype railroad, our Locomotive Airhorn History will prove invaluable.