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Choosing the Right Steam Sound

If you aren’t sure which sounds are appropriate for a given steam locomotive, choosing the correct decoder can seem confusing. Ultimately you should pick a decoder that appeals to your own sound tastes and preferences. This page will help you understand the various sound effects that are unique to each steam Tsunami2 Digital Sound Decoder.

Understanding the Exhaust Chuff

Our steam Tsunami2 decoders feature a variety different exhaust chuffs that were actually recorded from prototype locomotives in action. We record with multiple microphones and create different operating scenarios to capture the “characteristics” of a steam locomotive. We then take these sound recordings to our audio lab where we digitize and loop the exhaust chuffs for use in our decoders (no synthesized sounds are added to our exhaust chuffs). To further enhance the exhaust effects, our Tsunami2 decoders have a feature known as Dynamic Digital Exhaust (DDE), which causes the exhaust chuff to increase and decrease in volume and fullness based on the load it is pulling -- just like the prototype. In addition, a full 7-band equalizer will allow you to further customize the exhaust to sound exactly like the specific locomotive you are recreating.

Exhaust chuffs result from the movement of steam through the cylinders into the steam chest, the exhaust nozzle, and finally through the stack and into the atmosphere. It is important to understand that the dimensions and design of these parts on the prototype locomotive play a much larger role in how the exhaust sounds than the wheel arrangement or road name of a particular locomotive. For example, a small standard gauge engine built by Baldwin (such as a Mogul 2-6-0 with 34,000 pounds of tractive effort) will sound very similar to a larger narrow gauge Mikado 2-8-2 that produces nearly the same amount of power, assuming they are on similar grades and pulling similar tonnage. If you have two models (such as a 2-8-0 and a 2-8-2) that both have the same set of cylinders with a similar diameter boiler and smoke box, they should have very similar sounding exhaust chuffs.

How many exhaust chuffs should your locomotive produce to be realistic? Locomotives produce two exhaust chuffs each time the cylinder moves forward and back. Most locomotives have two cylinders that produce four exhaust chuffs per one wheel revolution (wheel rotating 360 degrees). Some locomotives have three cylinders (such as Shays and 3-cylinder rod engines) and thus produce six exhaust chuffs per full wheel revolution. To help achieve the proper chuff rate, once you've selected the type of engine (for example, a 3-cylinder engine), the Dynamic Digital Exhaust will create the best possible results for your model.

Some rod locomotives have multiple sets of cylinders (such as a Big Boy). These articulated locomotives often sound similar to a locomotive with only two cylinders because both sets are often synchronized. When one set of drivers slips, you will hear an extra set of exhaust chuffs. You can simulate this on our Tsunami2 steam decoders by using our “wheel-slip rate” feature. You can select an articulated exhaust with a slow, medium, or fast slip rate.

Understanding the Air Compressor

Tsunami2 steam decoders are equipped with a selection of air compressors based on the prototypes recorded. The sound of the air compressor comes on when the locomotive is placed on a live DCC track. On a prototype steam locomotive this sound is heard any time that the locomotive main reservoir falls below a pre-determined P.S.I. and will continue on until the governor shuts off steam to the compressor due to the main reservoir filling up. The two most common types were built by Westinghouse and are known as single-phase and cross-compound. Both designs are pictured below.

Single-Phase

Cross-Compound

Simply look at your model and determine which type of air compressor(s) your locomotive has to help you select which is appropriate for your model. Some locomotives will have two air compressors of the same type. Tsunami2 decoders include dual compressor options so you can make your sound decoder more prototypically accurate.

Older locomotives, that were built before the addition of air brakes, don’t have an air compressor on them. If you don’t see either of the compressor styles shown above, your model may be based on a prototype prior to the late 19th century air brake era. Tsunami2 decoders have individual volume controls for all sound features, this allows you to set the volume of the compressor to 0 if your model doesn’t have a compressor.

Understanding the Whistle

Undoubtedly the most loved and most beautiful sound feature of any steam locomotive is the whistle. Railroads sometimes chose to use just one whistle type for all the engines on their railroad, while others just used whatever whistle was on the locomotive when it was delivered from the factory. The purpose of the whistle was to warn people and to communicate to the trainmen. Below are a few examples of common whistle signals.

- is designated as along whistle blast

o is designated as a short whistle blast

- - o -

- o

- -

o

- ooo

ooo

oo

Approaching public grade-crossing (hold final blast until crossing is occupied)

Warning for areas where view is obstructed

Release brakes. Proceed forward.

Brakes applied

Flagman protect the rear of a train

When stopped, back up. When moving, stop.

Acknowledgement of signal not otherwise specified

One of the great features of SoundTraxx sound decoders and DCC is the ability to use prototypical whistle signals just like the real thing. Tsunami2 Digital Sound Decoders have functions for both a long whistle and a short whistle, making crisp and accurate whistle signals possible. Tsunami2 decoders also come with the ability to set up automatic whistle signals such as: forward (- -), reverse (ooo), a public grade-crossing (- - o -), and brakes applied (o).

Tsunami2 steam decoders come with over 60 different whistles! This gives you the opportunity to pick the correct whistle for a specific railroad or to pick one that you think sound the best. Remember, many whistles were used on multiple roads, or were extremely similar, so don’t get too caught up in the listed prototype.

Conclusion

Let your ears be your guide and select the one that you feel captures your model the best. This is your model and your layout after all, so ultimately you should pick the sounds that are most pleasing to your ear.

Understanding the Exhaust Chuff

Our steam Tsunami2 decoders feature a variety different exhaust chuffs that were actually recorded from prototype locomotives in action. We record with multiple microphones and create different operating scenarios to capture the “characteristics” of a steam locomotive. We then take these sound recordings to our audio lab where we digitize and loop the exhaust chuffs for use in our decoders (no synthesized sounds are added to our exhaust chuffs). To further enhance the exhaust effects, our Tsunami2 decoders have a feature known as Dynamic Digital Exhaust (DDE), which causes the exhaust chuff to increase and decrease in volume and fullness based on the load it is pulling -- just like the prototype. In addition, a full 7-band equalizer will allow you to further customize the exhaust to sound exactly like the specific locomotive you are recreating.

Exhaust chuffs result from the movement of steam through the cylinders into the steam chest, the exhaust nozzle, and finally through the stack and into the atmosphere. It is important to understand that the dimensions and design of these parts on the prototype locomotive play a much larger role in how the exhaust sounds than the wheel arrangement or road name of a particular locomotive. For example, a small standard gauge engine built by Baldwin (such as a Mogul 2-6-0 with 34,000 pounds of tractive effort) will sound very similar to a larger narrow gauge Mikado 2-8-2 that produces nearly the same amount of power, assuming they are on similar grades and pulling similar tonnage. If you have two models (such as a 2-8-0 and a 2-8-2) that both have the same set of cylinders with a similar diameter boiler and smoke box, they should have very similar sounding exhaust chuffs.

How many exhaust chuffs should your locomotive produce to be realistic? Locomotives produce two exhaust chuffs each time the cylinder moves forward and back. Most locomotives have two cylinders that produce four exhaust chuffs per one wheel revolution (wheel rotating 360 degrees). Some locomotives have three cylinders (such as Shays and 3-cylinder rod engines) and thus produce six exhaust chuffs per full wheel revolution. To help achieve the proper chuff rate, once you've selected the type of engine (for example, a 3-cylinder engine), the Dynamic Digital Exhaust will create the best possible results for your model.

Some rod locomotives have multiple sets of cylinders (such as a Big Boy). These articulated locomotives often sound similar to a locomotive with only two cylinders because both sets are often synchronized. When one set of drivers slips, you will hear an extra set of exhaust chuffs. You can simulate this on our Tsunami2 steam decoders by using our “wheel-slip rate” feature. You can select an articulated exhaust with a slow, medium, or fast slip rate.

Understanding the Air Compressor

Tsunami2 steam decoders are equipped with a selection of air compressors based on the prototypes recorded. The sound of the air compressor comes on when the locomotive is placed on a live DCC track. On a prototype steam locomotive this sound is heard any time that the locomotive main reservoir falls below a pre-determined P.S.I. and will continue on until the governor shuts off steam to the compressor due to the main reservoir filling up. The two most common types were built by Westinghouse and are known as single-phase and cross-compound. Both designs are pictured below.

Simply look at your model and determine which type of air compressor(s) your locomotive has to help you select which is appropriate for your model. Some locomotives will have two air compressors of the same type. Tsunami2 decoders include dual compressor options so you can make your sound decoder more prototypically accurate.

Older locomotives, that were built before the addition of air brakes, don’t have an air compressor on them. If you don’t see either of the compressor styles shown above, your model may be based on a prototype prior to the late 19th century air brake era. Tsunami2 decoders have individual volume controls for all sound features, this allows you to set the volume of the compressor to 0 if your model doesn’t have a compressor.

Understanding the Whistle

Undoubtedly the most loved and most beautiful sound feature of any steam locomotive is the whistle. Railroads sometimes chose to use just one whistle type for all the engines on their railroad, while others just used whatever whistle was on the locomotive when it was delivered from the factory. The purpose of the whistle was to warn people and to communicate to the trainmen. Below are a few examples of common whistle signals.

- is designated as along whistle blast

o is designated as a short whistle blast

- - o -

- o

- -

o

- ooo

ooo

oo

Approaching public grade-crossing (hold final blast until crossing is occupied)

Warning for areas where view is obstructed

Release brakes. Proceed forward.

Brakes applied

Flagman protect the rear of a train

When stopped, back up. When moving, stop.

Acknowledgement of signal not otherwise specified

One of the great features of SoundTraxx sound decoders and DCC is the ability to use prototypical whistle signals just like the real thing. Tsunami2 Digital Sound Decoders have functions for both a long whistle and a short whistle, making crisp and accurate whistle signals possible. Tsunami2 decoders also come with the ability to set up automatic whistle signals such as: forward (- -), reverse (ooo), a public grade-crossing (- - o -), and brakes applied (o).

Tsunami2 steam decoders come with over 60 different whistles! This gives you the opportunity to pick the correct whistle for a specific railroad or to pick one that you think sound the best. Remember, many whistles were used on multiple roads, or were extremely similar, so don’t get too caught up in the listed prototype.

Conclusion

Let your ears be your guide and select the one that you feel captures your model the best. This is your model and your layout after all, so ultimately you should pick the sounds that are most pleasing to your ear.