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Tutorials, Tips & Tricks -->>

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Streamlined Backshop Services is an authorized dealer for all major DCC manufacturers including:


CT Elektronik

DCC Specialties


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Speaker Baffles and Installation

Sound and volume... continued. 


In How To #7 we looked at the effects of using multiple speakers and how to wire them correctly.

Now, in How To #8 we will look at the the different types of enclosures available and different methods of installation.

The speaker baffle or enclosure is simply an air-tight box that is built around the speaker to trap the negative sound wave discussed in How To #7 and reflect it back through the diaphram to compliment the positive sound wave.

There is a lot of math and engineering that can be injected into this conversation about the ideal size and shape of the box, sound chamber porting, and so forth but in practice, we are constrained by the physical size of the model and space not occupied by motors, shafts and gears.

Considering that constraint, plus the fact that there are now many commercially available products geared for the model train appliaction, we'll forgo the math and focus on these products.  The bottom line here is this.  Baffle your speaker is some fashion to improve the quality of the sound. 

To be sure it gets mentioned here, it is also possible to build an enclosure from plastic, wood, or metal.  These are typically boxes much like the commercial products.  They can also be fashioned from bottle caps, film canisters, and medicine bottles.  Another popular method involves using the loco shell as the enclosure.

Here are a few key resources if you want to investigate enclusure theory further.

The Soundtraxx Tsunami Installation Guide

Accoustic Designs for Onboard Sound

Mr DCC U - Get the Sound Out

This is one for the engineers and designers...

Speaker Enclosure Calculator

And finally, ESU has released the 50326 Speaker that resonates the body shell to create the sound wave.  It is a very compact solution that may be right for your application.  One thing to be cautious of with this application is that, since it vabrates the body shell, loose details like the cab and Dynamic Brake housings may vibrate if not permanently secure to the shell.

Speakers and Baffles

There are several different types of baffles available today.  Some speakers include a baffle while others must be purchased seperately.  Be sure to check the specs for each model and brand.

AHD offers a nice variety of speakers in 8 ohms impedance and three sizes of enclosures.  These can be used with other brands but may require a bit of modification.

The Small Oval fits most 16x35mm speakers.

The Mini-Oval fits the AHD 14x25mm speaker.

The Micro-Oval fits the AHD 12x17mm speaker.

The speakers are sold seperately. 


CT Elektronik offers two types of speakers in 8 ohms impedance and these models include the speaker baffle.  

The model pictured is known as the "CT Sugar Cube" because of its size and color.  This speaker provides surprising sound quality and volume for its size.

Digitrax offers a nice variety of speakers in 8 and 32 ohms impedance.  Three models feature the Bass Reflex type of enclosure.  

ESU offers a wide variety of speakers in 4, 8, 50 and 100 ohms impedance and most models include the speaker baffle.

ESU also offers a new speaker, the 50326, that resonates the shell to generate the sound wave.


QSI offers a variety of High Bass speakers in 8 ohms impedance.

They do not include or offer speaker baffles.


Soundtraxx offers a wide variety of speakers in 8 ohms impedance and several models of speaker baffles and gaskets.

The Soundtraxx baffles and gaskets can be easily adapted to many brands of speakers.


Streamlined Backshop Services offers a wide variety of speakers in 4, 8, and 32 ohms impedance.  

We do not currently include or offer any speaker baffles.

Zimo offers a nice variety of speakers in 4 and 8 ohms impedance.  Three models feature the Bass Reflex type of enclosure.  

The model pictured is known as the "Zimo Sugar Cube" because of its size and shape.  This speaker provides surprising sound quality and volume for its size.

Speaker Installation

There are many ways to mount the speaker.

In steam engines and diesels, I always prefer to mount the speaker face down on the the floor so the that the sound wave reflects off the right-of-way.

I usually drill a pattern in the floor similar to the pattern below to protect the speaker and "let the sound out".  You can provide additional protection by covering the holes with a piece of cheese cloth or pantyhose material.

Typical 16x35mm Speaker Porting Pattern
Speaker Porting In A Tender Floor

Sometimes it is not convenient or possible to mount in the tank or tender floor.  When that happens I look for the most convenient alternative.

In N or HO Scale steam I tend to mount the speaker under the coal load and drill a series of tiny holes in the coal load.  This is my least favorite option but sometimes the only option.

In HO Scale steam, it is also possible to mount the speaker in the boiler shell.  This can be a preferred location when the shell can be used as the baffle.

In N or HO diesels I tend to mount the speaker under the radiator fans.  In either scale, it helps immensely to replace the radiator fans with etched or screen super-detail replacements.  Be sure to seal off any openings in the DB housing and unused radiator grilles so that the rear sound wave cannot escape.

Speaker Porting In A Tender Coal Load
Speaker Mounting In A Narrow Hood Diesel

Regardless of where the speaker is placed, it is important to make sure that the rear sound wave is isolated from the front sound wave.

The small baffle boxes provided with many speakers make this easy.  If you are building a box or using the body of the model as the baffle you need to use a gasket or other means to seal off the speaker.

Soundtraxx offers a selection of pre-cut gaskets that fit a variety of speakers

Soundtraxx Speaker Gasket

My favorite method (credited to Mr. DCC, Bruce Petrarca) is to use Adhesive Caulk to form a seal around the speaker face.  The caulk works well with any speaker mounting arrangement.

It also works well for securing the enclosures in the shell or frame since it also helps to dampen any vibration of the chamber.

Application of the caulk can be done in many ways including a putty knife or tooth pick.  My favorite tool for applying the caulk is a syringe I got from an ink cartridge refill kit.  I recently picked up a new set off ebay which included a nice variety of tips.

Adhesive Caulk and Ink Cartridge Refill Syringe
Application Of Caulk For Mounting Speaker On Molded Speaker Mount
Application Of Caulk For Mounting Speaker On Tender Floor

So that's that.

There is a lot of technical detail to designing and mounting speakers and enclosures.  Don't get bogged down in the details of the engineering and design.  

Just focus on the basics of speaker selection and mounting and your loco chuffs and chugs will be simply delightful.

  • Always use the biggest speaker possible and/or as many speakers as possible.

  • Always try to match the impedance and wattage of the speaker to the amplifier.

  • Always use a gasket, baffle or other means to isolate the back sound wave from the front.

  • Always mount the speaker in a manner that minimizes vibration.

  • Always try to mount in a manner that lets the sound out.

Be sure to visit the store to see our full line of Speakers and Baffles today!