The Rest of the Story,

The SD40-3 CSX Rebuild Version

I am one of those people who like to do my own DCC and speaker installs as I do not always agree with a manufacturers’ choices. For instance, I like a graphic equalizer facility to tune the sound to a specific speaker’s capabilities. And it keeps me off the street corners at night, according to my wife.

Factory Design

The speaker’s location is at the rear of the loco. Okay so far. It is in a housing, secured by two screws, which is integral to the main body weight’s design and it contains a mounting piece accommodating two sugar cube style speakers. Sound would be projected down through a small-ish opening where the truck mounts. Theoretically, the housing can be accessed by removing the screws.

I say this because of the wire bundle positioned along the top of the speaker from the rear lights: ditch, number boards, and headlight. They run along a well thought out and executed small recess running behind the lights mounts and then along the top of the speaker mounting piece to the mother board where they are soldered. They are quite snug and have almost no play.

I found it easier to remove the light boards from their frame mounting locations to allow access the speaker housing. Removal of the internal mount is easy in order to make room for a Scale Sound Systems (SSS) speaker designed specifically for this application. (I used the Coeval version) I used the wire recess and added the speaker wires to the others on the way to the mother board.

SSS Coeval in the factory speaker mounting arrangement.

Complications

As an aside, my Econami 21PNEM decoder did not play well with the ESU motherboard. I was unable to get the ditch lights to function, at all. I am informed there are variances between 21 wiring schemes. If true, it would be really nice if the producers were to read from the same sheet of music.

Also, I was not impressed with the sounds I heard coming from the speaker. I quit trying to work out the lighting issues and made plans to modify the speaker mounting before installing a T2.

Modifications to the Speaker Mounting

My modification to the factory speaker housing allows re-orienting the speaker to project sound through the incredibly detailed fan openings in the shell roof. There are five of those things! Easily said, but a little more effort to execute. Having access to a few select tools such as a band saw would make this a lot easier to accomplish.

I started by again removing all the wires in the rear of the loco so I could uninstall the speaker and the housing. After removing, I measured the length and depth of the SSS speaker and marked it on the sides of the housing piece

I used a hobby saw (think miniature hack saw) with a new, fine-toothed blade. I steadied the housing on a flat surface. As the housing is small, clamping is problem so I used my free hand. I gently scribed the cut lines with the hobby saw till it began to move below the surface of the metal. I continued slowly till I reached the depth I had marked. Both end cuts took less than 10 minutes. (Did someone say, band saw with the appropriate blade?)

The lateral cut was made with a Dremel using a thin cut metal blade. I dialed down the seed and lightly score the marked line. Once the cut was started, I upped the speed a bit and continued to trace the line till I penetrated the wall. I used the hobby saw’s blade to remove the last bits of metal at the corners left by the Dremel.

The removed portion of the speaker mounting housing.

After a little filing and paint touch up, the SSS speaker is easily installed and ready to  project it’s sounds through the roof fan openings. Yay team.

The last part of the process is rerouting the rear light wires. I merely replicated their original route through the frame access slots to mate with the T2 decoder.

Sound video to follow.

I bought 4 of the ScaleTrains

I bought 4 of the ScaleTrains tunnel motors (two with sound) but haven't tried them out yet because my basement has been in a perpetual state of being a dusty mess while finishing it since last Dec.  But I digress.

I've read a number of reports of disatisfaction with the speakers in those tunnel motors and quite a few people replacing them as well.  Some are using the very inexpensive I-phone speakers and reporting a major improvement in sound quality.  I plan on doing that when the dust settles.

Graphic Equalizer Sound Tuning

Duckdogger/Paul-

I've heard you mention graphics equalizer tuning using the Soundtraxx sound decoders many times on the MRH podcast and you've again mentioned it here in your post.  Can you provide a detailed, clear description of how you do this, so that we can all so the same to our locos if we desire.  I've seen posts by The Prof referencing some if it, but there's no explanation I could find on how it is specifically done.

Enjoy your posts and the MRH podcast!

Thanks much,

Jeff

@Jeff

Tuning the sound via the Tsunami/Econami equalizer? There is a context, if you will, of what are the capabilities of your speakers. There are very high performing offerings from Scale Sound Systems and others.  There are also a lot of mediocre speakers so you need to make wise choices. Seek forum members’ opinions.  Even close coupled sugar cube arrangements can yield robust sound. it is an asset if you are familiar with how the pro type locos sound. A side benefit of being a foamer .

My approach is to simply set the base register (CV218 ECO or CV 225 Tsunami 2) at 7, user adjustable, and then tweak the individual range values till the sounds are good to my ears. For instance, the lowest equalizer is pretty much under the capabilities of any speakers, so I cut this to zero. You do not want to attempt enhance a frequency range a speaker can’t produce. 

The next range’s upper limits are reproducible by better speakers so I start at the base level of 128. I load more gain into the third range, say 190. The next range is getting into the lower to mid midrange. I start with near flat, say 140. Next three ranges are flat at 128.

After loading the values into the CVs, start the sound and listen. Try the bell and horn. These are usually fine out of the box as they are midrange and usually produced easily by even marginally capable speakers. The key is the prime mover. Most have a decent amount of high bass range rumble and growl. From here it is a matter of making changes to suit your ears.

My process is to tune the lowers end first, the prime mover at ideal and up through the speed steps. Then I work on adding presence in the midranges where we can find the whines of the generator, dynamic brakes, poppet, etc. Did I mention toilet flush? Gotta have a good reproduction there.