Soundtraxx Sugar Cube speakers

[Jeff]

Hey yall,

I just did a introduction on the intro sub forum , but I thought I would get right to it...

I have a dilemma and no real hard answer other than (Yes you can do this)  I have a couple BL Alco RSD 15's which I'm getting ready to remove the DCC and Paragon speakers and install the Railpro  S decoder and soundtraxx speaker. I am wondering should I install two speakers I don't want them to drown out everything in the room, but when a RSD 15 comes around the bend or into a yard you know it down to your bones. so I'm looking for something prototypical, and any advice would be most appreciated.

also the decoders and sound systems I'm removing ... is there any market for that on eBay and if so what do they usually go for?

Thanks so much in advance.

[KPack]

Jeff - welcome to the forum!  In answer to your question, more speakers are always better.  With more speakers you will get more depth regardless of volume.  I don't run my locomotives loud, but all of them have a minimum of two speakers in order to allow for a more rounded sound.  Bonus if you can get one speaker in the front of the locomotive, and one in the rear.  That localizes the sound right in the center of the model.

Don't know about selling the old decoders.  I'd imagine there is a market for it, but I've never sold the old stuff at all.  It just goes in my trash can.

-Kevin

[Jeff]

Hey KPack thanks.

Just installed two in the first Alco per your suggestion...and wow between the Railpro sound samples and the dual sugar cubes the sound is just jaw dropping.

Thanks again for the reply

[KB02]

I wish that internet videos would do justice to a set up like this so we could all hear it, you know? Glad it worked out for you.
I've been using iPhone speakers and been pretty happy with them, but the results people are getting with sugar cubes makes me wonder about switching.

[ON28]

I've used iPhone 4s speakers but thinking of switching to 8s. My main issue is the lower range of the 567 ULT is about non-existent even with two speakers. The file sounds more like a steam chuff without it. How come we can't have have settings to boost bass?

[KPack]

I haven't been too impressed with the 4s speakers, which is why I ended up doing sugar cubes.  I thought those were great until I used Scale Sound System speakers (their duel CoEval) which were a night and day difference.  He stopped producing the Coeval line and now has a new speaker which I haven't tried yet.  I'm curious to see how it stacks up.  Now I'm experimenting with high-bass self enclosed speaker systems by TB Speakers.  They are huge and a pain in the rear to install, but they have by far the most bass I've heard from a speaker that can fit in HO scale.

Settings to adjust bass (an equalizer) is great and all, but the limiting factor here is the speakers.  Most speakers of this size are unable to play bass notes in any way close to what we would like.  So changing the settings to add more bass won't make a difference if the speaker can't play it.  The enclosure that the speaker is housed in, as well as the path for sound to exit, can help to some extent.  But still, a speaker that is only capable of playing notes above 200Hz will only be able to play sound above that level no matter what you do to it.  You need to find a speaker that is capable of playing sounds lower in the spectrum if you want more bass.

Lastly, some sound files are recorded with more bass, and some have less.  The 567 ULT does have bass (my TB speakers bring it out), but the exhaust is very prominent, drowning out some of the lower sounds.  Other sound files like the GE 7FDL-16 have more prominent bass within the recording itself.

-Kevin

[Alan]

Kevin is spot on about speakers having limits.

The primary lower limitation is resonance frequency. Sound pressure (volume) rolls off rapidly below a speaker's resonance frequency. Resonance frequency is mostly dictated by mass which is dictated by size. All things equal, a 12" speaker will have a lower resonance frequency than a 6" speaker because it has more mass. Greater mass gives a lower resonance frequency which gives the speaker the ability to reproduce lower notes. That's why woofers are big speakers and sub-woofers are really big speakers.

A Helmholtz resonator is a method widely used to get just a little more low end out of a speaker.  Often called "tuned port" or "bass reflex" a Helmholtz resonator is a specific cabinet design that resonates at a frequency slightly below the speaker resonance. This effectively adds a little bit of volume to the bottom end. The drawback to a Helmholtz resonator is cabinet size. It is quite large compared to sealed enclosures. I suspect the big cabinets Kevin is installing may be ported enclosures.   

Here's a novel way of thinking about it... Look at the diameter of the exhaust pipes on a locomotive diesel engine. There is your minimum required diameter speaker. Exhaust pipes have resonance frequencies too! Clearly these folks have figured that out.





Sorry, expecting such tiny speakers to reproduce anything remotely close to real train sounds is tilting at windmills. However, I wish you all the luck in the world trying. Any improvement is an improvement.

[KPack]

For reference, here's what I've been experimenting with.

TB Speakers T0-2008S: http://www.tb-speaker.com/products/t0-2008s

TB Speakers T1-1925S: http://www.tb-speaker.com/products/t1-1925s

The above speakers are an enclosed system with a passive radiator to effectively double the size of the speaker cone.  The smaller of the two has a bass frequency of 200 Hz, and the larger is 150 Hz.  They are difficult to install due to the size, but I have not found anything that offers as much bass as these two.  Video recording unfortunately does not do a great job at capturing how it sounds in person, but you can watch the end of this video to get a comparison between different setups:

What the camera can't accurately capture are the bass notes.  The locomotives actually vibrate when the prime mover is on.  The one thing I haven't loved about the above speakers is the sound level.  I typically have my sound low, but in a noisy place these speakers don't put out a ton of volume.  Not a huge issue for me, but others might want more volume.

-Kevin

[Alan]

Lower sound level from a passive radiator system is to be expected. The passive radiator cone increases the total moving mass which lowers the system resonance. That's good. Except the magnet and voice coil hasn't increased proportionally hence the lower volume. You have more mass but it is being moved by the same original motor. Given that you are working with 1/2" diameter voice coils, you can't simply pump more current to compensate. There isn't much voice coil area to dissipate a lot of heat.

They show the system resonance (F_s) as 200Hz. That's impressive for such a small unit. I have no doubt they sound better.

I also noticed their system response is eerily close to human speech range. No wonder they recommend it for soundbars.


https://www.dpamicrophones.com/mic-university/facts-about-speech-intelligibility

[KPack]

Thanks for the info Alan.  Makes sense now why the volume is lower.

I'll be experimenting with these some more.  Good quality products (made in Taiwan) and lots of options.  I may try out one of the larger sizes than what I have linked to above, if I can find a way to shoehorn it into a locomotive. 

-Kevin

[ON28]

All good, useful information! Since my motive power is F3s, BL2s and Geeps, I have some space to work with, so maybe give those speakers a go. You can also get a good overview/comparison of speakers for model RRs from Kaylee Zheng, who presented at one of the RPMs:

[KB02]

I've always found this video to be a great source of info for the sound installs that I have done:

[Jeff]

So a couple weeks have past and I have become a decent Solder...(er?) I have most of my speakers  set up in parallels of two. The big issue now is how in the heck do I place these in the engine shell?

I mean it has to be a shell right the old legacy RTR Athearns really doesn't have space on the chasse, but placing them inside the shell presents issues as well.

Any thoughts?

BTW using soundtraxx 810154 sugar cubes

Thanks in advance

[KPack]

I've done both (mount in shell vs. mount on chassis).  Athearn RTR and blue box are usually easier to mount in the shell facing down.  Give yourself some wire length to be able to take the shell off and set it next to the chassis when doing maintenance.  On most of my older RTR installs I ended up putting the LM up inside and mounted to the shell as well.  That way all the messy wiring stays up top (lights, speakers, etc), and only 4 wires come down in a neat bundle to the chassis....2 motor, 2 track.  Put one speaker in the front, and one in the rear.

I mount to the chassis when I can, but that's normally when the model has a chassis weight that I can use to mount.  Either cut the weight to create a mounting surface, or use the weight as a support for styrene shelves that the speakers then get glued to.

-Kevin

[ON28]

I'm prepping an upgraded Front Range Geep for RP, I may use a .060" styrene board to mount LM-2, bridge rectifier, keep-alive, lights and secure it to the roof of the shell with micro connectors for track and motor wires. With some care the styrene can be a press-fit for easy removal. Not planning on sound but that may change, too.