No enclosure? I like it

I've been thinking of how to get good sound into small models, and the need for enclosures has been a problem.  Now you tell me I can do without them.  That makes life so much easier!

I would love to see what you do with really small steam locomotives, like the Spectrum 4-6-0 with the smaller tender.  That's one of my less successful installations to date.

Timely

Good article, Bruce, I've been gearing towards doing a conversion soon, I just haven't had the time with all the other projects going on, namely Turkey Creek and this whole funeral/memorial business Saturday for my uncle. 

How do we say, there are those who are bored with life and say there's nothing to do, and here I sit with so many things to do I could go three lifetimes without knowing a bored moment!!

Great article Bruce. You

Great article Bruce. You clarified a lot for me. It should be a "must read" for anyone contemplating a sound decoder install or trying to understand why a factory installation is as it is.

Joe

Excellent explanation Burce,

written with your usual clarity. I particularly appreciate your inclusion of the principles involved so that modelers can figure out how to do novel installations. Bravo.

Now to figure out how to "Bose" a GP15-1.

Dick

Good info

Thanks for your continuing efforts on DCC and sound. They are really appreciated.

Dear Ken, No, not "no

Video Issues

Video

Bruce,

Thank you for an other great educational column. Even though I have followed you quite a while, I learned lots of new stuff. And even feel I got a bette understaning of your thoughts on the infinite baffle design.

I am going to try that on my next soundinstallations. My order from your old store and MRH sponsor Lichtfield station is close to home now

I was going to ask you about what seemed to be missing in the video, as it looked like things I really did want to watch. Thank you for clearing this up. Looking forward to see the whole video!

Very interesting article Bruce

Great Article Bruce!

I especially like the discussion of the different sides of the speaker canceling out each other's frequencies.  Have been a crypto maintenance tech in another life I found that you explained that very well.  In old crypto systems a set frequency of "white noise" / static injection was used to cover up a radio transmission.  Injecting the same white noise frequency at the receiving end canceled out the transmitted white noise allowing the transmission to be heard clearly.  Those trying to intercept the radio transmission could only hear the radio static/white noise.

I would like to know if you have any plans of an article covering one of the new under the table DCC sound systems that employs transponding?

Thanks!

Den

Bruce, I have a question on multiple speaker installations.

I'm no where near using the answer, so there is no need to answer until you get home. 

I'm hoping to join the La Mesa club in San Diego to run on Tehachapi.  Because of the grades, they don't encourage the use of dummy locomotives.  I'm thinking of setting up a few dummy's with sound and just treat them as another freight or passenger car when figuring out how much a consist can pull.  If I put two speakers in a dummy as you showed in the article, will the speakers be in phase so that they sound like one?  If they sound like one, what would be a method to get them out of phase so that it sounds like multiple units?  Would making the wires for one speaker longer than the wires for the other speaker be enough to accomplish the task, or do I need some other component installed in series with one speaker to do it?

Phasing = "2 seperate locos"?

Dear Russ,

We can dig into the low-level tech details if required, but in short, no. 2 speakers "out-of-phase" (as far as push/pulling on a common piece of air between the speakers and the ears) are unlikely to sound like (or be "blind-test" mistaken-for 2 discrete locomotive "noisemakers".

Phase cancelling _can_ be used in creative applications, such as LayoutSound to manipluate the soundfield and apparent point-sources of sounds. However, this is _intentional_ Phase manipulation (from minor phase shifts thru to 180-degree near-complete cancellation of some frequencies), and is applied to the _sound_file_, right back at the point of sound-file creation, in an audio editing app.

(IE the playback signal path and hardware are required to be "phase coherrent",
only the actual sound file should introduce "phase problems" to the signal path).

In contrast, deliberately (or accidentally) creating either _electrical_ phasing issues.
(2 speakers pointing at the listener, where the + and - connections are swapped on one speaker)

or mechanical/acoustic phase issues
(2 speakers in a common enclosure "back to back", thus inherrently causing both in-air wavefronts to be physically generated "out of phase")

is generally _not_ reccomended, if only to preserve one's own sanity...
(This is a creative hobby, and there's always room to "bend the rules".
However, Audio Physics are immutable, thru-air soundwaves stubbornly refuse to respect "model scale"... )
 

to recap, the primary "noisemakers" in the average prototype locomotive are in no way phase-accurately sync'd,
(capable of achieving consistent signal amplitude, frequency, and waveform between the 2 "noisemakers",
with a time-offset between thru-air waveforms of no-more than 30milliseconds),

Furthur, the "listener position" in such situations is unlikely to be perfectly stationary in the "180-degree phase cancellation sweeet-spot" between the noisemaker's overlapping soundfields for very long, if at all, as one stands trackside and the consist runs by...

Therefore, using "Phase cancellation" on a single audio signal to try and replicate the effect of 2 distinctly seperate un-sync'd "noisemakers" gives many indications of "not working the way you might hope".

Happy Modelling,
Aim to Improve,
Prof Klyzlr

You will probably need more than one sound decoder.

2 unit sound

One possible way to get more distinct sound from two units is to vary the transition steps.  Diesel electrics sort of "shift gears" electrically as they accelerate, and the better decoders recreate this effect by making the engine sound throttle back every few steps as you accelerate, and then rev back up gradually.  You can usually set how many steps there are between transitions, so this gives the opportunity to set the number of steps differently among your fleet; then after the first transition the sound will vary somewhat.  It does take two different decoders to do it, though.

I just noticed the multiple speaker set ups in Bruce's article.

I realize that the reason for one set up at least is to match the power put out by the decoder to the impedance requirement of the speakers, but wondered about some other way of doing things.  I'm totally ignorant about sound and how it works.  I really wondered why anyone would use 4 speakers in an O Scale application.  My idea would be to mount 2 speakers in line not back to back.

Multiple Speakers

I tangentially covered it.

I should have been more specific. Remember, early in the column when I said that "Nothing Beats Cubic Inches"? Well four speakers give you four times the cubic inches.

The best way to make a decoder sound like a pair is to use the reverb section of a Tsunami and set it up as shown on my web site: http://www.mrdccu.com/curriculum/soundtraxx/tsunami.htm- about the middle of the page.

Thanks for the tip, Bruce.

I just read the column and forgot completely about your web site.

Reverb = "Audible dither", does not equal 2x noisemakers

Dear Russ,

Russ, please do try the reverb technique, I'd love to hear your impressions compared to what your ears tell you is "the sound you're looking for"...
(and if it's not "up to par", what about it doesn't make the grade?)

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Dear Bruce, Russ, Bruce, I

Dear Bruce, Russ,

Bruce, I agree with the "nothing beats cubic inches" ethos,
but are you talking literally about the cube inches of the enclosure, or applying the analogy to cone area?

Also, any chance of doing an article covering exciters instead of traditional speaker drivers?
(The new B'mann Porter uses this technique with quite impressive results...)

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Cubic inches

Thank you all

The top five:
Three columns / articles tied at 4.3
One came in a 4.4
How Do I Get the Sound Out? topped the group at 4.7!

Thank you all for your loyal support.

When can we see the full video?

Wondering when the entire thing will become available.

The video is in Joe's hands

I usually skip these articles...

but I am never skipping it again!!

I have never been much into electronics and after reading about 4 lines of any electronics article my mind start to wonder off onto scenery. After reading your article I was actually motivated to complete a project needing a sound. I ordered my new sound decoder from Yankee Dabbler including a speaker and will post a video as soon as I finish. Thank you for the great article and for the motivation!!