Sound systems

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Overview:

Sound systems in G scale have challenges, but the good thing is that it's nowhere near the challenge of a smaller scale. You have enough electrical power for a good amplifier (output power), enough room for an adequate speaker, and a reasonable sized circuit board.

(yes battery power can make this tougher, but still pretty easy in relation to other smaller scales)

In the early days of sound, many "analog" circuits were used, that simulated the real sound, some did an amazing job.

Later, with the advent of inexpensive computer memory and inexpensive microprocessors, the sound unit could play various pre-recorded sounds on command.

Finally with more sophisticated microprocessors, you can get sound units that "shape" the sounds in volume, attack, rate, etc. You can actually get the chuff from a loco to change attack, decay, duration, pitch, etc.

Of course, as usual, you get what you pay for.

Low end sound units:

I'm not going to cover all the low end systems that are made. Most of these are  not realistic, or polyphonic. Polyphonic means capable of making multiple sounds at the same time. Many of these systems will "lose" the sound of the locomotive engine when blowing the horn, for example.

Not talking these products down, just that in my mind these are compromises based on cost, and some people will be fine with them, and to others they are as many people feel "just noise".

Most of these systems are around $80 - $100 and will usually have inputs or "triggers" to start or stop sounds.

Sound systems evolution

Historically, sound systems came from analog circuits to "intelligent" playback "loops" of digital recordings, to present day microprocessor driven units.

All modern "stand alone" sound systems are now based on DCC control. (there might be a few exceptions for sale right now, but I would argue they are not modern!) Some of them also work on DC.

Many large scale DCC decoders include sound, and all of them support DC also. Since sound is "big" in the largest market, HO, then it was a simple step to just make a decoder with the same sound capability with more power for larger motors.

What's in the rest of this "branch" of the web site?

There are some specific pages on some earlier sound systems.

There are tips to installing sound systems, how to wire, how to select and install speakers.

There is a list of speakers that work in various locomotives.

Examples of some sound systems:

httpv://www.youtube.com/watch?v=eO-s8lk6TZY

httpv://www.youtube.com/watch?v=iUcMHhKcb-A

 

Phoenix:

httpv://www.youtube.com/watch?v=lSiHCsMjBuQ

httpv://www.youtube.com/watch?v=S3xE-vpQXcA

 

Speakers

The basic rule is pick one as big as you can possibly fit. Normally people put speakers for steam locos in the tender, but in large scale you can put reasonable speakers in the boilers of larger locos.

See my page on the Aristo Mallet, this loco is so long, that a speaker in the tender sounded funny, because the sound comes from a place nowhere near the stack.

When you put a speaker in a loco or tender, you most often want to make a sealed enclosure for it. There are two reasons: One is that sound actually comes from both sides of a speaker cone. But, since when the front side of the speaker is moving out, the back side is moving in. Thus, two out of phase pressure waves are created. If they mix, they cancel each other. So you want to isolate the front from the back.

The second reason for an enclosure is that bass frequencies try to make the cone move a lot. When the cone moves too far, like at high volumes or low frequencies, it eventually stops due to the mechanical limits of the speaker. This abrupt stopping causes distortion, and makes the sound bad. You also want to limit the motion (called the excursion) of the cone to protect from actual damage to the speaker. A sealed enclosure acts very much like a shock absorber and spring on your car's suspension. When it trys to go too far, the spring and the shock absorber serve to smoothly stop the motion before the mechanical limits of  the suspension is reached.

Another commonly misunderstood item is speaker "impedance". Impedance is like resistance, but measured in the AC domain, which a sound signal is. The lower the impedance, the more current a speaker draws from the sound board. Draw too much current, and you distort, and draw way too much current an you destroy the output amplifier in your sound board.

Most sound systems have NO protection from too low an impedance speaker.  The impedance of speakers connected together in series or parallel follows the same rules as resistors.... put them in series, and the impedance is the SUM of the two. Parallel 2 speakers of the same impedance, and the resulting impedance is HALF the impedance of one speaker. DANGER! This will typically destroy a sound board. DON'T DO IT!

***need*** section on triggering sounds, sound volumes, etc.

What are "sound triggers"?

In the world before DCC, where the commands are directly received by the sound board, people first used reed switches triggered by magnets between the rails. When you passed over the magnet, it moves a small arm in the reed switch (the reed) to make contact. Closing a circuit to the sound board is called "triggering" the sound board.

From a practical sense, you could run a maximum of 2 different triggers, with the magnets offset towards one rail or the other.

As R/C systems progressed, they were built with multiple "outputs" which could be connected to the "trigger inputs" of the sound board. This is of course limiting, since every sound controlled needs a physical wire between the R/C system and the sound board.

What is all this about wattage?

There's no real magic here, and it's exactly the same as the home stereo market. Sound volume is measured in decibels, and one decibel was meant to be the smallest increment / change in volume that humans could perceive. In reality, most people can only discriminate between 2 or 3 db (decibels) in change. 

It takes DOUBLE the wattage to increase the sound level by 2 db. Read that again!

What this tells you is that the difference between a 2 watt system and 3 watt system will be NOTHING. If you are expecting to get your loco "louder" with wattage, you need to increase the wattage by a factor of TEN. This does not exist. 

To get a louder loco, you need to get a more efficient speaker, whether the speaker itself, or the effects of an enclosure. 

 

Top of the line systems, very realistic, recordings of actual locomotives:

Typically near $150-220, sometimes standalone, often combined with a DCC decoder, sometimes sound only, sometimes sound and motor and light controls combined.

Phoenix sound systems:

Phoenix only makes DCC compatible sound boards, no motor or lighting controls.

P5 - Basically a DCC only board. It seems that this is being discontinued, 6 watts, no trigger inputs.

P5T - $45 list - adds trigger inputs and motor speed inputs so it can be controlled by R/C systems, and sense motor speed. It has 6 trigger inputs.

P8 - $195 list - This product is the combination of the P5 & P5T basically, an all in one that has trigger inputs as well as DCC functionality. It has 5 trigger inputs, 6 watts.

PB9 - $245 list - this is the replacement for the 2K2 decoder (which is being discontinued)  - 4 triggers and 3 watts, low voltage operation - 3v (big boost) built in.

Bigboost - $45 list - allows the system to run at lower voltage, 3v (switching power supply)

 

Inexpensive systems

Typically $100 and under, nothing seems to be DCC compatible, some have "Trigger" inputs for remote control, and some are just random. Often the sounds are poorly digitized, or in low resolution, or just synthesized in an electronic circuit.

 

My personal opinion is they are not worth saving $40 over the quality sound systems available. Many people are happy with these. A lot of people say they cannot hear the difference, but everyone who I have demonstrated high end systems to CAN hear the difference. But, is the difference worth the cost? You must be the judge yourself.

 

Dallee:

Dallee seems to be digitized sound, and street price is about $90. There are limitations in the processing power, this system is not really "polyphonic" in that it cannot produce and "mix" multiple sounds at the same time. Here is a Dallee steam unit, notice the whistle is strangely "spliced"? Also the chuff sounds poor. The chuff disappears when the whistle is blown:

 

Here's a Dallee diesel, the horn sounds anemic and artificial. The prime mover sound is ok:

 

 

MyLocoSound.com

Here is the link: http://goo.gl/2vDGj which appears to be a personal google web page which resolves to mylocosound.com. It looks like Beacon Hill Trains is the exclusive supplier, and is owned by Mike Moran, who has often contributed on many large scale forums.

Interestingly, sounds are synthesized, not from recordings played back. This has certain advantages in modifying the sounds as the loco changes speed, noticably in the chuff. It's clearly less realistic, and the bell has kind of a buzz/sizzle to it. The chuff is more like modulated white noise. Again this is a low cost system, $80 for either the steam or diesel, and there is a steam version with a "chuff trigger". The horn/whistle can be remotely controlled. It appears that the bell and other sounds are automatic.

 

 

 

Sub-Pages

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