Speakers inside Locomotive Shells: Best Practices
The following are my conclusions regarding adding sound to locomotives after much research, engineering, and experimentation.
First, I would like to tell you that we are not supposed to put speakers inside little plastic (or metal) shells, from the audio purist's perspective. I asked Soundtraxx tech support if their speakers were designed to go into a shell, and the answer was "no". Wasn't that disappointing? Well, I am sure you have heard nice sound coming from locomotives and I am here to tell you that you can do it too. You just need to understand some basics.
All of Soundtraxx's speakers, as well as the Sugar Cube speakers I sell produce sound from both sides of the speaker. There is a real problem with this because the sound waves reflect and bend around the speaker and cancel a good portion of the sound from the opposite side. This happens because the sound emanating from one side of the speaker is the "opposite" of the other. In the professional audio word we call this: "180 degrees out of phase" because of how it would look on a waveform monitor. When you imagine the speaker producing sound from a diaphragm that moves "in-and-out", realize at the same time the opposite side is moving "out-and-in" creating a negative version. In a perfect scenario, the speaker would be producing no sound at all, but of course the conditions are not perfect. So what you get is a strange sound, some describe as "hollow". This is where enclosures, or baffles come in to play. If you cover the "back" of the speaker, you can all but eliminate cancellation. I put the word "back" in quotes because with speakers of the size we use pretty much produce the exact same sound from either side, so you could just as easily cover the "front" to get the same sound.
Tip: Most of Sountraxx's square/rectangular speakers have screw holes, and even with an enclosure, quite a bit of sound gets through. You need to plug these holes.
Remember when I said " we are not supposed to put speakers inside little plastic shells"? Some people do not agree, in fact they prefer the sound of the speaker inside a shell. I am not one of those people (but more power to them). I prefer to isolate the speaker from the rest of the shell and hopefully stick it facing out of a grill or out of the bottom of the locomotive. As an audio purist myself, I want the speaker to sound as it was designed to sound. However, that only works if you select a good-sounding speaker.
The Sugar Cube is a sweet speaker (pun intended). On paper, it has better frequency response than most other, much larger types of speakers. Their diminutive size multiplies mounting options, and they are cheaper than most other speakers as well. It is my opinion that they will largely replace the conventional speakers used in our hobby, it is only a matter of time. I created a small lab for the purpose of testing these speakers and comparing them to others and I can tell you that I will not be using anything else from now on. Visit my eBay store to try them out for yourself.
Happy rails!
Jon
First, I would like to tell you that we are not supposed to put speakers inside little plastic (or metal) shells, from the audio purist's perspective. I asked Soundtraxx tech support if their speakers were designed to go into a shell, and the answer was "no". Wasn't that disappointing? Well, I am sure you have heard nice sound coming from locomotives and I am here to tell you that you can do it too. You just need to understand some basics.
All of Soundtraxx's speakers, as well as the Sugar Cube speakers I sell produce sound from both sides of the speaker. There is a real problem with this because the sound waves reflect and bend around the speaker and cancel a good portion of the sound from the opposite side. This happens because the sound emanating from one side of the speaker is the "opposite" of the other. In the professional audio word we call this: "180 degrees out of phase" because of how it would look on a waveform monitor. When you imagine the speaker producing sound from a diaphragm that moves "in-and-out", realize at the same time the opposite side is moving "out-and-in" creating a negative version. In a perfect scenario, the speaker would be producing no sound at all, but of course the conditions are not perfect. So what you get is a strange sound, some describe as "hollow". This is where enclosures, or baffles come in to play. If you cover the "back" of the speaker, you can all but eliminate cancellation. I put the word "back" in quotes because with speakers of the size we use pretty much produce the exact same sound from either side, so you could just as easily cover the "front" to get the same sound.
Tip: Most of Sountraxx's square/rectangular speakers have screw holes, and even with an enclosure, quite a bit of sound gets through. You need to plug these holes.
Remember when I said " we are not supposed to put speakers inside little plastic shells"? Some people do not agree, in fact they prefer the sound of the speaker inside a shell. I am not one of those people (but more power to them). I prefer to isolate the speaker from the rest of the shell and hopefully stick it facing out of a grill or out of the bottom of the locomotive. As an audio purist myself, I want the speaker to sound as it was designed to sound. However, that only works if you select a good-sounding speaker.
The Sugar Cube is a sweet speaker (pun intended). On paper, it has better frequency response than most other, much larger types of speakers. Their diminutive size multiplies mounting options, and they are cheaper than most other speakers as well. It is my opinion that they will largely replace the conventional speakers used in our hobby, it is only a matter of time. I created a small lab for the purpose of testing these speakers and comparing them to others and I can tell you that I will not be using anything else from now on. Visit my eBay store to try them out for yourself.
Happy rails!
Jon
