Has anyone ever tried using a sound level meter to measure the sound levels of DCC decoders? I was wondering if this would work to tune each loco to approximately the same sound level for bells, whistles, etc. And perhapsfor clubs, to ensure a member does not exceed the max volume standard for that club.
If so, did it help?
Any recommendations for a good, but low priced (not professional level) digital meter and where available and approx. cost?
Thanks. Ken
I doubt that a DB meter would help much in this regard -- your own ears are (should be) much more sensitive.
Your asking for a "good," "low priced" DB meter is a mutually exclusive term -- any meter that is sensitive enough to measure the rather weak sounds emitted by a model railroad speaker is not going to be cheap. A quick Google search for decibel meters shows the cheapest price at nearly $80.
You're also going to need a very good microphone and audio amplifier in order for a DB meter to be usable.
Ken,
Yes, there are a few inexpensive sound level meters out there. As mentioned, the "cheap" ones will not measure much below around 50 dB. However, you can overcome this shortfall by measuring very close to each locomotive (within a few inches). If you are trying to balance the volume of each locomotive, make sure the measurement distance is constant for all measurements (decibel levels are worthless without a corresponding measurement distance). As for our ears being more sensitive, the opposite is actually true. Most people cannot reliably identify a change in sound level less than 3 dB. It requires a change of 10 dB for everone in the room to identify the change and a 10 dB increase is usually percieved as a doubling of volume!
Radio Shack has two models for around $35 (analog) and $65 (digital). Both are surprisingly accurate. Just make sure that these meters are set to the "A" weighting network as it simulates the way people hear sound. The default setting on the digital model is the "C" weighting network so you have to change it every time you turn it on. Neither Radio Shack meter is equipped with a wind screen so they aren't much good for outdoor measurements.
Parts Express has an even cheaper meter that goes on sale fairly often at $19. However, I have no hands-on experience with this unit. There are a few others available for under $100 but you really don't need a lot of features. The CenTech brand is carried by various contractor catalogs.
One thing to keep in mind is that similar prototype locos would be expected to produce similar sound levels while different prototype locos might produce wildly different sound levels. Even though I own several high quality sound level meters (and even a real time analyzer), I've never considered getting this specific about loco sound output, mainly because I only have three sound-equipped locos and all with the exact same decoder. However, this project does sound interesting. Please keep us posted.
Hornblower
I have used the Radio Shack analog version for years to test speaker systems. It is accurate and easy to use.
I shoud do just fine for such testing.
Sheldon
Thanks Cacole, Hornblower and Sheldon! I appreciate the comments.
Well, Christmas is coming and I have a LOT of sound locos. So what better time to get sometime that might be fun to use and maybe aid in sound tuning? Radio Shack, despite how much as I hate Radio Shack, has a digital version of the one Sheldon mentioned, that got fairly decent reviews and has been around for awhile. So it's on my Christmas list. I figure I can at least set the bell and whistle to approximately the same volume on the first try rather than hit and miss trys during programming after some runs.
Thanks again guys.
Ken
Hornblower, thanks also for the heads up on using the A weighting.
My lay out is all indoors so wind wouldn't be a factor.
Good point on the distance as I'm not sure I would have thought of that. I plan to set up a fixed mount on the layout (where to be determined of course) so every loco passing would be the same distance from the meter's mic.