| Author | Message | ||
| Jim Stewart (H3jim)
Rating: N/A |
Active noise control is the use of electronics to make a "negative", or out of phase sound wave to cancel out unwanted noise. Airplane cockpit headphones have long had this technology to keep the pilots from being fatigued as quickly. Bose and others make headphones for the general public as well. Has anybody tried this technology to reduce the noise of a generator? If the unit is in a box, and the sound is in a constant frequency and amplitude range, it would seem to be a natural. I just built a generator box per Dick Wrights specs. The radiator is outside the generator box, although the head unit and the engine still require some cooling air. The engine of course also requires a fresh air source to run. The basic design includes vents to allow for air movement from a 500 CFM fan. The vents are folded tubes with approximately 80 sq inches of flow cross section, and made from special sound deading plywood, lined with a 1" foam that has heavy sound absorbing polymer in the middle. The thinking is that the sound will not go around the corners, and neither will it be reflected off the walls. This turns out to be true for the higher frequencies. During construction, I tried running the generator with the box buttoned up, and no vents, just to see how quiet it was. I also ran it after I had the vents cut, and the tubes built and lined. Almost all of the higher frequency noise is stopped by this design. However, it was disapointing to hear the increase in lower frequency tones that now escape the "quiet" box since I cut the vents. From an earlier period where I was very involved in loudspeaker box design, I realize that the lower frequencies have wavelengths measured in feet, not inches. The longer wavelengths do go around corners better, and espcecially well in tubes, folded or not. They would not be attenuated unless the tube lengths were far greater than the amount of space I have available. In fact, certain wavelengths would actually be amplified by the tube as a function of its size and length. I also notice that a cheap set of noise canceling headphones I have seem to work better on the lower frequencies. Just the range I am wanting to attenuate further. Its true, the generator is pretty quiet already, very similar to the ones Dick was showing at last years Bus N USA. You can sit beside it and carry on a normal conversation, but I can still hear it and I want to get it quieter. Since the generator is captive in a box, maybe a little like a giant headphone, I could hook up an amp and an enclosed speaker box and broadcast the anti noise. It of course also needs the mike and the electronics to make the out of phase signals. It could thereby cancel out the objectionable frequencies that are still getting through. Has anyone tried anything like this? or know of any technology that is available to try it with? | ||
| James Maxwell (Jmaxwell)
Rating: N/A |
Wow Jim, are u installing a wireless sound system also. Get u a 500amp amplifier, 2 18" sub-woofers, and play Balero or William Tell Overture. That will cover up the damn air-polluting noise-maker. Did u put in a roof level exhaust also? Next you'll want to consider auto-pilot so u can go get a cup of coffee while you're cruising! | ||
| captain ron (Captain_ron)
Rating: N/A |
buy a new Prevost and you wont hear a thing.... but the syphoning sound of money comming out of your bank account for the payments...  Or you can buy my cd "Captain Ron's Greatest Tits" and blast it through above mentioned stereo set up.... much cheaper than the Prevost | ||
| niles steckbauer (Niles500)
Rating: N/A |
JIm - before proceding you might try using a home stereo with a 10 to 14 band EQ to see if you can isolate and find the offending bandwith first by mimicking the escaping frequency range - then research the capabilities available for masking those frequencies or whether you can 'noise cancel' them - BTW isn't 'noise canceling' similar technology to doppler radar?- Niles | ||
| Lin Rating: N/A |
I have read about the prospects for these noise canceling systems but have not seen any except the headphones. One article said that certain auto makers were experimenting with them to make there cars seem totally silent. Could be lots of uses if a reasonable one was marketed. Personally, my generator is not in a box, but if I use a shop exhaust extension to relocate the exhaust noise, it makes a huge difference. | ||
| DMDave Rating: N/A |
Capt Ron please send pictures of "Your Greatest...". Will deciede on music later LOL! | ||
| John that newguy Rating: N/A |
huh? "Captain Ron's Greatest Tits"?? Well....... TD did say he thought you were the greatest.... (who wudda thought~~~~) | ||
| Jim Stewart (H3jim)
Rating: N/A |
Chip, And don't forget the catheter to get rid of the coffee. With those 18" drivers I could always play rap music too, then no one would care about the genrator, they'd be so happy if I'd just turn off the (c)rap... Maybe I should take my headphones apart and see if I can't cobble together an experiment to see if it works at all. If it doesn't, all I sacrifice is some headphones and some work. Captain Ron, you can't miss with a title like that, they are all great. I can watch those, er rather listen for hours. Niles, Maybe I should just get an oscilloscope and hook it to a mike to see what frequencies and amplitudes there are. All, I did not find anything with a web search either, maybe some experiments are in order. Jim | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
jtng, Look at the motorcycles and then the art festival shots. Even FF may enjoy the Harleys. http://www.650motorcycles.com/ Richard | ||
| Bill moldenhauer (Hotrodbill)
Rating: N/A |
You must be single, with all the kids and the wife screaming at me i have learned to shut out almost all frequencies of sound | ||
| Doug G Rating: N/A |
Corvette had a noise cancelling exhaust one year. | ||
| Jim Stewart (H3jim)
Rating: N/A |
Its as much for the folks next to me as it is my camp. I am electric only, and now I'm looking for ways to still like my choice. Yes, I did kids, but she's now grown. Silence is golden. |