On 30 Jan 2005 18:49:29 GMT, Ignoramus24281
wrote:


A while ago I posted some questions on soundproofing a generator. For
details of the generator, see

http://igor.chudov.com/tmp/onan/Diesel/

particularly, check out the "Enclosure" link.

Unshielded, the genset produces 85 dB at 10 feet.

I finally have satisfactory results. The enclosure itself reduces
noise by 5 dB. If I put another sheet of plywood in the direction that
I need to block the most (my neighbors), the noise goes down to 76 dB,
giving the total of 9 dB reduction in the needed direction.

The other directions are less important because the house and the deck
and the shed are going to shield/scatter most of the noise. (see the
link on the above mentioned page to see where the genset will go).

I am going to call it a success and stop the soundproofing work. Maybe
I will add some sound dampener substance to the engine panels.

On a related note, I sealed the top with epoxy, and will probably use
"deck treatment" on the rest. This enclosure will be normally covered
by a heavy duty tarp, when not in use.

Thanks to all!

i

Where are the MP3s of the sound before an after?

d

Pearce Consulting
http://www.pearce.uk.com

since the motor has strong cyclic components to its noise why don't you
look into some kind of simple Active Noise Control with local speakers
and car amplifiers.

Maybe you could knock off another 5 with this.

Very good installations can do about 15 dBa

Paul

Ignoramus24281 wrote:

A while ago I posted some questions on soundproofing a generator. For
details of the generator, see

http://igor.chudov.com/tmp/onan/Diesel/

particularly, check out the "Enclosure" link.

Unshielded, the genset produces 85 dB at 10 feet.

I finally have satisfactory results. The enclosure itself reduces
noise by 5 dB. If I put another sheet of plywood in the direction that
I need to block the most (my neighbors), the noise goes down to 76 dB,
giving the total of 9 dB reduction in the needed direction.

The other directions are less important because the house and the deck
and the shed are going to shield/scatter most of the noise. (see the
link on the above mentioned page to see where the genset will go).

I am going to call it a success and stop the soundproofing work. Maybe
I will add some sound dampener substance to the engine panels.

On a related note, I sealed the top with epoxy, and will probably use
"deck treatment" on the rest. This enclosure will be normally covered
by a heavy duty tarp, when not in use.

Thanks to all!

i

cool. thanks.

I know of someone who runs their exhaust into one of those flexible
exhause pipes and runs it up the side of his RV so the exhaust is
effectively at roof level and going upwards when it finally exits. that
helps noise too but it isn't the reason he did it.

in an unrelated note ..... my dad couldn't stand the noise of his shop
vac so built an insulated wooden box on wheels for it with airflow only
out the bottom and a door with a hole in the front for the tube. it is
REALLY quieter. I know Kitchen Aid used to make a portable dishwasher on
wheels and with a butcherblock top that I think is big enough for my
shop vac so if I ever see one being tossed, I'm snarfing it.

Doug

Now go and get some foam for seat cushions and put that in there. 1/2" will
do wonders, especially if you apply another sheet of plywood to that. The
noise level will not only go down but the frequency will do so also.
I'll note that 9 db really isn't that much and you can do a lot better. It
may be that the high frequencies have been attenuated more than that which
will make the attenuation of the noise better than what the number
indicates.

--
Why isn't there an Ozone Hole at the NORTH Pole?

I think one may have to make one's own

In its most simplist form you invert the signal ( one of maybe a few
fundamental frequencies but just one may be enough) and send to some
speakers nearby thereby cancelling the noise in a zone around your machine.

One needs some kind of electronic guru to help here. Do you have any
handy friends who fit this bill. Maybe analogue more that digital
experience here may help.

I think most industrial gadgets would cost thousands.

Paul

Ignoramus24281 wrote:
On Sun, 30 Jan 2005 14:57:18 -0500, paul v birke wrote:

since the motor has strong cyclic components to its noise why don't you
look into some kind of simple Active Noise Control with local speakers
and car amplifiers.

Maybe you could knock off another 5 with this.


Do you have a specific device in mind? If so, which one, and how much
does it cost.

i


Very good installations can do about 15 dBa

Paul

Ignoramus24281 wrote:


A while ago I posted some questions on soundproofing a generator. For
details of the generator, see

http://igor.chudov.com/tmp/onan/Diesel/

particularly, check out the "Enclosure" link.

Unshielded, the genset produces 85 dB at 10 feet.

I finally have satisfactory results. The enclosure itself reduces
noise by 5 dB. If I put another sheet of plywood in the direction that
I need to block the most (my neighbors), the noise goes down to 76 dB,
giving the total of 9 dB reduction in the needed direction.

The other directions are less important because the house and the deck
and the shed are going to shield/scatter most of the noise. (see the
link on the above mentioned page to see where the genset will go).

I am going to call it a success and stop the soundproofing work. Maybe
I will add some sound dampener substance to the engine panels.

On a related note, I sealed the top with epoxy, and will probably use
"deck treatment" on the rest. This enclosure will be normally covered
by a heavy duty tarp, when not in use.

Thanks to all!

i

On 2005-01-30 said:
Newsgroups: alt.energy.homepower,rec.crafts.metalworking,rec.a udio.
tech
since the motor has strong cyclic components to its noise why don't
you look into some kind of simple Active Noise Control with local
speakers and car amplifiers.
Simple, huh?


Tom Willmon
near Mountainair, (mid) New Mexico, USA

Anybody wanna go for Krustyburgers?

Net-Tamer V 1.12.0 - Registered

don't be so fast

one needs imagination here and a good electronics friend who is willing
to try

get inspired by Prof Fuller


http://www.val.me.vt.edu/



see also

http://www.isvr.soton.ac.uk/ACTIVE/Projects.htm

fan noise (similiar except for fan blade higher noises) at

http://www.safetyline.wa.gov.au/pagebin/pg002860.htm

more stuff

http://www.engineeringtoolbox.com/27_81.html

http://users.erols.com/ruckman/Applications.htm

and quoting from the last one


Option 1: Noise cancellation demo

The easiest way to do a limited demonstration of sound cancellation is
to visit the following web site, maintained by the Vibration and
Acoustics Laboratory at Virginia Tech in Blacksburg, Virginia:


http://www.val.me.vt.edu


From this site you can download a simple Windows-compatible program
that conducts a demonstration of sound cancellation (which, in a narrow
sense, is a form of active noise control.) All you need is a PC, a sound
card, and two speakers. The program plays a "disturbance" sound from one
speaker and a "control" sound from the other, and demonstrate that one
speaker can cancel sound from the other. No fuss, no mess.

Of course, you can demonstrate cancellation without the software if you
have a stereo amplifier, two speakers, and a way to generate a send a
pure-tone signal to the amplifier (such as a signal generator). First,
play a pure tone through both speakers. Move the speakers close together
and far apart; you'll notice no real change in the sound level. Then,
cross-wire one of the speakers (i.e., swap the positive and negative
wires). Move the speakers close together and you'll hear the sound level
fall dramatically. Experiment with different frequencies to find what
works best for your particular setup.

Again, these setups only demonstrate that one sound wave can cancel
another, and some would argue that this is not truly active noise control.

Option 2: Build an analog feedback controller

The opposite end of the spectrum: It is possible to construct a simple
analog feedback controller using op-amps, capacitors, speakers, and
other parts available from any electronics supplier. While simple in
concept, constructing such a demonstration requires a pretty solid
foundation in acoustics, electronics, and control theory. A basic
outline is given below, but the details are well beyond the scope of
this FAQ. Readers interested in further discussion are encouraged to
contact Dr. Dexter Smith ) or visit
the following web site:
http://ourworld.compuserve.com/homep...ring/fanc1.htm

A simple analog system for feedback active control consists of a
microphone sensor, a loudspeaker actuator, and an equalizer to correct
for the delay from the speaker to the microphone and for the transfer
function of the speaker itself. The microphone is usually placed close
to the speaker, since the system transfer function (from power amplifier
to output of mic preamp) is increasingly difficult to equalize as the
mic moves away from the speaker. (The phase change goes from gradual to
rapid as frequency increases). A disturbance input at the sensor (low
frequency acoustic noise) can be attenuated by the proper choice of
equalization. The zone of silence around the sensor is approximately
1/10th of the wavelength of the noise to be attenuated. The system can
be equalized by taking data into a sound card on a PC, determining the
transfer function, and equalizing it with a biquad op-amp circuit using,
for example, 4 op-amps.

Option 3: Build Ostergaard's feedback vibration controller

A technical brief published recently in the Journal of the Acoustical
Society of America describes how to make a simple active control
experiment using a tuning fork, a function generator, and some simple,
inexpensive electronics components. The reference is:

*
Ostergaard, P.B., "A simple harmonic oscillator teaching
apparatus with active velocity feedback," Journal of the Acoustical
Society of America, Vol. 99, No. 2, February 1996.


Option 4: Buy an off-the-shelf active control module

This approach is much more powerful and flexible than any of those
mentioned above, but only if you have a budget on the order of US$2000
or so: the EZ-ANC from Causal Systems. This comprehensive kit includes
hardware, software, and a complete theoretical/user's manual. (See
Section 4.2 for contact information, or check out their web page:
http://www.io.org/~causal/cs/csdir01.htm). Other companies also offer
controllers that you can purchase and apply to your own problems; see,
for example, http://www.technofirst.com.

Option 5: Modify an active control headset

This alternative is much less expensive, but not as flexible: the "ANR
Adapter" from Headsets, Inc. The ANR Adapter is an add-on kit that
transforms an ordinary passive pilot's headset into an active noise
control headset. The kit costs only US$100; you supply the headset. The
makers claim roughly 22 dB attenuation from 20 Hz to 700 Hz. If you
simply want a demonstration in which you flip a power switch to hear
active noise control at work, this kit may be for you. (See Section 4.2
for contact information. For a review of the product, see the following
magazine article: Picou, Gary, "Low-Rent ANC," The Aviation Consumer,
vol.25, No.7, MAY 01 1995, p.10-12.)




so please don't give up

Paul



Ignoramus24281 wrote:
On Sun, 30 Jan 2005 17:34:19 -0500, paul v birke wrote:

I think one may have to make one's own

In its most simplist form you invert the signal ( one of maybe a few
fundamental frequencies but just one may be enough) and send to some
speakers nearby thereby cancelling the noise in a zone around your machine.

One needs some kind of electronic guru to help here. Do you have any
handy friends who fit this bill. Maybe analogue more that digital
experience here may help.

I think most industrial gadgets would cost thousands.


Then this is not a practical idea.

i


Paul

Ignoramus24281 wrote:

On Sun, 30 Jan 2005 14:57:18 -0500, paul v birke wrote:


since the motor has strong cyclic components to its noise why don't you
look into some kind of simple Active Noise Control with local speakers
and car amplifiers.

Maybe you could knock off another 5 with this.


Do you have a specific device in mind? If so, which one, and how much
does it cost.

i



Very good installations can do about 15 dBa

Paul

Ignoramus24281 wrote:



A while ago I posted some questions on soundproofing a generator. For
details of the generator, see

http://igor.chudov.com/tmp/onan/Diesel/

particularly, check out the "Enclosure" link.

Unshielded, the genset produces 85 dB at 10 feet.

I finally have satisfactory results. The enclosure itself reduces
noise by 5 dB. If I put another sheet of plywood in the direction that
I need to block the most (my neighbors), the noise goes down to 76 dB,
giving the total of 9 dB reduction in the needed direction.

The other directions are less important because the house and the deck
and the shed are going to shield/scatter most of the noise. (see the
link on the above mentioned page to see where the genset will go).

I am going to call it a success and stop the soundproofing work. Maybe
I will add some sound dampener substance to the engine panels.

On a related note, I sealed the top with epoxy, and will probably use
"deck treatment" on the rest. This enclosure will be normally covered
by a heavy duty tarp, when not in use.

Thanks to all!

i

On 31 Jan 2005 01:41:56 GMT, Ignoramus24281
wrote:

On Sun, 30 Jan 2005 17:34:19 -0500, paul v birke wrote:
I think one may have to make one's own

In its most simplist form you invert the signal ( one of maybe a few
fundamental frequencies but just one may be enough) and send to some
speakers nearby thereby cancelling the noise in a zone around your machine.

One needs some kind of electronic guru to help here. Do you have any
handy friends who fit this bill. Maybe analogue more that digital
experience here may help.

I think most industrial gadgets would cost thousands.

Then this is not a practical idea.

You're right, it isn't. Active noise cancellation can be very
effective, but it's a project to do it right and it isn't cheap.
Your approach fits your sit far better. Good job!

A year ago or so we needed to set up a generator in a field to power stuff
for a church "tent event". Needed to be really quite so that the service
wouldn't be disturbed. As a quick and dirty sound deadener, I made up a 4'
square, three sided box with a top, out of two 4x8 sheets of waferboard cut
in half. I stapled used carpet pad (the stuff made from lots of chunks of
recycled foam) on each inside surface. That really worked. From 50' away
with the open side facing away from the tent, you couldn't hear the
generator at all unless you listened very carefully. If you know someone
getting a carpet replaced, scrounge the foam pad. Works really well as an
acoustic sound absorber, and it's free.

We saved the enclosure for future use (it knocks down) but had to strip off
the foam - the guy who donated it was replacing his carpeting because his
cat ****ed all over it. It did keep curious kids away from the generator
during the service, though. What a smell.

--
Bob (Chief Pilot, White Knuckle Airways)


"Ignoramus24281" wrote in message
...

A while ago I posted some questions on soundproofing a generator. For
details of the generator, see

http://igor.chudov.com/tmp/onan/Diesel/

particularly, check out the "Enclosure" link.

Unshielded, the genset produces 85 dB at 10 feet.

I finally have satisfactory results. The enclosure itself reduces
noise by 5 dB. If I put another sheet of plywood in the direction that
I need to block the most (my neighbors), the noise goes down to 76 dB,
giving the total of 9 dB reduction in the needed direction.

The other directions are less important because the house and the deck
and the shed are going to shield/scatter most of the noise. (see the
link on the above mentioned page to see where the genset will go).

I am going to call it a success and stop the soundproofing work. Maybe
I will add some sound dampener substance to the engine panels.

On a related note, I sealed the top with epoxy, and will probably use
"deck treatment" on the rest. This enclosure will be normally covered
by a heavy duty tarp, when not in use.

Thanks to all!

i

Active Noise Control, unfortunately, doesn't work well with dull
waveform low frequency noise, like a generator would be,or for
filtering out air-handling system noise, like blowers and vents, for
instance. They work best with high frequency stuff with a sharp
waveform.

And as another poster mentioned, a good ANC system is well the wrong
side of ten grand.

DJ