In article , Ignoramus1606 says...

I am soundproofing my genset. I built a little 1/2" doghouse, mounted
on the generator carriage. I am going to install lead lining inside,
using 1mm thick 2.5 lbs per square foot lead sheet. The weight of all
this lead is going to be approximately 100 lbs.

My question is, is "roofing lead" as good as "soundproofing
lead". Perhaps the alloy composition is different and it might impact
sound transmission characteristics? Any thoughts?

I would use sonex.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

"Ignoramus1606" wrote in message
...
I am soundproofing my genset. I built a little 1/2" doghouse, mounted
on the generator carriage. I am going to install lead lining inside,
using 1mm thick 2.5 lbs per square foot lead sheet. The weight of all
this lead is going to be approximately 100 lbs.

My question is, is "roofing lead" as good as "soundproofing
lead". Perhaps the alloy composition is different and it might impact
sound transmission characteristics? Any thoughts?

i

It is overkill, but it will work just fine. Usually the soundproofing lead
is 1/64 thick and about 1lb. per Sq.Ft.

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

"jim rozen" wrote in message
...
In article , Ignoramus1606 says...

I am soundproofing my genset. I built a little 1/2" doghouse, mounted
on the generator carriage. I am going to install lead lining inside,
using 1mm thick 2.5 lbs per square foot lead sheet. The weight of all
this lead is going to be approximately 100 lbs.

My question is, is "roofing lead" as good as "soundproofing
lead". Perhaps the alloy composition is different and it might impact
sound transmission characteristics? Any thoughts?

I would use sonex.

Jim


Owens Corning makes something similar called 703 insulation board. I've
used it and it works pretty well.

Steve.

On 20 Jan 2005 22:35:27 GMT, Ignoramus1606
wrote:

On Thu, 20 Jan 2005 13:49:42 -0800, Roger Shoaf wrote:

"Ignoramus1606" wrote in message
...
I am soundproofing my genset. I built a little 1/2" doghouse, mounted
on the generator carriage. I am going to install lead lining inside,
using 1mm thick 2.5 lbs per square foot lead sheet. The weight of all
this lead is going to be approximately 100 lbs.

My question is, is "roofing lead" as good as "soundproofing
lead". Perhaps the alloy composition is different and it might impact
sound transmission characteristics? Any thoughts?

i

It is overkill, but it will work just fine. Usually the soundproofing lead
is 1/64 thick and about 1lb. per Sq.Ft.


Thank you. When you say overkill, in what sense is it an overkill? In
terms of benefit per weight of lead shielding added? Am I not going to
get better soundproofing from 2.5 times thicker lead?

I would sure think the additional mass would help a lot at lower
frequencies. Lead is used because it's "dead"; no flexural
resonances because it's soft. If your roofing lead is soft (bends
easily), it'll be a good sound barrier.

"Ignoramus1606" (clip) Am I not going to get better soundproofing from 2.5
times thicker lead?
^^^^^^^^^^^^^^^
Very likely yes. Much or most of the sound reduction comes from the mass.
Your lead, being much thicker, will be much heavier. I don't know the
compositions of the two types of lead being compared, but I would guess that
soundproofing lead is unalloyed, in order to make it very soft, to maximize
damping. Roofing lead could have something added to make it stiffer, or
springier, so the damping would be less--which would make it less effective
for sound deadening.

There must be a reason you are asking about roofing lead--you've got some to
use up, maybe, or it's available as scrap. In that case "overkill" won't
cost you anything. You can't really make a genset TOO quiet.

Ignoramus1606 wrote:

I did a quick google search and found many types of sonex. Which one
would you use?

You may want to think about this for a minute. You are looking for
transmission loss and vibration damping, properties for which Sonex is
not noted. You want to look at how the noise is being coupled to the
air. The big problem in this type of system is providing the combustion
air while maintaing some acoustical isolation. Some time in the library
may save your buying materials (lead, foam, or whatever)that don't do
the job you had envisioned. You may want to try integrating the sound
isolation properties into the structure instead of tacking up stuff and
hoping for the best.

Kevin Gallimore

If you have to buy it. Why not look at SoundDown or Whispermat? They are
about the twice the price you are lookimg at but is made for the purpose and
far more effective and 1/3 the weight..

Just lead fixed to the inside of the cabinet will not be all that effective.
Lead needs a decoupling layer between it and the cabinet sides to prevent
mechanical transmission of the lows and an absorbent layer in front to take
care of the higher frequencies. Also the smallest crack will make the whole
effort almost worthless.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Ignoramus1606" wrote in message
...
I am soundproofing my genset. I built a little 1/2" doghouse, mounted
on the generator carriage. I am going to install lead lining inside,
using 1mm thick 2.5 lbs per square foot lead sheet. The weight of all
this lead is going to be approximately 100 lbs.

My question is, is "roofing lead" as good as "soundproofing
lead". Perhaps the alloy composition is different and it might impact
sound transmission characteristics? Any thoughts?

i

"Ignoramus1606" wrote in message
...
On Thu, 20 Jan 2005 19:15:58 -0500, axolotl wrote:
Ignoramus1606 wrote:

I did a quick google search and found many types of sonex. Which one
would you use?

You may want to think about this for a minute. You are looking for
transmission loss and vibration damping, properties for which Sonex is
not noted. You want to look at how the noise is being coupled to the
air. The big problem in this type of system is providing the combustion
air while maintaing some acoustical isolation.

If only it was about combustion air. This is an air cooled genset that
requires a huge quantity of cooling air to cool the cylinder fins.

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

The problem of having to have an opening is, therefore, rather
serious. It has to be a big opening and airflow cannot be obstructed
by too much baffles etc.

Some time in the library may save your buying materials (lead, foam,
or whatever)that don't do the job you had envisioned. You may want
to try integrating the sound isolation properties into the structure
instead of tacking up stuff and hoping for the best.

I have been reading about this stuff, it seems that there is not as
much systematic knowledge available.

i

i

I've done alot of rebuild and repair of a similar gen set, DOD model
MEP-018A which is about 10 KW, air cooled, gas engined. I am not
optomistic about your *ever* getting the sound level low enough to be
satisfied. Those things are noisy. The maintenance manual shows how to
lessen the noise by locating the gen set far away and covering it with sand
bags.
This is my way of saying you have a real task ahead of you.

Jerry

Ignoramus1606 wrote:


If only it was about combustion air. This is an air cooled genset that
requires a huge quantity of cooling air to cool the cylinder fins.

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

Oh boy.
The usual treatment is a serpentine air path lined with absorbent
material. You might try a box made of cement board with a serpentine
path (lined with rigid fiberglass insulation) in the front and back for
cooling air. I don't believe Sonex, Soundown or lead in an open box is
going to buy you much. The fix may end up to be a larger piece of
property and heavier electrical cable.

Kevin Gallimore

In article , Ignoramus1606 says...

I did a quick google search and found many types of sonex. Which one
would you use? Do you have experience with it?

Sonex is basically anechoic foam. We use it because we have
many very noisy vacuum pumps that run in our labs, and they
would drive us nuts otherwise.

These are hp and up pumps that are electrically driven.

We build a large plywood box around them lined with sonex
foam, and install one or two large muffin fans to circulate
air through the box so the pumps don't overheat.

Once they're boxed, you can't tell they're running, except
for the fan white noise.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

"Ignoramus1606" wrote in message
...
On Fri, 21 Jan 2005 02:36:01 GMT, Jerry Martes
wrote:

I've done alot of rebuild and repair of a similar gen set, DOD model
MEP-018A which is about 10 KW, air cooled, gas engined.


MEP-018A is not at all the same. I am very familiar with MEP-017a,
which I bought from the miitary and resold at a modest profit. With
MEP-018A, cooling air exhaust cannot be ducted outside, whereas with
my Onan, it can be. So, I made a duct out of some tinned ducting
materials. I hope that it holds up.


I am not
optomistic about your *ever* getting the sound level low enough to be
satisfied. Those things are noisy. The maintenance manual shows how to
lessen the noise by locating the gen set far away and covering it with
sand
bags.

Yeah, I remember that.

This is my way of saying you have a real task ahead of you.

I completely agree. That's why I wonder if lead sheets are going to be
a waste of time and effort, given the air requirements.

i

i

As long as you are already familiar with the noise level and think you
will ever be content with the level, I agree that a big, thick lead box is a
good way to lower the noise. I dont think you could have choosen a better
material.

Jerry

In article , Ignoramus1606 says...

I feel that some experimenting is educational, although there is some
point at which it will become more tiring than educational.

The nice thing about the sonex is it's relatively cheap and the
shipping won't kill you. If you buy a few hundred pounds of
sheet lead and find that it won't do, then you still have to
dispose of it somehow.

Plywood box, lined with sonex. Labyrinth to allow cooling air
and a big muffin fan, driven electrically.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

I am using SoundDown in my engine room. It and Whispermat are the standard
sound insulation for marine engine compartments. Panda, Onan and other
genset makers use it in their cabinets. Basicly they are 1/2 to 3/4" of PVC
acustical foam either side of a 1 lb/ft lead filled vinyl sheet. It is
appiled with spray on adhesive and welded or epoxied spikes and caps.

The general recomendation is to design baffel boxes so that the air has to
make at least one 180 turn so there is no direct path and the baffel should
be lined with the acustical barrier. Being cooled by a seawater heat
exchanger my diesel doesn't need quite that much vent area but here is an
example. The 28"wide x 6"high vent is on the back wall of the engine
compartment. The baffel box is 30"D x 8"H x18"D. It is oversize because
the first chamber is lined with 1.25" sound barrier. (I hope this comes out
in fixed width font.)

+----------------+
| |
| | |
| | Vent
| +--------+
Engine Compartment

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Ignoramus1606" wrote in message
...
On Thu, 20 Jan 2005 20:18:45 -0500, Glenn Ashmore
wrote:
If you have to buy it. Why not look at SoundDown or Whispermat? They
are
about the twice the price you are lookimg at but is made for the purpose
and
far more effective and 1/3 the weight..

I will check them out. Do you have experience with them?

Just lead fixed to the inside of the cabinet will not be all that
effective.
Lead needs a decoupling layer between it and the cabinet sides to
prevent
mechanical transmission of the lows and an absorbent layer in front to
take
care of the higher frequencies. Also the smallest crack will make the
whole
effort almost worthless.

Glenn, can you elaborate on this last point (about cracks invalidating
this). I will need an air opening for intake of cooling air, which
will be exhausted from the back. It has to be at least 2 square feet,
but I can somehow baffle it.

Again, I would love to be dissuaded from this idea of buying lead, if
in fact it is a wrong idea. I do not want to waste money.

i


--

I created a little "marine service company" so I could buy direct from
several distributors. Bought direct from Soundown http://www.soundown.com/.
They are the best but a bit pricy as they work primarily in the marine
market. They do have a couple of manuals on line with lots of technical
information.

A more industrial oriented site is http://www.soundprooffoam.com/. They
have a 1" thick 1 lb/ft barrrier on line price about $115 for a 4x8 sheet.
It comes rolled so it can ship UPS. Not quite as effective as Soundown but
about the same price as you were planning to spend for lead.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Ignoramus1606" wrote in message
...
On Thu, 20 Jan 2005 23:58:24 -0500, Glenn Ashmore
wrote:
I am using SoundDown in my engine room. It and Whispermat are the
standard
sound insulation for marine engine compartments. Panda, Onan and other
genset makers use it in their cabinets. Basicly they are 1/2 to 3/4" of
PVC
acustical foam either side of a 1 lb/ft lead filled vinyl sheet. It is
appiled with spray on adhesive and welded or epoxied spikes and caps.

Are you talking about "Barrier Composite Insulation" or some other
type of insulation. They have a lot of choices. What was the retailer
whom you used?

The general recomendation is to design baffel boxes so that the air has
to
make at least one 180 turn so there is no direct path and the baffel
should
be lined with the acustical barrier. Being cooled by a seawater heat
exchanger my diesel doesn't need quite that much vent area but here is
an
example. The 28"wide x 6"high vent is on the back wall of the engine
compartment. The baffel box is 30"D x 8"H x18"D. It is oversize
because
the first chamber is lined with 1.25" sound barrier. (I hope this comes
out
in fixed width font.)

I got it. Thanks.

+----------------+
| |
| | |
| | Vent
| +--------+
Engine Compartment



--

On 21 Jan 2005 03:26:18 GMT, the inscrutable Ignoramus1606
spake:

On Thu, 20 Jan 2005 21:58:03 -0500, axolotl wrote:
Ignoramus1606 wrote:


If only it was about combustion air. This is an air cooled genset that
requires a huge quantity of cooling air to cool the cylinder fins.

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

Oh boy.
The usual treatment is a serpentine air path lined with absorbent
material. You might try a box made of cement board with a serpentine
path (lined with rigid fiberglass insulation) in the front and back for
cooling air. I don't believe Sonex, Soundown or lead in an open box is
going to buy you much. The fix may end up to be a larger piece of
property and heavier electrical cable.

Thanks Kevin. I have some hopes that what I do will improve situation
somewhat. Specifically what is going to be behind the generator is a
high and wide deck. So, if I manage to redirect sound towards that, as
opposed to towards the front of the genset, my situation will improve.

It's better to muffle all sound than to try to redirect. If there are
trees (or neighbors!) in the direction of the redirect, they will be
sending some of that sound back, particularly in the higher freqs.
It's better to dampen it from -all- angles. It would also keep the
patio/deck nice to use all the time. Make sure you have the quietest
muffler system that the diesel will allow. I've heard they don't like
any backpressure at all.

I feel that some experimenting is educational, although there is some
point at which it will become more tiring than educational.

Want to try a low-cost solution? I've successfully used carpeting to
baffle noise from a compressor, primarily in the higher frequencies
but much of the lower frequencies were quieted as well. On something
that large, I'd try building a modified box at least twice its size,
(larger if you need exhaust cooling area) Spray a couple inches of
foam on the interior of each panel, then drape (old or new) carpeting
over the wet foam to form a triple skin, each with its own frequency
deadening attributes. You could later skin that with lead (and paint)
if needed. Alternatively, build double-walled shapes and fill with
foam, then tack carpeting on the inside. Indoor/outdoor carpet (as
thick as it comes) with foam backing, or used SHAG.

Top view of "box" showing venting between walls. Put carpet on the
outer side walls in inner passages (and floor/roof) for more sound
reduction. It's amazing how much noise it cuts by itself.

to deck
|===============================|===|
| | |
| | | genset | | |
| | | area | | |
| | | | | |
| | | | | |
| | | | | |
| | |
|====|==============================|
to home/shop

The long, tall side openings allow for full air flow.


-
Yea, though I walk through the valley of Minwax, I shall stain no Cherry.
http://diversify.com

I have small amount of knowledge, I took EE360 Acoustics in electrical
engineering, I built a house with the interior walls sound proofed, and
I have built allot of loudspeaker enclosures.

1) Don't mount the dog house to the carriage.
Mount the carriage with some isolation from the ground, like rubber,
tires, or better still: hanging with springs.
2) Go for the layered effect. Walls within walls.
A wall made with 2x6 top plate and bottom plate, but 2x4 studs staggered
on interior and the exterior and fiber glass wall insulation filling the
interior is good, the interior and exterior are still coupled at the top
plate and bottom plate. Other walls, such as the sonex or lead, should
not be connected anywhere and have their own foundation. Stagger the
sound leakage of the top and bottom plate of one wall with the weak
spots of the other.
3) Treat the air intake passage as carefully as the exhaust muffler.
4) Get the exhaust stack up high, the further up, the less sound comes
back down, and the less you will have to breathe.

Be careful what you pray for, it can happen.

"Ignoramus13187" wrote in message
...
On Fri, 21 Jan 2005 03:52:03 GMT, Jerry Martes
wrote:

"Ignoramus1606" wrote in message
...
On Fri, 21 Jan 2005 02:36:01 GMT, Jerry Martes
wrote:

I've done alot of rebuild and repair of a similar gen set, DOD model
MEP-018A which is about 10 KW, air cooled, gas engined.


MEP-018A is not at all the same. I am very familiar with MEP-017a,
which I bought from the miitary and resold at a modest profit. With
MEP-018A, cooling air exhaust cannot be ducted outside, whereas with
my Onan, it can be. So, I made a duct out of some tinned ducting
materials. I hope that it holds up.


I am not
optomistic about your *ever* getting the sound level low enough to be
satisfied. Those things are noisy. The maintenance manual shows how
to
lessen the noise by locating the gen set far away and covering it with
sand
bags.

Yeah, I remember that.

This is my way of saying you have a real task ahead of you.

I completely agree. That's why I wonder if lead sheets are going to be
a waste of time and effort, given the air requirements.

i

i

As long as you are already familiar with the noise level and think you
will ever be content with the level, I agree that a big, thick lead box
is a
good way to lower the noise. I dont think you could have choosen a
better
material.

Thanks Jerry. I feel that if a plywood box reduced noise by 5dB, then,
making same box even more soundproofed and adding baffles can get me
somewhere, especially considering the fact that the genset will be
outside and I care about some directions of sound propagation more
than others.

i

i

I read most of your RCM posts, and consider you to be a bright guy with an
interest in learning. I respect that. I dont offer any advice so that it
might diminish your plans. I do suspect that the noise from an air cooled
diesel generator will be so extreme that there will be no way to quiet it to
a level you will be satisfied with. I'm considering that this sound
absorbing is done with a limited budget.
I think you have already considered the wide bandwidth of the noise
spectrum produced by the generator. The highs are something you can absorb
in alot of affordable materials. The lows are going to be real difficult
to diminish to a level you'll accept (I think).
Remember, 5DB and even 10 DB wont hardly make any difference when the
level is so high to begin with. I assume you know about "3 DB" as being
the least amount of power level change thats agreed to have been adjusted.
And, less noise is still too much noise when the noise is so great at the
source.
The quieter it gets, the more your ears adjust and seem to hear better.
I think Alexander Graham Bell had that figured out 'way back when'.
I am not qualified to calculate the DB level you'll be trying to acheive.
I suspect you are better qualified in than calculation department than I am.
I do have some experience with trying to reduce noise levels from noisy
machinery and generators. It seems that the the quieter you get it, the
more 'quietness' you want. I wouldnt be surprised to learn that you will
want to diminish the noise level by 50DB or more when that generator is
producing power.

All that said, my advice would be to not spend alot of money on materials
till you are convinced you will ever achieve your acceptable goal within
your budget.

Jerry

"Ignoramus1606" wrote in message
...
On Thu, 20 Jan 2005 13:49:42 -0800, Roger Shoaf
wrote:

"Ignoramus1606" wrote in message
...
I am soundproofing my genset. I built a little 1/2" doghouse, mounted
on the generator carriage. I am going to install lead lining inside,
using 1mm thick 2.5 lbs per square foot lead sheet. The weight of all
this lead is going to be approximately 100 lbs.

My question is, is "roofing lead" as good as "soundproofing
lead". Perhaps the alloy composition is different and it might impact
sound transmission characteristics? Any thoughts?

i

It is overkill, but it will work just fine. Usually the soundproofing
lead
is 1/64 thick and about 1lb. per Sq.Ft.


Thank you. When you say overkill, in what sense is it an overkill? In
terms of benefit per weight of lead shielding added? Am I not going to
get better soundproofing from 2.5 times thicker lead?


i

Sure it will be a little better, but only a little bit. The thin stuff will
reduce the noise to near zero. The thicker stuff might be available in
smaller quantities however so that might be it's biggest point.
--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

Ignoramus13187 wrote:
On Fri, 21 Jan 2005 16:43:55 GMT, Jerry Martes wrote:


I read most of your RCM posts, and consider you to be a bright guy
with an interest in learning. I respect that.


Thanks.


I dont offer any advice so that it might diminish your plans. I do
suspect that the noise from an air cooled diesel generator will be
so extreme that there will be no way to quiet it to a level you will
be satisfied with. I'm considering that this sound absorbing is
done with a limited budget.


I have a sound level meter. The noise level from an un-enclosed
generator running in the open, at 10 feet, is 85 dB. I believe that it
is not so bad.


I think you have already considered the wide bandwidth of the noise
spectrum produced by the generator. The highs are something you can absorb
in alot of affordable materials. The lows are going to be real difficult
to diminish to a level you'll accept (I think).


This is an excellent point. The question is, from the standpoint of
not ****ing off neighbors too much, is 70 db of 125 Hz noise just as
annoying as 70db of 1000 Hz noise. I think that the answer is that
lower frequencies might be less annoying.



Remember, 5DB and even 10 DB wont hardly make any difference when the
level is so high to begin with. I assume you know about "3 DB" as being
the least amount of power level change thats agreed to have been adjusted.
And, less noise is still too much noise when the noise is so great at the
source.


Well, if I quiet it down from 85 unshielded to say 75 or even (maybe I
am dreaming) 70 db, that would be a very big improvement.

I know that I generally do not mind people running a lawnmower in
their yard, and those would produce noise comparable to my unshielded
generator. Google for lawnmower decibel, the most common number cited
is 90 dB for a lawnmower. My unshielded genset is 85. If my generator
produces even 80 decibel shielded, I would be basically fine.

I used to have an awful, disgusting 3600 RPM diesel generator that was
much, much noisier than my current Onan. Fortunately, I sold that POS
and the buyer is apparently satisfied (he left me good feedback).

So, perhaps you are thinking about such very noisy units, but my Onan
is a bit better.



The quieter it gets, the more your ears adjust and seem to hear better.
I think Alexander Graham Bell had that figured out 'way back when'.
I am not qualified to calculate the DB level you'll be trying to acheive.
I suspect you are better qualified in than calculation department than I am.
I do have some experience with trying to reduce noise levels from noisy
machinery and generators. It seems that the the quieter you get it, the
more 'quietness' you want. I wouldnt be surprised to learn that you will
want to diminish the noise level by 50DB or more when that generator is
producing power.


This is an excellent point, yes.


All that said, my advice would be to not spend alot of money on materials
till you are convinced you will ever achieve your acceptable goal within
your budget.


Thanks Jerry. The lead purchase was kind of a big leap for me. A big
(relatively) expense that is a real gamble. The reason for accepting
this gamble is that lead is the best material, and also that other
than this, there are no unknowns. The generator runs, and does so
quite well.

If I fail, I can always sell this lead on ebay for at least a fraction
of my original price.

i

But the buyer better be able to pick it up himself. G

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"As long as there are final exams, there will be prayer in public
schools"

On Fri, 21 Jan 2005 10:31:28 -0800, "Roger Shoaf"
wrote:

Sure it will be a little better, but only a little bit. The thin stuff will
reduce the noise to near zero. The thicker stuff might be available in
smaller quantities however so that might be it's biggest point.

I would expect it to be noticably better. If the lead acts as the
mass in a second-order system, 2.5X the mass per unit area should drop
the corner frequency by 2.5 x or 1.32 octaves. At a given frequency
above the corner freq, at 20 dB/octave that's 26.4 dB more
attenuation. The biggest issue will probably then be muffling the
air passage.

Since a genny runs at essentially constant speed, the air vent could
greatly benefit from tuned resonators, at least at higher freqs. A
heroic solution might be forced-air (a blower) moving air thru the
enclosure, with automotive mufflers on inlet and outlet.

On 22 Jan 2005 03:16:33 GMT, Ignoramus13187
wrote:

I will read on tuned resonators.

There is a program called "silencer" that is mainly for designing the
chemer sizes in mufflers. Might be worth a look - a freebie on the
Net.
Geoff

On 20 Jan 2005 20:59:01 GMT, Ignoramus1606
wrote:

I am soundproofing my genset. I built a little 1/2" doghouse, mounted
on the generator carriage. I am going to install lead lining inside,
using 1mm thick 2.5 lbs per square foot lead sheet. The weight of all
this lead is going to be approximately 100 lbs.

I understand that this is a fixed position genset so if you could
mount it below ground level and reflect the sound upwards you may get
about 6dB reduction, similar to bund walls alongside freeways, with
virtually no cost. Do not mount your box on the frame, leave it
freestanding, then vibration noise will not be transmitted to the box
from the frame. If possible, the lead sheet sides should hang from
the top of the box , not be fixed to the plywood sides, similarly the
top should be fixed only around the edges, with the centre free to
absorb sound. Suspending the lead on old carpet can help to stop it
sagging.

HTH
Alan
in beautiful Golden Bay, Western Oz, South 32.25.42, East 115.45.44 GMT+8
VK6 YAB ICQ 6581610 to reply, change oz to au in address