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Old 05-02-2012, 08:15 AM   #1
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DB or not DB - Generators

Something to remember about "close to" when talking about decibels of noise. Decibels are on a logarithmic scale.

That means if a generator is rated at 30 is compared to a generator that is rated at 40 at full power, the one rated at 40 is 10 TIMES louder than the one rated at 30.

Decibel - Wikipedia, the free encyclopedia

Another way of putting it; if the "sound pressure" on your ears has a power of 1,000 at 30 DB, the 40 DB generator puts out 10,000 pounds of ear pressure at 40 DB.

A "normal" conversation comes in at 60 DB; at 85 DB, permanent hearing damage is guaranteed. The sound pressure of a 747 at takeoff power is 80 DB.

While sound pressure decreases with the "square" of the distance from the source; you can see that a very small increment of sound measured in DB is a LARGE increase in sound pressure.

We won't go into when the DB level of generator "drone" becomes annoying since that is different for different people.
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Old 05-02-2012, 01:31 PM   #2
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Originally Posted by thehamguy1 View Post
I looked up the specs on the Champion 73531i and the Honda eu2001i and they're nearly the same. The Champion at 1/4 load is said to run at 54 dB; the Honda at the same load is 53 dB. The Honda weighs 46.3 lbs; the Champion, 48lbs. The Champions have parallel kits available just as the Hondas do, plus they're stackable as Hondas aren't. And at least one buyer said he saw the Champion at Sam's Club in NH for US$499.
Once again I have to say that 1 DB is 100% louder (twice as loud).
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Old 05-02-2012, 02:27 PM   #3
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Originally Posted by herk7769 View Post
Once again I have to say that 1 DB is 100% louder (twice as loud).
Sorry to disagree, Herk...

An increase of 3db is twice the sound "power", 6db is 4 times the sound "power", 9db is 8 times, etc.

At issue is the use of the word "loud". The db scale is used to measure sound because our ears hear "loudness" in a logarithmic scale. In other words twice as much sound "power" does NOT sound twice as loud.

So 4 times the power "sounds" twice as loud (0db to 3db) and 8 times the power "sounds" three times as loud (0db to 6db).

So although the db scale is logarithmic, so are our ears.

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Old 05-02-2012, 02:32 PM   #4
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Originally Posted by bean View Post
Sorry to disagree, Herk...

An increase of 3db is twice the sound "power", 6db is 4 times the sound "power", 9db is 8 times, etc.

At issue is the use of the word "loud". The db scale is used to measure sound because our ears hear "loudness" in a logarithmic scale. In other words twice as much sound "power" does NOT sound twice as loud.

So 4 times the power "sounds" twice as loud (0db to 3db) and 8 times the power "sounds" three times as loud (0db to 6db).

So although the db scale is logarithmic, so are our ears.

Bean
So with the 49db of the Honda verses the 53db of my Yamaha, do you think there will be a disernable difference? Really curious to see. The safety guy at work says I won't.
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Old 05-02-2012, 02:38 PM   #5
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Quote:
Originally Posted by bean View Post
Sorry to disagree, Herk...

An increase of 3db is twice the sound "power", 6db is 4 times the sound "power", 9db is 8 times, etc.

At issue is the use of the word "loud". The db scale is used to measure sound because our ears hear "loudness" in a logarithmic scale. In other words twice as much sound "power" does NOT sound twice as loud.

So 4 times the power "sounds" twice as loud (0db to 3db) and 8 times the power "sounds" three times as loud (0db to 6db).

So although the db scale is logarithmic, so are our ears.

Bean
Oh. I reread that Wiki entry and I think see, generally, what you are saying. What is confusing me is the table to the right in the Wiki article.
The sound "power" seems to go up by a exponential factor of one increment for every DB.

10 DB to 20 DB is 10 times more sound power.
10 DB to 30 DB is 100 times more sound power.

Where I am not following is the "your ear hears" part. If the sound is 100 times more powerful, why is it not 100 times "louder"?

I am going to move all this to another thread called "DB or not DB"
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Old 05-02-2012, 03:03 PM   #6
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About Decibels (dB)

I think I see what you are driving at and this article explained it so even I, (dense as I am) can understand it. My problem was equating an increase in power as a direct relationship with "loudness."

When talking about power:

3dB represents a ratio of two to one or a doubling of power.

Thus, a gain of 10dB would represent a ratio of ten to one for power
- so 10 dB is 10 times the power

A 40dB power gain would be 10,000 times the power.

However when talking about Loudness:

A 10 Db gain would seem to be about twice as loud
And a 20 Db gain would seem to be about 4 times as loud.
And a 40 Db gain would seem to be about 16 times as loud
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Old 05-02-2012, 05:47 PM   #7
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There have not been a lot of comparisons between Honda, Yamaha, and Champion. One I read about shows that at full load all are almost equally as loud at 7 meters.

Still I did find one interesting PDF on the Internet that shows just how different these inverter style gensets are when compared to a contractor style genset.

Check this link Honda EU2000i Generators in Single and Parallel Operation

It really is nice for some college students to show just what real db numbers are...
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Old 05-02-2012, 06:50 PM   #8
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I just received the Honda eu3000is today. Took it out of the box, attached the cables to the battery, added oil and gas and fired it up. All I can say is wow! This thing is quiet! As a comparison I pulled out my Yamaha ef2400 and started it up about 10ft away from the Honda. The Yamaha is quiet but the Honda is noticeably quieter. I tried both at idle as well with loads and the Honda is quieter in all. Not a huge difference but noticeable. So I answered my earlier question if the difference between DB and DB is actually noticeable to the human ear. I can say for sure it is to mine. Now I have to get the Yamaha cleaned up and ready to sell. It has served me well and would still highly recommend it. The Honda started the air conditioner on my TT with no problem.
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Old 05-02-2012, 08:16 PM   #9
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Just used a meter to check sound levels around the house. Held it at 5 feet from source.

Birds outside singing 50
TV at normal level 62
Dishwasher running 74
My Yamaha 2000 74 in Eco mode
My Yamaha 2000 88 top idle
My sweet 1 year old baby girl 102 (she was mad)

I only have about 60% hearing so my generator seems very quiet to me.
This is why I used a meter to measure.
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Old 05-02-2012, 08:29 PM   #10
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Quote:
Originally Posted by Mad4sax View Post
Just used a meter to check sound levels around the house. Held it at 5 feet from source.

Birds outside singing 50
TV at normal level 62
Dishwasher running 74
My Yamaha 2000 74 in Eco mode
My Yamaha 2000 88 top idle
My sweet 1 year old baby girl 102 (she was mad)

I only have about 60% hearing so my generator seems very quiet to me.
This is why I used a meter to measure.
My flight manual says ear plugs required at 85 DB.
You house must be a treat
Keep that baby HAPPY
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