# Why so loud?



## crabjoe (Apr 20, 2020)

On a generator.. shoot, it could be a mower.. Why are they so loud? Is it the vibration of the whole generator or is it mostly because the almost non-existent mufflers?

I know cars engine are crazy loud if you remove the muffler and cat... But the mowers, generators and what not.. small engine products, they're small.. If it's just mostly because of the exhaust, why can't I run the the exhaust into a small motorcycle muffler or something to get the sound level down?


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## iowagold (Jan 22, 2020)

this is plain and simple!!
lol
buy a honda eu7000is or any eu series of gen set!!
at less than 67 db as they sit..
they are some of the super quiet gen sets.

now for the noise and any of the small engines...
thin, low mass block as well as did I mention thin?? lol
then there is the exhaust...
the more the exhaust is restricted the less the performance and more heat run away.

to combat this generator noise on a large frame gen set insolated rooms.
and the best way to stop the trumpet noise from any gen set is redirection of the sound..
up is the best thing to do with a gen shack..
some have tried a water muffler, glass pack, auto mufflers, steel wool. just to mention a few.

there is a couple of companies that make after market cat converters now.
and the price is the big issue... $300.00 usd and up for a small cat for like a briggs engine.








BlueCAT™ SSI (Small Spark-Ignition Engines) Catalytic Converter


BlueCAT™ Small Spark Ignition (SSI) engine emission control system is ideal for LPG, CNG and gasoline engines used in small off-road engines




www.nettinc.com




and this one
GENCAT Catalytic Converter for small engines
the cool think on the small cats is they reduce the C/O in the exhaust..
the bad thing is the cat is Heat.
you need to make sure the exhaust is well ventilated with good air flow.

one of the methods that does work is the vortex style muffler insert.


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## speedy2019 (Jan 29, 2019)

My 2800watt gen is 69db but it sounds really loud to me, you cant have a conversation next to it, thats for sure... But the powerful they are the nosier they get and thats 1 of the reasons I didnt buy a overly powerful gen.


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## drmerdp (Apr 10, 2018)

Most of the noise from an aircooled engine is from the engine block itself. Small engine mufflers these days are pretty good. Definitely better then the junk from the old days of flat head engines. 

Watercooled engines have thicker blocks, but more importantly water jackets filled with a water-glycol solution which does a great job of reducing noise.

A sound attenuated and properly ventilated enclosure is the best way to quiet down a generator. In the case of the very quiet inverter style generators the inverter has little to do with the sound. Yeah being able to adjust rpms to a given load and "idle down" helps, but the trick is in the fact that the engine is incased in a sound deadening plastic enclosure, then an outer shell.

Open frame inverter gens are as loud as standard alternator style generators.


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## crabjoe (Apr 20, 2020)

drmerdp said:


> Most of the noise from an aircooled engine is from the engine block itself. Small engine mufflers these days are pretty good. Definitely better then the junk from the old days of flat head engines.
> 
> Watercooled engines have thicker blocks, but more importantly water jackets filled with a water-glycol solution which does a great job of reducing noise.
> 
> ...


Good to know it's mostly from the block and not the exhaust. 

I watched a few youtube videos on using a generator shed. The ones I saw, where the had the generator running with the shed opened or closed show a difference in sound levels, seemed to show it made almost zero difference. I wish they had used a sound meter to show what kind of difference the sheds made.

If I were to build a generator shed, how much in noise reduction do you feel I can achive? I really hate running my Generace GP15000e because of how loud it is.. I feel like you can hear it from the next county over...


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## Melson (Dec 8, 2019)

crabjoe, well engineered sound attenuating enclosures can be impressively quite, even spookily quiet. Simply building a wooden shed, installing a generator, then shutting the door probably won't do much without some amount of sound deadening material and techniques.
There can be several modes of source noise, but typically are: Vibration; airflow; exhaust. Each component uses specific attenuation techniques.
One excellent example of 'how quiet can it be?' is Onan's (now discontinued) turbo-diesel powered QuietSite 30 and QuietSite 60 models, which were quiet enough to be used next to sensitive locations such as bedrooms. 
Basically, these trailerized packages embodied the low noise level of a Honda eu-series generator but with a 30 or 60 KW rating. It all depends upon how you engineer the enclosure.


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## tabora (Sep 6, 2018)

crabjoe said:


> ...The ones I saw, where the had the generator running with the shed opened or closed show a difference in sound levels, seemed to show it made almost zero difference...


The shed makes a huge difference. I've been doing this for 30 years with LOUD generators and they are MUCH quieter when run in the enclosure, especially from a distance.


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## speedy2019 (Jan 29, 2019)

My generator is at the side of the house near my door and the difference in noise with the door shut, it must be 80% quieter and I can barely hear it if I am in the sitting room and thats at the other end of the house.. amazing.


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## crabjoe (Apr 20, 2020)

Thanks folks.. Seems like my next project will be a gen shed, with lots of sound absorbing panels added..


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## Melson (Dec 8, 2019)

sure, tabora, I get it. Noise is subjective: Get far enough away from a sound source and it's no longer a nuisance. 
But not everyone has the luxury of wide-open space for noise suppression.

The OP's original question was why so loud even with doors and walls. And I took that to mean 'standing close by'. 
I was pointing-out, if you want something truly quiet, you need to dampen the standing waves, the vibs, the fast-moving air noises. 

I have my generator in an acoustic enclosure underneath my deck. it's quiet we don't hear it inside, our neighbors don't hear it. Still, if you're on the deck you can hear or maybe feel vibrations.

I thinking that maybe at my age my ears are particularly sensitive? On the other hand, maybe after "30 years" of running generators yours are shot?


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## tabora (Sep 6, 2018)

Melson said:


> sure, tabora, I get it. Noise is subjective: Get far enough away from a sound source and it's no longer a nuisance. But not everyone has the luxury of wide-open space for noise suppression.


Even standing right next to (well, 10 feet away from) the Suncast with the big Powermate, the truck box with the small Powermate, or the Onan with the service door closed, the difference between uncovered and covered is 10-15dB.


Melson said:


> The OP's original question was why so loud even with doors and walls. And I took that to mean 'standing close by'.
> I was pointing-out, if you want something truly quiet, you need to dampen the standing waves, the vibs, the fast-moving air noises.


This is true. The truck box had Sonex foam attached to all the inner surfaces and the Onan enclosure has sound deadening insulation. The Suncast has double-walled plastic that certainly helps, although having the large louvered openings on both ends for cooling negates that somewhat. It's almost as quiet as my neighbor's big propane Generac, and MUCH quieter than the uncovered portable open-frame generators in the neighborhood.


Melson said:


> I thinking that maybe at my age my ears are particularly sensitive? On the other hand, maybe after "30 years" of running generators yours are shot?


Nope, not even close. Still have wolf ears, apparently.


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## tabora (Sep 6, 2018)

tabora said:


> ...The Suncast with the big Powermate... the difference between uncovered and covered is 10-15dB... The Suncast has double-walled plastic that certainly helps, although having the large louvered openings on both ends for cooling negates that somewhat. It's almost as quiet as my neighbor's big propane Generac, and MUCH quieter than the uncovered portable open-frame generators in the neighborhood.


Here are a couple of videos of my Coleman PM0126000 running with the shed open/closed...









Closed.mp4


Shared with Dropbox




www.dropbox.com













Open.mp4


Shared with Dropbox




www.dropbox.com


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## crabjoe (Apr 20, 2020)

tabora said:


> Here are a couple of videos of my Coleman PM0126000 running with the shed open/closed...
> 
> 
> 
> ...


Holy Moses! I can't believe how much of a difference that it makes. And it looks like you didn't add any sound deadening foam or anything. Just cut openings for ventilation and to run wire through it!

I think I might head over to HD tomorrow and tell them to keep the Q6500 I ordered and have them get me the Champion DH 8750. With that kind of noise reduction, I think an open framed generator would be fine in a box.


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## ToolLover (Jan 13, 2020)

Well, if you are going to dance, then you have to pay the preacher!
I took notice that Generac reduced the sound deadning properties of their new generacs.
I don't like the loss of sound reduction but I certainlt would not let that be a deteriant to my generators.
Oh, by the way, that little 6500 watt Honda is so quiet I have to strain to hear it.


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