How to sound proof a pair of s-7 miners.

Quote from: philipma1957 on October 30, 2015, 06:06:59 PM

the wall between the garage doors is a support beam. No can do

Well, actually it's a column, but that's the engineer in me speaking through my OCD.

Quote from: OgNasty on October 30, 2015, 06:52:48 PM

I have 6" non-insulated ducting to exhaust the heat and I'm surprised at the noise reduction. That alone makes a 100% fan quieter than a 65% fan without it. Have you tried a shorter length, like say 10" over the exhaust fan only? I am wondering if that would be enough to make a noticeable difference.

I'm not understanding the physics as to why a 6" long tube on the end makes it any quieter. Do you have dB meter readings to back this up?

I boosted fans to 70% and hash to freq 581.25

now I have a 'good' batch 1 and a 575 marked batch 2

but the 581 numbers with both combined below are decent

Quote from: Mikestang on October 30, 2015, 08:48:30 PM

I'm not understanding the physics as to why a 6" long tube on the end makes it any quieter. Do you have dB meter readings to back this up?

The 6" was diameter. Sorry. It is actually multiple feet long and leads outside, so that is where a majority of the noise is routed. I was just curious if a shorter 7" diameter insulated duct over the exhaust fan would also have a good noise reducing effect. I thought it might.

Quote from: Mikestang on October 30, 2015, 08:48:30 PM

Quote from: philipma1957 on October 30, 2015, 06:06:59 PM

the wall between the garage doors is a support beam. No can do

Well, actually it's a column, but that's the engineer in me speaking through my OCD.

Quote from: OgNasty on October 30, 2015, 06:52:48 PM

I'm not understanding the physics as to why a 6" long tube on the end makes it any quieter. Do you have dB meter readings to back this up?

the pitch changes with more length and since the air travels further it also exits that tube at a slower speed.

my meter readings on non insulated tubes were about 1db less but a bit pitch difference.

I used 7 inch concrete forms (sonotubes)
I used 7 inch metal duct work.

7 inch tubes fit right over the fan the 7 inch product from homedepot is very good

here is a cheap home depot product - but it is six inches it will not fit right

http://www.homedepot.com/p/Master-Flow-6-in-x-25-ft-Insulated-Flexible-Duct-R6-Silver-Jacket-F6IFD6X300/100396935

here is what I used 7 inch r8

http://www.homedepot.com/p/Thermaflex-EverClean-7-in-x-25-ft-HVAC-Ducting-R8-0519-0700-0003/203767737

big price difference

this 8 inch will fit and is a good price. it is in many stores and may the best choice along with duct tape.

http://www.homedepot.com/p/Master-Flow-8-in-x-25-ft-Insulated-Flexible-Duct-R6-Silver-Jacket-F6IFD8X300/100396936

It would be easier to just buy the right size ductboard and then use egg crates padding.

http://www.certainteed.com/resources/3034015.pdf
http://www.certainteed.com/products/insulation/mechanical-industrial/317382

You can find simple ductboard locally and they make it in squares, which is easier to work with if needed.

I just force vent the exhaust into the garage and have a window mounted attic fan that forces air into the room next to the detached garage. I live in Texas, so we can't seal things up otherwise we wind up with mold.

Ufo

temps dropped to 45f
my heat is turned off
coldest part of the house =74f
the garage is 86f
sound is good----------looking for the meter

good overnight numbers fan at 60% freq at 587

saw this old youtube video on "PC Fan Muffler"

https://www.youtube.com/watch?v=-5vvtt_vwgo

My S7s will be outdoors so all I need to keep the noise down.

Will this fan muffler work ? It certainly use all the concepts discussed in this thread but its look so simple without ducting.

Quote from: citronick on November 01, 2015, 07:42:59 AM

I would be worried about restricting the airflow with something like that.

Quote from: OgNasty on November 01, 2015, 08:15:44 AM

I would be worried about restricting the airflow with something like that.

Definitely WAY too restrictive... There's nothing wrong with the principle behind what they're doing, it's simple: eliminate direct paths for the soundwaves, and replace highly reflective (audible-wise) surfaces with non-reflective ones (ie; foam). I have a huge rack mount case that does much the same thing, but you need to make sure the air channel is at least the same size as the fan, and if you're introducing turns and obstructions then you need more space than that.

Quote from: citronick on November 01, 2015, 07:42:59 AM

won't work it will cut down the fan speed and air flow way too much.

the ducts I use work they are 7 inch and fit the fans easy.

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