Phresh duct silencer good or no?

hey i got a phresh filter silencer today... i wanted to cut my exhaust sound down as much as possible saw these and thought id give it a go.. anyone have them? I'm about to hook it up now.. i run a carbon but anyone that runs straight exhaust knows how old the damn things are outside when blowing.... ill let you know how it works IMOP but love to hear anyone else that has one...

Those are less than effective for lower frequencies. They're not long enough

Rrog said:

Those are less than effective for lower frequencies. They're not long enough

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AGGHHHH seriously... that pisses me off.. i thought the same thing when i pulled it our i was thinking i should really have had two it makes more sense... well ill see what the Decible rating is and then put it on and see what changes were made if any..

well wait when you say lower frequencies are you referring i assume to the pitch and not decible rating.. so it will still have the roar sound.. maybe a bit less but the hollow roar will always be present?

Frequency = pitch

Decibel = volume

So high frequency bird calls will be affected by the muffler, but not lower frequencies. The dB rating they give is very likely measuring very high frequencies, giving a big dB drop rating, but not necessarily satisfy you.

insulated ducting will muffle the sound pretty good. To cut out sound completely you would need the fan to be in a sound proof box. That would require sound proofing foam, sound dampening carpet, mdf board, and spacers (1/2 inch gaps between 2 walls). The carpet and the mdf (micro density fiber) board you can get at home depot. The foam from foambymail.com. The idea is to make the sound bounce around in the box. just like a music studio or sound stage

phil k said:

hey i got a phresh filter silencer today... i wanted to cut my exhaust sound down as much as possible saw these and thought id give it a go.. anyone have them? I'm about to hook it up now.. i run a carbon but anyone that runs straight exhaust knows how old the damn things are outside when blowing.... ill let you know how it works IMOP but love to hear anyone else that has one... View attachment 3407491View attachment 3407492

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I been using mine for a few yrs....works just fine..

Filter>fan>silencer>ducting.....

Went from jet engine,to something like an electric engine..

Not to be picky, but "soundproof" and "foam" don't belong in the same sentence. Whether you're building a wall or a box, simple fiberglass is about as good as it gets. The key is to make the inner and outer surfaces massive. Ply, OSB, MDF, and 5/8" drywall are common examples. The insulation material is more minor element.

You would be building a box like Hyroot said, where sound gets in, and is forced through the fibrous insulation, robbing the sound wave of energy each time it passes through.

Rrog said:

Not to be picky, but "soundproof" and "foam" don't belong in the same sentence. Whether you're building a wall or a box, simple fiberglass is about as good as it gets. The key is to make the inner and outer surfaces massive. Ply, OSB, MDF, and 5/8" drywall are common examples. The insulation material is more minor element.

You would be building a box like Hyroot said, where sound gets in, and is forced through the fibrous insulation, robbing the sound wave of energy each time it passes through.

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sound proofing foam makes the sound bounce in different directions. That's why the egg carton shape. Not just any foam but foam made for studios. Its acts as a bass trap. Then some some higher pitch gets through the dampening carpet, then bounces back and forth in the spacers. What I explained before is how you build a studio. I'm a audio engineer. I learned to build studios from one of my teachers in audio school. Look up bill Dooley. One of the most famous engineers in the industry. He testified in court when judas priest supposedly had satanic messages of played backwards. He testified how that's impossible.

Rrog said:

Frequency = pitch

Decibel = volume

So high frequency bird calls will be affected by the muffler, but not lower frequencies. The dB rating they give is very likely measuring very high frequencies, giving a big dB drop rating, but not necessarily satisfy you.

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well what about extending it? what if the chamber length was doubled or tripled by adding 1-2 more? or am i going to be basically just muffling anyway i go about it? honestly i want it to sound like my dryer sounds coming out of my house and not like theres a wind tunnel in my basement...

hyroot said:

insulated ducting will muffle the sound pretty good. To cut out sound completely you would need the fan to be in a sound proof box. That would require sound proofing foam, sound dampening carpet, mdf board, and spacers (1/2 inch gaps between 2 walls). The carpet and the mdf (micro density fiber) board you can get at home depot. The foam from foambymail.com. The idea is to make the sound bounce around in the box. just like a music studio or sound stage

Click to expand...

well its not the sound of the actual fan itself my grow room is almost sound proof.. i have 2 drywall layers inside the rooms.1 plywood layer under that .. then the outer walls have 2 layers of drywall.. so sound from the fans not the issue.. its more the GUSHING sound outside from my exhausts blowing the air out that i want to control....

have you ran insulated duct work? i assumed it would be the same effect but for the price i didn't wanna just buy it on a whim and try it..

This is a common misconception. In-room treatment vs in-wall treatment. Two different beasties.

Foams and denser insulations are better for on-wall surface attenuation. So in a studio, theater, gymnasium, etc where reverberation control is needed you would reach for a denser material. This might be foam or compressed fiber like duct liner or OC703, etc. This is a measured test, yielding a NRC- Noise Reduction Coefficient. Denser foams and insulations give a higher NRC. One surface in play in this scenario (the surface of the wall being tested). The sound wave has one interaction with the insulation. One bounce.

For in-wall sound control, we have two parallel surfaces now, generally the backs of the two drywall layers. Multiple bounces through the insulation. This is the box we've been discussing. Close parallel surfaces, bounded by mass. When we look at the role of foam / insulation in this setting, we find that the lowly, humble fiberglass works as well as anything. The finest acoustics lab in the world is Canada's National Research Council, the NRC. Look at their data in reports IR-761 and IR-693. 18 months of data describing the role of insulation in a wall or ceiling.

Insulation is one instance where you don't get what you pay for. In this instance, the best material to use is also the least expensive.

So a massive box made from MDF will contain the initial sound wave, forcing it to bounce through the insulation, robbing it of energy. To increase the effectiveness, make it longer. If this were a studio or theater, such a muffler (field assembled, not purchased) would be 10 feet long due to the extraordinary sound levels you're dealing with. For a vent fan, you could test if a 2' or 4' piece would work better.

k .... i appreciate that

Also, if the exit point of the vent is larger, the air will slow. So a transition from a 6" duct, to a 10" muffler sort of thing. You see the P filters are wide

I have an htg 6 inch version of that and it works good. I have to be within a few feet of the exhaust to hear it....very happy with that.

Hmmm. Seems Phresh makes that duct silencer with a fan mounted inside. It is a bit longer to accommodate the fan.

That's a sweet looking assembly!

i do like the insulated ducting myself, and a good speed controller to dial in the right sound for your application

phil k said:

hey i got a phresh filter silencer today... i wanted to cut my exhaust sound down as much as possible saw these and thought id give it a go.. anyone have them? I'm about to hook it up now.. i run a carbon but anyone that runs straight exhaust knows how old the damn things are outside when blowing.... ill let you know how it works IMOP but love to hear anyone else that has one... View attachment 3407491View attachment 3407492

Click to expand...

i have seen these types of silencers in use at the hydro shops, they really do quiet the exhaust noise allot,, good luck

The Phresh Hyper Fan Stealth comes with a speed controller.