What do you think of this DIY Reflexion filter design?

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brassplyer

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What do you think of this DIY Reflexion filter design?

Making A Homemade sE Electronics Reflexion Filter For $50 Part 1 of 3 - YouTube

The short version is he makes 4 panels which have these layers in this order:

-Stiff felt
-dowel rod for air gap
-aluminum foil - supposed to absorb/block low freq
-cotton balls
-wool khaki felt
-Soft felt wrapped and glued around previous layers - this is the layer that faces the mic

All mounted with velcro to a sheet of Lincane perforated aluminum.

How would you expect this to perform compared to an SE Electronics Reflexion filter which it's supposed to emulate? I see that the actual SE Electronics unit has the backing layers as continuous pieces across the whole width, rather than all incorporated into individual panels. Also the SEE unit has an additional layer of perforated plastic.

Do you have a DIY design you like and know works? It's my understanding an overly simple one like just a layer of black A/C insulater foam over bent paint screens which are common online isn't adequate because it doesn't do anything about low frequencies.

What about A/C insulator foam over a layer of rigid fiberglass?

Thanks.
 
Rigid fiberglass or rockwool, wrapped in cloth, mounted on hard backing surface.
The a/c foam won't do anything for you - it's in the a/c to block dust. The fiberglass or rockwool will absorb all frequencies, the hard backing surface will reflect back outside sound trying to get in.

"aluminum foil - supposed to absorb/block low freq" - where do people get this stuff? :facepalm:
 
I'm curious.

I don't think the materials the kid in the youtube video uses will work well, but I just watched the video from sE Electronics and they are using different stuff, not aluminum foil and cotton balls. The sE filter looks like it might work. I think they are capitalizing on the fact that when energy (sound, light, etc) passes from one medium to another, part of it gets converted to another form of energy, mostly heat. The denser and stiffer the mediums, the more energy gets converted.

So, here's the test. Build it, set it up as normal and add a 2nd mic behind the filter. Sing or use a freq sweep signal or whatever, record both mics, then flip the polarity of one mic and sum them together. See which freqs don't get filtered.
 
Yeah, but they had something different with wires or embossed lines for stiffness. It wasn't aluminum foil from the kitchen. LOL.
 
Here's what the sE Pro has:
Reflexion Filter Pro (RF Pro): The Reflexion Filter Pro has 6 main layers. The first of these is a strong layer
of punched aluminium, which diffuses the sound waves as they pass through it. The next is a section of
absorptive wool, and then a layer of aluminium foil to dissipate energy and break up the lower-frequency
waveforms. From this the sound travels through an air gap, which acts as an acoustic barrier, through a
further layer of wool and lastly an outer, punched polymer wall, which provides additional absorption
and diffusion of the remaining acoustic energy.

So the layer facing the singer/mic is punched aluminum? Interesting that all their lower models have an aoucstic foam layer facing the singer/mic.
 
mjbphotos said:
Here's what the sE Pro has:
Reflexion Filter Pro (RF Pro): The Reflexion Filter Pro has 6 main layers. The first of these is a strong layer
of punched aluminium, which diffuses the sound waves as they pass through it. The next is a section of
absorptive wool, and then a layer of aluminium foil to dissipate energy and break up the lower-frequency
waveforms. From this the sound travels through an air gap, which acts as an acoustic barrier, through a
further layer of wool and lastly an outer, punched polymer wall, which provides additional absorption
and diffusion of the remaining acoustic energy.

So the layer facing the singer/mic is punched aluminum? Interesting that all their lower models have an aoucstic foam layer facing the singer/mic.
Click to expand...

No, the punched aluminum is the rearmost layer. The side facing the singer is some kind of felt. There's also a layer of punched plastic (polymer) toward the front. The description you quoted has it backwards.
 
mjbphotos said:
The a/c foam won't do anything for you - it's in the a/c to block dust.
Click to expand...

Just to be clear, I don't think you're thinking of the right kind of foam, this stuff is fairly thick - looks a lot like Auralex type foam. I'm sure there's some degree of filtering.

p329055b.webp
 
brassplyer said:
Just to be clear, I don't think you're thinking of the right kind of foam, this stuff is fairly thick - looks a lot like Auralex type foam. I'm sure there's some degree of filtering.
View attachment 86227
Click to expand...

Ok, you're talking about foam designed to go NEXT TO the a/c unit (I assume to block external noise form th eplastic accordian-like thing that blocks the opening), not the foam that is INSIDE as a dust catcher.


brassplyer said:
No, the punched aluminum is the rearmost layer. The side facing the singer is some kind of felt. There's also a layer of punched plastic (polymer) toward the front. The description you quoted has it backwards.
Click to expand...

You may be thinking of a different model. The quoted construction is from their manual HERE
 
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