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desk tower 3way WIP.. (BlieSMa t25b + ETON 3-212 + Seas l26roy) + Hypex + PE boxes

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headshake

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Thread Starter #41
Awaiting the end result with excitement!
Cheers! It will be a week+.

Do you have idea on what frequency can be attenuate by felt only and what frequency need to use MPP? I am thinking is whether 2000Hz a good number there or we can go lower and leave the higher frequency to felt.

Splitting the baffle can attenuate multiple frequencies, but does it make the effect lower because you have less area per frequency range?
I expect the felt to run out of steam around 1-2khz. I went up to 3khz because I wanted to overlap the tweeter's range. Where each section is tuned should shift down with each layer of felt that I add.

I hope to measure over each area of the baffle and see if there is anything to see. Again, my baffle is tiny so this could all be a waste.

https://www.researchgate.net/figure...lt-and-wool-felt-with-membrane_fig4_316773713

That is one view of wool felt. The MPP paper used a plant-based jute felt.

more:

https://www.scirp.org/pdf/OJA_2017061616554618.pdf
https://www.researchgate.net/public...ials_with_Improved_Sound-Absorbing_Properties
https://www.researchgate.net/public...xtile-Based_Waste_for_the_Automobile_Industry

The felt I am using is listed as between f1 and f5. This is the more dense stuff so it should be good for what I need it to do.
http://www.usfelt.com/sae_felt_specs.html

The pics are ripped from the papers. They mostly show different densities of felt and different ways of making it. WHXXX, WM, and CML are all felt.
 

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Thread Starter #42
I did not want to solder the tweeter out of fear of cooking it. I also have the need to change out the baffles. Crimping it is! The BlieSMa has gold connectors and I wanted to show it some non-corrosive love. I had to buy all of the gold "Female Disconnect" sizes since none of my drivers are the same. (Thanks, manufacturers!)

I had to use a tiny screwdriver to open up the fem. disconnect. You will go mad if you just try the fem. disconnects out of the package on a driver. Dry fit FTW. The wires are soldered to a SpeakON connector.

https://www.parts-express.com/Gold-...2yHENYAIuG5UM0kc5Uv2_vq0bKy9JYqsaAvBHEALw_wcB
 

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Thread Starter #43
Woot! I got my parts today for the final round of my little experiments. I did a dry fit and things look great.

The scientific paper for the perforated metal that I based lots of this off of is kinda old. There are newer papers that cover what is happening inside the chambers I am making. Looks like a larger hole size could let me control the phase.

I hope to be listening and measuring tomorrow.
 

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Thread Starter #44
Some pics/measurements of the new baffle....

"dry_fit_2layerfelt_mpp_noMELAMINEvsMDF.png " Shows what would happen if you had a mic 6" above the new baffle on a table while you played 500-5000hz pink noise from a speaker in the center of the room 2m away. My aim was to measure some off-axis room soup off the surface. Each measurement is made from 10 RTA averages. I would place a 1/2" thick mdf board on top for the mdf measurements. There is no melamine in the new baffle for this measurement, just 2 layers of felt on top and the steel plate. This was my sneak peek before I glued it up. So far so good!

The unexpected thing is I both hear and measure more bass. Steel seems to really start reflecting around 600hz.

I also need to take a higher SPL distortion sweep.

The decay looks great to me. None of my felt-alone measurements look this good.

Back to measuring....
 

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