Anyone using Sendust (Fe,Si,Al) to absorb stray EMI?


Sendust is a magnetic metal powder that was invented by Hakaru Masumoto at Tohoku Imperial University in Sendai, Japan, about 1936 as an alternative to permalloy in inductor applications for telephone networks. Sendust composition is typically 85% iron, 9% silicon and 6% aluminum.

Molex and Oyaide make tape and sheets with varying thickness to control stray EMI.

I have used the Oyaide Sendust sheets with power distribution builds. I find it works best with power distribution. 
I would enjoy hearing others experiences. 
sonicshading
No, but I tried to order one A4 sheet from Mouser. It was going to cost $145 delivered to Australia, so I cancelled the order.

At that price, I hope it’s good! It does sound interesting...
Hi, whostolethebatmobile

Yeah, I found the Mouser pricing to be really high too.

If you're down under, I recommend the Oyaide MWA-030L (A4 size).
Not sure about your conversion, but it cost me about 50-60 USD.
You can get smaller sheets for half the price too. they also have a tape.
these smaller sheets are around 20 USD:
https://oyaide.com/catalog/products/p-3974.html

The only place on audio gear that I used the sheets is around the AC iec inlet or power supply. But mostly just in and around the AC outlets and breakers.
Here are some examples for those interested:
https://oyaideshop.blogspot.com/search?q=MWA

Stay away from the MWA-100 S as it is 1 mm thick, and I find it affects frequencies in the audio band. The only place you might find use for this is in a AC breaker box with all your circuits radiating and possibly absorbing EMI.




Thanks sonicshading - Oyaide seems much more reasonable for a trial sheet. 
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Sendust appears to be a type of mu metal, aka Kool Mu, high permeability alloy used to absorb magnetic fields in transformer applications, for example, not RF, which is a horse of a different color. 🦓  Examples of materials that are good for RF absorption/shielding include high-conductivity graphene, carbon fiber cloth, copper sheeting.
Hi geoffkait,

clearly you are qualified to make these points?!?! Your website of tweaks  (machina dynamica) - omg...

Sendust does have more than one application
I believe they are referring to EMI (further up the spectrum sir) - and yes this material does absorb it. This is actual science not hearsay. If you bother to do your research you would know that.

But please enlighten us with your bag or tricks?!?!
Yes, I’m qualified to make those comments. You obviously are not qualified to understand them. No offense.
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@gogogadget Joined AudiogoN July 18, 2019. Member for one day. AudiogoN has been around for 20 years. In his first posts, he’s right - everybody else is wrong. Very unusual way to introduce himself to the community.
Quick Study on mu metal (Sendust is a type of mu metal alloy with specific applications, e.g., high power inductors). Mu metal in audio applications is found in wrapping speaker magnets and wrapping transformers. The percentages of metals and the metals used in the  various types of mu metal can varying according to application. 

”Mu-metal is a nickeliron soft ferromagnetic alloy with very high permeability, which is used for shielding sensitive electronic equipment against static or low-frequency magnetic fields. It has several compositions. One such composition is approximately 77% nickel, 16% iron, 5% copper, and 2% chromium or molybdenum.[1][2] More recently, mu-metal is considered to be ASTM A753 Alloy 4 and is composed of approximately 80% nickel, 5% molybdenum, small amounts of various other elements such as silicon, and the remaining 12 to 15% iron.[3]The name came from the Greek letter mu (μ) which represents permeability in physics and engineering formulae. A number of different proprietary formulations of the alloy are sold under trade names such as MuMETAL, Mumetall, and Mumetal2.

Mu-metal typically has relative permeability values of 80,000–100,000 compared to several thousand for ordinary steel. It is a "soft" ferromagnetic material; it has low magnetic anisotropy and magnetostriction,[1] giving it a low coercivity so that it saturates at low magnetic fields. This gives it low hysteresis losses when used in AC magnetic circuits. Other high-permeability nickel–iron alloys such as permalloy have similar magnetic properties; mu-metal’s advantage is that it is more ductile, malleable and workable, allowing it to be easily formed into the thin sheets needed for magnetic shields.[1]



Wow, you guys are hilarious,

Please enlighten the world and delete posts that speak to the truth.

https://www.researchgate.net/publication/250232490_Permeability_and_EMI_Characteristics_of_Sendust-Polymer_Composite

Sorry guys, I have to get back to actually working on the Albums you purchase.

Obviously the acronym EMI can have more than one meaning, such as electromagnetic induction. That’s why Sendust is used in inductors and induction motors. It’s a mu metal. Am I repeating myself? But most people take EMI as the acronym for electromagnetic EM interference, which is the same thing as RFI. The difference between (stationary) magnetic fields and electromagnetic EM waves (RF) which travel at lightspeed is like the difference between a goat 🐐 and a watermelon 🍉