Ferrite Beads & Noise Suppression

[Ginsly]

I've checked out past discussions about these, but I'm still left with some questions.

I rarely see these incorporated into high-gain/high-noise circuits - really just Spaceman Effects, though there may be others.

Do they really make an audible difference? I was going to pick some of these up, but they're always sold out... rats.

When I was looking at ferrite chokes years ago, it seemed that the "Mix" was an important consideration regarding what the ferrite may filter out. I don't see that info listed often, and the Tayda ones just mention "76ohm". I had initially researched clip-on beads for guitar cables, etc a while back (didn't seem worth it), but these are axial ferrites that would be soldered into the circuit itself. This AMZ article is a good start, but I'd love to hear from anyone who might have insight into this.

I have a noisy environment, love high-gain fuzz, am surrounded by crappy LED lights and Bosnian (?) radio stations, and sometimes have a floating ground due to battery-powered gear. What a winning combination! Obviously a good power supply helps, and I use a Truetone CS6 - it's been great.

I'm always looking for good in-circuit ways to minimize RFI/EMI noise without throwing too much of a blanket over everything. Still haven't tried incorporating ferrite, so thought I'd ask what the scoop was!

 

[pingpongcomputer]

I've used them in DEFX Spaceman projects, all of which are pretty low noise, but I can't say how much the ferrite beads are contributing. I never thought to check Tayda, just got a roll from a seller on ebay like these, probably the same thing at Tayda.

Edit just found these at digikey for 18 cents each, same dimensions and close to the same resistance/noise filtering, though it's never specified in the build docs, just "ferrite bead"

 

[jwin615]

They're made to block RFI. Think 1Mhz and up. May help control an oscillating opamp via cleaning up the power connection that's coupling with audio through bleed?
But generally, it's to clean up RFI that's picked up via a transmission line. That's why you see them on DC power cables for digital devices.

 

[Stickman393]

From what I've read - yeah, it's a RF thing. It can help remove noise in a DC power supply. Sometimes that noise gets shifted into the audio spectrum - can't say I know the exact mechanisms at play there, but I've certainly wrapped a ferrite choke around a DC power supply cable and heard an immediate difference on the piece of equipment that it was supplying power to.

In audio circuits, however, it's unlikely to make much of a difference. The frequencies involved are way beyond the range of human hearing.

 

[Aentons]

There is a section on it in this book. Pg.264 .
It talks about material types on Pgs 241-243

RF Components And Circuits

 

[Ginsly]

I've used them in DEFX Spaceman projects, all of which are pretty low noise, but I can't say how much the ferrite beads are contributing.

Yep, I have to assume he thinks they make a difference since they're in so many Spaceman pedals...

In audio circuits, however, it's unlikely to make much of a difference. The frequencies involved are way beyond the range of human hearing.

This is kind of what I'm assuming- otherwise we'd probably see these a lot more.

There is a section on it in this book. Pg.264 .
It talks about material types on Pgs 241-243

RF Components And Circuits

Thanks for the link! Seems like Mix 26 might (?) be the best bet for dealing with EMI, but the problem would be locating a ferrite bead that was labeled as such; even then, it sounds like it might not do too much.