Page 1 of 4 1234 LastLast
Results 1 to 10 of 39

Thread: RF and ferrite beads

  1. #1
    Join Date
    Aug 2001
    Location
    Fort Wayne, IN, USA
    Posts
    27,246

    Default RF and ferrite beads

    I have one particular preamp that I can't use in one studio because of a radio tower that is about 1/10th of a mile away. Would ferrite beads on the input solve this?

    If so, what's a good source for ferrite beads? I guess I would only need three or two.

    Any advice would be appreciated.
    Lynn Fuston
    3D Audio

    Making beautiful music SEEM easy since 1979.

  2. #2
    Gio's Avatar
    Gio is offline 3D VIP 2008, '09, '10, '11
    Join Date
    Apr 2008
    Location
    Mid-Hudson Valley
    Posts
    2,952

    Default

    Something like this?

    http://www.fullcompass.com/product/260981.html
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	In-line RFI filte&.jpg 
Views:	48 
Size:	33.1 KB 
ID:	3092  
    Giovanni Fusco
    On Staff Here
    My Place

    "Real People, Real Performances."

  3. #3
    Join Date
    Aug 2001
    Location
    Fort Wayne, IN, USA
    Posts
    27,246

    Default

    Actually just want the beads to put inside the unit.
    Lynn Fuston
    3D Audio

    Making beautiful music SEEM easy since 1979.

  4. #4
    Troy Baldwin's Avatar
    Troy Baldwin is offline 3D VIP 2005, '06, '07, '08, '09, '10, '12
    Join Date
    Mar 2004
    Location
    Sacramento, CA
    Posts
    1,651

    Default

    I can tell you that for the mixer problem I brought up here awhile back, the beads did NO good. But then neither did anything else I tried.
    AD9 Audio Services
    ad9audio.com

  5. #5
    Join Date
    Jan 2006
    Location
    NorCal, USA
    Posts
    63

    Default

    Some months ago I put a ferrite choke on the cable at an audio input and it did absolutely no good. The problem was that I simply laid the cable through the choke and snapped it shut, figuring that was all there was to it. The key to "unlocking the secret of the beads" :-) I found, was to loop the cable a couple times around/through the choke and, like magic, realized a definite improvement. They're under $6 US at Radio Shack. Here's a link:

    http://www.radioshack.com/search/ind...w=ferrite&sr=1
    _________
    Dave P.

  6. #6
    Join Date
    Mar 2006
    Location
    West coast, USA
    Posts
    277

    Default

    I usually go to Digi-key for parts. But they only have 3100 different ferrite beads, and you'd be asking "which one"?

    Better: http://www.jensen-transformers.com/prices.html, bottom of the page, get a lifetime supply for $20. They also have knowledge about this sort of thing, so might give them a call.

    Beads may not help. For good RF immunity, mic input generally needs very short ("zero-length") connection from shield / pin 1 to chassis, as well as rf bypass caps on pins 2 &3 with "zero-length" to chassis. Once you have this, best first guess for ferrite placement is inboard of the rf bypass caps, although outboard could be the better - just depends on... lots of stuff.

    see also http://www.rane.com/note151.html and pdf at bottom.

    Wayne
    Last edited by TonemeisterW; 01-07-2011 at 09:46 PM. Reason: mo' info

  7. #7
    Join Date
    Sep 2001
    Location
    Inver Grove, MN
    Posts
    532

    Default

    I've got all sorts, give me a call, I'll send a care package.

  8. #8
    Join Date
    Aug 2001
    Location
    Fort Wayne, IN, USA
    Posts
    27,246

    Default

    Quote Originally Posted by TonemeisterW View Post
    Beads may not help. For good RF immunity, mic input generally needs very short ("zero-length") connection from shield / pin 1 to chassis, as well as rf bypass caps on pins 2 &3 with "zero-length" to chassis. Once you have this, best first guess for ferrite placement is inboard of the rf bypass caps, although outboard could be the better - just depends on... lots of stuff.
    Quote Originally Posted by Dan Kennedy View Post
    I've got all sorts, give me a call, I'll send a care package.
    Maybe I'll call the manufacturer. I don't want to mess with installing the beads if that won't help.
    Lynn Fuston
    3D Audio

    Making beautiful music SEEM easy since 1979.

  9. #9
    Join Date
    Mar 2004
    Location
    Eastern NC
    Posts
    2,639

    Default

    Take a 20+ ft mic cord and wrap it around a paper towel cardboard tube, forming an inductor. You should be able to hear a major improvement. I have this on my ham radio audio setup between the mic and preamp, which keeps the RF from getting back into the mic preamp. Works great...and I tried ferrite chokes--several of them--with no success.
    Quarter Note Recording
    Kinston, NC
    www.quarternotestudio.com
    QNS on Facebook

  10. #10
    Join Date
    Aug 2001
    Location
    Fort Wayne, IN, USA
    Posts
    27,246

    Default

    Quote Originally Posted by QNote View Post
    Take a 20+ ft mic cord and wrap it around a paper towel cardboard tube, forming an inductor. You should be able to hear a major improvement. I have this on my ham radio audio setup between the mic and preamp, which keeps the RF from getting back into the mic preamp. Works great...and I tried ferrite chokes--several of them--with no success.
    I'll give that a shot. Sounds just quirky enough to work. Do I have to put a rubber chicken in a paper bag and wave it over my head three times too?
    Lynn Fuston
    3D Audio

    Making beautiful music SEEM easy since 1979.

Page 1 of 4 1234 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •