RFI AM radio SR 32.4 XLR Mic inputs

Studio log 2 Minutes

Hello I have a Mackie SR32.4 mixing Board.
Its about 7 years or less old SN.9M1811.
I get AM radio on Mic line inputs with a new double shield snake hooked up to sure SM58’s and sure Laples. The nearest AM transmitter is 4 miles or more. The RFI comes and goes depending on weather.Mackie has a solder in RFI filter fix that you can make yourself.. I know as we did it once on diffirent install…
But I see no mention of it here… anyways does someone know of a prebuilt RFI filter xlr cable or barrel for a good price?In older mackies IMHO RFI is a know problem (do a google search) in some cases… Mackie wanted a wide frontend… well its a little to wide ! Like DC to Daylight.. hehe just kidding.. I like Mackie
but AM radio in the mix is a little to much!Any ideas are welcome?
Link to Mackie mystery filter?
Prebuilt filters?Thanks in advance
Vis.here is mackies reply:This LC Filter network has proven to be effective in filtering out AM RFI.
Install this filter by hard wiring it (i.e. soldering) into an XLR shell on the end of a mic cable.Attach the modified end of the mic cable to the mixer?s mic preamp input.
(For very extreme RFI environments, the capacitor can be changed to 0.01mF.)Parts RequiredCoil Digikey part#
Unsheilded 220mH DN-2576-ND 800-344-4539
Sheilded 220mH DN-41224-NDCapacitor Mackie part#
Poly 0.0047mF/50V 200-034-00 800-258-6883
Ceramic 0.01mF/50V 210-001-00Note: Mackie Designs makes no claims as to 100% effectiveness of the above mod.
Factors such as location and sound system installation techniques can make a drastic
difference in RFI intensity.? link to drawing
mackie_rfi_filter.jpg

Mackie RFI filter?PDF FILE

Sure Filter

sure

  • Engineering Says:
    May 9th, 2007 at 6:01 pm eSure makes a XLR filterA15RF In-Line RF Interference Attenuator
    The Shure A15RF In-Line RF Attenuator provides all types of balanced audio systems with greatly improved immunity to radio frequency interference (RFI). It is especially useful in applications where balanced audio devices near strong RFI sources, such as AM radio stations, are connected by long cable runs.

    http://shure.com/ProAudio/Products/Accessories/us_pro_A15RF_content

    • Unknown's avatar

    Published by wtjrengineering

    Published

    2 thoughts on “RFI AM radio SR 32.4 XLR Mic inputs”

    1. I most likely will order 2-3′ mic cable and install filters in xlr shell as I can not find cheap prebuilt source yet

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    2. Sure makes a XLR filter

      A15RF In-Line RF Interference Attenuator
      The Shure A15RF In-Line RF Attenuator provides all types of balanced audio systems with greatly improved immunity to radio frequency interference (RFI). It is especially useful in applications where balanced audio devices near strong RFI sources, such as AM radio stations, are connected by long cable runs.

      http://shure.com/ProAudio/Products/Accessories/us_pro_A15RF_content

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