Spring Reverb Shielding

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by ekp, Jul 26, 2013.

  1. ekp

    ekp Member

    Messages:
    402
    Joined:
    Sep 2, 2003
    Location:
    Berkeley Springs, WV
    Spring reverbs were a problem for years, when I was prototyping amps. I solved that problem by putting the reverb guts into a steel tube and then putting that in a pocket in the cab. The tube shielded the magnetic fields and the pocket reduced the soundwaves.

    But recently, I decided to shield standard tanks. And some interest in the shields prompted me to make ones for the long tanks as well.

    To test the shields, I made a huge electromagnet and tested the tanks with and without shields. One of the seven tanks I tested (Accutronics and Mod) did work properly without a shield, but the others really needed a shield to lower the hum.

    The shields cover the open side of the reverb tank and consequently reduce the access that soundwaves have to the springs. There is still slight access via the cracks. But they can be sealed with some caulk or tape if needed.

    The grommets that the tank stands on poke through the shield, so that feature is not compromised.

    Have a great day, Eric
     
  2. J M Fahey

    J M Fahey Member

    Messages:
    2,151
    Joined:
    May 22, 2009
    Cool !!! :D

    Care to share some pictures? :D
     
  3. Blue Strat

    Blue Strat Member

    Messages:
    30,061
    Joined:
    Aug 2, 2002
    Location:
    Sterling, VA (not far from Washington DC)
    Isn't any metal tank with a ground connection shielded?
     
  4. ekp

    ekp Member

    Messages:
    402
    Joined:
    Sep 2, 2003
    Location:
    Berkeley Springs, WV
    NO and Sort of. A true shield completely encloses. If the shield is made of magnetic material, such as steel, then the magnetic field is conducted around what is enclosed, namely the magnetic structures of the reverb. For electric fields, then the shield needs to be conductive, between the reverb and electric field source, and grounded.

    What these shields do is give the reverb tank the needed sixth side. That then provides the magnetic path around the reverb magnetic structures and provides an electric shield from the sixth side.

    Have a great day, Eric
     

Share This Page