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New Findings on the IOD/Mass Thread PLEASE READ!

Discussion in 'Amps and Cabs [BG]' started by Tapp, May 12, 2003.

  1. Tapp


    Aug 29, 2001
    USA, Mississippi
    Okay guys, I definitely need to give an explanation on safely using the WeberVST Mass with the SWR IOD pre.

    The IOD has a fixed 8ohm/10W resistor across the secondary of the output transformer (aka OT). This resistor helps keep a load on the OT which must be there or possible OT failure may result. When a speaker is connected to the "speaker out" jack on the IOD, this 8ohm fixed resistor is switched out of the circuit and the speaker becomes the load.

    Now, enter the Weber Mass. The Mass provides a load for the OT, BUT the Mass must be set to "1" on the "Speaker" control on the Mass unit!! Here is a quote from Ted Weber from an e-mail on the subject to me:

    I started thinking about how the Mass works and it dawned on me that if the Mass was set at "10" on the "speaker" control then it would be effectively out of the circuit (I'm told though that it still has some loading even on 10) and the OT would have an open load, causing possible OT failure. It's a good thing that I only tried the Mass once on "10" and nothing happened to my IOD's OT.

    So please, if you use the MASS, do NOT set it's speaker control above "1"!!!

  2. jasonbraatz


    Oct 18, 2000
    Oakland, CA
    i had kind of a weird thought on this subject:

    if you took a speaker and cut the cone off of it - would it provide a similar result? it'd still provide a load...
  3. Petebass


    Dec 22, 2002
    QLD Australia
    You've just described the "shakers" they put into computer game consoles and posh cinemas. I bought one and strap it to the drummers stool for that extra bit of drum fill. It has specs the same as a normal speaker - ie, rates watts, nominal impedance etc.......