another quick question about impedance..

Discussion in 'Amps and Cabs [BG]' started by inputoutput, Oct 30, 2005.

  1. inputoutput


    Oct 4, 2005
    i've been trying to figure this out, but i'm having trouble finding adequate resources. i am using a traynor yba-3 custom special [a classic canadian tube head, rated at about 160w at 4 ohms]. as far as i can tell, this amp has a 4 ohm output [from the main speaker jack]. according to manufacturer specifications, the extension port is wired in series [so that i would need two 2 ohm cabs, or one 4 ohm load]

    this is where i run into a problem. i have two swr cabs [2x10, and a 1x15], both rated at 8 ohms. if i run both out of the main + ext ports, i would have a 16 ohm load.

    can this tube amp handle this? or is this going to result in an overworked amp? unfortunately, i don't have access to any 4 ohm cabs.. guh.

    thanks so much in advance.
  2. Daisy-chain the two cabs, and run them off one output.
  3. inputoutput


    Oct 4, 2005
    regardless of whether i run them daisy-chained or from the ext port [because it is wired as being in series], it's still going to be a 16 ohm load [because 8 ohm + 8 ohm in series = 16 ohm]. if my output port is rated at 4 ohms, would the impedance mismatch [ie. the 16 ohm load from the two cabs either daisy chained or ext ported] cause serious damage to either the amp or the speakers?
  4. ESP-LTD


    Sep 9, 2001
    He is suggesting that most common cabs which have (2) jacks on them, are wired so that if you use those jacks to daisy-chain, you are connecting your cabs in parallel.

    So- you connect your cabs together using the jacks on the back of the cabs, and the amp sees a single 4 ohm load- the sum of the 2 cabs in parallel.

    Amp --- cab --- cab

    Whether the jacks on the amp are wired in series or not is only relevant if you are using both jacks, which is not what is being suggested. My *guess* is that those jacks on the amp are designed to be a dead short when not in use, so that you can use one if you like. Tube amps tolerate a dead short but an open connection is bad news; solid state amps are just the opposite.
  5. inputoutput


    Oct 4, 2005
    i wasn't aware that the output jack on the back of the swr cabs was a direct output [resulting in a parallel wiring configuration].. that's great! i always assumed that it was a series configuration.

  6. They're almost invariably parallel connections in that situation.