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Ampeg Portaflex speaker impedence?

Discussion in 'Amps and Cabs [BG]' started by nil, Jan 14, 2001.

  1. hello,

    what is the lowest impedence you can run from a 60's B-15 or B-18 portaflex amp? can they handle 4Ohms or just 8/16?

  2. moss


    Dec 24, 2000
    hey i think a b-15 is an 8 ohm. they have an extension speaker jack so they must have a 4 ohm tap on the transformer. i dunno if you can, but you might be able to wire up to just the 4 ohm. i'll try and find out.
  3. mchildree

    mchildree Supporting Member

    Sep 4, 2000
    I've run a Portaflex B-15N with the integrated 8-ohm speaker plus another 15" extension and it really didn't make any difference...there's just not enough juice there to push more than one cab.
  4. Consult the schematic, my friends. There are 2 taps on the output tranny, but they are 8 and 16 ohms. When a second 8 ohm cab is plugged in, it is connected in series with the first 8 ohm load to give a total of 16 ohms.

  5. Thanks Chris, does that mean the "integrated" speaker is 8Ohms, and the extension can be 8 as well? Or does the extension need to be 16?
  6. The built in speaker is 8ohms, and the extension should be 8 ohms. These add together to be 16 ohms for the 16 ohm tap.

    Dig this stolen link:

    Note the output jack and the way it will break the connection to the 8 ohm tap when a plug is inserted into the jack, and the 2 wires of the ext speaker will be connected between the + wire of the built-in speaker and the 16 ohm tap.



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