Effect of Overall Impedance on an Amp

Discussion in 'General Electronics Chat' started by Not An Audiophile, Jan 9, 2004.

  1. Not An Audiophile

    Thread Starter New Member

    Jan 9, 2004
    I know little about electronics, so please excuse the elementary questions that follow. By way of background, I listen to a lot of classical, jazz, and Sinatra, usually at moderate volume levels.

    I have two sets of speakers (8-ohms each) that I wish to connect via a speaker switch box (Radio Shack catalog no. 40-244) . One combination of switches will result in overall impedance of 16 ohms. I assume that this is a series circuit.

    Another combination of switches will result in overall impedance of 4 ohms. I assume that this is a parallel circuit.

    What will be the effect on my amp by having an overall impedance of 16 ohms? What will be the effect on my amp by having an overall impedance of 4 ohms? What will be the effect on sound output and sound quality in either situation? Please weigh in.

    Thanks very much.
  2. Battousai

    Senior Member

    Nov 14, 2003
    Every amplifier is designed for operation at a certain load. You want to setup your speaker system to present a load closest to the one the amplfier was designed for.

    To get the best sound I'm assuming you want to deliver the most power to your load. :rolleyes:

    The parallel connection presents a lower load (4-ohm) and will draw less voltage, but more current. YOu will get the same voltage across both loads.

    The series connection presents a higher load (16-ohm) and will draw more voltage and less current. You will get the same current across both loads.

    Assuming the amplifier has a large output resistance, the increase in drawn voltage when using the series connection will not be very significant and you will get a higher power delivered using the parallel connection (and better sound quality?).
  3. Davis


    Jan 5, 2004
    I could just be talking right out of my ass, but you could have 2 sets of 2 series speakers in parellel which would provide the same resistance as 1 speaker but would require the 4 times the power. You might not want to do this, because you might overload your amp Battousai, might have a better idea.

    GND/AMP|------speaker1----speaker2----|----to amp chan1
    GND/AMP|------speaker3----speaker4----|----to amp chan1

    Sorry for the shitty drawing, it's soo hard to make it clear.

    - Davis
  4. mozikluv

    AAC Fanatic!

    Jan 22, 2004
    :rolleyes: hi,

    just a simple rule when connecting speakers, whatever your amp is set to drive, just follow that. if it says 8ohms stick to 8 ohms, if 6ohms do it. series or parallel connection of speakers does not matter as long as it totals whatever the specs of your amp. that is your safest approach. ;)
  5. eldon


    Jan 24, 2004
    Having spent a few years repairing stereo equipment in a high end service shop, I feel qualified to comment. The concern about impedence matching with current "solid state" stereo amplifiers is not nearly as critical as it was years ago with the vacuum tube amps with output transformers. Of primary concern is the current capacity of the amplifiers output section, generally specified as watts into 8 ohms or 4 ohms. Sometimes even less (1 or 2 ohms) on high end equipment. If your amplifier has a power rating listed for 4 ohms, then you are OK setting your switch box up for 4 ohm loading. 2 speakers each channel, in parallel. Usually if this is the case, your amplifier will already have 2 speaker outputs with speaker select switches on the front. Otherwise it will be best to connect in 16 ohm (series) to prevent overloading the outputs. Many systems are designed for the speakers supplied with the set and will not easily handle higher loading (2 sets of speakers in parallel). If you are not sure about your particular amplifier, rest assurred that the 16 ohm load will not dammage the system. You will notice a need to turn the volume level up slightly in this case. If the system is unable to deliver quality sound in this mannor, you may need a higher powered amplifier to run 2 sets of speakers. :rolleyes: