1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  

PA head outputs 4 ohm Parallel question...

Discussion in 'Live Sound [BG]' started by atticpenny, Jun 12, 2012.


  1. atticpenny

    atticpenny

    Jan 5, 2011
    Virginia
    yes, another thread dealing with ohms and speakers. lol.

    My band has an old Peavey PA head that we would like to use to power our monitors. The outputs state that they are:

    4 ohm Parallel.

    Does a 4 ohm parallel dual channel output power amp mean that each channel can handle a 4 ohm load, or does it mean that the entire load for the PA (both channels) must be 4 ohms?

    In short, what speaker combinations can we run from this old thing?

    Does this mean that we can run a total of two 4 ohm monitors (one from each channel), or only just two 8 ohm monitors (one from each channel).

    If we can run two 4 ohm monitors, I presume we can instead run four 8 ohm speakers (daisy-chained, two on each output channel)?

    Now, if we CAN run four 8-ohm monitors (daisy-chained, two on each output channel), would it be bad if we only had THREE (two daisy chained on one channel, and only one 8-ohm on the other channel). Would the single 8-ohm monitor cause the load to be imbalanced and cause problems, or is it okay to have that kind of imbalance as long as it is under the specified load?

    Thanks in advance!
     
  2. I have an 1978 vintage PV XR600 PA head and you can run it safely down to 2 ohms. Those outputs are paralleled so two 8 ohm cabs will be 4 ohms, four 8s (daisychained) will be 2, etc.
     
  3. TimmyP

    TimmyP

    Nov 4, 2003
    Indianapolis, IN
    Yep, one 4 Ohm load.
     
  4. ggunn

    ggunn

    Aug 30, 2006
    Austin, TX
    Not so. It means 4 ohms per channel. It will run four 8 ohm speakers - two in parallel on each channel.
     
  5. Red Planet

    Red Planet Inactive

    May 29, 2005
    Atlanta
    I'm cranky in my old age.
    I think you need to read the FAQ on OHMS.

    If you have a stereo PA head that has two power amps (an A and a B) and the minimum load is 4 ohms for each then you can use four 8 ohm speakers (two on a side for 4 ohms per side) or like you said one 8 ohm (8 ohms) on one side and two 8 ohms (4 ohms) on the other side. Please understand the side with the 4 ohm load will be louder so you will need to compensate with the volume controls to make them even in loudness.

    Now be carefeul there are PA heads out there with two speaker jacks but only hooked to one mono power amp and the minimum is 4 ohms. Should you hook four 8 ohm (2 ohms) or three 8 ohm (2.67 ohms) speakers into that you will fry your head in just a couple of minutes. If this is the case you can still use three spekaers but would have wire two in paralele and one series to those and it can be a brain teaser to do that (I know I just did it). This ends up at 12 ohms I believe.
     
  6. Red Planet

    Red Planet Inactive

    May 29, 2005
    Atlanta
    I'm cranky in my old age.
    How many jacks are on the back of your PA head? If there are two and it says paralel then there is only one power amp not two. Just trying to clarify.


    Got a pic?
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.