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Quick questions about head units

Discussion in 'Amps and Cabs [BG]' started by aabassist, Dec 26, 2002.


  1. If i have a head unit that is rated at 300 watts RMS and have it connected to an 8 ohm cab rated at 250 watts then will it be outputting 250 watts from the cab??

    Then if i connect another 8 ohm cab, also rated at 250 watts then what power is being output throught each? is it 250 through each?
     
  2. PollyBass

    PollyBass ******

    Jun 25, 2001
    Shreveport, LA
    Well, is your head rated at 300watts RMS into 8ohms? or 4? if it's 4, and you hooked up to 8ohm cabs to it, you would be in a sense running at 4 ohms, delivering all your heads power to both cabs. if you hook up one 8ohm cab, it should be about half, or around half your power(that is, if your head is rated at 300 watts RMS @ 4ohms.) Your cab's power rating is HOW MANY watts it can take, if you put more than the recomended amount into any speaker cab, you get blown speakers, or worse. but this is the magic of "Volume". you can hook up a 1000 watt head to your cabs, and not blow them out (could if you wanted to,,,, but you get the idea). if you ran both your 8 ohm cabs, you should be fine, only thing you will need to worry about is clipping,.
     
  3. all i know is that it is 300 watts RMS and it says max power consumption 600watts above the plug
     
  4. Just to clarify a little, the power rating of the head is how much power it can supply, and the power rating of the cabinets are how much power they can safely handle for a long period of use.

    That's the important concept that needs to click in your head and then the rest of the stuff makes sense.

    Chris
     
  5. PollyBass

    PollyBass ******

    Jun 25, 2001
    Shreveport, LA
    Might look back at my post, i edited it a little.

    Well, do you have a booklet? or anything?it's most probly into 4ohms, so what i said above is probably right. If you had a 4 ohm cab you could tell...
     
  6. PollyBass

    PollyBass ******

    Jun 25, 2001
    Shreveport, LA
    right, i just take thing for granted sometimes.;)
     
  7. 300 Watts is the power output of the amp.

    600 Watts is how much power it will draw from the wall outlet.

    There should be something like "4 ohms minimum load" or something like that on the back near the output jacks.

    Chris
     
  8. This sort of question comes up a lot....The HEAD supplies power. The Cabinet has an impedance (usually 8 ohms or 4 ohms) and a rating for the maximum amount of power it (the cab) can accept.

    A head (amplifier) will put out more power (watts) into lower impedance cabs, up to the current limit of the amplifier. For example, an amp may be rated to deliver 100 watts into 8 ohms and 150 watts into 4 ohms, but may not be able to run into a 2 ohm load (what the amp would encounter if one were to hook up two 4 ohm cabs in parallel).

    Another amp may be rated to run into 2 ohm loads, delivering even more power. But this is hard on amps, so a lot of amps don't recommend 2 ohm loads. Yet another amp may be only rated to run into an 8 ohm load.

    Your head is rated at 300 watts RMS, is that into 8 ohms or 4? Regardless, the 8 ohm 250 watt cab should be OK with the 300 watt head. And if the amp is rated at 300 watts into 4 ohms it'll actually deliver less into an 8 ohm load, so the single cab will be fine anyway.

    If the amp is indeed rated at 300 watts into 4 ohms, plug in both 8 ohm cabs and rock on, you'll get the full 300 watts out of the head, split into two cabs. There will be 150 watts into each cab.

    Hope this helps.:)
     
  9. i assume its 300 watts into 4 ohms, i have the cabs recommended for use with the head. so when i hook up both the 8 ohm cabs i will be getting 150 watts through each one? is that what you're saying??
     
  10. Yep, 150 Watts goes into each 8 ohm cab.

    Chris