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Bass amp ohms question

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  • 06-07-2006 3:14pm
    #1
    billycox
    Closed Accounts Posts: 79 ✭✭


    I have a question about my bass amp, im looking into buying another cab for it to add to the existing two. I currently have one 2X10" cab and one 15" cab, a standard sort of setup. Im looking into buying another 2 X10" cab.

    Basically im just looking for advice on wheather it will work properly or not, heres a few pieces of info about it.

    The head has max impedance of 4 Ohms

    Both 2 X 10" Cabs are rated at 8 Ohms

    The 15" Speaker Cab is rated at 8 ohms

    If i put the two 2 X10" Cabs in series they will be be rated at 16 ohms

    If i then parrell this with the 8 0hms of 15" Cab that will give me an impedance of 5 .333333 ohms

    Two questions:

    1. Will this be ok for the head?
    2 . Will the 15" speaker be getting too much power to it compared to the four 10" speakers?


    Thanks a million if you can help.


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    #2
    Doctor J
    Closed Accounts Posts: 11,848 ✭✭✭✭Doctor J


    Once you don't go below 4 ohms your amp will be fine. However, two 2x10s isn't going to sound like a 4x10 and isn't going to make your amp put out any more watts.

    What wattage is your amp and the two cabs you already have?


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    #3
    billycox
    Closed Accounts Posts: 79 ✭✭billycox


    Im not putting in more speakers for more power, Its so i can reduce the power going to two 10" speakers.

    The head is a 450watt, the 2X10" cab is 500 watts RMS, the 15" is 600 watts RMS.


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    #4
    Doctor J
    Closed Accounts Posts: 11,848 ✭✭✭✭Doctor J


    But as is 450w is being spread between 1100w of cabs. Each cab is only getting about 225w at full power. You've got bags of headroom as is. Your amp can only put out 450w total. It doesn't push 450w through each cab, the wattage gets dispersed between the two cabs. If you introduce another cab and increase the impedance you will get less output than you currently have.

    Edit -> just saw your edit - if you're worried about the 2x10 maybe get a crossover and remove the lower frequencies from the 2x10?


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    #5
    billycox
    Closed Accounts Posts: 79 ✭✭billycox


    That crossover idea is great! The 10"s cant really handle low frequencys and tend to REALLY move, cutting low end out of them would defintely solve that.
    Im only really familar wih crossovers for cars, could you recommend one to me for the bass amp?


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    #6
    Doctor J
    Closed Accounts Posts: 11,848 ✭✭✭✭Doctor J


    I've never used on that wasn't built into the cab or head, but I'll have a look around.


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    #7
    billycox
    Closed Accounts Posts: 79 ✭✭billycox


    I've been thinking about it and i think i might just go with my original idea of replacing both 10" speakers with higher rated 16ohm speakers, basically i just need more head room.
    They are currenty both 250 watt 16ohm speakers, i was looking at a nice set of emminace 350watt 16ohm speakers and they were only 150 euro for the pair so i think that might be the way to go.


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    #8
    Paladin
    Closed Accounts Posts: 2,313 ✭✭✭Paladin


    I dont understand why you need more headroom?

    Even if you used the 2x10" on its own with the 450W head its a 500W cab.
    As it is you have 1100W rated collection of cabs with an amp that can supply 450W. It looks like you have more headroom then you need :/

    High wattage cheap speakers will sound like donkey cock btw.


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    #9
    billycox
    Closed Accounts Posts: 79 ✭✭billycox


    Ya, i agree about the sound quality point, still though emminace speakers are generally great, i mean they are in most fender and ampeg amps.

    The reason i need more headroom is because the 10"s move WAY to much when at my disiered sound level and i have already bolwn up one of the exact same cabs, lol, im just trying to think ahead a little on this one!


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