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8ohm cab vs 4ohm

Discussion in 'Amps and Cabs [BG]' started by bass nitro, Jan 2, 2012.


  1. bass nitro

    bass nitro

    Feb 21, 2011
    BG,SZ
    Hi there,happy new year to everyone here.Just one stupid question - which cab 8ohm or 4 is louder if is true there is such thing?Thank you
     
  2. 4-string

    4-string

    Jul 23, 2006
    Norway
    No such thing. ;)
     
  3. bass nitro

    bass nitro

    Feb 21, 2011
    BG,SZ
    Thank you very much.
     
  4. 1958Bassman

    1958Bassman

    Oct 20, 2007
    Depends- how many speakers?

    If you look at a speaker's spec sheet, it will show the sensitivity, which is the SPL resulting from a specified input voltage. If a 4 Ohm speaker shows 93dB with 2.83V and an 8 Ohm shows the same 93dB, the 4 Ohm will actually be driven by 2 Watts, compared with the 8 Ohm speaker, which is being driven by 1 Watt. P=E²/R (Power equals Voltage, Squared, divided by the resistance), so P= (2.83)²/4, or 2.002 (close enough for jazz) and....

    A cabinet's impedance is for making the amplifier happy, nothing else. Radiating surface area makes it loud. One 4 Ohm speaker of 93dB/W sensitivity will be 3dB quieter than two 8 Ohm speakers of equal sensitivity, wired parallel for a 4 Ohm load if fed the same voltage. If you feed one speaker 1 Watt and compare that with two identical speakers that are each fed one Watt from different amplifiers, the two speakers will be 6dB louder.

    What's your goal- to be loud, or to sound good?
     
  5. bass nitro

    bass nitro

    Feb 21, 2011
    BG,SZ
    My goal is to get both.In this case just have asked because i will buy 410 TVX Peavey cab but unfortunately for me,i could take hand on 4ohm one.It seems that i am not going to loose much power according to what you have wrote or i ma wrong?
     
  6. Hopkins

    Hopkins Supporting Member Commercial User

    Nov 17, 2010
    Houston Tx
    Owner/Builder @Hopkins Guitars
    Get an 8 ohm cab, if your amp can't handle a 2 ohm minimum you will have no options for expansion if you get a 4 ohm cab. The 4 ohm cab will give you more power from your amp but the volume gains will be minimal. Assuming you are using a solid state amp.
     
  7. ^This
     
  8. 1958Bassman

    1958Bassman

    Oct 20, 2007
    If there's a chance that you would add a second cabinet and the amp or cabinet has an extension speaker jack, you'd want 8 Ohm cabinets because most speaker jacks are wired parallel. I have seen some that were switching jacks, where the extension cable went to a dedicated jack that caused the signal to pass through it before getting back to the amp but that was mostly 1960's gear. If you want reliable performance and the amp has two output jacks, use one cabinet on each and maintain correct impedance. Just buy the cabinet that sounds best at all levels and I think SPL will take a back seat to sound quality.
     
  9. bass nitro

    bass nitro

    Feb 21, 2011
    BG,SZ
    Thank you all of you.You helped me a lot.
     

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