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How many ohms would this be?

Discussion in 'Amps and Cabs [BG]' started by B String, Aug 1, 2004.


  1. B String

    B String Supporting Member

    Apr 11, 2002
    Los Angeles
    What would 5.3 ohms and 8ohms, come out
    to be? Wondering if i could still use a 4ohm
    minimum amp, or if i need a 2ohm minimum amp.
     
  2. xcental34x

    xcental34x

    Feb 28, 2003
    Memphrica, TN
    It'd be less than 4 ohms. You need a 2 ohm minimum. 8 + 8 ohms= 4 ohms, so obviously 5.3 + 8 would be less. I'd take a wild guess and say it'd be 3.
     
  3. bennettsteve

    bennettsteve Guest

    Dec 14, 2002
    Good guess! It would be approximately 3.2 Ohms.
     
  4. Right. To figure this out in the future, multiply the 2 resistances then divide that by the sum of the resistances:

    8 * 5.3
    ________ = 3.1879699

    8 + 5.3
     
  5. xcental34x

    xcental34x

    Feb 28, 2003
    Memphrica, TN
    Woohoo! I rule! :bassist:
     
  6. B String

    B String Supporting Member

    Apr 11, 2002
    Los Angeles
    Hey... you guys is smart! thanks!
     
  7. De Teng

    De Teng

    Oct 27, 2003
    Utrecht, Holland
    The exact formula is in fact this one:

    1/R(total) = 1/R1 + 1/R2 + ..etc..

    Now you can always do the ohm job yourself. :D
     
  8. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    by the way.....................

    don't do it.............you won't even hear the 8 ohm cabinet, the 5.3 ohm cabinet will get most of the juice, so unless the 8 ohm cabinet is at least 3 dB more sensitive, it won't sound like much if you have them both on the same load

    on the other hand, if you have them on opposite channels of a stereo rig with seperate level controls, no problemo
     
  9. Basspolizei

    Basspolizei Pseudo bass player/collector Gold Supporting Member

    Jun 23, 2004
    US
    Buy basses and lots of guns before it's too late! You have been warned.
    If and when you sell, buy matching OHM Ampeg gear and be happy for life! Enjoy..........
     
  10. De Teng

    De Teng

    Oct 27, 2003
    Utrecht, Holland
    Good point dude...I just forgot! A small example to understand a bit more of the power/ohm blabla.

    For instance... using a 2.10" and a 4.10", you'll have to choose the 2.10" with twice the resistance of the 4.10". The 2.10" will get then half the power but also has half the amount of speakers. If they are from the same brand (and most of the characteristics resemble in general) then you have the same power to every speaker.

    Example, hypthetically speaking

    600W ... in a 4 ohm and an 8 ohm cab.

    The 4ohm gets twice the power than the 8 ohm. Thus 4 ohm > 400W and 8 ohm > 200W. The 4 ohm (4.10) gets 100W a speaker and the 8 ohm too (which was 2.10 remember?)

    (That's why I want a Bag End 4 ohm 2.10" in the future, so I can wire it to 16 ohm -speakers in series instead of parallel- and use it with the 8 ohm 4.10".... awesome sound and still managable!!!)
     
  11. B String

    B String Supporting Member

    Apr 11, 2002
    Los Angeles
    AARRGH!! Just when I think i've got it figured
    out, you guys come up with logic! DAMN!!
    So the idea of adding an 8ohm 112 box to the
    5.2 ohm 310 box won't work well? I can't always
    carry tons of gear to gigs, but when i need more,
    I like having things modular. Now I'm back to square
    uno!
     
  12. De Teng

    De Teng

    Oct 27, 2003
    Utrecht, Holland
    In theorie...no...but it depends on how you think about it. Just listen to it, but I can't garantee you satisfaction. ;)
     
  13. BassIan

    BassIan Supporting Member

    Apr 27, 2003
    Cupertino, California
    This may not be exactly as you expect. Right now I have a 4-ohm SWR Goliath Senior in parallel with an 8-ohm SWR Big Ben. Both of them get similar levels, particularily when I open the amp up a bit, then the 18 really gets going, which I actually really like. So, it's at least worth a try. Cabinet sensitivity really comes into play. In my setup, the Big Ben gets half the power of the Senior, but seems to be more sensitive, which makes up for the power difference.
     
  14. De Teng

    De Teng

    Oct 27, 2003
    Utrecht, Holland
    It depends on the total square inches of the speaker too. An 18" has a lot more than a 10"... together with the fact it is more sensibel, he comes (as shows) pretty close a 4.10" which gets more power.

    In my example, I didn't want to mention it, because it makes it even more complex. But in fact, it is very important. My excuses...

    So we have now a few variables:

    Total impedance thus power each speaker
    Sensibility
    Total square inches

    (complex isn't it..??) :D
     
  15. B String

    B String Supporting Member

    Apr 11, 2002
    Los Angeles
    Ouch my head! ... I thought adding the 5th string
    was hard enough!
     
  16. BassIan

    BassIan Supporting Member

    Apr 27, 2003
    Cupertino, California
    Speaker area has little to do with anything in the real world. Besides, 6 10" speakers have nearly twice the surface area of 1 18" speaker...

    There are too many factors to consider, but a very useful one is the sensitivity rating of a cabinet, assuming you know all useful parameters (power applied, frequency of test signal, distance of measuring device from baffle or dust cover, etc).
     
  17. B String

    B String Supporting Member

    Apr 11, 2002
    Los Angeles
    I think in this situation, mixing a 5.3 ohm 310
    cab at 103db sensitivity, and an 8 ohm 112 cab
    at 100db sensitivity, may not work too well if
    the information i'm getting is correct.
     
  18. BassIan

    BassIan Supporting Member

    Apr 27, 2003
    Cupertino, California
    Very true. I hadn't looked at the sensitivity ratings of those cabinets. IF it were the other way around, with the 8 ohm cab having the higher sensitivity, it wouldn't likely be a problem, but in this case it is likely that the 112 will be pretty quiet compared to the 310.
     
  19. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    all very good points...............
    one thing to consider, just because a 210 has half the speakers and surface area than a 410 doesnt mean that it would be a good idea to run a 16 ohm 210 with an 8 ohm 410
    i used an 8 ohm 210 and an 8 ohm 410 together on the same mono amp for years and it sounded fantastic - the 210 sounded equally as loud as the 410, this is a very common setup with eden gear
     
  20. De Teng

    De Teng

    Oct 27, 2003
    Utrecht, Holland
    Alright... but how come? May be it is because the 4.10 has a bigger housing, thus produces more sound.... so it is in the end equally loud?

    I'm getting confused about this. :D