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changing ohmage of cab?

Discussion in 'Amps and Cabs [BG]' started by robotic, Apr 14, 2010.


  1. robotic

    robotic

    Apr 14, 2010
    hi everyone, my first post after being away for a while. long story.

    anyway, i was wondering if anyone could offer any suggestions or ideas to help me make my extension cabinet to 8ohms (from 4 ohms).

    the other cab i'm using is already 8 ohms and i dont want to risk running it at 2 ohms.

    is there a dummy speaker/ transformer/conversion i can to to solve this problem? (without replacing the speaker)

    thanks!
     
  2. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Read the FAQ.
     
  3. robotic

    robotic

    Apr 14, 2010
    thanks, i did.

    and didn't see anything specifically answering this query.
    could you point me to a specific FAQ topic?

    (Just to be clear, I'm not new to talkbass, nor am i a bass newbie. I had to re-register, and am very aware of the talkbass FAQ)
     
  4. I think you can only change a 4 ohm to a 16 ohm, but a 8 ohm can be done in 2 ohm. Very generally speaking
     
  5. kegbarnacle

    kegbarnacle

    Nov 18, 2003
    Phoenix
  6. If there is one speaker you cannot change the impedance. If there are two you can wire them in series for twice the impedance of the individual drivers or parallel for half. Four speakers in series for 4 times the impedance of the drivers or parallel for a quarter. You can also wire one pair in series, the other pair in series and then both sets in parallel for the same impedance os the drivers.

    Paul
     
  7. robotic

    robotic

    Apr 14, 2010
    i'm cool with an iron, and DIY stuff.
    thanks, i'll check out that glockenklang dealy.
     
  8. robotic

    robotic

    Apr 14, 2010
    thanks for the replies!

    i should be slightly clearer.

    i am knowledgeable about ohms law, and series/parallel wiriring, etc.
    its a just an idea, as i have this extra cab laying around, and wondered if i could amke use of it with some neat soldering or something!

    cheers
     
  9. pacojas

    pacojas "FYYA BUN"

    Oct 11, 2009
    MEXICANADAMERICA
    WÖW, great answer from a speaker professional,.. (NOT!!!!) i guess we could all reply to each other in that tone and not discuss any more subjects here on TB.

    /thread
     
  10. Just as a question, have you not seen how often this subject comes up??? literally once a week. That is the purpose of the FAQ to answer such queries without starting yet another superfluous thread. Check the FAQ was a reasonable reply.

    Paul
     
  11. robotic

    robotic

    Apr 14, 2010
    actually the question was about if i could change the rating of a cabinet.
    i wasnt asking about how ohmage/speaker ratings etc work.

    that isn't covered specifically in the FAQ. its a reasonable question.

    nice welcome home thread!
     
  12. The answer is no. Unless you spring for the transformer.
     
  13. pacojas

    pacojas "FYYA BUN"

    Oct 11, 2009
    MEXICANADAMERICA
    i agree on that basis. it just seems like everything on the planet is either search-able or FAQ'd. it's still okay to be directed to a solution by a professional.
    i admire the efforts by pro's to be personable. i.e., Jeff Berlin!!! this guy responds to redundant queries, tirelessly, to make his point. unless there's a question or comment about a current or future event, this forum should be used as a "SEARCH-ONLY" resource.
    infact, the GOOGLE option is very efficient!!!
    (apologies go out to Bill and to the OP for hi-jacking)
     
  14. billfitzmaurice is more than helpful on these forums, and answers a ton of more complicated questions regarding speakers, cab construction, etc. His response is valid because all you need to do is think a little bit harder and apply the knowledge in the FAQ.

    NO you cannot simply change the ohms rating with "fancy soldering." If you want 4 ohms, run two 8 ohm cabinets or one 4 ohm cabinet, or 2 2ohm cabinets in series.
     
  15. ehque

    ehque

    Jan 8, 2006
    Singapore
    instead of springing for that fancy schamnzy transformer stuff, you could always wire YET another 4 ohm cab in series with your existing 4 ohm. That gives 8 ohms, which parallel with your 8 gives you 4 again.
     
  16. silky smoove

    silky smoove Supporting Member

    May 19, 2004
    Seattle, WA
    Ohmage is a made up word. Impedance is what you're looking for ;)
     
  17. Thor

    Thor Gold Supporting Member In Memoriam

    Or model a suitable 8 ohm replacement speaker to the existing
    box using WinISD. The driver is built to have a certain
    impedance, there is no 4/8 ohm switch that is going
    to change the laws of physics.
     
  18. nostatic

    nostatic Supporting Member

    Jun 18, 2004
    lost angeles, CA
    Endorsing Artist: FEA Labs
    I would change the ohmage by finding a decent Buddhist retreat center and leaving the cabinet there for a few days or weeks. While the impedance might not change, the cab will probably sound a bit more clear and calm.
     
  19. yodedude2

    yodedude2 Supporting Member

    Nov 19, 2005
    san antonio, texas
    From: http://www.talkbass.com/forum/showthread.php?t=166225 to: http://www.talkbass.com/forum/showthread.php?t=144244 came this:

    "A cabinet’s Impedance Depends on the impedance of the speakers in it and how they are wired. Speakers can be internally wired in series, parallel, or a combination of both. If a cabinet has one speaker in it, you guessed it, the cabinet’s impedance is equal to the speaker’s impedance. When wired in series the ohms of the speakers get added together for more resistance (so a 2x10 cabinet wired in series with 4 ohm speakers would have a net impedance of 8 ohms.). When wired in parallel, the impedance is decreased according to a formula. The formula is based on adding and reducing fractions. (For you in school this should be no problem, for us older people - this will seem familiar (maybe) if a bit hazy - lol. The formula for parallel impedance is as follows;

    Total impedance = 1/(1/a + 1/b + 1/c ... + 1/n)."

    applied to the cabs in your original post, 1/(1/8 + 1/4) = 2&2/3.

    hth, later, ron
     
  20. your OP specifically mentioned changing the impedance which is what was answered.

    BTW Welcome home!!! :) :) :)

    Paul
     

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