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Tech-questions? -Don't ask me!!!

Discussion in 'Amps and Cabs [BG]' started by carl-anton, Jan 19, 2001.


  1. As the title implies I'm a tech-imbecile, so somebody please enlighten me. Why is it that adding cabs lower the resistence? Why do two 8 ohm cabs make 4ohms? How about running cabs in series (and is that, by the way, connecting one cab only to the amp, and the rest cab to cab?), whats the difference?

    Thanks in advance!

    Lars the not so clever...
     
  2. CS

    CS

    Dec 11, 1999
    UK
    http://www.webervst.com/sptalk.html

    I have nothing to do with Weber speakers. I use the BBS sometimes but I found the above link useful as I too am less than technical. Scroll down and there are diagrams and explainations of speaker types and resistance.
     
  3. Think of it like this, 8 ohms is the impedance, which means how much it impedes the flow of current. If you put another one beside it, so now the current has 2 paths to flow through, it is impeded less. So the impedance is a measurement of how hard it is to get through, and if you put another one beside it (hooked in parallel) it is easier to get through.

    Chris
     
  4. JimM

    JimM

    Jan 13, 2000
    Northern California
    Pretty good explaination T,
    I hope this doesn't confuse things,but knowing the extremes helps me to keep the in-between measurements in perspective.the extreme measurements of impedence are zero(0)ohms and infinite (sideways"8")ohms.An example of zero ohms would be a thick,short wire.But infinite resistance is like an insulator such as the vinyl coating on cords etc.

    The thick wire doesn't resist current flow because it has plenty of room for the electrons to travel.On the other hand,vinyl.plastic,glass etc.are non-conductors so they are said to have an infinite amount of impedence.
     
  5. Matthias

    Matthias

    May 30, 2000
    Vienna, Austria
    Running two cabs in series ('one after the other') makes it 'harder' for the current to pass through, you have to add impedances (e.g. 8+8=16). This can NOT be done with standard cables, what you describe is still parallel connection. Series connection would mean: Connecting the '+' of the amp output with '+' of the 1st cab, then from '-' of the 1st cab to '+' of the 2nd cab and on from '-' of the 2nd cab back to '-' of the amp.

    But for some reasons I do not know it isn't good to run cabs in series anyway. Just forget about it.

    Matthias

     
  6. OK, Thanks! Think I finally got it... - ...but you probally wont see me answering tech questions anyway!!!
     
  7. For a little while there I thought I was being mocked. Sorry I didn't trust you carl-anton.

    Should you be interested in why I made the above comment, look for my thread "tech questions? Ask me!!!".

    Rock on,
    Joris.
     
  8. Hi Joris!

    I don't want to muck you at all. Just thought it sounded funny, as an opposition to your thread. And by the way I think it's very nice of you to answer all these questions. Don't know why I didn't ask you.

    Cheers!
    Lars
     
  9. rickbass

    rickbass Supporting Member

    carl-anton; Glad there are people who ask about these kinds of issues. I'm a non-techie, but there are important issues where, "trust your ear," has no relevance.

    I understand the watts/impedance - volume of water/water pressure analogy but what I DON'T get is-

    - why jerk us around with 2/4/8 ohms? why not set a standard and be done with it, make setting up in parallel a non-issue? (I imagine there's a legit reason)

    - why not have a standard for how power is measured instead all the ways THD/wattage is tweaked? Just A/B'ing various makes of heads requires an electrical engineering degree as far as I'm concerned. I've been playing ofr 30+ years and if the thing feels like it can fracture bedrock and still sound clean, I consider buying it.

     
  10. MikeyD

    MikeyD

    Sep 9, 2000
    Yeah, some come to mind:
    _ (1) If you have a driver that can take tons of power, why not wire it with a low-impedance coil so that it can take the additional current an amp can deliver to it?
    _ (2) If you have a large array of "weak" drivers, why not wire them with high-impedance coils so that, when they are combined, you get a reasonable load to the amp?
    _ (3) With various speaker cabinets, you might have 1, 2, 3, 4, 6, 8, etc. of the same (or similar) drivers on the same side of a crossover network (if there is one), so how do you ensure all of these configurations present the same impedance to an amp?

    I'm sure there may be other reasons I haven't thought of.

    - Mike
     
  11. I think we did a pretty good job putting up a standard. 4, 8 and 16 ohms, are the only existing impedances. Imagine the confusion if there were 3.2 ohms, 12.9, 5.2, 1.4, 8.8, 20.1, and 9.5 ohms drivers.

    I think impedances are pretty standard as they are.
     
  12. rickbass

    rickbass Supporting Member

    Thanks, gents. Most of my electrical engineering knowledge resides in my ear. It's for people like me that they make http://www.daisyrock.com:eek:
     
  13. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    carl -

    I would also point out one very important fact. Whether you run two speakers out of two jacks on your amp, or "daisy-chain" the speakers (one cord out of the amp to the first speaker, then a cord from the first speaker to the second), you're still running the speakers in parallel. To run them in series, you would have to get a special cable not generally available, or make it yourself.