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amps running at 2 0hms

Discussion in 'Amps and Cabs [BG]' started by bass_extremes, Dec 12, 2005.

  1. bass_extremes


    Jul 9, 2005
    Hey everyone, For some reason I always thought that when you have a cab running a 2 ohms that it would sound crappier dont ask me why I just thought because of the higher volumes at 2 ohms the sound would get crappier. I dont think this is true so when an amp its played a 2 ohms can it play louder because there isnt as much resisance in the circuit. I dont need a big explanation I just want to know if at 2 ohm will the sound be crappier then at 4 ohms? Also for Kustom goove bass owners how do you like the amp?
  2. KJung

    KJung Supporting Member

    This is a topic that has been talked about a lot, with no closure.

    Here's my 2 cents, based on quite a number of discussions with a few amplifier manufacturers.

    This is totally based on SS amps, since impedence regarding tube amps is a totally different matter:

    1) If you aren't pushing an amp to full power, none of this matters, in practical terms anyway.

    2) If you are pushing an amp to full power at various impedences, the lower impedence and hence the higher power will produce more heat and more THD. However, if an amp is truly designed to run safely at 2ohms, the THD will still be within acceptable limits, and it will sound fine.

    3) However.... I don't think saying an amp is SAFE running at 2 ohms is the same thing as saying that amp is designed to sound wonderful at 2ohms (per, for example, the user manuals of amps like Mesa Boogie and a recently posted Eden550 example.

    So..... from what I've been told, if you really need, for example, a 500 watt amp (i.e., given the volume you play at, the dynamics of your playing style, the efficiency of your speaker cab, etc., your typically push an amp to 500 watts of output), then it's best to get an amp that can achieve that wattage at a lower ohmage (typically 4 versus 2, if you have a lot of money, 8 versus 4), in order to minimize THD, and maximize the long term reliability of the amp.

    All of the above is again based on a layman's understanding of the issue, so I'm sure the EE's will help fix any blunders.
  3. bass_extremes


    Jul 9, 2005
    well ive been thinking about getting a kustom groove bass head at 2 ohms it pushed 1200 watts would it start sounding worse at 2 ohms then at 4 ohms? and What cabs would you recommend for this head I want to get a 4X10 and a 1X15 both 4 ohms and it would be nice if the 4X10 was 800 watts so I could use it by itself for gigs
  4. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    If the amp is designed for 2-ohm loads, and is competently designed, it shouldn't sound worse driving 2 ohms than 4 unless you drive it into clipping (and it'll be easier to clip into 2 ohms than 4 ohms, but the additional power from the amp might make you less likely to overdrive it). Yes, I said "might," but not "will". ;)
  5. I believe it is safe to say that the noise floor will move up if you are cranking the rig at 2 ohms. That being said, if you are operating at stage volumes such that all those watts and speakers are appropriate, you A) wont be able to hear the noise over the rest of the music and B) probably have enough hearing loss to miss the noise even in a quiet room. So I really don't see a problem there.

    As for needing a cab rated at 800 watts for 4 ohm usage, don't worry about it. As long as you don't make the speaker fart out or otherwise pound it or your amp to distortion you should be fine.
  6. KJung

    KJung Supporting Member

  7. winston


    May 2, 2000
    Berkeley, CA
    I've heard that the damping factor is reduced as the ohmage goes down, which results in a "looser" or blurrier sound. Is this correct, and if so, will an amp sound noticeably looser at, say 2 ohms vs. 8? Thanks...
  8. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    It can, but you can also keep the damping factor up by using speaker cables that are as short and large-gauge as is practical. If you actually lose enough damping factor that you can hear a difference in tightness at 2 ohms versus 8, then either your speaker cabling has too much resistance or the amp has a pretty high output impedance.
  9. ras1983


    Dec 28, 2004
    Sydney, Australia
    There must be some validity to this myth. but i think that it matters more with the cabs. i have a few friends who are 'audiophiles' and they always tell me that the better studio monitors and surround sound speakers are anywhere between 16 and 32 ohm.
  10. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    Fremont, Ohio
    Editor-in-Chief, Bass Gear Magazine
    I don't know about that, but I do know that some of the best (generally larger) main speakers (L/R, not surrounds) in top notch home audio systems present some loads on the opposite end of the spectrum. My Thiel CS3.6's are rated at 4 ohm, but actually present closer to a 2 ohm load overy much of their lower end frequency range.

  11. impedance ;)

    Dunno, never any noticable difference in sound quality when i run my firebass at 2 ohms (or my SVT at 2 ohms, but, tube amps work differently as said), altho, im apparently getting nothing but noise because i use the master at full and control the volume by the pre gain, but thats another story