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112 or 212 at 4ohms

Discussion in 'Amps, Mics & Pickups [DB]' started by timobee4, Dec 23, 2011.

  1. G'day! I just bought a AI Clarus 1 S3 and I was looking at getting a Bergantino 112 or 210 but they all seem to be 8ohm! I dont want an 8ohm cabinet because my AI will only give me 250W at that rate so if I want to enjoy its full potential 400W I need a cabinet at 4ohm! I would appreciate any suggestions. I have found 212 and 410 cabs at 4 ohm but I am not interested in those. I would be using it strictly for DB so Heeeeelp!
  2. Sam Sherry

    Sam Sherry Inadvertent Microtonalist Supporting Member

    Sep 26, 2001
    Portland, ME
    Euphonic Audio "Player"
    There is no difference between 250 Watts at 8 Ohms and 500 Watts at 4 Ohms. Your amp moves the same amount of current either way. See Ohm's Law. Even if the numbers don't quite add up, it's the same shtuff.
  3. tornadobass

    tornadobass Supporting Member

    Nov 20, 2000
    Iowa City, Iowa
    ...or consider a Wizzy 12 if you're set on a 4 ohm extension. I have a pair that sound very nice with that model of amp...it's okay down to 2 ohms.
  4. Steve Freides

    Steve Freides Former Mannes College Theory Faculty Supporting Member

    Dec 11, 2007
    Ridgewood, NJ
    Ohm's law not withstanding, have you considered AI's own cabinets? They're not as efficient as some, but they sound great for double bass, IMHO. A used Contra-EX can often be had for $250-300, or you could go for a Ten2-EX and have your 2 x 10" speakers in a single cabinet.

  5. I had a Ten2 combo up until not long ago I sold because I didnt like the sound too much, to me AI speakers sound a little to hifi and no balls IMO. Interestingly when I pulled the head out and connected it to my friends 210 cabinet built by Labsystems my bass sounded full and sweet organic. So as tempting it is to get AI speaker I might try something in a wooden box first. If its true what they say about ohms law I might just get a Berg 210. Thanks heaps! T.

  6. Are you saying that if I get a Bergantino 210 that is rated at 8ohm it'll be the same as if I bought a 212 at 4 ohm? Of course the tone, the punch, bottom end and the rest will be different but the overall volume is the same???????? (I only understand ohm inside a radio, this speaker ohm business is science to me :))

  7. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004
    Well, Sam, my friend, that's not correct. According to the extensions to Ohm's law, power is equal to I[SUP]2[/SUP]R. So let's fill in the values for 250 watts/8 ohms and 500 watts/4 ohms:

    250 = I[SUP]2[/SUP]8
    250/8 = I[SUP]2[/SUP]
    I = 5.6 amps

    500 = I[SUP]2[/SUP]4
    500/4 = I[SUP]2[/SUP]
    I = 11.2 amps

    Notice that, in the latter case, the current is twice that in the former.

    Now, if it were 250 watts into 4 ohms, that would require the same amount of current as 500 watts into 8 ohms.

    When choosing a particular cabinet and amp in terms of the power delivered, what matters is the sound pressure level delivered for a given amount of power (watts) developed. It is true that, given typical modern solid-state designs, an 8-ohm load will result in an amp developing half the power that it would develop into a 4-ohm load. Keep in mind, however, that losing half the power corresponds to losing 3 dB, all other things being equal.

    More often than not, all other things are not equal. For example, suppose cabinet A is rated at 8 ohms and produces 110 dB SPL given a 1-watt input. Now, suppose cabinet B is rated at 4 ohms and produces 104 dB SPL given a 1-watt input. Purely on the basis of power output, you would want cab A, the 8-ohm cab! Why?... because it requires one-quarter of the power to produce the same sound pressure level as cab B (notice that I chose cab B to be 6 dB less sensitive than cab A).

    The maximum power developed by your amp into cab A will be 1/2 (3-dB less) than that developed into Cab B... but cab A, being 6-dB more sensitive, will end up producing 3 dB more sound pressure than would cab B at the amp's maximum output for each.

    This is why I've posted here many times:
    Think SPL, not watts!

    All of this ignores other important factors in choosing a cab, such as frequency response, dispersion, excursion limit of the driver, and on and on.

    Here's a nice power calculator resource.

    Geeky side note:
    When applying Ohm's law to AC circuits, V = IR does not strictly hold. Complex AC impedances (not resistances) can shift the phase between the voltage and the current. The cosine of the angle of the phase-shift is called the power factor (PF). The real equation for power in an AC circuit would be:

    Power = I[SUP]2[/SUP]*R*PF. By the way, if the angle is 90[SUP]0[/SUP] (cosine = 0), NO POWER is actually developed across the load.
  8. Sam Sherry

    Sam Sherry Inadvertent Microtonalist Supporting Member

    Sep 26, 2001
    Portland, ME
    Euphonic Audio "Player"
    Doc -- Thank you very much for setting me straight. I should shut up more often!

    "And with that, I'm gone. You'll probably read on TB soon about some old fart who . . . "
  9. Mike Arnopol

    Mike Arnopol Supporting Member Commercial User

    Jan 4, 2005
    Owner of MAS Soundworks
    I think that the Thunderchid cab is the best out there. (for my needs---50/50 electric and DB) It's 4 ohms and goes WAYYYYY loud and has the most natural mids and highs I've heard.
  10. 250W is more than enough for a single 112.
  11. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004
    Sam, perish the thought! If anything, I wish you would post more often. I enjoy your thoughtful, intelligent, and, yes, elegant additions to these threads.
  12. iiipopes

    iiipopes Supporting Member

    May 4, 2009
    Indeed! System efficiency is the most neglected aspect of a system setup after everything is matched for impedance and power handling.

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