Acme cabs and power opinion (last question)

Discussion in 'Amps and Cabs [BG]' started by incubus2432, Apr 8, 2002.

  1. I couldn't disagree more, I've got a K1 instead of a k2, but I run it bridged into a 4 ohm load (each channel is therefore running at 2 ohms, a brutal test for an amp with no cooling fan) for years now, into 2 VL-210 EA cabs. 1500 W of pure sweet power. I'm getting a woody just thinking about it. :hyper:

    Maybe its just the k2 model that had issues? Did you have adequate airflow around the amp? Just cause it doesn't need a fan doesn't mean the case doesn't need ventilation to keep cool. If you cram it in a rack with another power amp with no space between them I would expect it to have heat problems.

    FWIW, The only problem with inefficient speakers is you need lots of power to drive them. Got the power, got no problem. A more efficient cab rated at 500W will be louder than a 500W low eff cab, but if the more efficient cab is rated at 100W, the low eff cab rated at 500W could be louder @500 w than the high eff cab is at its max of 100W. Or not if the one cab is efficient enough. Need to compare efficiency AND power handling to see which cab will be louder overall, given you have enough power to drive both. Twice the power handling with half the efficiency (-3dB) = tie. And take the efficiency numbers with a grain of salt, guideline, I bet there are ways to fudge them.

    How many watts RMS continuous are the cabs rated at? Make sure of the cab ohms and compare to the power rating at the same ohmage. Amp with [email protected] 4 ohms into could be closer to [email protected] 8 ohms. Isn't B2 [email protected] 4 ohms each? If you've got stereo amp with 500W [email protected] 4ohms into 2 350W 4 ohm cabs you're fine power wise. I wouldn't get an amp rated any more than double what the cab will handle, beyond that you'll have plenty of headroom, and likely even more trouble with blown speakers. Since 700w vs 500w amp won't be a noticeable difference, I wouldn't bother upgrading, unless you think your 500W amp is overrated.

    More likely, a compressor (ratio between 2:1 or no more than 4:1) and the threshold set up so it only engages close to the limit should tame the peaks without squishing the sound too much. Much cheaper and better than getting more power if you're already around 1.5 x the speaker RMS wattage rating.

    I like putting a subsonic filter on my amp too, there's lots of subsonics (string handling, etc) that suck up a lot of power, cutting those out may help, save all the power for audible freqs. Something around 30 Hz (5 string) or 40 hz (4 string) would be fine. Look for "Fmods" on google. It'll require a RCA to 1/4" adapters to put in your signal path. I put it on the amp input (between wireless and preamp), so the subsonics are gone and don't needlessly trigger the compressor. Before compressor is preferrable, but anywhere is better than nothing, even in effects loop as a "passive" effect.

  2. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    What are your preamp settings? I rarely push my lows (~60 - 90 hz) beyond 1:00. It eats up a lot of power and produces little or no sonic benefit.

  3. tombowlus

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

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
    I'm surprised no one has suggested using a high pass filter... ;)

    Seriously, though, if you can cut out some of the super ultra lows, you may find that your overall headroom increases, and that your effective low end is tighter and more well heard.

    Oh, and my amp of choice for stupid thick and tight low end is the Crest CA9. 900 watts per channel into 4 ohms.
  4. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    little late to the party,

    but i REALLY dig my B-4 for the louder gigs. with my K2, i've got plenty of low end monster booty to battle with anyone! i dare you all!!
  5. jerry

    jerry Too old for a hiptrip Gold Supporting Member

    Dec 13, 1999
    When I used Acmes, I used a QSC2402 to push 700 watts a side into each one.....sounded great! The 2402 also has 30hz cutoff and clip limiters, that made it ideal for the Acmes IMHO :cool:
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