Question about power upgrade

Discussion in 'Amps and Cabs [BG]' started by Bardolph, Oct 30, 2003.

  1. Bardolph


    Jul 28, 2002
    Grand Rapids, MI
  2. BTW, the specs on the GK site say the Backline 115 runs at 125 watts. With more power and more than twice as much speaker area the stack should sound at least twice as loud. Can vary a bit depending on speaker effieciency.
  3. Bardolph


    Jul 28, 2002
    Grand Rapids, MI
    Whoops, my mistake. I really did mean 125W. Gosh darnit I KNEW that :rolleyes:
  4. No big deal, I "misremember" often. :meh: Only reason I pointed it out was to show that you were getting a lot more watts out of the stack (along with the extra speaker area).
  5. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    No, it won't be twice as loud. You'd need 10 times the power, or 10 times the efficiency, or some combination thereof, to achieve that. Your alternative should be perceptibly louder than what you have now, but not hugely so.
  6. Right, if he was only increasing wattage. Did you check the stack he was talking about, Richard? He's more than doubling speaker area (and supplying at least as much wattage to each cab as he was to the single 15). That's what I was basing the prediction of twice as loud (perceived) on.
  7. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    You're right, there should be a pronounced difference in acoustic output; we only differ on how big a bump it's likely to be. I think "at least twice as loud" is optimistic. In part because even though adding speakers is a great way to increase output, you still have to take the efficiency of the speaker into account. If his two new cabs are less sensitive than his old one, he may gain little or nothing in the way of volume from adding speakers. For example, you can find plenty of 1-12s that would be more efficient and thus louder with the same power than my Acme 2-10, despite having less speaker area. However, if his new cabs are *more* efficient, AND he doubles his wattage, then maybe he could get to a 10 dB gain.

    But enough of my quibbling; the main point is that yes, the new rig should be noticeably louder. Whether it's loud enough is up to the player and his particular situation.
  8. marc40a


    Mar 20, 2002
    Boston MA
    Watts and decibels aside... You will hear a big difference in volume by adding a 2x10 to your combo.

    Adding speaker area is the most successful way to add volume - Much moreso than adding wattage - taking of into consideration the volume level we're talking about.

    Whether the appreciable volume increase will be enough for your playing situation, setup, or playing style is tough to say. If you're 'almost' loud enough should do the trick.
  9. Bardolph


    Jul 28, 2002
    Grand Rapids, MI
    Now that you've got me thinking, what would be a good loud 15" 8 ohm cabinet to go with the 400RB 2x10 combo just in case I didn't want the GK cab? and not too pricey
  10. Good point and as a fellow Acme owner I am quite aware of it. :(

    My assumption was that similiar cabs from one manufacturer would be very close in efficiency. Wrong! Apparently this is not the case with the larger companies who have "families" of cabs (and goes to show I've been spending most of my time reading specs at the "boutique" suppliers ;) ).

    I couldn't find any sensitivity data for the combos. However, in checking the GK cabs I found a huge claimed difference (10db!!!) between their high power (RBH) line and the rest of their cabs (RBS and BLX).

    In Eskimo's case, it looks like they are pairing a RBS 1X15 with the 400mb 2X10 (the recommended pairing on the GK site). The RBS cabs do have the same sensitivity rating as the Backline series, so he should hear a big boost in volume.
  11. Bardolph


    Jul 28, 2002
    Grand Rapids, MI
    Pardon me for being ignorant but how exactly does the sensitivity work?
  12. Scott D

    Scott D

    Apr 21, 2003
    Minneapolis, MN
    BTW, its a 2x10, not a 2x12.
  13. It's a way of measuring speaker (and cabinet) efficiency, how well it turns watts into sound pressure. When comparing two similiar cabs, the sensitivity rating can tell you if one will be louder than the other. Note that a 3 decibel (dB) difference is generally considered to be perceptible by human ear as louder. To make up for that 3db difference you need twice the watts!! 5dB is noticeably louder and a 10dB difference is perceived as twice as loud.

    "Sensitivity ratings are derived from the sound level produced by a speaker when fed a 2.83 volt input signal (equivalent to one watt of power into an 8 ohm impedance) with the sound pressure measured from one meter." from:

    Another good explanation along with how to figure out the maximum loudness if you know the sensitivity and the RMS rating of a speaker.

    Nice catch, I've edited my post to the real spec.
  14. Aussie Mark

    Aussie Mark I come from a land down under Supporting Member

    Oct 26, 2002
    Sydney, Oz
    Endorsing Artist: Fender; O'Neill Amps; Cave Passive Pedals
    Weird physics: You'll gain 3dB if your cabinet is within 12 inches of a wall, and another 3dB by pairing it with an identical cabinet (stacked or adjacent).
  15. Kevin V

    Kevin V

    Mar 12, 2003
    Union, New Jersey
    I hope to god that I learn all this jargon in physics class.