How much volume does a second speaker add?

Discussion in 'Amps [BG]' started by skychurch, Sep 14, 2013.


  1. skychurch

    skychurch

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    Greetings,

    I have a question I am hoping someone(s) can answer. I have spent days reading posts on the forums and cannot find a definitive answer.

    My current bass rig is:
    GK MB Fusion 500
    GK 115MBE-II

    I have been trying to decide what cabinet to add to what I have. I think at this point I have been convinced (maybe not 100% but pretty close) that my best option is another 115MBE-II.

    My main question is this ... will adding another 15" cabinet necessarily make my rig louder?

    Here is a scenario I have come up with. Let's say I have the following settings on my current rig:

    1. Channel B of the MBF
    2. Gain B at 1:00
    3. Volume B at 11:00
    4. Contour at 0
    5. All EQ settings flat

    If I add a second 115MBE-II, how much will I have to lower volume B to get the same output as I had with one 15" speaker?

    I know that a second 15" speaker will give me more volume (and 500 watts from my MBF) but I am trying to determine how much? The reason is, I really don't need any more volume, I just want a fuller sound. If it comes to that I have to lower volume B to 9:00 (or lower) to get the same perceived output volume, I will probably just stick with one 15" speaker. I play at home, jams at other's houses and small to medium venues.

    Does anyone have any idea if I can add another 15" speaker WITHOUT adding vast quantities of volume?

    This question may even be stupid but I'd still like to figure this out. I don't have any place to try out another 15" cabinet to check this out myself. Your experience is greatly appreciated!

    Thanks much,
    Jim
     
  2. Bass_Pounder

    Bass_Pounder

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    Doubling you speaker area gives +3db

    Doubling your wattage also gives +3db

    Most amps do not double their power going from 8 ohms to 4 ohms, so it will more likely be about a total increase of +4-5db.

    Cannot tell you about "knob position" because knob position is different for every amp, and gives absolutely no indication of your power output (noon or "5" does NOT equal half power).
     
  3. KJung

    KJung

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    +1 to every point. I'll just sum up by saying 'a lot' to the OP's question:p And, to the OP, there will also be an impact on the low end due to coupling two cabs, so it will have a fuller low end. In addition, there is a lower probability that either your cab will start to compress on transients, or your amp will hit its limiting on transients, meaning that as you crank up and dig in, even at the same volume as your single cab and amp running at 8ohms, you will notice a more full, less compressed, more open low end.
     
  4. Downunderwonder

    Downunderwonder

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    You can eq in more booty, then you may run out of headroom with only one cab. The deliciousness of bass headroom is a large part of why one becomes a bass player. When you get into a volume war and lose your headroom it becomes much less fun.

    Headroom is the extra oomph you have in reserve to lean on an accent and have it come out clean before returning to regular volume. Can you not drag your rig to a store to try out 2 cabs?
     
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  6. FretlessMainly

    FretlessMainly

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    Right; my GK 700RB-II goes from 320W at 8 ohms to 480W at 4 ohms, so you get a 50% add-on. But do you really get both of the increases you cited? Sure you've doubled your speaker area and increased your wattage, but, for my case, I'm splitting the 480W into two cabinets at ~240W each. So effectively, I've decreased the wattage going to my original single speaker.

    I guess what I'm asking is are you double-dipping your increases here?
     
  7. Downunderwonder

    Downunderwonder

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    Read Ken's post again. It's all about what the speaker can do with the first 150w before the compression gets into action.
     
  8. Bass_Pounder

    Bass_Pounder

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    Not double dipping..........

    Doubling speaker area ALONE still gives a +3db increase due to sonic coupling (the two speakers/cabs now act as one big one).
     
  9. KJung

    KJung

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    Nope, doesn't work that way. You will get around a 5db increase (which is huge... db is a log scale) with the additional power, and ESPECIALLY because that additional power is now driving more drivers... pushing more air, and each driver is 'working less hard'.

    Think about having one 300 watt combo with an internal 8ohm 115, compared to two separate combo's, each with 250 watts driving two of the identical drivers. That is basically the situation with adding a second identical cab to a solid state head (assuming both cabs are 8ohms).

    Per Downunder's post, this results in the wonderful triple impact of:

    - More absolute volume capability on average
    - A bit more low end extension due to the coupling
    - A nice boost in headroom from both the amp (more power) and the speakers (each speaker 'sharing' the additional power and less likely to reach their mechanical limits)
     
  10. JimmyM

    JimmyM Supporting Member

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    No. Your original single speaker is having to work much harder than two of them would to equal the same volume so no double dipping. Yes, you are splitting the wattage that way, but the two cabs will also be putting out more volume as a result, so it more than makes up for it.

    Anyway, the only thing you have to lose from doubling up on your cabs is a couple extra minutes setting up and tearing down. Bigger is always better for bass. And even the best and biggest sounding small cabs sound better when you double up on them.
     
  11. Downunderwonder

    Downunderwonder

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    Not only that.

    You get better monitoring from having speaker closer to your ears. So much win you need to get old and lazy to leave second cab at home.
     
  12. yodedude2

    yodedude2 Supporting Member

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    post #2 nailed it.
     
  13. FretlessMainly

    FretlessMainly

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    OK, thanks. I often run a second cab, I just couldn't tell how much extra I was getting.
     
  14. Joedog

    Joedog

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    Also, your coolness factor goes up about 33.75%. A lot of people listen with their eyes. For cabs that light and cheap, I'd go for it. As said above, you dont have to take it to every little gig.
     
  15. skychurch

    skychurch

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    Thanks for all the great advise. If I'm understanding this correctly, an added speaker cabinet will give me approximately 5db increase. From what I read on the net, this adds about a 50% increase in perceived volume (subjectively, for sure). So, with the same settings on my MBF and two 115MBE-II, it will sound half again as loud to me.

    This being the case, I probably don't need another speaker cabinet.

    What I am trying to avoid is having to turn my MBF down so much (for an acceptable volume) that I don't get the growl I'm getting now that I really like. Back in the day, I played guitar professionally. I had a 100 watt tube amp that sounded amazing when it was at the sweet spot (volume about 7). We were young and stupid and played too loud (we all did).

    I quit the music scene for a while so I could go to college. After I started playing again, that 100 watt amp was just waaaaaay too loud. I had to turn it down so low (to get a "normal" volume) that it just didn't sound good any more.

    I ended up selling it and buying a 25 watt tube amp so I could push the amp to it's sweet spot and still be at a decent volume. I also got some pedals to control the volume and learned to use the volume on my guitar (imagine that).

    Anywho, I don't want to repeat that with my bass so I guess I'd better stick to one speaker as the volume and push of the amp is acceptable now.

    Although I suppose I could get another cabinet and not plug it in and still have my coolness factor increase by 33.75% :)

    Thanks again,
    Jim
     
  16. Downunderwonder

    Downunderwonder

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    It only gets louder when you turn it up to the same level. It gets fuller for the same volume level. I recommend you to give it a try. Most solid state bass amps get their tone from the preamp, the output volume knob is just that.
     
  17. Downunderwonder

    Downunderwonder

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    The other way of looking at the 5dB is extra pure headroom, choice juicy prime headroom which you can tap into as infrequently as you like, but when you do, oh boy. The other word for it is dynamic range.
     
  18. will33

    will33

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    Ken had it right. The vast mojority of any speakers volume increase happens in the first 100 watts....maybe 200 if you have a lot of speakers. The rest is headroom, acoustic coupling (fullness to the sound), narrowing of vertical dispersion (playing more to the ear and less floor and ceiling), and just the fact that you have a speaker(s) up closer to ear level.

    Add it all up and it is a very noticable/substantial increase.
     
  19. will33

    will33

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    "mojority" may've been a typo but it looks cool so I'm leaving it. :)
     

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