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Watts vs Decibels is it worth it?

Discussion in 'Amps and Cabs [BG]' started by Moordoom, Nov 24, 2016.


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  1. Moordoom

    Moordoom

    Feb 8, 2016
    I have a Crate BH220 bass head, and I play it out of 2 Carvin 4x10s. At 8ohms I am pushing about 150 watts.
    Was thinking about getting a new bass head but was doing some research first.
    These are the approximate value for watts to decibels:
    200w = 53dbw
    500w = 56dbw
    1000w = 60dbw

    With this being said, and assuming that my cabinets can handle 1000w (which they cannot), is there really that much of a difference in loudness and cut thru from 200w to 1000w for a 7dbw increase?

    Reason I ask is my stack is not mic'd or XLR connected to the PA we use in medium size venues, and is struggling to cut thru on my 1000w (500w x2) PA, in which we mic our leads 100w amp, and our rhythm (acoustic) plays straight thru the PA.
     
  2. Nev375

    Nev375

    Nov 2, 2010
    Missouri
    Watts does not equal loudness.

    Im curious where you got those watts to decibel values.
     
  3. ehque

    ehque

    Jan 8, 2006
    Singapore
    I think this question is better asked in the Amps section.

    With 150W I don't really think you can compete with a 100W guitar head. Roughly estimate to need 5-10 times as much wattage. Also, while watts are great to a point, it is easier to get louder with cabinets that turn watts into sound more effectively. Bigger cabinets with more speakers, generally.

    I don't know what size a "medium" venue is (nor the acoustics of such venues), but you can consider turning the electric guitar down instead of having a volume war with everyone. This really depends on the venue, the genre you play, and the purpose of your music.
     
    Munjibunga likes this.
  4. Moordoom

    Moordoom

    Feb 8, 2016
    dBW (Decibel-Watt)
     
  5. Moordoom

    Moordoom

    Feb 8, 2016
    I did select the Amps section, then new thread, but I did it from my phone so I may have missed something.

    The "medium" venues or what I consider medium, large bars (300 people or less) and 6000 to 10000sqft, indoor or a small music venue outside.

    Yea it is sort of a volume war, but the sound person is "related" to the lead player. But I do not want to be louder necessarily, just to cut thru a little more.
     
  6. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    I'm wondering how two 410 cabinets are being connected to give you eight ohms. Normally, if you connect two cabinets to a head, they are connected in parallel. If the cabinets are eight ohms each, the head would see four ohms.

    If you have two four ohm cabinets and are connecting them in series, the total impedance would be eight ohms. However, this is not how it is normally done.

    Your amp is rated 220w at 4 ohms. Four ohms is the minimum rating, so you should not connect cabs with a lower impedance. For instance, two four ohm cabs connected to the amp presents an impedance of two ohms. This should not be done.
     
    Last edited: Nov 24, 2016
  7. basscooker

    basscooker Commercial User

    Apr 11, 2010
    cincy ky
    Owner, ChopShopAmps
    I read the op the same way. Are you hooking up two 4 or 8 ohm cabs? How are you getting 8 ohms with two cabs?

    Sounds to me you're running about 220 watts through 810 at 4 ohms and just need more sensitive drivers, or to go into the PA. I do think that even at "only" 220 watts you have got to be loud through that. Maybe a head upgrade to a more powerful head ([email protected] ohm) may give you that extra you need. And yes, seven decibels AT BASS GUITAR FREQUENCIES is significant enough to notice a marked loudness increase.
     
    Last edited: Nov 24, 2016
    HolmeBass likes this.
  8. Pilgrim

    Pilgrim Supporting Member

    As pointed out above, Watts do not determine loudness. The numbers you cite are simply incorrect and cannot be depended upon.

    Cabinet impedence and sensitivity are big factors, and the acoustics of the room also play a big part.

    That said, unless you have a loud band, 150W into two reasonably sensitive 4x10 cabs should generate a LOT of sound. Tell the guitar players they don't need to play with their amps and PA at 11 all the time.
     
  9. If you're losing the fight with a 100w guitar amp you might consider a DI and let your amp just fill the stage.
     
    skwee and SanDiegoHarry like this.
  10. A little bit of EQing may correct your problem, as far as cutting through the guitars.
    As the others here have stated, watts do not create volume.... Speakers do. I use a Kilo which is 1000 watts bridged mode or 500 watts "stereo" mode. However, I do not use the 1000 watts or even 500 watts, for that matter. I run a AK410 in each side (stereo mode) which equals to 200 watts @ 8 ohms each side. And I cut through my guitarist's (absolutely ridiculous) 3 Marshall stacks with plenty of headroom.
    My point being, you may have a lot of volume already going and maybe you are just hearing 'mushy' stage mix. I would play around with your EQ and see what happens.
     
  11. Rick James

    Rick James Inactive

    Feb 24, 2007
    New Jersey
    You didn't read the fine print. It's referring to dBW, not dB SPL, which is what sound levels are measured in. The average single driver bass cab has 1 meter/1 watt sensitivity of 95dB.
    Going to your question, it takes a doubling of power to get 3dB of additional output, which is audible but not huge. If you're going to increase power from what you have it should be by a factor of four to be worthwhile, and your speakers have to be able to use that power. The average speaker will only take about half its rated power before it maxes out the driver excursion, so consider that before getting an amp that puts out much more than that.
     
  12. Cirk

    Cirk

    Jan 16, 2011
    Panama City, Florida
    Efficiency is also impacted by how the cabs and drivers interact. This can have a lot to do with all.
     
    Nev375 likes this.
  13. WaynerBass

    WaynerBass Inactive Suspended

    Jan 12, 2016
    Southwest Florida
    I had an old Acoustic 4x15 cabinet that had a plate in the back stating that the cab is capable of deafening SPL's greater than 130db
     
    tattooSAM likes this.
  14. Thumper19605

    Thumper19605

    Jun 29, 2013
    You want more sound, more speakers, acoustic energy.
    The reason I use 2 cabs with 15's. Works for me.
    I also use a 300w head.
    To prove this out, unplug one speaker to a stereo. Less sound.
    Doubling watts does not double volume.
    A second speaker cab with the appropriate ohms load would help you more.
    A 100w guitar amp will be hard to compete with in any event, crazy loud!
    Good luck!
     
  15. MDBass

    MDBass Supporting Member

    Nov 7, 2012
    Los Angeles, CA
    Endorsing Artist: Dingwall-Fender-Bergantino-Dunlop-Tech 21-Darkglass-Nordstrand
    A more powerful head will get you significantly more volume with those cabinets.

    But why are you mic'ing the 100 watt guitar cab and not using a DI for the bass?
     
    HolmeBass and pudgychef like this.
  16. ficelles

    ficelles

    Feb 28, 2010
    Devon, England
    This. It's not a sound pressure level unit.
     
  17. ficelles

    ficelles

    Feb 28, 2010
    Devon, England
    Yes, but only if you put a vast amount of power into it :)
     
  18. MVE

    MVE

    Aug 8, 2010
    I'm very confused by many of the answers here. ;)

    The answer is always, YES!!!

    Get a bigger amp!
    If that doesn't work, get bigger speakers.
    That is the only way to properly deal with guitarists that play too loud.
     
  19. monsterthompson

    monsterthompson The Eighth Note Wonder Of The World Supporting Member

    Nov 25, 2008
    Hollywood
    Displacement generally gets you more bang for your buck than watts. There's a point at which the doubling of watts to get 3db more (all else equal) gets into silly territory. If you want to move air, add speakers.
     
  20. SanDiegoHarry

    SanDiegoHarry Inactive Supporting Member

    Aug 11, 2008
    San Diego, CA
    As with amps, not all cabs are the same.
    If you are struggling to hear yourself with TWO 4x10 cabs, you have some issues here.
    I have a 2x10 + 1x12 rig that I drive with a 500 watt class D head that I assure you would have no issue being heard.

    So at the very least you need more wattage to drive those cabs.

    Oh - and don't forget - DB run on a logarithmic scale
    http://www.acoustics.salford.ac.uk/acoustics_info/decibels/
     
    lamarjones likes this.
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    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
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