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Bass Amp vs. Guitar Amp Watts

Discussion in 'Amps [BG]' started by amusicalperson, Feb 5, 2014.

  1. amusicalperson

    amusicalperson

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    Ok, I was really hoping someone can explain this to me. Why is a 60 watt guitar amp deafing loud and a 60 watt bass amp is a joke?
  2. bigchiefbc

    bigchiefbc Supporting Member

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    A lot of it depends on how it's EQ'd. If you boost the hell out of your low-end, the speakers have to work a lot harder to push those frequencies. I tend to not really care about the room-shaking lows and EQ my amp to be mid-heavy, and I'm able to keep up with my guitarist, and our amps are the same wattage (100W)
  3. AaronVonRock

    AaronVonRock

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    I was told a long time ago by guys who know their stuff that as a rule a bass amp should be at least 3 times as loud as a guitar amp. So a 60 watt guitar amp would need a 180 watt (or more) bass amp.

    Can anyone confirm or deny the logic in this?
  4. bigchiefbc

    bigchiefbc Supporting Member

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    I can tell you that if I followed that rule in my band, I would completely and totally drown out the guitar.
  5. BioWeapon

    BioWeapon

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    I can keep up with my guitarist, who's got 150 watts into a 4x12, with a 200 watt 115 (with an extension cab for a boost of volume when needed). So, the wattage rule doesn't really apply if you're being volume sensible.

    BUT, if you have the same speaker surface as your guitarist and he/she is blasting your head off with the volume at 11, you'll probably need 3-4 times more watts to keep up comfortably.

    Anywho, that's why the Volume control knob was invented!

    EDIT: There needs to be a formula that factors in speaker efficiency, surface/displacement, volume per watt per note ratio, etc. that would help us simply calculate this stuff.
  6. JimmyM

    JimmyM Supporting Member

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    Endorsing: Ampeg Amps, EMG Pickups
    Low notes take a lot more wattage to amplify to the same level as other higher notes.
  7. Rick Auricchio

    Rick Auricchio Registered Bass Offender Supporting Member

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    Your ears are almost ten times more sensitive in the upper ranges than in the low ranges, so as to be able to hear speech. That's why guitars were invented---so they could be heard in the same frequency range as voices.

    When people have severe hearing loss in the 4KHz region they need hearing aids. They often have no problem hearing lower frequencies, but they lose their ability to understand speech.
  8. Downunderwonder

    Downunderwonder

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    In addition to what Jimmy and Rick said.

    Halve frequency, double wavelength, means the air must be pushed and pulled twice the distance, which takes a whole lot more power, Duke can remind us how much more.
  9. willbassyeah

    willbassyeah

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    not hijacking TS, but one thing i notice about bass freq is that it travels farther away than guitar, whenever i go to a small festival of any sort which has only FOH at the front of the stage, i can hear the bass clearly when i am further away from the stage but it is slowly drowned out by the guitar as i move closer to the stage, not sure if anyone experience this
  10. Baird6869

    Baird6869 Supporting Member

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    My dumb dumb math (based only on experience, no speaker/cab discussion, etc.) is 4-5x the power is required for a bass amp to keep up with a tube guitar amp. So IME, I need at least 200-250w to be heard with a 50w tube guitar amp.

    YMMV, but this is what I have seen. 2 guitarists with 50w amps? 400-500w.
  11. BFunk

    BFunk Gold Supporting Member

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    Its been a long time since I studied wave mechanics, but I believe your assumptions about wavelength and energy are exactly wrong. Higher wavelengths have more energy.

    http://hubblesite.org/reference_desk/faq/answer.php.id=73&cat=light
    Also, the reason low frequencies travel farther is that high frequencies get absorbed more readily by solid materials.

    The reason why it takes more amplitude to hear low frequencies is that at low to moderate listening levels we have a much harder time hearing bass frequencies. We are very sensitive to the 1-3 kHz range. That is why a typical fire alarm is rarely more then 20 watts. As the volume increases our sensitivity evens out. That is why many home stereos have a loudness button or dial. It adds more bass and treble to give us the same audio effect as playing recordings loudly.

    Take a look at Fletcher Munson curves to see the uphill battle for us bass players.
    http://en.wikipedia.org/wiki/Fletcher–Munson_curves
  12. Vince Klortho

    Vince Klortho

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    Read the previous question also. That relationship is for light - not sound. Light waves and sound waves are two entirely different things.
  13. nolezmaj

    nolezmaj

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    Another thing, higher frequences are much more directed than lower f, produced from the same speaker. So, if you are not standing direct in front of speaker, the effect of lost high f. gets even more emphasized.
  14. vbchaos

    vbchaos

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    Wave mechanics are a bit ago for me too, but as far as I remember you have to differ the dB scale from the dB(A) scale.
    Watts = Watts. Electrically, Watts is the unity for electrical power, which is the amount of current times the applied voltage! P=U*I. And neither current nor Voltage cares for their source! Current is just an amount of electrons streaming through a conductor, and Voltage is just the difference between two electical potenials.
    So, the 60 Watts of your guitar-amp are the same as the 60 Watts of your bass-amp (taken that both amps are equally efficient).
    The difference is (as far as I remember it from university) that your ear does not listen in a linear way. You are much more sensitive to frequencies around the 3-6 kHz than to 100 Hz (as has been stated earlier).
    The dB(A) scale holds to the (average) hearing curve of the human ear and will tell you that you need alot more energy to make a 100Hz signal as loud as a 3kHz for a human ear.

    If you do a hearing test, you will note that you hear very high and low tones much later than med-frequency tones. That is because the tone volume is risen in dB scale, not in dB(A).
  15. alexclaber

    alexclaber

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    We don't hear watts, we hear decibels. Well actually, we hear Phons (which is the dB SPL scale adjusted to compensate for the human ear's inconsistencies across the frequency band and at different SPLs).

    A 12" driver which does not have to do any lows can be easily 6dB more sensitive than one which has to do lows. 6dB extra sensitivity is like quadrupling your power. The human ear is much worse at hearing lows than mids so for the bass guitar to sit in the mix right against an electric guitar then it needs to be another few dB louder minimum. It's therefore perfectly reasonable to expect a bass amp to need 8-10 times the power output of a guitar amp if both are driving single 12" drivers.

    There are very few 12" bass guitar drivers that can handle that much power, so you'd need to drive a 2x12" stack instead to keep up - which means you can halve the power requirement because you've doubled the cone area (increasing the sensitivity by 3dB).

    So a bass cab twice as big as a guitar cab and about five times the power should work out fine.
  16. Mr. Foxen

    Mr. Foxen

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    Amp tinkerer at Ampstack
    I play bass into an approximately 60w amp most of the time, its loud enough for practicing with metal drummer, live its the drivey half of my rig. The loads of watts thing is marketing and inability to work eq.
  17. BFunk

    BFunk Gold Supporting Member

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    I was taught the physics of waves are the same regardless of media.

  18. mbelue

    mbelue Supporting Member

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    So what you are saying is you choose to sacrifice how you sound just to be louder?
    Using EQ tricks to achieve more volume is not an acceptable compromise for some.
  19. tekdiver500ft

    tekdiver500ft Supporting Member

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    This. Plus, you aren't just mixing with one guitar, but two or three, drums, and maybe keys, too. I've found that in general, I need to add the total power of the other instruments and quadruple that to blend well. Fortunately, my acoustic guitarist goes only through the mains and his vocal monitor, rhythm has fifty watts through a 112, and lead has 15 watts through a 1x8 (stage only, we all go through the FOH), so I don't need a ton of power. I am happy with 450 watts and a 115.
  20. kikstand454

    kikstand454 Supporting Member

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    You can exchange watts for speaker area in the volume war. My guitarist has 120watt 212 ....usually no louder than 9oclock. I've been playing for 6 years now with him with a 410 only getting about 130 watts. I'm also never past 10oclock. We've turned up to noon before for an outside flatbed gig with no pa support. I hung right there with him just fine.

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