Bravo mate,
Well said.
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That makes so much sense.
Iâm impressed
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Seriously dude, talking the talk like that, why are you doing a course?
It sounds like you know whatâs what.
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WTF!
I have no idea what you just said.
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Dude, you explain things so well even a dumb ass like me can understand what you are sayingâŚsort of
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It is deceptively simple.
The sensitivity indicates how sensitive a speaker is to energy being put into it. The more noise a speaker produces per watt of input, the more sensitive it is.
The unit of energy being fed to the speakers is expressed in watts, and the amount of noise coming out of a speaker is expressed in decibels (dB). In order to compare the sensitivity of speakers, we measure the number of dBs being produced at a 1 meter distance for a 1 Watt input.
Unfortunately, the scale for sound pressure (noise) is not as you would expect. 93 dB is in fact twice as loud as 90dB, but it is only perceived as âa noticeable difference, but not moreâ, even though you do need twice the air movement to get at it. For this reason, the scale for sound pressure is what it is.
So⌠if you would want to hear a noticeable increase in noise, you need to double the energy you put into your speaker: double your amplifierâs power. Or⌠you could, you know, work with a speaker that has a sensitivity that is 3 dB higher than the one you have.
And that is why a 3 dB step up in sensitivity equals the noise level of an amplifier with twice the power.
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Thanks buddy.
I sort of get it now but Iâll have to reread it all a couple of times for it to really sink in.
I need to learn about it though because itâs important.
Thanks again.
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Ok, here we go. A non scientific approach to speaker configuration (multiple speakers in the same box)
A speaker is essentially an air hammer. It projects sound by pushing on a column of air. the rate of âpushâ you get is measured as decibels (dB). Iâm not going to get into dB here because it isnât necessary in order to understand the principle. Nor am I going to get into the math involved in determining how big of a column of air you are pushing on. It isnât necessary to understand the relationship between column size, power applied, and push achieved.
When you apply a signal to a speaker at a given power level, the speaker will flex in and out or âoscillateâ. The more power you apply, the more it will flex, the more it flexes, the harder it pushes on the air in front of it, the harder it pushes on the air, the more intense the effect on your ears. which produces what we perceive as VOLUME.
All speakers work on the same principle so they all have the same limitations. Mainly, they can only flex so much therefore, for a given size, they can only handle so much power before something has to give.
For this reason you will note that a 110 amp will be marketed in a given power range and a 115 amp will be rated in a higher power range. Does this mea that a 15 is louder than a 10? NO. It means that you can apply more power to a 15. I should say it this way, It takes more power to drive a 15 with the same intensity as a 10. Does that mean that the 10 is louder? NO
It means nothing is free. It takes more power to push on more air. More air moved= more sound produced. Not louder, just more. You say that doesnât make sense. To that I can only say that ohms law is in full effect. Volts X Amps = watts. Thatâs how it is. You simply get the same âper wattâ overall effect, itâs just spread over a different size area depending on the speaker size in question. Bigger speaker, softer push. Smaller speaker, harder push. Overall amount of force imposed on air is the same, more or less.
So that means if you want more sound, you need to move more air, in order to move more air, you need to apply more power. Since speakers are limited as to how hard they can push before they break, you need MORE SPEAKERS so you can push on MULTIPLE COLUMNS OF AIR.
PLEASE HEAR ME: Iâm not saying more speakers is better. Iâm not advocating everyone getting an 815 cabinet and buying a generator to power the amp. Remember we are playing for the human ear and all that is overkill. The ear has a given frequency range and a thresh hold for intensity.
The most common speaker configurations are 115, 112, 212, 210, 410, 810, and 208. Iâll be back later to put the speaker size and speaker configuration together by talking about the general particulars of each. Hopefully, this will give you an idea how to most efficiently produce YOUR UNIQUE TONE in multiple acoustic environments.
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Interesting discussion, @Gorch . . . 
A single 15" speaker has about the same amount of area as 2 x 10" speakers. So they should be fairly even in the amount of air they push . . . right?
I always thought that a smaller 10" or 12" speaker would react faster than a larger 15" or 18" speaker would. Put another way, they would be more responsive to an input signal, thus making them slightly clearer and âpunchierâ.
Did I get that right?
Cheers, Joe
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Yes. Exactly. Also, earlier I talked some about frequency response. Certain size speakers have certain inherent characteristics. Starting with a configuration that naturally delivers a sound closer to what you are going for is much more efficient than starting with something contrary to what you want simply because itâs cool, then having to wrestle with your tone all the time. For the sake of conversation, a smaller speaker has a greater sensitivity to a certain frequency band within itâs design range so naturally it will enhance those frequencies. Punchy, as itâs called.
The genre of music you play figures in as well. Thatâs why there is such variety in the market place. Thatâs also why I preach tone over power. Tone matters but after a certain point, power really doesnât.
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Using a 210 as opposed to a 115 give the air column of the 115 with the characteristics of 10 inch speakers.
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@Gorch thanks for all this information. You explain it so well. Even I can understand it. Might take me reading it a few times though 
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So @Jazzbass19 gave me a fabulous segue into putting speaker size and count together so on to the next subject⌠HOW DOES ALL THIS WORK TOGETHER.
We are going to apply some easy math here to show how it works. The numbers ARE NOT accurate, they just demonstrate relationship.
Letâs say you play with a clean signal, no effects. You like a punchy tone as in the example provided by @Jazzbass19. After much weeping and gnashing of teeth you discover that you like the natural characteristics of 10 inch speakers so you have a 110 in the music cave rated at 100 watts. You have a drummer friend that invites you to play a gig in town at the local community center. You grab your gear and go downtown to do sound check. You discover that nobody can hear you because you just donât have enough power to be present in the mix. The guitarist, for some strange reason has a 300 watt 115 bass amp. You hook that up and find that you are in the mix quite easily volume wise but you just donât have the crispness that you get with your 110. You finish the set with a tone that you donât like but you had fun and the crown didnât seem to know the difference. The band liked you and you get asked back in a few weeks to do it again. You had a blast so you accept the invitation.
Now back at the music cave you realize you have a problem. You need more amp. Off you go to your local music store with your bass. You plug in to several amps and strike up a conversation with the salesman. He points you to a 410 amp that is the same brand, same series as your 110 but itâs rated at 400 watts. (4x100=400) time goes by and you show up to the gig with your 410 and play. The experience was phenomenal. You sounded like you wanted to sound and you were heard with no problem.
This scenario highlight the basics of why somebody would want a certain configuration of amp. The 115 you played on the first gig had plenty of power, it just wasnât right. I wasnât you. So obviously itâs about more than power. The 410 you bought gave you a much better experience. It sounded and acted like your 110 because it was the same brand with the same characteristics so it produced the TONE you wanted at an adequate power level. Letâs continue our storyâŚ
Some time and a few gigs later, you pop by your drummer friendâs house and the guitarist with the 300 watt 115 is there. It turns out that guitarist has a cousin who plays a 5 string bass. The cousin invites you to try your hand with a 5 string so you sit down and jam with them. You decide you like the rumble of the B string and you notice that that 115 actually sounds pretty good. Later on you are back at the music store talking to the same salesman and you buy a 5 string bass. you take it home and plug it in to your 110 and play and discover that it sounds like crap. So you jack with your EQ trying get the rumble to come out and it just isnât happening. You plug into your 410 and jack with that EQ. Itâs a little better but still sounds nothing like the 115. This canât be. Both the 410 and the 115 can do the same thing, right? So you get on the internet for some research and you discover that the low freqs on the 5 string are pushing the bottom of your 410 freq envelope you hardly push on it at all and it flubs out. some additional research reveals that the same company that makes the amps you already have also offers a 212 amp that offers 500 watts and a freq range that will accommodate the B string. Off you go to the music store with both of your basses in tow. The same salesman sees you coming and already has a good idea what you are after so he takes you to where the 212 is already plugged in. You play both basses through the amp and find that it sounds good on both guitars with only some minor tweeking. You strike a deal with the sales guy and trade your 410 in on the 212. You continue to gig, get a record deal and move on to fame and glory and live happily ever after.
What all can you take away from this story based on everything youâve read throughout this thread?
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⌠GAS
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LOL! Thatâs great.
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On a more serious note: you make it sound as if driver diameter is the only factor in determining the lower end of the frequency range.
Is that what you are trying to get across?
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No sir. Thatâs only part of the equation. Iâve talked some about power, some about drivers, some about frequency, some about sensitivity. My goal is to show a relationship between the puzzle pieces without promoting a particular set up, focusing on a certain genre of music, or promoting a certain brand. furthermore, to do all of that as it applies to the taste of the individual bassist. Your tone is your signature, if you will, and nobody can tell you what that should be.
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The 12" speaker is a compromise between the 10" and the 15" ? . . . 
Also, the TONE is indeed what you want to go after! 
Cheers, Joe
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OK good I wouldâve been all up in arms if youâd have said yes. 
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The story is just something that is intended show show the different elements discussed in the thread working either with, or against each other. Itâs intended to provoke thought.
Different drivers of the same diameter have different characteristics from each other. Different configurations have advantages and disadvantages. Some brands of amps, in fact all brands of amps have their own signature sound as well. There is no way all that could be discussed in a reasonable amount of time. Even if it could, my opinions would be just that. Opinions. People have to go encounter it for them selves. Iâm just trying to hand them a map.
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