OT Idiot friend need a little help.
|
Silver Member Username: Woofers4lifeLexington, Tennessee Post Number: 112 Registered: Mar-09 | He was like if one sub hits 130dbs and you have 4 of them same subs hitting 130dbs are you hitting 520 dbs... i laughed but can anyone kinda give me an indepth explaination to explain to him how wrong he is? Basiclly what i said was its wayy more complex than that but he doesnt seem to wanna listen to me, so can someone help me out here? |
|
Diamond Member Username: WingmanaliveWww.stainles... .ecrater.com Post Number: 20727 Registered: Jun-06 | Tell him if that were true then if anyone wanted to break the record cheaply then all they would have to do is run 1000 pairs of headphones. Or something like this lol.  Many small does not equal one big. Kinda like an earthquake. Several 2.2 shakes happening simultaneously does not equal a 7.0 magnitude rumble. Kinda like the female 0rgasm.  P.S. 520 dbs would destroy matter. Nothing has been measured that high.....ever. I think your internal organs liquefy at like 190 or some chit. |
|
Diamond Member Username: WingmanaliveWww.stainles... .ecrater.com Post Number: 20728 Registered: Jun-06 | This is if you wanted the technical jargon: C/P "As audio/video hobbyists, most of us grew up thinking that if we have an amplifier with 50 watts of rated output power into 8-ohm speakers, and that combination produces reasonably clean and loud music, then by doubling the amplifier power to 100 watts per channel, the system would then play twice as loud. Many readers likely still believe that. Not so. Although it's not the easiest thing to comprehend, doubling the amplifier power does not double the loudness. In the above example, the sound from the speakers would not be "twice as loud"; it would only be "a little louder," an increase of 3 decibels. How loud is that? Hearing tests with large groups of people have revealed that a one-decibel (1 dB) change in loudness is approximately the smallest audible step that the average listener can detect, so an increase of 3 dB most listeners term "slightly louder." So why doesn't that 100-watt amplifier always sound twice as loud? Because the acoustic decibel--the decibel (dB) being the unit of measurement used worldwide to quantify the acoustic loudness of sound--has a peculiar relationship to amplifier power output measured in electrical watts. That relationship is called "logarithmic." If that word gives you an instant headache (nightmares of high-school math), then here's a simpler explanation: If a sound gets louder by 3 decibels or "slightly louder," it takes twice as much electrical power from your receiver or amp to produce that modest increase. Therefore, a 100-watt amplifier will produce sound only slightly louder than a 50-watt amplifier. So far, so good. But what if it's party time, and you're listening to music "very loud," a level defined as about 90 dB Sound Pressure Level (SPL), and your speakers are gobbling up swings of 15 to 20 watts per channel on those musical peaks. Drink in hand, you advance to the volume control on your receiver thinking, "I'll just crank this up to make the music twice as loud," and you turn up the volume control until there's a 10 dB increase in the sound level. Now your party-time goal of "twice as loud" will make huge electrical demands on your nice little multi-channel receiver or power amp. The receiver must deliver ten times as much power to double the subjective loudness. Between 6 dB and 10 dB is double the volume level, where 6 dB is four times the power and 10 dB is 10 times the power. In the aforementioned example, the amp must produce 150 to 200 watts per channel for those peaks in loudness. Therefore, every 10-dB increase in acoustic loudness--from 80 dB to 90 dB, or 90 dB to 100 dB--requires ten times as much electrical power in watts. That's all very well if you have a monster amplifier or multi-channel A/V receiver with huge reserves of power output (most of us don't). If not, watch out. Your receiver or amp may "clip" or distort (or both), which will put a clamp on the output of the amp. When you push your amplifier into overload or "clipping," several things may happen. First, the top and bottom of the waveforms (representing the audio signals) are clipped off, generating distortion. Next, the amplifier's protection circuits are activated, removing those portions of the signal that are causing the overload, generating distortion. And finally, the amplifier's power supply may fluctuate according to the demands of the music signals. Not everyone is affected by this scenario, of course. Some people (increasingly few, it seems) don't listen to loud music. They like background levels, and with average speakers, background levels demand 1 watt or less of amplifier power. Or they may have very efficient speakers (Klipsch, Cerwin-Vega, Tannoy, and the like) that will play extremely loud using modest amplifiers, the trade-off being a very large degradation in tonal accuracy, a definite harshness, and a complete loss of off-axis performance that accompanies horn-loaded designs. But in many situations, speakers will be damaged and distorted sound will offend many ears. No discussion of decibels, acoustic loudness, and electrical watts is complete without an explanation of loudspeaker "sensitivity." (Another way to define a speaker's sensitivity is to look at how efficiently the speaker converts electrical power, in watts, to acoustic sound output in decibels.) Let it be said in a general way that speakers are not very efficient or sensitive devices. They need a lot of electrical power input to produce relatively little acoustic output. Nevertheless, speakers do vary quite a bit in sensitivity. To determine a speaker's sensitivity, we feed the speaker with 1 watt of amplifier power, using a test signal of pink noise, and measure in decibels how loud the sound is at a distance of 1 meter (about 3 feet). A lot of domestic hi-fi speakers measure in at about 89 or 90 dB SPL at 1 meter. Larger speakers, with bigger woofers and more drivers, typically produce greater acoustic output; smaller bookshelf models have to work harder, and their output is typically less, often between 86 and 88 dB SPL at 1 meter. Placing the speaker in a room helps (the walls, ceiling, and floor reflect and reinforce the speaker's sound), adding about 4 dB to its output. For example, a speaker like Axiom's M80ti has a measured sensitivity in an anechoic chamber of 91 dB SPL at 1 watt at 1 meter. But putting the M80ti in a room raises its sensitivity rating to 95 dB SPL at 1 watt, 1 meter. A 95-dB sound level happens to be "very loud," as most of us would subjectively describe it. And it is--from 3 feet (1 meter) in front of the speaker. But let's move our listening seat back twice as far, to 6 feet. Guess what happens? We instinctively know that sound gets weaker as the distance from the source is increased, but by how much? A formula called the "inverse square law" tells us that when the distance from the source is doubled, the sound pressure weakens by 6 dB. Among sound engineers, there's a common saying: "6 dB per distance double." So at a 6-ft. distance, the M80ti is now producing 89 dB. Now let's double that distance again to 12 feet, a fairly common listening distance. The speaker now produces 83 dB, which isn't all that loud at all. And if you sat 24 feet away, a not uncommon distance in big rooms, the speaker would produce 77 dB SPL. But what about stereo, I hear you shout. Here's another oddity of loudness and the decibel. When one speaker is producing a level of 90 dB, adding a second speaker playing at the same level only increases the overall loudness by 3 dB! (The loudness does not double!). So the two speakers in stereo produce a loudness level of 93 dB. So adding a second M80ti will raise the loudness at 12 feet from 83 dB to 86 dB. And don't forget we're still using 1 watt of amplifier power output into Axiom's most sensitive speaker. But how loud are real-life instruments, orchestras and rock bands? Now, while 86 dB SPL is "fairly loud," it's not nearly as loud as what you might hear from a good seat at an actual rock concert or from an orchestra or pianist in a concert hall. A solo grand piano can reach peak levels of 109 dB SPL, a full orchestra and chorus in a concert hall will measure 106 dB, and a rock group, 120 dB SPL. Now let's try and get our peak speaker sound levels to 96 dB, "twice as loud" as our 86-dB listening level. That isn't that difficult because right now we're only using 1 watt per channel to drive the M80ti's to 86 dB. So we'll need ten times as much power, or 10 watts, to reach 96 dB. Big deal. We've got lots more. But things begin to change, and rather dramatically. Let's push the M80ti's to what we might experience from a solo grand piano, 109 dB. We're at 96 dB with 10 watts per channel. Let's go to 106 dB. So that requires 10 x 10, or 100 watts. Close, but not quite there yet. Just 3 dB more. Remember, we have to double the power for a 3-dB increase in sound level. So 100 watts becomes 200 watts. Yikes! Our receiver has only 110 watts maximum output! We've run out of amplifier power! And what about the rock concert? Let's lower our expectations and aim for 119 dB. Going from 109 dB SPL, which needs 200 watts per channel, to 119 dB SPL (get out your ear plugs) is another 10-dB jump and--you do the math--that requires 10 x 200, or 2,000 watts per channel! From all this you can see the huge power requirements inherent in reproducing real-life acoustic sound levels in average or big rooms. The M80ti's are tested to levels of 1,200 watts of input power so they come very close. But the truth is that if we are seeking real-life acoustic sound levels in our listening rooms, there's a very persuasive argument for very large, powerful amplifiers. And if your speakers are less sensitive (and many are), then the power demands rise even more dramatically. Sizeable rooms and greater listening distances will also increase power demands tremendously. And what many of us don't realize until we hear it, is that clean undistorted loud sound often does not sound that "loud." The key here is that in most or our home listening, there are small amounts of distortion caused by a lack of dynamic headroom (but more on that next month). It's the distortion that makes it sound "loud" in a domestic setting. To remove those distortions and increase dynamic headroom relates to even more power. We've become accustomed to accepting some distortion with our reproduced music, because all amplifier's distortion ratings gradually increase as they approach their output limits or slightly clip the audio signals. When that happens, we turn down the volume, because distortion starts to intrude on our listening pleasure, and it sounds "too loud." The lesson in all this is that you can never have too much power, and that big amplifiers rarely damage speakers. Little amplifiers driven into clipping burn out speakers. In the scheme of high fidelity, that last barrier to realism is having enough power and being able to approximate real-life loudness levels. " The article is referencing home audio but the principals are the same. Have fun reading. See you next year.  |
|
Gold Member Username: RiconissanPost Number: 1604 Registered: Feb-09 | Yeah those little ones just do not cut it. You better be able to rock her world on demand or you will lose houses and cars. |
|
Diamond Member Username: WingmanaliveWww.stainles... .ecrater.com Post Number: 20729 Registered: Jun-06 | Here's a good pic describing the concept. By adding drivers it's just like adding power, but not doubling output, only increasing it "slightly". Hope it helps.  |
|
Gold Member Username: The_image_dynamicSan Diego, California Post Number: 5215 Registered: Dec-06 | Paul pretty much covered it -- but tell your "friend" that the highest decibels that can be achieved above water and without modifying the Earth's atmospheric pressure is 194dB. The Space Shuttle has been said to have reached somewhere around 215dB because the combustion of the rocket engine chemicals causes the atmospheric pressures to change. Underwater, due to the immense pressures and density, I think I remember it can reach in the high-200's. Also, don't forget that at around 177dB or so, your inner ear tissue is destroyed. So....in summary, your "friend" is a moron. |
|
Platinum Member Username: Rovin1 15 = 149.5 DBs ...Trinidad & T... Post Number: 15179 Registered: Jul-05 | good going pauly tell ur friend about wikipedia let him go take a read ...... |
|
Silver Member Username: Woofers4lifeLexington, Tennessee Post Number: 113 Registered: Mar-09 | Thanks i knew it was way more complex than i had thought, yes i know he is a moron and i have told him so but he dont want to listen to me. He thinks his 2 JBL 10s and his other 2 mis matched 10s hit 130 atleast, i tell him its no were close maybe 100dbs if that, it causes physical feeling of the pressure but nothing like 130 would. He is starting to listen to me a bit and is getting a DD 9515 from one of our friends but he yet again made an idiot of himself by saying im gonna put a 760 watt pioneer and a JBL 1000 watt on it, I told him he was a moron again i told him unless he can match the RMS wattage exactly he is running the risk of frying the voice coil and he said how yet again i told him the uneven load would cause distortion and heat the coil till it melts, is this right or was i mistaken? Thanks paul just reading that made my IQ higher So let me see if i fully get it. so if you double the wattage its only gonna show a 3 db increase? So lets say my friend was hitting 60dbs before he adds 3 more tens and lets just say they have 60dbs at 6 ft because its in a blazer he would only have a DB increase of 18dbs? would the adding of subs and a non increaseing power supply bring down the gain is spl? |
|
Gold Member Username: TejcurrentPost Number: 1842 Registered: Apr-07 | "so if you double the wattage its only gonna show a 3 db increase?" Yes. "So lets say my friend was hitting 60dbs before he adds 3 more tens and lets just say they have 60dbs at 6 ft because its in a blazer he would only have a DB increase of 18dbs?" No. The subs don't actually have any dbs inherently. Just look at it like adding 3 decibels every time you double the quantity of subs. From one sub to two = 3 db higher, from two to four = 6 db higher. So if he was hitting 60db he would now be (theoretically) at 66 if he had one sub. If he has 4 subs now adding 3 more would gain him less than 3 db. I've never seen a car with a sub meter lower than 100db, unless you are talking about 6 feet outside the vehicle. "would the adding of subs and a non increaseing power supply bring down the gain is spl?" Not usually. Both subs should be getting the same signal from the amp(s), so by increasing the number of subs it should continue to get louder. |
|
Silver Member Username: Woofers4lifeLexington, Tennessee Post Number: 115 Registered: Mar-09 | i guesstimate that he is hitting around 110-115 maybe 120, i will see if he will let me post a vid of his setup he is uber proud of the mis matched stuff.... ok i understand it i think.. what i meant was that one sub had a sensitvity of 60 but im pretty sure there around 85 db sensitvity(or lets just say that for theory) and he has a pioneer 760 and running a bout 100 watts rms to each so 400 watts rms give or take so let me try this out. gain in db from watts would be 9dbs from the woofers would be 6dbs so lets say 85 plus 16 is 101dbs? and the bouncing of the sound from inside the vehicle, would that add to the db gain aswell? im sorry if im wrong again im just trying to fully understand all the information of this so i can give him a detailed answer so he doesnt try to call me out and i not have the math to back up what im saying. |
|
Diamond Member Username: WingmanaliveWww.stainles... .ecrater.com Post Number: 20734 Registered: Jun-06 | To gain 9dbs you need to either have 8X the original power or drivers. Say you start out with one 100w sub hitting 100dbs. 103dbs requires 200w or 2 100w drivers. 106dbs requires 400w or 4 100w drivers. 109dbs requires 800w or 8 100w drivers. Seeing as it's usually easier to run a one sub setup alot of ppl opt for the higher powered single sub setup as opposed to multiple drivers, just to keep it simple. Think of the concept like filling up a martini glass with water, or vodka, or everclear or whatever. As the cup's diameter widens it fills slower and slower with the same rate of water flow. If the depth of the water in the glass represents dbs you can see that with every inch of water rise (db) it takes more water (power) to do so. At the top of the glass it takes MANY more units of water (power) to achieve the same increase in height (dbs) as when you first started filling it. This is why record setters/holders HAVE to run 10's of thousands of watts simply to gain the few more dbs required to attain a higher score. Power plays a big roll but at that level efficiency in design, product and execution are just as if not more important than muscle. I say we all break out our martini glasses and practice. |
|
Diamond Member Username: WingmanaliveWww.stainles... .ecrater.com Post Number: 20735 Registered: Jun-06 | Sorry for the redundancy but another comparison you might relate to if you're somewhat familiar with aviation is like comparing the energy required for an airplane to reach high altitudes. The higher you go the thinner the air becomes thus requiring a higher airspeed to maintain lift. The energy required to raise altitude from sea level to 10,000 ft is say X. Now raise your altitude from 30,000 ft to say 40,000 ft and it becomes a demand from the plane's engines somewhat like XXXX. Same raise in altitude but a much greater demand in power to do so. Ok I'm done now. |
|
Gold Member Username: Hittin1TEAM REVOLUTIONLake Charles... Post Number: 3537 Registered: May-07 | fun note: there is a shrimp that produces 218 db. just by snapping it's claws together. comparable to the loudness of a sperm whale. IIRC it is called a pistol shrimp. That is fu<kin' crazy if you think about it. |
|
Gold Member Username: Hittin1TEAM REVOLUTIONLake Charles... Post Number: 3538 Registered: May-07 | and the space shuttles hit 155 db from 1000 or 2000 feet away @ 20 hz. on the TL |
|
Gold Member Username: Hittin1TEAM REVOLUTIONLake Charles... Post Number: 3539 Registered: May-07 | found something on the shrimp http://www.dailymail.co.uk/sciencetech/article-1085398/Deadly-pistol-shrimp-stun s-prey-sound-loud-Concorde-UK-waters.html definetly an interesting read if you are bored |
|
Silver Member Username: Woofers4lifeLexington, Tennessee Post Number: 116 Registered: Mar-09 | lol wow thats actually pretty interesting lol Things we do when were board lol... ok i get it now thanks for all the help fellas |
|
Gold Member Username: JkidderWorlds gunna end, In 2012 Post Number: 4165 Registered: Nov-05 | i wanna fish with some pistol shrimp.... |
|
Gold Member Username: TejcurrentPost Number: 1844 Registered: Apr-07 | I just finished researching and typing a 2000 word final exam as well as creating a survey, a graph, and a flow chart in the last 3 hours. Paul, I am ready to learn more about your martini glass example |
|
Diamond Member Username: WingmanaliveWww.stainles... .ecrater.com Post Number: 20738 Registered: Jun-06 | Learns yourself some son lol.  |
|
Silver Member Username: M0nstarToledo, OH U.S. Post Number: 314 Registered: Dec-08 | "and the space shuttles hit 155 db from 1000 or 2000 feet away @ 20 hz. on the TL" dang!!!!!!!! that space shuttle was POUNDINNNNNNNNN!!!!!!!!!! |
|
Diamond Member Username: WingmanaliveWww.stainles... .ecrater.com Post Number: 20744 Registered: Jun-06 | Well, Chauncey works for NASA so.......... Damn that's beneath even me.  **Walks off to room in shame** |
|
Platinum Member Username: Nd4spd18Philadelphia, PA Post Number: 10551 Registered: Jul-06 | chauncey hahaha |
Main Forums
Today's Posts- Home Audio Forum
- Home Video Forum
- Home Theater Forum
- Car Audio Forum
- Accessories Forum
- All Forum Topics