posted
If I'm not mistaken amperage is what drives a sub. To find amperage, acording to ohms law, you take power out and divide it by the subs resistance and then square root the number. Theoretically amps that are rated to put out a certain amount of power, say 1200 watts at one ohm will put out more amperage than an amp that is only rated to 4 ohms. eg 1100a2(I know its not 1200 wats but its close) vs orion hcca 275r. The orion should put out around 34 amps while the 1100a2 puts out 17 amps that would mean the orion would be way more powerfull than the rockford. I hope I'm right about current driving the motor in speakers because if i'm not I just wasted a bunch of time figuring this out.
posted
If you want to know what kind of amperage the amplifier is actually putting out, get an inductive ammeter, and clamp it around the positive cable from the amplifier, then rock out, and get your reading.
------------------ STILL waiting to hear a GOOD pair of HLCD's!!
If it dont fit, force it... if it breaks, it needed to be replaced anyway...
posted
Hey audiophyle.. actually think this one out, he has a pretty interesting point, in theory.
Because the magnetic field in the coil of wire that drives a circuit becomes stronger in the presence of more current, shouldn't an amplifier producing more current into the load drive it harder than and amplifier producing less current?
Answer- the point is moot. In order to produce MORE current into a given load, you must increase the voltage. If you increase the voltage, to increase the current, you increase the power. The two ALWAYS go together. And if you decrease the load to get more current, keeping the voltage constant, the power increases then as well.
Therefore, whenever you get more *power* into a speaker, you are getting more *current* too. It always goes together.. You can't change any factor in the ohms law equation without changing current, however, you can keep voltage the same, or resistance the same. Current is an effect of the other two, and only exists in their presence. And since the heat generated by the coil is power, it's rated in watts to simplify things. BUT, you have raised an interesting point that spawns some thoughts that make me wonder.
Now here is a rephrase of your question, to see what other people say.
If you have 34 amps through a 1 ohm load, and you get 1200 watts, the amp is producing 35 volts.
If you have a 4 ohm load, get 1200 watts and have 17 amps of current, you have seventy volts.
You take a sub, and it is 4 ohm, you plug it in to the amplifier producing 1200 watts at 4 ohm, and it produces 120 db of spl in a given situation.
Now, you change the coil for one of the same weight, out of a different material, that is 1 ohm. The sub stays the same, the situation stay the same. NOW, you plug it into the amplifier that does 1200 watts into 1 ohm. In this situation the current through the speaker is greater than the current through the other speaker.
Because the amount of *magnetic power* generated with a coil of wire is increased by CURRENT increase, not power, wouldn't a speaker of lower impedance be louder (move more, more efficient) than an equivalent speaker with a greater impedance?
Now I am NOT talking practical application here. This is theory, so don't tell me "well speakers like that don't exist" or anything like that.. Tear this up and tell me what you think.
Oh, and by the way, if I missed something stupid, point it out to me nicely
ShadowStar
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Computers are a lot like air conditioners.. Open Windows and they become useless..
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Posts: 2578 | From: Somewhere In the Northeast | Registered: May 1999
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posted
Yikes, my head is spinning. It always does after i read posts about this stuff. I guess its pretty easy to understand. Ahh well, it will come in time.
------------------ 2 MTX Thunder 3000 12" Power Acoustik 500x2 130watts x 2 Can you say DISTORTION!?
posted
I have wondered about how coils are wound. lets take an 8 ohm and compare it to an 4 ohm. the current in the 4 ohm will be double the 8 ohm. but I have noticed that 8 ohm speakers are some times just as loud as the 4 ohm version at half the power. I have also read that 8 ohms are more efficient than 4's, and that 4's are more eficient than 8's. I dont know who to believe. do the 8 ohms have smaller magnetic wire and double the turns? if so since the number of turns doubled that would make up for only half the current. I was told once that coils are made the same but with different material in them to get different resistances. I dont know what info is accurate. I dont even know how much the resistance changes once the coil gets hot. I think I remember reading somewhere that its a lot. so maybe 1 ohm subs become so hot that they are really two ohm? there must be something else to this picture because an 8 ohm sub at 1000W (11.1A) is definatly a lot louder than a 1 ohm sub at 200 watts (14.4A).
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Posts: 1259 | From: Fullerton. CA ,USA | Registered: Oct 1999
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posted
Because the amount of *magnetic power* generated with a coil of wire is increased by CURRENT increase, not power, wouldn't a speaker of lower impedance be louder (move more, more efficient) than an equivalent speaker with a greater impedance?
A 4 ohm speaker with 5 amps of current is approx. 2 times as loud as a 2 ohm speaker with 5 amps of current. The 4 ohm speaker has more windings than the 2 ohm speaker. The wire used in the 4 ohm is of a lower guage. What's louder, 5 amps through more windings or 5 amps through less windings.
The thing is, with an amp, the voltage is supposed to constant for any load (theoretical). If the load decreases in impedance, and the voltage at the output of the amp stays the same, the current will double. The lower impedance is twice as loud on the same amp.
Works for me!
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Posts: 76 | From: Quispamsis, New Brunswick, Canada | Registered: Oct 1999
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posted
ShadowStar: you have way too much time on your hands! You also raise some interesting points! Yes, all other things being equal, a lower impedance sub will play louder due to the increase in current due to the lower impedance. Voltage should not change, and current will double, if the amplifier can actually do it, and only a handful can fully double current into lower loads. But we all knew that. Most amplifiers outputs and power supplies are lucky to keep up with 4 ohm mono operation. I dont mean to say that a lot of amps arent capable of doing it, because being capable of doing it, and doing it "right" are 2 completely different things! How do they make 2 subs exactly the same, but with different impedances? As Shadow said, less windings, and different guage magnet wire. The tighter the turns on a coil, and the more turns on a coil, and the guaging of the wire on the coil, and the diameter of the coil, and the length of the coil determine the coils impedance. Efficency is determined by the coils impedance, the BL product of the magnet structure, the weight of the cone, the compliance of the surround and spiders, and this does vary among different brands, obviously. But it also differs among the same brand and model number. This is why ShadowStar, in the "Appearance of Quality" post wanted to see spectral decay plots. By using a waterfall plot of this type, you could theoretically find drivers that match better than just a pair tossed into a box by a manufacturer. They're are so many variables that will affect the way a speaker sounds, the least of which, IMO is the box it goes in, after all, if the manufacturer is doing his job, everything else about the sub SHOULD be the exact same as everything else about every other sub in that particular run. Oh yeah, just one more thing on this, when buying subs, try to get serial numbers that match numerically, no more than 2 or 3 digits off, this will lower the chances of things being different between otherwise matching subs. Hope this all made sense, and was accurate, but if it wasn't, I expect a good flaming for it!
------------------ STILL waiting to hear a GOOD pair of HLCD's!!
If it dont fit, force it... if it breaks, it needed to be replaced anyway...
But take it farther than practical application. THEORETICALLY, you could make a coil of the SAME WEIGHT, number of windings AND LENGTH (keep ALL physical dimensions the same) but change the material to change the resistance. This is the situation i'm talking about, keeping the sub the same but lowering the resistance to induce more current in a coil of equivalent weight, length and number of windings.
Think about it.. It's stumping me.. is there some other variable to keep the performance constant?
ShadowStar
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Computers are a lot like air conditioners.. Open Windows and they become useless..
The day Microsoft makes something that doesn't suck is the day they make vacuums.
Posts: 2578 | From: Somewhere In the Northeast | Registered: May 1999
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posted
Shadow, your right, you should be able to do it that way. I'm not sure what kind of different material you'd use, other than different guage wire on the coil, which would lower your power handling. But, yes, you should be able to do that, extract more current from the amp. I dont know if this would help at all on SPL though, considering the woofer will have the same output characteristics, but with lower power handling. I guess at that point you could do a liquid cooled sub to minimize power handling limits.
------------------ STILL waiting to hear a GOOD pair of HLCD's!!
If it dont fit, force it... if it breaks, it needed to be replaced anyway...
posted
I was just going to say... If you lower your impedance, which in turn draws more current, you have a by-product called heat. You are moveing more electrons, which creates more heat because of them moveing, right? SO! If you cool the VC on the driver, then that lets electrons flow easier, which allows more current to be drawn, while saveing the coil from overheating, melting the VC which shorts the sub out. Imagine a Jugg. with a hose that runs right up into the vent on the magnent. The hose sprays nitrogen into the sub, which cools the coil. Oh wait. It also would condense, which would short the sub out right?
------------------ 2 MTX Thunder 3000 12" Power Acoustik 500x2 130watts x 2 Can you say DISTORTION!?
posted
Actually, you'd want a controlled heating of the voice coil. The warmer the coil gets, the more current it can pass, inversely, the warmer the coil is, the less current can physically pass, so, finding a happy medium would be the real trick. I was thinking more along the lines of using the liquid they use to cool the machines used in grinding valves for engines. It is non-conductive, cheap, and easily cleaned by anything like a fish tank filter.
------------------ STILL waiting to hear a GOOD pair of HLCD's!!
If it dont fit, force it... if it breaks, it needed to be replaced anyway...
posted
from my understanding its not electrons moving that creates heat, it's the resistance to the flow of electrons. so in a perfect world we would all have amps that could drive a nail and all spekaers would have supercooled ceramic voice coils . If your really that concerned with effiency, work on the real problem that all cone speakers have: the 2%-10% effiency rating or try to make something that is efficent : like a compression driver that will sound just as natural as a cone driver
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Forget the bite, How loud can you bark ?
[This message has been edited by buggsz24 (edited 11-09-99).]
posted
Well, let's touch upon the ribbon driver then. My limited understanding of this driver type is that it is more efficient than conventional drivers, although it presents your amplifier with a truly capacitive load, and many of today's amplifier designs cannot run a ribbon due to this capacitive load. I have done some limited critical listening to the small and the big Magnaplanars, both being powered by a Mark Levinson home amplifier, and I am convinced by the time that I had with them, that they are, by a far stretch, more "true" to the original recording. Whether that is good or bad is up to the listener... any one care to comment?
------------------ STILL waiting to hear a GOOD pair of HLCD's!!
If it dont fit, force it... if it breaks, it needed to be replaced anyway...
posted
Tell me, IF you had 200v @ 30 amps RMS into a 5.2ohm load, going to your subs, would they hit hard??
Thunder. Because Size Does MATTER! ---------- It seems to work just fine for you guys... If the banana plugs stay on the speakers, and they don't arc to the frame (nice butt connectors btw), etc etc etc.... Your van rocks!
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Jeff Owner, Sweet Sounds. Team Sweet Sounds is gathering information....all are welcome Authorized Dealer for Cerwin Vega, Image Dynamics, Clarion Pro Audio, Stinger, Hifonics and more..... Digital Desings & more coming soon
posted
Mr. Dank- Your comment earlier that an 8 ohm speaker at 1000w (11.1A) is louder than a 1 ohm sub at 200w (14.4A).
Well....
My contention (and my "boggle") is that the 1 ohm sub will actually be louder, because current is what drives a sub. Thats the problem at hand.
In actual practice, the 8 ohm sub will be louder? Well, take into consideration the difference in the coil... Either the 1 ohm sub has LESS coil (less weight, less windings) or a coil bigger in cross sectional area (more weight, different amount of windings) and this will be the issue.. I'd prefer not to split those calculus type hairs right now though
ShadowStar
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Computers are a lot like air conditioners.. Open Windows and they become useless..
The day Microsoft makes something that doesn't **** is the day they make vacuums.
[This message has been edited by ShadowStar (edited 11-10-99).]
Posts: 2578 | From: Somewhere In the Northeast | Registered: May 1999
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posted
Not that I dont care about liqid cooled subs and all,(I do find it interesting) But I havent heard a anything about the two amps I listed. What do you guys think about the orion hcca 275r and the RF 1100a2. The orion puts out twice as much amperage so should it be equivilent to two rockfords. Lets just say that you dont have to worry about blowing your subs
Let's assume that all amps of brand X have the same voltage at their output stages, and the power rating is merely based on current flow. Brand X also makes a DVC woofer with 2 4 ohm coils.
Wire them in series (essentially one long coil) for an 8 ohm load. Hook this up to a 1000 watt Brand X amp and it will pass 11.1 amps through the speaker.
Wire them in parallel (two short voice coils in parallel) for a 2 ohm load. Hook this up to a 400 watt brand X amp and it will pass 14.4 amps.
Now for the practical answer. Picture Rockford Fosgate as Brand X.
1 DVC 12 on an 1100@2 (8ohm) vs. 1 DVC 12 on an 250@2 (2ohm)
which do you think will be louder. I'm willing to bet on the 1100@2 everyday and twice on Sunday. Just my opinion.
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posted
shedluv, I dont mean to be ungreatfull for others help but what are you talking about the orion amp does not put out 400 watts it puts out 1200 into 1 0hm bridged, so the advice you give is not what I'm looking for.This is still asuming that you are answering my question.
Answer- the point is moot. In order to produce MORE current into a given load, you must increase the voltage. If you increase the voltage, to increase the current, you increase the power. The two ALWAYS go together. And if you decrease the load to get more current, keeping the voltage constant, the power increases then as well.
Therefore, whenever you get more *power* into a speaker, you are getting more *current* too. It always goes together.. You can't change any factor in the ohms law equation without changing current, however, you can keep voltage the same, or resistance the same. Current is an effect of the other two, and only exists in their presence. And since the heat generated by the coil is power, it's rated in watts to simplify things. BUT, you have raised an interesting point that spawns some thoughts that make me wonder.
The answer was given in the third post :-)
The sub, and its resistance, is the variable. For equivalent subwoofers, then the orion is NOT equal to 2 rockfords, you should just go by the power rating of the amplifiers. Sorry for the confusion :-)
ShadowStar
------------------ Computers are a lot like air conditioners.. Open Windows and they become useless..
The day Microsoft makes something that doesn't suck is the day they make vacuums.
Posts: 2578 | From: Somewhere In the Northeast | Registered: May 1999
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