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#1
Posted to rec.audio.car
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Amps and Ohms
Let's say I have a 4-channel amp which has a rating of 200x4 @ 2-ohms.
Let's say I connect a pair of *2-ohm* component speakers to the front channels of the amp. Additionally, let's say I also connect a pair of *4-ohm* coaxials to the rear channels of the amp. Now my question is: do the rear coaxials get 200 watts each since they are only 4-ohm speakers, or will they only get 100 watts each? |
#2
Posted to rec.audio.car
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Amps and Ohms
In article , Alan wrote:
Let's say I have a 4-channel amp which has a rating of 200x4 @ 2-ohms. Let's say I connect a pair of *2-ohm* component speakers to the front channels of the amp. Additionally, let's say I also connect a pair of *4-ohm* coaxials to the rear channels of the amp. Now my question is: do the rear coaxials get 200 watts each since they are only 4-ohm speakers, or will they only get 100 watts each? 100. Most amps when lightly loaded tend to output more peak volts, so it may really be 120 watts, just playing with figures. It would depend on the efficiency of the speakers as to what set plays louder, but a 3dB difference is not much. Will only shift the sound slightly to the front or rear. It does not matter much anyway, because you would have to start clipping the sound if you got anywhere near max output. greg |
#3
Posted to rec.audio.car
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Amps and Ohms
G wrote:
In article , Alan wrote: Let's say I have a 4-channel amp which has a rating of 200x4 @ 2-ohms. Let's say I connect a pair of *2-ohm* component speakers to the front channels of the amp. Additionally, let's say I also connect a pair of *4-ohm* coaxials to the rear channels of the amp. Now my question is: do the rear coaxials get 200 watts each since they are only 4-ohm speakers, or will they only get 100 watts each? 100. Most amps when lightly loaded tend to output more peak volts, so it may really be 120 watts, just playing with figures. It would depend on the efficiency of the speakers as to what set plays louder, but a 3dB difference is not much. Will only shift the sound slightly to the front or rear. It does not matter much anyway, because you would have to start clipping the sound if you got anywhere near max output. And if you really want to be accurate, you can also point out that power/load calculations like this are approximate only - IN THEORY an amp rated 200W into 2 ohms will only drive 100W into 4 ohms, and IN THEORY would drive 400W into a 1 ohm load... but theory alas must always bow to reality, which mostly comes in the form of inefficiency and losses to heat. As noted, the difference will not usually be noticeable or even audible, so we tend to speak "in theory" most of the time... |
#4
Posted to rec.audio.car
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Amps and Ohms
i'm so tired coming here n seeing you trying to figure out car audio
stuff. its like watching monkeys try to figure out a simple task.lol 100w at 4ohm are equal to 200watts 2ohm. which means niether is louder. theyre equal! same with 1ohm. 400 1ohm is equal to 200 2ohm. |
#5
Posted to rec.audio.car
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Amps and Ohms
On Nov 13, 2:34 am, Matt Ion wrote:
G wrote: In article , Alan wrote: Let's say I have a 4-channel amp which has a rating of 200x4 @ 2-ohms. Let's say I connect a pair of *2-ohm* component speakers to the front channels of the amp. Additionally, let's say I also connect a pair of *4-ohm* coaxials to the rear channels of the amp. Now my question is: do the rear coaxials get 200 watts each since they are only 4-ohm speakers, or will they only get 100 watts each? 100. Most amps when lightly loaded tend to output more peak volts, so it may really be 120 watts, just playing with figures. It would depend on the efficiency of the speakers as to what set plays louder, but a 3dB difference is not much. Will only shift the sound slightly to the front or rear. It does not matter much anyway, because you would have to start clipping the sound if you got anywhere near max output. And if you really want to be accurate, you can also point out that power/load calculations like this are approximate only - IN THEORY an amp rated 200W into 2 ohms will only drive 100W into 4 ohms, and IN THEORY would drive 400W into a 1 ohm load... but theory alas must always bow to reality, which mostly comes in the form of inefficiency and losses to heat. As noted, the difference will not usually be noticeable or even audible, so we tend to speak "in theory" most of the time... not necessarily true. Two ohms could be the peak output of the amplifier, which means; if you decrease the load resistance further, most of the amplifier power will be allocated to heat dissipation of the amplifier, instead of 50/50. It all depends on impedance matching. If it matches best with 2 ohms, then 1 ohm will actually be worse and it might burn the components in your amplifier. You probably already know this though. |
#6
Posted to rec.audio.car
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Amps and Ohms
bob wald wrote:
i'm so tired coming here n seeing you trying to figure out car audio stuff. its like watching monkeys try to figure out a simple task.lol 100w at 4ohm are equal to 200watts 2ohm. Equal? Your saying its equal, but what is equal? The watts aren't equal, the ohms aren't equal, The current isnt equal! That's not very equal ! ;-) which means niether is louder. theyre equal! Louder? How can you say that without knowing the sensitivity of the speakers? We only know the speakers are one set of 4 ohms coaxials and one set of 2 ohms components. There are WAY too many unknown variables for you to make the statement that the speakers will be equal in loudness. If ANYTHING were equal, it would be the amp output voltage, ASSUMING were using the same sound and not touching the volume control or gains, and assuming the amp can keep the same stability of the output voltage at 2 ohms that it normally does at 4 ohms. (You know if 2 ohms is more of a strain the voltage could drop.) way too many variables for you to make those statements! Eddie Runner |
#7
Posted to rec.audio.car
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Amps and Ohms
Mariachi wrote:
On Nov 13, 2:34 am, Matt Ion wrote: G wrote: In article , Alan wrote: Let's say I have a 4-channel amp which has a rating of 200x4 @ 2-ohms. Let's say I connect a pair of *2-ohm* component speakers to the front channels of the amp. Additionally, let's say I also connect a pair of *4-ohm* coaxials to the rear channels of the amp. Now my question is: do the rear coaxials get 200 watts each since they are only 4-ohm speakers, or will they only get 100 watts each? 100. Most amps when lightly loaded tend to output more peak volts, so it may really be 120 watts, just playing with figures. It would depend on the efficiency of the speakers as to what set plays louder, but a 3dB difference is not much. Will only shift the sound slightly to the front or rear. It does not matter much anyway, because you would have to start clipping the sound if you got anywhere near max output. And if you really want to be accurate, you can also point out that power/load calculations like this are approximate only - IN THEORY an amp rated 200W into 2 ohms will only drive 100W into 4 ohms, and IN THEORY would drive 400W into a 1 ohm load... but theory alas must always bow to reality, which mostly comes in the form of inefficiency and losses to heat. As noted, the difference will not usually be noticeable or even audible, so we tend to speak "in theory" most of the time... not necessarily true. Two ohms could be the peak output of the amplifier, which means; if you decrease the load resistance further, most of the amplifier power will be allocated to heat dissipation of the amplifier, instead of 50/50. It all depends on impedance matching. If it matches best with 2 ohms, then 1 ohm will actually be worse and it might burn the components in your amplifier. You probably already know this though. Can you not read?? This is exactly my point: all these numbers being tossed around are THEORETICAL calculations; the ACTUAL output will depend on a lot of other factors, such as those you've listed. |
#8
Posted to rec.audio.car
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Amps and Ohms
On Nov 14, 12:57 pm, Matt Ion wrote:
Mariachi wrote: On Nov 13, 2:34 am, Matt Ion wrote: G wrote: In article , Alan wrote: Let's say I have a 4-channel amp which has a rating of 200x4 @ 2-ohms. Let's say I connect a pair of *2-ohm* component speakers to the front channels of the amp. Additionally, let's say I also connect a pair of *4-ohm* coaxials to the rear channels of the amp. Now my question is: do the rear coaxials get 200 watts each since they are only 4-ohm speakers, or will they only get 100 watts each? 100. Most amps when lightly loaded tend to output more peak volts, so it may really be 120 watts, just playing with figures. It would depend on the efficiency of the speakers as to what set plays louder, but a 3dB difference is not much. Will only shift the sound slightly to the front or rear. It does not matter much anyway, because you would have to start clipping the sound if you got anywhere near max output. And if you really want to be accurate, you can also point out that power/load calculations like this are approximate only - IN THEORY an amp rated 200W into 2 ohms will only drive 100W into 4 ohms, and IN THEORY would drive 400W into a 1 ohm load... but theory alas must always bow to reality, which mostly comes in the form of inefficiency and losses to heat. As noted, the difference will not usually be noticeable or even audible, so we tend to speak "in theory" most of the time... not necessarily true. Two ohms could be the peak output of the amplifier, which means; if you decrease the load resistance further, most of the amplifier power will be allocated to heat dissipation of the amplifier, instead of 50/50. It all depends on impedance matching. If it matches best with 2 ohms, then 1 ohm will actually be worse and it might burn the components in your amplifier. You probably already know this though. Can you not read?? This is exactly my point: all these numbers being tossed around are THEORETICAL calculations; the ACTUAL output will depend on a lot of other factors, such as those you've listed. But what I stated was electrical theory. |
#9
Posted to rec.audio.car
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Amps and Ohms
eddie i guess i didnt write it simple enough for you.
if everything else is the same except the ohms n the watts = one another but they are just being run on different ohms..even tho the numbers may be different theyre EQUAL!!!!!! as far as loudness....but not every tiny spec.... |
#10
Posted to rec.audio.car
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Amps and Ohms
its been great fun watching over the yrs. pros talk about they changed
thier 4ohm to 2 ohm with the same equipment n it sounds much louder...hAHAhaHahaHAHaha.... i think you all need to look up the meaning equal. |
#11
Posted to rec.audio.car
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Amps and Ohms
Reality Check:
The "rated impediance" and the actual impediance may be quite different. The actual impediance varies with audio frequency. What is typically reported is the lowest impediance measured over the audio frequencies, typically a low audio frequency. The first priority in matching an amp with a speaker with respect to impediance is to avoid too low an impediance load on an amp because that can lead to overheating and damage to the amp. Additional potential power output is merely a minor secondary consideration. Remember, one needs to double output to get even a just noticable increase in volume (about 3dB). Most of the specs you have come to rely upon are written by advertising guys not the tech nurds at the company. You would be shocked at how little power is needed to provide good clean sound. The trick is to find an amp that puts out good clean sound. My home system can deliver about 120 watts into 8 ohms and at typical sound levels is called upon to deliver about 1 to 5 watts. When cranked up to levels my wife would not accept, my sub can suck up all of the 350 watts into 4 ohms my sub amp can deliver. |
#12
Posted to rec.audio.car
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Amps and Ohms
On Nov 16, 10:39 am, "Richard" wrote:
Reality Check: The "rated impediance" and the actual impediance may be quite different. The actual impediance varies with audio frequency. What is typically reported is the lowest impediance measured over the audio frequencies, typically a low audio frequency. The first priority in matching an amp with a speaker with respect to impediance is to avoid too low an impediance load on an amp because that can lead to overheating and damage to the amp. Additional potential power output is merely a minor secondary consideration. Remember, one needs to double output to get even a just noticable increase in volume (about 3dB). Most of the specs you have come to rely upon are written by advertising guys not the tech nurds at the company. You would be shocked at how little power is needed to provide good clean sound. The trick is to find an amp that puts out good clean sound. My home system can deliver about 120 watts into 8 ohms and at typical sound levels is called upon to deliver about 1 to 5 watts. When cranked up to levels my wife would not accept, my sub can suck up all of the 350 watts into 4 ohms my sub amp can deliver. the only way to prove how much power you are using is to use an oscilloscope. What do you consider typical sound levels? 90 Decibels at your ears? If this is true, then you are probably using 2 Watts of power if the speaker sensitivity is 90 dB for 1 W @ 1 m, because your ear is probably much a little further away than 1 meter. But what if you listen to your music at 96 dB to your ears. Then, I'm estimating that the speaker would have an electrical power of around 10 Watts. Additionally, different frequencies have different sensitivities, but usually an audiophile speaker has the same sensitivity at each frequency that its supposed to cover. However, the perceived loudness of one frequency to another at a given SPL differentiates because of our ear sensitivity. For example, humans' ears are less sensitivity to 100 Hz and below and are more sensitive in the midrange. Humans' ears are also less sensitive in the high range 10 kHz and above. This is where subwoofers come in handy. Subwoofers intentionally boost the SPL level of the low range to purposely make up for the ears low sensitivity to bass, in order for the listener to perceive that all frequencies are at the same perceived loudness. |
#13
Posted to rec.audio.car
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Amps and Ohms
Mariachi wrote:
the only way to prove how much power you are using is to use an oscilloscope. How do you do it with an oscope?? Just Curious. Eddie |
#14
Posted to rec.audio.car
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Amps and Ohms
"Eddie Runner" wrote in message
... Mariachi wrote: the only way to prove how much power you are using is to use an oscilloscope. How do you do it with an oscope?? Just Curious. Eddie If you want to measure power, you'll need a current sense resistor (non inductive) and a two-channel digital o'scope with the ability to multiply the two channels. I seem to recall that either Tek or Fluke had a scope which was optimized for this, but that's been some time ago. Most of the PC based scopes can do this as well. Pretty straightforward from there. Set the volts/division as needed to correctly scale the CSR and hook up a signal generator to the amp. If you have HP Vee or Labview or something similar, it would be pretty easy to setup a jig to automatically measure power for virtually any configuration of amp and speaker. As a side note, I spent 2 years at HP working on a tool to measure the energy delivered to inkjet resistors (on the silicon printhead) which did almost the same thing as I described above, only with a bunch more detail and about $4million invested. Inkjet is big money baby! Chris |
#15
Posted to rec.audio.car
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Amps and Ohms
Normally a bench tech would measure power with a dummy load and a volt
meter. There really isnt a need for a scope, but many use it just to watch the waveform for anything strange during testing. I dont think I have seen a tech try to measure power on a scope itself, although you could take the time to calibrate the screen marks to voltage but anyone with a scope probably have a wheelbarrow load of meters and that way easier.... BTW, a little trivia... Since you worked for HP, can you tell me what the first thing they build commercially? Hint, it was test gear! Eddie Christopher "Torroid" Ott wrote: "Eddie Runner" wrote in message ... Mariachi wrote: the only way to prove how much power you are using is to use an oscilloscope. How do you do it with an oscope?? Just Curious. Eddie If you want to measure power, you'll need a current sense resistor (non inductive) and a two-channel digital o'scope with the ability to multiply the two channels. I seem to recall that either Tek or Fluke had a scope which was optimized for this, but that's been some time ago. Most of the PC based scopes can do this as well. Pretty straightforward from there. Set the volts/division as needed to correctly scale the CSR and hook up a signal generator to the amp. If you have HP Vee or Labview or something similar, it would be pretty easy to setup a jig to automatically measure power for virtually any configuration of amp and speaker. As a side note, I spent 2 years at HP working on a tool to measure the energy delivered to inkjet resistors (on the silicon printhead) which did almost the same thing as I described above, only with a bunch more detail and about $4million invested. Inkjet is big money baby! Chris |
#16
Posted to rec.audio.car
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Amps and Ohms
That would be an audio oscillator. It was the first product to come from
"the garage". I've heard it was in common use well into the 60's. I've got the schematic around here somewhere. It was really simplistic by today's standards. Chris "Eddie Runner" wrote in message ... Normally a bench tech would measure power with a dummy load and a volt meter. There really isnt a need for a scope, but many use it just to watch the waveform for anything strange during testing. I dont think I have seen a tech try to measure power on a scope itself, although you could take the time to calibrate the screen marks to voltage but anyone with a scope probably have a wheelbarrow load of meters and that way easier.... BTW, a little trivia... Since you worked for HP, can you tell me what the first thing they build commercially? Hint, it was test gear! Eddie Christopher "Torroid" Ott wrote: "Eddie Runner" wrote in message ... Mariachi wrote: the only way to prove how much power you are using is to use an oscilloscope. How do you do it with an oscope?? Just Curious. Eddie If you want to measure power, you'll need a current sense resistor (non inductive) and a two-channel digital o'scope with the ability to multiply the two channels. I seem to recall that either Tek or Fluke had a scope which was optimized for this, but that's been some time ago. Most of the PC based scopes can do this as well. Pretty straightforward from there. Set the volts/division as needed to correctly scale the CSR and hook up a signal generator to the amp. If you have HP Vee or Labview or something similar, it would be pretty easy to setup a jig to automatically measure power for virtually any configuration of amp and speaker. As a side note, I spent 2 years at HP working on a tool to measure the energy delivered to inkjet resistors (on the silicon printhead) which did almost the same thing as I described above, only with a bunch more detail and about $4million invested. Inkjet is big money baby! Chris |
#17
Posted to rec.audio.car
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Amps and Ohms
In article , Eddie Runner wrote:
Normally a bench tech would measure power with a dummy load and a volt meter. There really isnt a need for a scope, but many use it just to watch the waveform for anything strange during testing. I dont think I have seen a tech try to measure power on a scope itself, although you could take the time to calibrate the screen marks to voltage but anyone with a scope probably have a wheelbarrow load of meters and that way easier.... I don't think I would measure power without a scope. How else would you watch for the clipping point. To measure max power I usually find the clip then back off. You would need a THD meter to find out how much to back off and make the distortion spec look good. greg BTW, a little trivia... Since you worked for HP, can you tell me what the first thing they build commercially? Hint, it was test gear! Eddie Christopher "Torroid" Ott wrote: "Eddie Runner" wrote in message ... Mariachi wrote: the only way to prove how much power you are using is to use an oscilloscope. How do you do it with an oscope?? Just Curious. Eddie If you want to measure power, you'll need a current sense resistor (non inductive) and a two-channel digital o'scope with the ability to multiply the two channels. I seem to recall that either Tek or Fluke had a scope which was optimized for this, but that's been some time ago. Most of the PC based scopes can do this as well. Pretty straightforward from there. Set the volts/division as needed to correctly scale the CSR and hook up a signal generator to the amp. If you have HP Vee or Labview or something similar, it would be pretty easy to setup a jig to automatically measure power for virtually any configuration of amp and speaker. As a side note, I spent 2 years at HP working on a tool to measure the energy delivered to inkjet resistors (on the silicon printhead) which did almost the same thing as I described above, only with a bunch more detail and about $4million invested. Inkjet is big money baby! Chris |
#18
Posted to rec.audio.car
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Amps and Ohms
Yes, not too many folks know it was an audio oscillator.
audio test equipment seems strange to folks that think of HP today. In the past I have had MANY pieces of HP audio test gear. Eddie Christopher "Torroid" Ott wrote: That would be an audio oscillator. It was the first product to come from "the garage". I've heard it was in common use well into the 60's. I've got the schematic around here somewhere. It was really simplistic by today's standards. Chris "Eddie Runner" wrote in message ... Normally a bench tech would measure power with a dummy load and a volt meter. There really isnt a need for a scope, but many use it just to watch the waveform for anything strange during testing. I dont think I have seen a tech try to measure power on a scope itself, although you could take the time to calibrate the screen marks to voltage but anyone with a scope probably have a wheelbarrow load of meters and that way easier.... BTW, a little trivia... Since you worked for HP, can you tell me what the first thing they build commercially? Hint, it was test gear! Eddie Christopher "Torroid" Ott wrote: "Eddie Runner" wrote in message ... Mariachi wrote: the only way to prove how much power you are using is to use an oscilloscope. How do you do it with an oscope?? Just Curious. Eddie If you want to measure power, you'll need a current sense resistor (non inductive) and a two-channel digital o'scope with the ability to multiply the two channels. I seem to recall that either Tek or Fluke had a scope which was optimized for this, but that's been some time ago. Most of the PC based scopes can do this as well. Pretty straightforward from there. Set the volts/division as needed to correctly scale the CSR and hook up a signal generator to the amp. If you have HP Vee or Labview or something similar, it would be pretty easy to setup a jig to automatically measure power for virtually any configuration of amp and speaker. As a side note, I spent 2 years at HP working on a tool to measure the energy delivered to inkjet resistors (on the silicon printhead) which did almost the same thing as I described above, only with a bunch more detail and about $4million invested. Inkjet is big money baby! Chris |
#19
Posted to rec.audio.car
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Amps and Ohms
GregS wrote:
I don't think I would measure power without a scope. How else would you watch for the clipping point. To measure max power I usually find the clip then back off. You would need a THD meter to find out how much to back off and make the distortion spec look good. greg To measure power you would use a distortion analyzer, you dont need a scope. I have worked in many service centers and have done it 100s of times. There is usually a scope there, because it is a part of all audio test benches, but you run the oscillator into the amp, measure the output voltage with a volt meter, and the THD on the distortion analyzer. You dont read the power from the scope, you read it from the volt meter. then voltage squared divided by the test resistors (dummy load). Since most amps are rated at very low THD, the clipping point would not be an issue, you wont get close. Eddie Runner |
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