Actually, I'm looking for an old thread to settle an argument in another discussion group.
This is the thrust of the thread I'm looking for and I'm sure it was at this website that I read it. -
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The original poster wrote in reporting that he has built a really nice Power Amp, and one of his friends said he had wasted his time since he could by a 1800 watt amp for only $400. As it turns out, that was for a used commercial power amp.
I questioned whether 1800W amps really existed, and he provided a link to the manufacturer's website, and low and behold, there it was a $10,000 1800w amp.
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Now my details may be wrong, maybe it was a 1,000w amp, but overal, above is how the conversation went.
The original poster eventually posted picture of the amp he built.
Does this sound familiar to anyone? Could anyone point me to this thread?
I have tried searching for it, but I'm a little foggy on the details so I haven't been able to find it in any forum here.
The reason I'm asking, is that someone in another forum is claiming that 4 ohm speakers are EASIER to drive than 8 ohms speakers. Several of us have pointed out that it takes more current to drive 4 ohms and that means the power amp and the power supply have to work harder. I've also pointed out that more power consumption equals more work, but he is absolutely convinced low impedance is easier. Of course, I sense he is using a relatively obscure definition of 'easier'.
He keeps bring up the issue that current demand is only a problem for crappy £1000 (US$2,000) amps. That REAL amps, meaning outrageously expensive commercial amps, don't have this problem.
In the thread above, the original poster, tested the power output on a expensive commercial amp, and posted the voltage and current draws for various power outputs up to the maximum capability of his amp. I need those voltage and current draws to demonstrate that even expensive commercial amplifiers still have current limitations.
The other discussion is going on here. You can read but you can't post without joining.
"Ohms help"
http://www.avforums.com/forums/showthread.php?p=5319950#post5319950
Steve/BlueWizard
This is the thrust of the thread I'm looking for and I'm sure it was at this website that I read it. -
- - - - - - - - - - - - - - - - - -
The original poster wrote in reporting that he has built a really nice Power Amp, and one of his friends said he had wasted his time since he could by a 1800 watt amp for only $400. As it turns out, that was for a used commercial power amp.
I questioned whether 1800W amps really existed, and he provided a link to the manufacturer's website, and low and behold, there it was a $10,000 1800w amp.
- - - - - - - - - - - - - - - - - -
Now my details may be wrong, maybe it was a 1,000w amp, but overal, above is how the conversation went.
The original poster eventually posted picture of the amp he built.
Does this sound familiar to anyone? Could anyone point me to this thread?
I have tried searching for it, but I'm a little foggy on the details so I haven't been able to find it in any forum here.
The reason I'm asking, is that someone in another forum is claiming that 4 ohm speakers are EASIER to drive than 8 ohms speakers. Several of us have pointed out that it takes more current to drive 4 ohms and that means the power amp and the power supply have to work harder. I've also pointed out that more power consumption equals more work, but he is absolutely convinced low impedance is easier. Of course, I sense he is using a relatively obscure definition of 'easier'.
He keeps bring up the issue that current demand is only a problem for crappy £1000 (US$2,000) amps. That REAL amps, meaning outrageously expensive commercial amps, don't have this problem.
In the thread above, the original poster, tested the power output on a expensive commercial amp, and posted the voltage and current draws for various power outputs up to the maximum capability of his amp. I need those voltage and current draws to demonstrate that even expensive commercial amplifiers still have current limitations.
The other discussion is going on here. You can read but you can't post without joining.
"Ohms help"
http://www.avforums.com/forums/showthread.php?p=5319950#post5319950
Steve/BlueWizard
Well, PassLabs comes to mind. At least I am fairly sure the data is reasonably correct and not masked. There you can see big dollar amps with current limitations as well 
www.passlabs.com
Magura
www.passlabs.com
Magura
Well, "easier" in this case might mean the fact that one needs less supply voltage to produce the same output power into 4 ohms than into 8 ohms, at the cost of increased current. And if you go bridged it is even less, again. Available power in terms of current times voltage from the supply is one factor, power dissipated in the amp another. For a given power to be delivered into specific load impedance there is one optimum set of trade-offs between supply voltages and currents, internal power dissipation, drive voltage etc. Under this conditions amplifier/supply "works equally hard" for the same output power, it's the power that counts.BlueWizard said:
Very low impedance can compromise amplifier performance, but not primarly from increased current demand per se.
Of course it's simple math that a 4 ohms spkr with the same sensivity will play louder ("easier") with a given volume setting (== output voltage) than a 16 ohms specimen.
Regards, Klaus
Well, as long as I have some people interested in discussing this, what really drives a speaker? Is it Power or is it Voltage?
Certainly Power is consumed by the speaker, but if you give speakers of similar sensitivity the same input signal won't you reasonably get the same acoustical power?
So, I say, speakers are driven by Voltage, and in the process consume power.
So, I question which is the more fair test of Sensitivity, to drive speaker with an identical signal source (voltage; 2.83v) or to drive them with equal power(1 watt) which implies different voltages.
Let me illustrate -
Applied signal for fixed power and variable impedance-
1W, 4 ohms, = 2.000 volt
1W, 6 ohms, = 2.449 volts
1W, 8 ohms, = 2.828 volts
1W, 16 ohms = 4.00 volts
This would measure sensitivity to a power standard. But note that the signal to the 16 ohm speaker is very high.
Fixed input signal, variable power, variable impedance-
2.83V, 4 ohms, = 2.000 W
2.83V, 6 ohms, = 1.335 W
2.83V, 8 ohms, = 1.000 W
2.83V, 16ohms, = 0.501W
This would measure sensitivity to a voltage standard, but conversely, notice the difference in real power.
This is how the discussion started-
Someone wanted to know which was EASIER to drive -
8 Ohm (88db sensitivity)
6 Ohm (86db sensitivity)
But it hinges on how you define easier.
88db is louder than 86db, so in that sense, 88db is easier to drive. Depending on on what you mean by easier.
Then someone claimed that the 6 ohm speaker was easier to drive because it had a lower impedance. Which in turn lead to an argument that LOWER Impedance is HARDER to drive because for a given input signal, it consumes more power, more power means more work, more work mean harder, not easier. So, more work, but not necessarily more resulting acoustical output.
And the argument has gone on for 71 post arguing the point back and forth.
So, do we drive a speaker with an input voltage, and achieve an acoustical output, and the power burned in between is incidental. Or, conversely, do we drive our speaker with power, and voltage means nothing relative to acoustical output.
I'm saying that for a given input voltage, and assuming similar speakers, a 4 ohms speaker consumes twice the electrical power, but doesn't deliver twice the acoustical power relative to an similar 8 ohm speaker driven with the same voltage.
Essentially, you consume twice the power at twice the rate and get nothing extra for it.
As to Allen's comment, he misunderstood what I said. I do agree with the point he made in post#67, though it is unrelated to the point I was trying to illustrate.
Frustrated-
Steve/BlueWizard
Certainly Power is consumed by the speaker, but if you give speakers of similar sensitivity the same input signal won't you reasonably get the same acoustical power?
So, I say, speakers are driven by Voltage, and in the process consume power.
So, I question which is the more fair test of Sensitivity, to drive speaker with an identical signal source (voltage; 2.83v) or to drive them with equal power(1 watt) which implies different voltages.
Let me illustrate -
Applied signal for fixed power and variable impedance-
1W, 4 ohms, = 2.000 volt
1W, 6 ohms, = 2.449 volts
1W, 8 ohms, = 2.828 volts
1W, 16 ohms = 4.00 volts
This would measure sensitivity to a power standard. But note that the signal to the 16 ohm speaker is very high.
Fixed input signal, variable power, variable impedance-
2.83V, 4 ohms, = 2.000 W
2.83V, 6 ohms, = 1.335 W
2.83V, 8 ohms, = 1.000 W
2.83V, 16ohms, = 0.501W
This would measure sensitivity to a voltage standard, but conversely, notice the difference in real power.
This is how the discussion started-
Someone wanted to know which was EASIER to drive -
8 Ohm (88db sensitivity)
6 Ohm (86db sensitivity)
But it hinges on how you define easier.
88db is louder than 86db, so in that sense, 88db is easier to drive. Depending on on what you mean by easier.
Then someone claimed that the 6 ohm speaker was easier to drive because it had a lower impedance. Which in turn lead to an argument that LOWER Impedance is HARDER to drive because for a given input signal, it consumes more power, more power means more work, more work mean harder, not easier. So, more work, but not necessarily more resulting acoustical output.
And the argument has gone on for 71 post arguing the point back and forth.
So, do we drive a speaker with an input voltage, and achieve an acoustical output, and the power burned in between is incidental. Or, conversely, do we drive our speaker with power, and voltage means nothing relative to acoustical output.
I'm saying that for a given input voltage, and assuming similar speakers, a 4 ohms speaker consumes twice the electrical power, but doesn't deliver twice the acoustical power relative to an similar 8 ohm speaker driven with the same voltage.
Essentially, you consume twice the power at twice the rate and get nothing extra for it.
As to Allen's comment, he misunderstood what I said. I do agree with the point he made in post#67, though it is unrelated to the point I was trying to illustrate.
Frustrated-
Steve/BlueWizard
Tapco J2500, USD$399 delivered.
Most pro power amps are only rated at 1Khz for power. The Tapco is rated per channel, both channels driven,20Hz-20kHz:
* 2 ohms: 1400W
* 4 ohms: 750W
* 8 ohms: 575W
If that won't make your 88dB audiophile speaker sit up and bark, nothing will.
Same basic design as Behringer EP2500 and QSC RMX2450, but more transformer.
Most pro power amps are only rated at 1Khz for power. The Tapco is rated per channel, both channels driven,20Hz-20kHz:
* 2 ohms: 1400W
* 4 ohms: 750W
* 8 ohms: 575W
If that won't make your 88dB audiophile speaker sit up and bark, nothing will.
Same basic design as Behringer EP2500 and QSC RMX2450, but more transformer.
Power is what counts, not voltage in testing and in determiniting 'easier'.
It is very easy to get a nice 200V driver (National's LM4702, for example) to drive a ton of voltage but there is no power because there is no current capability. Even an op amp can drive tons of voltage but not much current. So voltage is not the right parameter to use. Power is a combination of voltage and current and covers both bases when talking about different load impedances. High impedance means more voltage but less current, low impedance is more current but less voltage. Comes out 6's either way you figure it. This is why speakers are often rated at 1W, not 2.83V (only 1W for 8 ohms). But in practical applications, lower impedance loads take slightly more work (power) to drive. Not output power but total power. This is due to IR loss increasing because of higher current. There are also other issues like cost for higher part counts for higher output current, stability differences between loads, etc. Anyway, easier could have many definitions so that has to be locked down before any real discussion can take place because if defined in terms of voltage or power with a given supply voltage, then 4 ohms are easier to get more power to.
-SL
It is very easy to get a nice 200V driver (National's LM4702, for example) to drive a ton of voltage but there is no power because there is no current capability. Even an op amp can drive tons of voltage but not much current. So voltage is not the right parameter to use. Power is a combination of voltage and current and covers both bases when talking about different load impedances. High impedance means more voltage but less current, low impedance is more current but less voltage. Comes out 6's either way you figure it. This is why speakers are often rated at 1W, not 2.83V (only 1W for 8 ohms). But in practical applications, lower impedance loads take slightly more work (power) to drive. Not output power but total power. This is due to IR loss increasing because of higher current. There are also other issues like cost for higher part counts for higher output current, stability differences between loads, etc. Anyway, easier could have many definitions so that has to be locked down before any real discussion can take place because if defined in terms of voltage or power with a given supply voltage, then 4 ohms are easier to get more power to.
-SL
Thanks to everyone who replied. This person is still stubbornly clinging to the notion that there is some advantage to low impedance speakers. Meaning, his belief is that, as a general rule, 4 ohm speakers will always sound better than 8 ohm or 16 ohm speakers, all other things being equal.
But that does bring up another questions. Certainly as you go to lower impedances you run into the trouble of supply all that current and the problems related to it. But what happens when you go to a higher impedance? What is the disadvantage of using 16, 24, or 32 ohms speakers.
Certainly, it is not current draw, but there must be other factors related to the amp that cause problems if the impedance gets too high?
Could someone explain the drawbacks and danger of high impedance speakers?
Just curious.
Steve/BlueWizard
But that does bring up another questions. Certainly as you go to lower impedances you run into the trouble of supply all that current and the problems related to it. But what happens when you go to a higher impedance? What is the disadvantage of using 16, 24, or 32 ohms speakers.
Certainly, it is not current draw, but there must be other factors related to the amp that cause problems if the impedance gets too high?
Could someone explain the drawbacks and danger of high impedance speakers?
Just curious.
Steve/BlueWizard
I would think that high impedance speakers are 'somewhat" dangerous that to get some power, you'd need a high voltage which could lead to electric shock at the speaker terminals.
power drives a speaker. if you have voltage but no current, you get a potential difference but no power. hence, no sound.
I also say higher impedance is easier to drive since it requires less current, the amplifier could be made simpler and speaker wiring doesn't need to be as thick your finger.
the only advantage I could think of in low impedance speakers is that you could get more power from low voltage.
power drives a speaker. if you have voltage but no current, you get a potential difference but no power. hence, no sound.
I also say higher impedance is easier to drive since it requires less current, the amplifier could be made simpler and speaker wiring doesn't need to be as thick your finger.
the only advantage I could think of in low impedance speakers is that you could get more power from low voltage.
thanks djQUAN, but that bring up another question.
Low Impedance speakers CONSUME more power, but do they produce more power? Does the excess consumption of electrical power really get translated into more acoustical power? And, even if it does, is that significant and is it a good thing?
I checked Parts Express for identical woofers available in both 4 ohms and 8 ohms. It seems that 4 ohm speakers have an inherently higher SPL.
Examples-
Goldwood GW-10PC-40-x 10" Heavy Duty
4 ohms: SPL: 92.7 dB 2.83W/1m
8 ohms: SPL: 90.4 dB 2.83W/1m
Goldwood GW-8PC-30-x 8" Heavy Duty
4 ohms: SPL: 91 dB 1W/1m
8 ohms: SPL: 88 dB 2.83V/1m
Goldwood GW-6PC-x 6-1/2" Heavy Duty
4 ohms: SPL: 85.1 dB 2.83V/1m
8 ohms: SPL: 87.2 dB 2.83V/1m
Notice the discrepancy though. Were these all tested at equal power inputs, or equal voltage/signal input? I'm not sure the specs as we see them can be trusted. The Goldwood website indicates 1W/1M for the SPL, though it doesn't give detailed spec sheets, and doesn't make a distinction between 8 ohm and 4 ohms.
We see more and more 4 ohm and 6 ohms speakers systems appearing on the market, but I wonder if there is an advantage, or if this is just action to no end?
I think some people are fooled into thinking they have more power if they run their amps at 4 ohms, but while the amp might have twice the capability to deliver power to 4 ohms, it also consumes power at twice the rate, so the net gain is really nothing. You have the same relative or proportional headroom whether you run your amps a 4 ohms, 8 ohms, or 16 ohms. But the demands and strain on the amp would seem much higher at 4 ohms.
Still slightly confused and frustrated by this whole issue
Steve/BlueWizard
Low Impedance speakers CONSUME more power, but do they produce more power? Does the excess consumption of electrical power really get translated into more acoustical power? And, even if it does, is that significant and is it a good thing?
I checked Parts Express for identical woofers available in both 4 ohms and 8 ohms. It seems that 4 ohm speakers have an inherently higher SPL.
Examples-
Goldwood GW-10PC-40-x 10" Heavy Duty
4 ohms: SPL: 92.7 dB 2.83W/1m
8 ohms: SPL: 90.4 dB 2.83W/1m
Goldwood GW-8PC-30-x 8" Heavy Duty
4 ohms: SPL: 91 dB 1W/1m
8 ohms: SPL: 88 dB 2.83V/1m
Goldwood GW-6PC-x 6-1/2" Heavy Duty
4 ohms: SPL: 85.1 dB 2.83V/1m
8 ohms: SPL: 87.2 dB 2.83V/1m
Notice the discrepancy though. Were these all tested at equal power inputs, or equal voltage/signal input? I'm not sure the specs as we see them can be trusted. The Goldwood website indicates 1W/1M for the SPL, though it doesn't give detailed spec sheets, and doesn't make a distinction between 8 ohm and 4 ohms.
We see more and more 4 ohm and 6 ohms speakers systems appearing on the market, but I wonder if there is an advantage, or if this is just action to no end?
I think some people are fooled into thinking they have more power if they run their amps at 4 ohms, but while the amp might have twice the capability to deliver power to 4 ohms, it also consumes power at twice the rate, so the net gain is really nothing. You have the same relative or proportional headroom whether you run your amps a 4 ohms, 8 ohms, or 16 ohms. But the demands and strain on the amp would seem much higher at 4 ohms.
Still slightly confused and frustrated by this whole issue
Steve/BlueWizard
I'm a total amateur, but this keep popping up in the bass forum I frequent.
Drivers are almost always tested with 2.83 V RMS @ 1kHz, regardless of impedance. Hence a 4ohm driver will get twice the power of an 8ohm driver. Which predictably leads to a 3dB higher number for sensitivity. Strange in a way, but logical in another. If you parallel a 4ohm and an 8ohm driver, the 4ohm driver will be louder.
As for easy load, it shouln't make a difference. However, high voltages are difficult for semiconductors. As you raise the power, you'll approach the levels where it's going be hard finding usable power transistors. So in that regard, 4ohm drivers are an easier load.
Drivers are almost always tested with 2.83 V RMS @ 1kHz, regardless of impedance. Hence a 4ohm driver will get twice the power of an 8ohm driver. Which predictably leads to a 3dB higher number for sensitivity. Strange in a way, but logical in another. If you parallel a 4ohm and an 8ohm driver, the 4ohm driver will be louder.
As for easy load, it shouln't make a difference. However, high voltages are difficult for semiconductors. As you raise the power, you'll approach the levels where it's going be hard finding usable power transistors. So in that regard, 4ohm drivers are an easier load.
BlueWizard said:
A statement as general as that usually means the guy doesn't know what he is talking about and is just passing on what someone else told him. Regardless, the argument really is all about semantics.
From the most basic standpoint (assuming a voltage amplifier is trying to amplify a signal to the same output level regardless of load), a purely resistive 8 ohm load is easier for an amplifier to drive than a purely resistive 4 ohm load because the 8 ohm load draws half the current. Doesn't get much simpler than that.
You can take the argument in whatever direction you want from there.
BlueWizard said:
Almost everyone (meaning most who are new to the world of audio
)gets caught up on the issue of power when it comes to amplifiers. The general misconception is that you need a lot of power to make a lot of noise, but you need to look at the whole picture.The louder a speaker is the more SPL it is capable of producing. Speakers have sensitivity ratings that tell you how much amplifier power you will need in order to achieve a certain SPL at a certain distance from the speaker. The more sensitive a speaker is the louder it will get with less amplifier power. For instance, a typical car audio subwoofer has a sensitivity around 82dB @ 1W/1m. That means with 1W of power from an amplifier, the speaker will produce a SPL of 82dB 1m away from the speaker.
Now look at a pro audio driver with a sensitivity of 96dB @ 1W/1m. With 1W of power this speaker will produce a SPL of 96dB 1m away from the speaker! That's a whole lot louder than the car audio sub for the same amount of power.
In theory, every time you double the input power you add 3dB to the SPL @ 1m. So 2W will mean 99dB @ 1m for the theoretical pro audio driver.
Some more tidbits. 3dB increase in loudness from the same speaker takes twice as much power. For the speaker to be twice as loud means 10dB in loudness and that requires 10x more power. To see what 3dB louder sounds like, just put of the same speaker side by side and switch one of them on/off. The change will be about 3dB more loudness. If you want the loudness you hear to be twice as loud then you need a lot more amplifier power.
As mentioned already, the ~3dB difference you see in the sub specs is because 2.83V is 1W for 8 ohms but 2W for 4 ohms. The major reason car audio uses 4 ohms (or even lower) is because the battery is only 12V. Power amplifiers for cars create a voltage supple that is higher (+/-35V for example) for more power but then the current is very high from the battery. This is why you see lights dim on cars and the wire is HUGE to connect the amp, tons of current because power is the same (ignoring losses). So 100W from a car amp means lots of current from 12V (12.6 with engine off, 14.4V with it on).
-SL
As mentioned already, the ~3dB difference you see in the sub specs is because 2.83V is 1W for 8 ohms but 2W for 4 ohms. The major reason car audio uses 4 ohms (or even lower) is because the battery is only 12V. Power amplifiers for cars create a voltage supple that is higher (+/-35V for example) for more power but then the current is very high from the battery. This is why you see lights dim on cars and the wire is HUGE to connect the amp, tons of current because power is the same (ignoring losses). So 100W from a car amp means lots of current from 12V (12.6 with engine off, 14.4V with it on).
-SL
I don't have time right now for a detailed post, but I wanted to mention something that I did not see in the previous discussion.
Applying a classical definition of efficiency to a loudspeaker, we would have that efficiency is the aoustic power out divided by the electrical power absorbed by the speaker.
Hence, if the signal voltage is always the same, a 4-Ohm speaker will draw more power from the amplifier and will produce more acoustic output, but will not necessarily be more efficient.
Isn't the definition of speaker sensitivity based on one watt power absorbed by the speker and acoustic SPL out measured at one meter? (In order to calculate efficiency, we'd have to integrate the acoustic power in all directions to get the total power out.)
It seems to me that I've seen some sensitivity specs more recently that state a specific voltage applied to the speaker terminals for the 1-meter SPL measurement. In this case, the 4-Ohm speaker would appear to be more sensitive than an 8-Ohm speaker. This is true, because the 4-Ohm speaker is more sensitive to VOLTAGE and VOLTAGE is the independent variable in this type of test. A 4-Ohm speaker is more sensitive to voltage because the same voltage will result in more power being absorbed by the speaker.
Regarding the definition of "easy", it depends on the context. A circuit designer may consider either high current or high voltage as easier to design, depending on the design constraints and the circuitry elements available. (e.g., high voltage requires high slew rate as well.)
Electrically, the only definition of "easier" that matters is "that which requires the lesser power," regardless of the voltage to current ratio.
Tom
Applying a classical definition of efficiency to a loudspeaker, we would have that efficiency is the aoustic power out divided by the electrical power absorbed by the speaker.
Hence, if the signal voltage is always the same, a 4-Ohm speaker will draw more power from the amplifier and will produce more acoustic output, but will not necessarily be more efficient.
Isn't the definition of speaker sensitivity based on one watt power absorbed by the speker and acoustic SPL out measured at one meter? (In order to calculate efficiency, we'd have to integrate the acoustic power in all directions to get the total power out.)
It seems to me that I've seen some sensitivity specs more recently that state a specific voltage applied to the speaker terminals for the 1-meter SPL measurement. In this case, the 4-Ohm speaker would appear to be more sensitive than an 8-Ohm speaker. This is true, because the 4-Ohm speaker is more sensitive to VOLTAGE and VOLTAGE is the independent variable in this type of test. A 4-Ohm speaker is more sensitive to voltage because the same voltage will result in more power being absorbed by the speaker.
Regarding the definition of "easy", it depends on the context. A circuit designer may consider either high current or high voltage as easier to design, depending on the design constraints and the circuitry elements available. (e.g., high voltage requires high slew rate as well.)
Electrically, the only definition of "easier" that matters is "that which requires the lesser power," regardless of the voltage to current ratio.
Tom
Thanks again to everyone who responded. I appreciate it.
Here are a couple of points I would like to make -
Regarding 4 ohms speakers and 8 ohms speakers, we must not confuse power consumed with power produced. When we are talking about current, impedance, and voltage, we are talking about power consumed.
When we are talking about perceived or measured loudness, we are talking about power produced.
A 4 ohms speaker will consume twice the electrical power, but only produce slightly more perceived or measured loudness.
In my view, perceive or measured loudness is a function of signal; that is, it is the listening equivalent of voltage, and by extension, and from experience, it seems to be linear.
Proportional tweaks of the volume control seem to produce equally proportional increases in volume.
Which brings me to my second point, though, since I am in the Chip Amp forum, I really shouldn't be surprised. But I am surprised that no one challenged my statement, that for a given amp, regardless of whether you are using 4 ohm, 8 ohm, or 16 ohms, you have the same functional headroom.
Let me illustrate, and then you can tell me whether I am right or wrong.
First, let us assume we have an amp that can deliver 200 watts to 4 ohms, 100 watts to 8 ohms, and 50 watts to 16 ohms. I'm saying that while you have 200 watts at 4 ohms, it really doesn't do you any good, because you are consuming power at twice the rate. You have double the headroom, but you are chasing the limit at twice the speed.
For the moment, let's assume 100 watt at 8 ohms is our standard for comparison. We will let this rate of power consumption equal ONE.
So, 100w/1 = 100 = relative rate of power consumption.
4 ohms consumes power at twice the rate, so TWO
200w/2 = 100 = relative rate of power consumption.
16 ohms consumes power at HALF the rate, so 0.5
50w/0.5 = 100 = relative rate of power consumption.
I think many people are fooled into thinking they have gained something by using 4 ohms speakers because the absolute power of the amp seems to have doubled to 200w.
But, I say it is an illusion.
So..., right on,...or all wet?
Steve/BlueWizard
Here are a couple of points I would like to make -
Regarding 4 ohms speakers and 8 ohms speakers, we must not confuse power consumed with power produced. When we are talking about current, impedance, and voltage, we are talking about power consumed.
When we are talking about perceived or measured loudness, we are talking about power produced.
A 4 ohms speaker will consume twice the electrical power, but only produce slightly more perceived or measured loudness.
In my view, perceive or measured loudness is a function of signal; that is, it is the listening equivalent of voltage, and by extension, and from experience, it seems to be linear.
Proportional tweaks of the volume control seem to produce equally proportional increases in volume.
Which brings me to my second point, though, since I am in the Chip Amp forum, I really shouldn't be surprised. But I am surprised that no one challenged my statement, that for a given amp, regardless of whether you are using 4 ohm, 8 ohm, or 16 ohms, you have the same functional headroom.
Let me illustrate, and then you can tell me whether I am right or wrong.
First, let us assume we have an amp that can deliver 200 watts to 4 ohms, 100 watts to 8 ohms, and 50 watts to 16 ohms. I'm saying that while you have 200 watts at 4 ohms, it really doesn't do you any good, because you are consuming power at twice the rate. You have double the headroom, but you are chasing the limit at twice the speed.
For the moment, let's assume 100 watt at 8 ohms is our standard for comparison. We will let this rate of power consumption equal ONE.
So, 100w/1 = 100 = relative rate of power consumption.
4 ohms consumes power at twice the rate, so TWO
200w/2 = 100 = relative rate of power consumption.
16 ohms consumes power at HALF the rate, so 0.5
50w/0.5 = 100 = relative rate of power consumption.
I think many people are fooled into thinking they have gained something by using 4 ohms speakers because the absolute power of the amp seems to have doubled to 200w.
But, I say it is an illusion.
So..., right on,...or all wet?
Steve/BlueWizard
I'm sorry, Bluewizard, but most of what you had to say in the previous post is incorrect.
You need to fully educate yourself on these issues before you attempt to expound on them.
This might sound nasty but it's not really. There are a lot of well educated people here who would set you straight much harsher.
You need to fully educate yourself on these issues before you attempt to expound on them.
This might sound nasty but it's not really. There are a lot of well educated people here who would set you straight much harsher.
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