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Post by Wideawake on Nov 18, 2016 14:54:41 GMT -5
The 4 ohms nominal impedance speaker rating is an indication that the designer of the speaker has at least gone through the extra effort of optimizing the parameters. But it doesn't necessarily always translate to a better quality speaker. Similarly, if a speaker is rated to 4 ohms, then, although this still generally depends, the 4 ohms rating can translate to a higher speaker sensitivity vs. if this same speaker had been rated to 8 ohms instead. But this [the 4 omhs rating in conjunction with higher sensitivity] doesn't necessarily always translate to higher efficiency. That said, due to there being affordable, excellent sounding power amps out there that can deliver both high current output and high power output at the same time (and I think we all know exactly which power amps I am referring to here, but just in case someone doesn't know it yet: it's always been the Emotiva ones) nowadays the 4 ohms speaker designs are opening new doors with regards to the dollar per dollar sonic performance of a total playback system. Not quite. A 4 ohm speaker design is no indication of "optimizing the parameters" and it has no bearing on the sensitivity either. You will need double the power to drive a 4 ohm load as opposed to an 8 ohm load to produce the same volume. And 4 ohm speakers do not open "new doors with regards to the dollar per dollar sonic performance of a total playback system". I would argue that an 8 ohm speaker is more economical to operate since it requires less capable amplifiers to run them than a 4 ohm speaker would. It also allows the amp to operate cooler and thereby lengthens the life of the components. The final impedance of a speaker depends on the number and choice of drivers and their impedance along with how they have been wired together; in series, parallel or series/parallel. There is no mystery here. Speaker manufacturers try and keep the load to between 4 and 8 ohms. The fluctuations in impedance (dips and rises) present more of a problem to the amp than a more stable load does. |
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Post by Deleted on Nov 18, 2016 15:43:25 GMT -5
Hello Huskydog55,
I can give some definitive answers.
1) Connecting the speaker wires to only one set of terminals on the T1 towers will not give an 8-ohm impedance.
Both the HF and the LF sections of the T1 are 4 ohms. The reason that you get a 4-ohm load when you connect to both sets of terminals is that the crossover network of the speaker works by increasing impedance at frequencies that a particular driver is not meant to play. The crossover does this through the inherent reactance of passive components, so it does not draw any power to accomplish this (although there are miniscule power losses in each component that are not typically significant). At frequencies below the crossover frequency, the high pass filters on the midrange and tweeter speakers present very high impedance, so little to no current flows. At frequencies above the crossover frequency, the low pass filter on the woofers presents a very high impedance. So in each section of the crossover, the current follows the path of lowest impedance, through "only" the drivers intended for reproducing that range of frequencies.
2) Typically, you can connect 4-ohm speakers to an amplifier rated 8 ohms, and you will be fine, as long as the overall power drawn from the amplifier is not greater than its 8-ohm rating.
The amplifier delivers voltage into a load, in this case your speakers. As a consequence of this, current is drawn, causing the amp to deliver power to the speaker. The power delivered is equal to the square of voltage divided by resistance. As your amplifier supplies this power, some of the power is dissipated in the amplifier, creating heat. As the load resistance decreases, heat generation increases. This heat is generated in the AC power transformer and in the output transistors, and smaller amounts of heat are also generated in other components. As stated before, power is a function of voltage and impedance, so if the impedance of the load is cut in half, the amplifier tries to deliver twice the power. This can cause some components of the amplifier to overheat. Many amplifiers have protection built-in to prevent this. Additionally, your amplifier may not output its full rated power into a lower impedance; it might come close, but not completely. In reality, no amplifier truly 'doubles down' or delivers twice its 8-ohm power into a half-impedance load; physics prevents that. If your amplifier or receiver is a modern one, you should be able to drive 4-ohm speakers with it perfectly safely, as long as you realize that these limitations are in play. More robust amps like the ones we sell have no trouble driving a 4-ohm impedance. If you hear distortion, or if your amplifier goes into thermal protection, then you will need to turn down the volume, but even at elevated listening levels you should have no problems.*
*Some amps have been made that have highly sensitive self-protect circuitry to prevent overcurrent, and these might react adversely to the 4-ohm load. But most amps being made today can tolerate a 4-ohm load even though they are labeled for 8 ohms.
Best regards,
Rory
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Post by yves on Nov 18, 2016 18:36:06 GMT -5
The 4 ohms nominal impedance speaker rating is an indication that the designer of the speaker has at least gone through the extra effort of optimizing the parameters. But it doesn't necessarily always translate to a better quality speaker. Similarly, if a speaker is rated to 4 ohms, then, although this still generally depends, the 4 ohms rating can translate to a higher speaker sensitivity vs. if this same speaker had been rated to 8 ohms instead. But this [the 4 omhs rating in conjunction with higher sensitivity] doesn't necessarily always translate to higher efficiency. That said, due to there being affordable, excellent sounding power amps out there that can deliver both high current output and high power output at the same time (and I think we all know exactly which power amps I am referring to here, but just in case someone doesn't know it yet: it's always been the Emotiva ones) nowadays the 4 ohms speaker designs are opening new doors with regards to the dollar per dollar sonic performance of a total playback system. Not quite. A 4 ohm speaker design is no indication of "optimizing the parameters" and it has no bearing on the sensitivity either. You will need double the power to drive a 4 ohm load as opposed to an 8 ohm load to produce the same volume. And 4 ohm speakers do not open "new doors with regards to the dollar per dollar sonic performance of a total playback system". I would argue that an 8 ohm speaker is more economical to operate since it requires less capable amplifiers to run them than a 4 ohm speaker would. It also allows the amp to operate cooler and thereby lengthens the life of the components. The final impedance of a speaker depends on the number and choice of drivers and their impedance along with how they have been wired together; in series, parallel or series/parallel. There is no mystery here. Speaker manufacturers try and keep the load to between 4 and 8 ohms. The fluctuations in impedance (dips and rises) present more of a problem to the amp than a more stable load does. Well, a properly designed 4 ohm speaker can present an easier load than a poorly designed 8 ohm speaker. But a poorly designed 4 ohm speaker the parameters of which haven't been optimized is practically asking for trouble so although there certainly can be no absolute guarantees, the fact that there is still an indication is nonetheless trivial. As for speaker sensitivity, I didn't say choosing a 4 ohm speaker design necessarily always helps to improve it. It obviously depends, but my point was that having higher sensitivity in a speaker doesn't necessarily also mean it will be more efficient. Speaker impedance alone says nothing about the volume that will be produced, you are simply confusing speaker impedance with speaker sensitivity here. Finally, I still stand by my conclusion that 4 ohm speakers nowadays have significantly improved in pure terms of total value of the speakers-and-amp combination because of there being lots of relatively cheap clean power on tap, and, as Rory Buszka also points out in his reply to this thread, with modern power amps 4 ohm loads aren't usually that much of a limiting factor anymore. This, then, allows experienced speaker designers to create 4 ohm speakers that can, and do successfully debunk the classic old "8 ohms is better because I say so". |
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Post by Wideawake on Nov 18, 2016 19:40:36 GMT -5
yves - It's one thing to spew out gibberish, but you now want to defend it too? Well, I'm not playing. Believe whatever you want and good luck with that.
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Post by siggie on Nov 18, 2016 20:20:58 GMT -5
Hello Huskydog55, I can give some definitive answers. 1) Connecting the speaker wires to only one set of terminals on the T1 towers will not give an 8-ohm impedance. Both the HF and the LF sections of the T1 are 4 ohms. The reason that you get a 4-ohm load when you connect to both sets of terminals is that the crossover network of the speaker works by increasing impedance at frequencies that a particular driver is not meant to play. The crossover does this through the inherent reactance of passive components, so it does not draw any power to accomplish this (although there are miniscule power losses in each component that are not typically significant). At frequencies below the crossover frequency, the high pass filters on the midrange and tweeter speakers present very high impedance, so little to no current flows. At frequencies above the crossover frequency, the low pass filter on the woofers presents a very high impedance. So in each section of the crossover, the current follows the path of lowest impedance, through "only" the drivers intended for reproducing that range of frequencies. 2) Typically, you can connect 4-ohm speakers to an amplifier rated 8 ohms, and you will be fine, as long as the overall power drawn from the amplifier is not greater than its 8-ohm rating. The amplifier delivers voltage into a load, in this case your speakers. As a consequence of this, current is drawn, causing the amp to deliver power to the speaker. The power delivered is equal to the square of voltage divided by resistance. As your amplifier supplies this power, some of the power is dissipated in the amplifier, creating heat. As the load resistance decreases, heat generation increases. This heat is generated in the AC power transformer and in the output transistors, and smaller amounts of heat are also generated in other components. As stated before, power is a function of voltage and impedance, so if the impedance of the load is cut in half, the amplifier tries to deliver twice the power. This can cause some components of the amplifier to overheat. Many amplifiers have protection built-in to prevent this. Additionally, your amplifier may not output its full rated power into a lower impedance; it might come close, but not completely. In reality, no amplifier truly 'doubles down' or delivers twice its 8-ohm power into a half-impedance load; physics prevents that. If your amplifier or receiver is a modern one, you should be able to drive 4-ohm speakers with it perfectly safely, as long as you realize that these limitations are in play. More robust amps like the ones we sell have no trouble driving a 4-ohm impedance. If you hear distortion, or if your amplifier goes into thermal protection, then you will need to turn down the volume, but even at elevated listening levels you should have no problems.* *Some amps have been made that have highly sensitive self-protect circuitry to prevent overcurrent, and these might react adversely to the 4-ohm load. But most amps being made today can tolerate a 4-ohm load even though they are labeled for 8 ohms. Best regards, Rory I was just about to say that. siggie |
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