- Joined
- Jun 7, 2011
First i want to say this is really a difficult topic and it could probably fill a whole book, but i just want to make aware and take the chance to increase my own knowledge. My knowledge is pretty much at the lowest stage and it can be a issue when seeking for the "true stuff" and taking care at good HIFI for not damaging it.
I write this stuff, so people can 1. Confirm it is correct, 2. Working out whats specs are considered safe to use because manufacturers are hidding many important stuff, for example the exact operating limit information regarding the Neodymium magnets. I will add the issue at the end of the topic, first i want to show my maths.
So, the general issue to all electronics is the heat tolerance, thats clear and its the main issue all the Overclockers are facing but not only overclockers, it can safely by taken over to all electronics, especially high powered HIFI electronics. Liquid cooled speakers or even Amps making sense? Most people may laugh at me... but it may sound fun but it makes strong sense. The same rule will apply to any electronic, as cooler it runs the higher the lifetime and as lower the risk of damage. To some extend mechanical stuff such as HDDs should not be below zero else the mechanics may become alignment issues (because not build with those temperatures in mind), so i may not recommend below zero but this is almost the only exception and the only reason is because there is mechanics involved, not electronics only.
When it comes to speakers, i noticed that the magnets which is a main part of the drivers and extremely critical, every speaker works using a magnet, can have very low tolerance to heat. This is a serious issue because most speakers are very inefficient. A 87dB@1W speaker is wasting around 99% of energy into heat*. It will result into a lot of heat affecting the drivers, i made a short example for how much heat the drivers will have to handle in term of my setup. 99% of the energy used in the specs below is wasted as heat (efficiency already taken into account), it will directly heat up the drivers and magnets in general. The higher the heat as lower the efficiency of the speakers, so the values listed below are in fact inaccurate and rated at 24 room temp, but it could be a good amount less effective especially when even more heat added to the speaker.
*Note: Heat isnt necessarely a waste in economical terms as long as someone can heat their room using it (currently i can use it as a room heater because to cold without heater). The main issue is the damage it can cause...
Continuous handling: The capacity able to handle at permannent use (24 C room temp).
3 speaker at 100 dB @1m range. This value is safe to use in short term (probably less than 3h).
KEF Q300: ~7W (~87 efficiency)
Klipsch RB61II: ~2.25W (~92 average efficiency, tweeter 93, cone 90)
Wharfedale 10 CS: 5W (~88.5 efficiency)
KEF R400b: ~40W (~81 efficiency, actually a good value for a subwoofer). Note: It only counts as 2 speaker.
3 speaker at 100 dB @3m range.This value is safe to use in short term (probably less than 3h). (effective dB@1m = 110)
KEF Q300: ~65W (~87 efficiency)
Klipsch RB61II: ~20W (~92 average efficiency, tweeter 93, cone 90)
Wharfedale 10 CS: ~45W (~88.5 efficiency)
KEF R400b: ~350W (~81 efficiency, actually a good value for a subwoofer). Note: It only counts as 2 speaker.
3 speaker at 85 dB @3m range. This value is safe to use in very long term (probably 12h a day). (effective dB @1m = 95)
KEF Q300: ~3W (~87 efficiency)
Klipsch RB61II: ~1W (~92 average efficiency, tweeter 93, cone 90 )
Wharfedale 10 CS: ~2W (~85.5 efficiency)
KEF R400b: ~12W (~81 efficiency, actually a good value for a subwoofer). Note: It only counts as 2 speaker.
3 speaker: Maximum continous dB @1m range. This value is safe to use in very short term (probably less than 5 min) but at a critical spot. The maximum value should be avoided at a range of 1m.
KEF Q300: max rating surpassed at ~112.5 dB crossing 120 W line (it would be exactly 111 dB @2 speaker)
Klipsch RB61II : max rating surpassed at ~116.75 dB crossing 100 W line
Wharfedale 10 CS: max rating surpassed at ~115 dB crossing 150W line
KEF R400b: max rating surpassed at ~111 dB crossing 500 W line Note: It only counts as 2 speaker.
3 speaker: Maximum continous dB @3m range. This value is safe to use in pretty short term (probably less than 2h).
KEF Q300: max rating surpassed at ~103 dB crossing 120 W line (dB+4-6*)
Klipsch RB61II : max rating surpassed at ~107.25 dB (average value of cone/tweeter) crossing 100 W line
Wharfedale 10 CS: max rating surpassed at ~105.5 dB crossing 150W line (dB+2.5-4.5*)
KEF R400b: max rating surpassed at ~101.5 crossing 500 W line (dB+4* + external 12 clock). Note: It only counts as 2 speaker.
*Adjustment to catch up to the Klipsch cone and tweeter.
Theoretical power capacity required in order to drive speakers at max rating: 1240 W
Practically sustainable capacity related to Amp specs: ~1000 W (sufficient for ~101-102 dB@3m range).
Concert peak loudness =110 dB possible at a range between 1.5 m and 2 m, Amp is sufficient
Rule of the thumb:
+1 speaker = +1.5 dB
+2 speaker= +3 dB
Because different mode use different speakers, average value is used (+1).
Calculator used: http://www.sengpielaudio.com/Rechner-wirkungsgrad.htm
Peak handling: This term is of low use because the dB should never exceed 110 , because it is considered unsafe to the ears, even in short duration. Although not a single (consumer grade) speaker can realisticaly handle above 110 dB @3m without having a clirr factor (above -+ 6 dB) that is easely hearable and in that term "not favorable". It got no meaning for real use and is not more than simply showing off muscles. Above 110 dB (110 dB = concert peak loudness, which is the max a audiophile may ever wish for), even short duration, should always be avoided. The question is what will last longer, the ear or the speaker... so the peak values of speaker is foolish but i would take the one from the ear instead.
Lets say someone want just have highest noise possible... it may simply require the most huge tweeter, Amp and a very big horn in order to guide the sonic waves in a direct front lined condition... this kind of technique is partially used by Klipsch so they use a trick in order to raise efficiency, but it is not necessarely due to the quality of other parts but simply a tech feature that got pros and cons at the same time. A tweeter of big size may not necessarely sound better, usualy even worse because the sonic dispersion when it comes to the angle will be rerduced (the same issue a horn is facing), so a 25 mm tweeter could be a sweet spot and size related to tweeter isnt necessarely a cost factor. In term of Klipsch, they seems to use the efficiency of the horn "loaded" tweeter and the tweeter is going all the way down to the 1500 Hz line, so it will cover so much frequency that the bass driver is kinda a minor component but with lacking efficiency it seems. So thats the reason i have to add +2 dB to the horn "loaded" frequency in order to become harmonic in sound balance. So the truth is a bit more brittle then the stuff Klipsch seems to claim. But in overall it is a nice and affordable almost audiophile grade speaker with some tricks added, that may be in favor or disfavor, dependable on hearer. Although i was using my own "by hearing" rating and not the official one because i noticed it is not able to keep up the claimed efficiency when i was comparing it with other speakers and trying to adjust the balance. Generally the Klipsch are outstanding when the Amp is weak, perhaps some audiophile Amp with low power but high sound quality and generally for very large room that may require some more dB pushing.
Now the main cause why im writing this:
I was investigating the safe operation limits of Neodymium magnets, known as Nd2Fe14B, the currently strongest magnets on earth and usually used on high end tweeters. The raw Neodymium material from Nd2Fe14B magnets is vulnerable to heat above 80 C and at that point the magnet can suffer permanent damage, but it will still continue to work in a "reduced efficiency state", so as soon as the magnet is heated up above 80 C it will already suffer efficiency and may have decreased sound quality. The Curie point, the the point where a magnet will suffer critical damage, to the point of a total loss of any magnetic power and when that line has been passed the speaker will be destroyed... because the magnet will completely stop to work and unable to be recovered. The Curie point for Nd2Fe14B is 310 C, this is not the "safe operation limit" but the point of "badaboom". However, there is more heat tolerant versions of Neodymium magnets available with additional rare earth materials. In some term the manufacturers use certain solutions, they may actively air-vent the tweeters (probably used by KEF) or even use liquid cooling, but i dont know if sufficient or not and under what conditions.
2 questions will appear now:
1. Whats the exact material used (manufacturers rarely hand out informations)
2. How hot will it become in usual, is there any real risk involved.
Question 1 is difficult because there is many versions of Neodymium magnets possbible, some got other rare earths added in order to raise the operation limits. In most terms such a "raise" is not needed because the magnets wont heat up a lot. But for HIFI it can truly become a issue, because able to heat up a lot, even above the usual safe operation limits. The logical result is that HIFI is not only in need of powerful magnets but heat resistant magnets too... which can be considered the most expensive magnets on the market, in term they are used. It truly is a matter of quality... and simply hard to be cheap on that matter, else the risk of damage can be high.
Question 2 is difficult too because way to many factors and actually almost no one know good numbers...
I write this stuff, so people can 1. Confirm it is correct, 2. Working out whats specs are considered safe to use because manufacturers are hidding many important stuff, for example the exact operating limit information regarding the Neodymium magnets. I will add the issue at the end of the topic, first i want to show my maths.
So, the general issue to all electronics is the heat tolerance, thats clear and its the main issue all the Overclockers are facing but not only overclockers, it can safely by taken over to all electronics, especially high powered HIFI electronics. Liquid cooled speakers or even Amps making sense? Most people may laugh at me... but it may sound fun but it makes strong sense. The same rule will apply to any electronic, as cooler it runs the higher the lifetime and as lower the risk of damage. To some extend mechanical stuff such as HDDs should not be below zero else the mechanics may become alignment issues (because not build with those temperatures in mind), so i may not recommend below zero but this is almost the only exception and the only reason is because there is mechanics involved, not electronics only.
When it comes to speakers, i noticed that the magnets which is a main part of the drivers and extremely critical, every speaker works using a magnet, can have very low tolerance to heat. This is a serious issue because most speakers are very inefficient. A 87dB@1W speaker is wasting around 99% of energy into heat*. It will result into a lot of heat affecting the drivers, i made a short example for how much heat the drivers will have to handle in term of my setup. 99% of the energy used in the specs below is wasted as heat (efficiency already taken into account), it will directly heat up the drivers and magnets in general. The higher the heat as lower the efficiency of the speakers, so the values listed below are in fact inaccurate and rated at 24 room temp, but it could be a good amount less effective especially when even more heat added to the speaker.
*Note: Heat isnt necessarely a waste in economical terms as long as someone can heat their room using it (currently i can use it as a room heater because to cold without heater). The main issue is the damage it can cause...
Continuous handling: The capacity able to handle at permannent use (24 C room temp).
3 speaker at 100 dB @1m range. This value is safe to use in short term (probably less than 3h).
KEF Q300: ~7W (~87 efficiency)
Klipsch RB61II: ~2.25W (~92 average efficiency, tweeter 93, cone 90)
Wharfedale 10 CS: 5W (~88.5 efficiency)
KEF R400b: ~40W (~81 efficiency, actually a good value for a subwoofer). Note: It only counts as 2 speaker.
3 speaker at 100 dB @3m range.This value is safe to use in short term (probably less than 3h). (effective dB@1m = 110)
KEF Q300: ~65W (~87 efficiency)
Klipsch RB61II: ~20W (~92 average efficiency, tweeter 93, cone 90)
Wharfedale 10 CS: ~45W (~88.5 efficiency)
KEF R400b: ~350W (~81 efficiency, actually a good value for a subwoofer). Note: It only counts as 2 speaker.
3 speaker at 85 dB @3m range. This value is safe to use in very long term (probably 12h a day). (effective dB @1m = 95)
KEF Q300: ~3W (~87 efficiency)
Klipsch RB61II: ~1W (~92 average efficiency, tweeter 93, cone 90 )
Wharfedale 10 CS: ~2W (~85.5 efficiency)
KEF R400b: ~12W (~81 efficiency, actually a good value for a subwoofer). Note: It only counts as 2 speaker.
3 speaker: Maximum continous dB @1m range. This value is safe to use in very short term (probably less than 5 min) but at a critical spot. The maximum value should be avoided at a range of 1m.
KEF Q300: max rating surpassed at ~112.5 dB crossing 120 W line (it would be exactly 111 dB @2 speaker)
Klipsch RB61II : max rating surpassed at ~116.75 dB crossing 100 W line
Wharfedale 10 CS: max rating surpassed at ~115 dB crossing 150W line
KEF R400b: max rating surpassed at ~111 dB crossing 500 W line Note: It only counts as 2 speaker.
3 speaker: Maximum continous dB @3m range. This value is safe to use in pretty short term (probably less than 2h).
KEF Q300: max rating surpassed at ~103 dB crossing 120 W line (dB+4-6*)
Klipsch RB61II : max rating surpassed at ~107.25 dB (average value of cone/tweeter) crossing 100 W line
Wharfedale 10 CS: max rating surpassed at ~105.5 dB crossing 150W line (dB+2.5-4.5*)
KEF R400b: max rating surpassed at ~101.5 crossing 500 W line (dB+4* + external 12 clock). Note: It only counts as 2 speaker.
*Adjustment to catch up to the Klipsch cone and tweeter.
Theoretical power capacity required in order to drive speakers at max rating: 1240 W
Practically sustainable capacity related to Amp specs: ~1000 W (sufficient for ~101-102 dB@3m range).
Concert peak loudness =110 dB possible at a range between 1.5 m and 2 m, Amp is sufficient
Rule of the thumb:
+1 speaker = +1.5 dB
+2 speaker= +3 dB
Because different mode use different speakers, average value is used (+1).
Calculator used: http://www.sengpielaudio.com/Rechner-wirkungsgrad.htm
Peak handling: This term is of low use because the dB should never exceed 110 , because it is considered unsafe to the ears, even in short duration. Although not a single (consumer grade) speaker can realisticaly handle above 110 dB @3m without having a clirr factor (above -+ 6 dB) that is easely hearable and in that term "not favorable". It got no meaning for real use and is not more than simply showing off muscles. Above 110 dB (110 dB = concert peak loudness, which is the max a audiophile may ever wish for), even short duration, should always be avoided. The question is what will last longer, the ear or the speaker... so the peak values of speaker is foolish but i would take the one from the ear instead.
Lets say someone want just have highest noise possible... it may simply require the most huge tweeter, Amp and a very big horn in order to guide the sonic waves in a direct front lined condition... this kind of technique is partially used by Klipsch so they use a trick in order to raise efficiency, but it is not necessarely due to the quality of other parts but simply a tech feature that got pros and cons at the same time. A tweeter of big size may not necessarely sound better, usualy even worse because the sonic dispersion when it comes to the angle will be rerduced (the same issue a horn is facing), so a 25 mm tweeter could be a sweet spot and size related to tweeter isnt necessarely a cost factor. In term of Klipsch, they seems to use the efficiency of the horn "loaded" tweeter and the tweeter is going all the way down to the 1500 Hz line, so it will cover so much frequency that the bass driver is kinda a minor component but with lacking efficiency it seems. So thats the reason i have to add +2 dB to the horn "loaded" frequency in order to become harmonic in sound balance. So the truth is a bit more brittle then the stuff Klipsch seems to claim. But in overall it is a nice and affordable almost audiophile grade speaker with some tricks added, that may be in favor or disfavor, dependable on hearer. Although i was using my own "by hearing" rating and not the official one because i noticed it is not able to keep up the claimed efficiency when i was comparing it with other speakers and trying to adjust the balance. Generally the Klipsch are outstanding when the Amp is weak, perhaps some audiophile Amp with low power but high sound quality and generally for very large room that may require some more dB pushing.
Now the main cause why im writing this:
I was investigating the safe operation limits of Neodymium magnets, known as Nd2Fe14B, the currently strongest magnets on earth and usually used on high end tweeters. The raw Neodymium material from Nd2Fe14B magnets is vulnerable to heat above 80 C and at that point the magnet can suffer permanent damage, but it will still continue to work in a "reduced efficiency state", so as soon as the magnet is heated up above 80 C it will already suffer efficiency and may have decreased sound quality. The Curie point, the the point where a magnet will suffer critical damage, to the point of a total loss of any magnetic power and when that line has been passed the speaker will be destroyed... because the magnet will completely stop to work and unable to be recovered. The Curie point for Nd2Fe14B is 310 C, this is not the "safe operation limit" but the point of "badaboom". However, there is more heat tolerant versions of Neodymium magnets available with additional rare earth materials. In some term the manufacturers use certain solutions, they may actively air-vent the tweeters (probably used by KEF) or even use liquid cooling, but i dont know if sufficient or not and under what conditions.
2 questions will appear now:
1. Whats the exact material used (manufacturers rarely hand out informations)
2. How hot will it become in usual, is there any real risk involved.
Question 1 is difficult because there is many versions of Neodymium magnets possbible, some got other rare earths added in order to raise the operation limits. In most terms such a "raise" is not needed because the magnets wont heat up a lot. But for HIFI it can truly become a issue, because able to heat up a lot, even above the usual safe operation limits. The logical result is that HIFI is not only in need of powerful magnets but heat resistant magnets too... which can be considered the most expensive magnets on the market, in term they are used. It truly is a matter of quality... and simply hard to be cheap on that matter, else the risk of damage can be high.
Question 2 is difficult too because way to many factors and actually almost no one know good numbers...
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