DigitalJunkie said:
It wasn't a 160Wrms speaker then...
Really, read this-
http://forum.carstereos.org/clipping-test-results-t47441.html?t=47441
Wayne Parham mentioned a good idea.
However, if I'm not mistaken, EWorkshop1708 stated that he is using the Sony in the recommended 1.25cu ft sealed box. If you apply for a longer time an average of i.e. just 200 watt to this speaker the vented voice coil might exchange heat through the hole in the magnet, but the heat is trapped because of the closed box. Can you imagine how hot it'll get inside that box?!
I guess the box is made up of wood which is not known for excellent heat transfer capabilities. Therefore it would be just necessary to measure the inside temperature of the enclosure and turn down the volume continuously with raising temperature or just shut it off to let it cool down.
The temperature sensor can be placed i.e. at the far most top position of the enclosure.
For a fellow of mine I 'invented' the forced closed box cooling with Peltier cells/elements running at 12V in a car. Depending on the size (and the current requirement) of those Peltier cells/elements you might need a bunch of them to get rid of the power (and therefore heat) you want.
After these 'modifications' he never fried a voicecoil of his sub anymore. It stays always 'cool' - at least inside the box.
At the outside, with the huge heatsinks, the temperature is not always in the range to call it nice and comfortable. So be aware that the heatsinks might get really hot (of course depending on size, convection abilities in the trunk, etc.). The Peltier cells/elements will generate a max. difference of 60° centigrade between the two plates, which should be considered when planning such an active cooling system. 😉
For PC cooling purposes I've even seen someone stacking two of 'em to increase the temp difference between the most outer plates.
However, if I'm not mistaken, EWorkshop1708 stated that he is using the Sony in the recommended 1.25cu ft sealed box. If you apply for a longer time an average of i.e. just 200 watt to this speaker the vented voice coil might exchange heat through the hole in the magnet, but the heat is trapped because of the closed box. Can you imagine how hot it'll get inside that box?!
I guess the box is made up of wood which is not known for excellent heat transfer capabilities. Therefore it would be just necessary to measure the inside temperature of the enclosure and turn down the volume continuously with raising temperature or just shut it off to let it cool down.
The temperature sensor can be placed i.e. at the far most top position of the enclosure.
For a fellow of mine I 'invented' the forced closed box cooling with Peltier cells/elements running at 12V in a car. Depending on the size (and the current requirement) of those Peltier cells/elements you might need a bunch of them to get rid of the power (and therefore heat) you want.
After these 'modifications' he never fried a voicecoil of his sub anymore. It stays always 'cool' - at least inside the box.
At the outside, with the huge heatsinks, the temperature is not always in the range to call it nice and comfortable. So be aware that the heatsinks might get really hot (of course depending on size, convection abilities in the trunk, etc.). The Peltier cells/elements will generate a max. difference of 60° centigrade between the two plates, which should be considered when planning such an active cooling system. 😉
For PC cooling purposes I've even seen someone stacking two of 'em to increase the temp difference between the most outer plates.
Heat transfer from motor core
I think solid state heat pumps are a great idea. Put one on the pole piece and use it to wick heat out of the motor core. That's the most important thing - getting the heat away from the immediate proximity of the voice coil. It is an added complexity, but it is still a good idea.
Motor core heat is caused by magnetic losses and by voice coil radiation, and if it isn't removed, it just builds up inside the motor. The magnet surrounding the pole is a good container for heat, like a thermos bottle. So wicking heat out of the core is a good idea, whether by cooling plug, heat pump or any other mechanism.
I used to think heat would build up in the box, and it does to some degree. But what I found is that is a secondary problem, and it's a distant second, to be honest. Once you get the heat out of the core, you're way ahead of the thermal runaway problem. If you pump heat out of the core into a sealed box, the air temperature will rise, but not to the blistering levels present in the core. Naturally, the smaller the box, the higher the air temperature can rise because there is less air volume and internal surface area to dissipate heat.
Of course, if you remove heat from the core only to the inside of a sealed box, the cooling vents are less effective because the local ambient air temperature becomes higher. In some sense, that robs Peter to pay Paul, but it is better to remove the heat from the motor core than to leave it there. But it is best to remove the heat to outside ambient air. An easy way to do this is with a cooling plate mounted on the outside of the box. In my 12Pi hornsub, I use aluminum plates that provide access to the woofers for service. It is physically connected to the cooling plug, so it doubles as a cooling plate.
An external cooling plate works like a heat sink. Large surface area is a good thing, so grooves can be cut into the plate if desired. In my case, grooves weren't needed, as the access panels had more than adequate surface area without fins or grooves. However it is fashioned, a cooling plate is a good way to remove heat to the outside. The heat is transferred from the motor core by conduction through a cooling plug or by solid state heat pump or any other mechanism.
I think solid state heat pumps are a great idea. Put one on the pole piece and use it to wick heat out of the motor core. That's the most important thing - getting the heat away from the immediate proximity of the voice coil. It is an added complexity, but it is still a good idea.
Motor core heat is caused by magnetic losses and by voice coil radiation, and if it isn't removed, it just builds up inside the motor. The magnet surrounding the pole is a good container for heat, like a thermos bottle. So wicking heat out of the core is a good idea, whether by cooling plug, heat pump or any other mechanism.
I used to think heat would build up in the box, and it does to some degree. But what I found is that is a secondary problem, and it's a distant second, to be honest. Once you get the heat out of the core, you're way ahead of the thermal runaway problem. If you pump heat out of the core into a sealed box, the air temperature will rise, but not to the blistering levels present in the core. Naturally, the smaller the box, the higher the air temperature can rise because there is less air volume and internal surface area to dissipate heat.
Of course, if you remove heat from the core only to the inside of a sealed box, the cooling vents are less effective because the local ambient air temperature becomes higher. In some sense, that robs Peter to pay Paul, but it is better to remove the heat from the motor core than to leave it there. But it is best to remove the heat to outside ambient air. An easy way to do this is with a cooling plate mounted on the outside of the box. In my 12Pi hornsub, I use aluminum plates that provide access to the woofers for service. It is physically connected to the cooling plug, so it doubles as a cooling plate.
An external cooling plate works like a heat sink. Large surface area is a good thing, so grooves can be cut into the plate if desired. In my case, grooves weren't needed, as the access panels had more than adequate surface area without fins or grooves. However it is fashioned, a cooling plate is a good way to remove heat to the outside. The heat is transferred from the motor core by conduction through a cooling plug or by solid state heat pump or any other mechanism.
EWorkshop1708 said:
If your speakers are frying then its simply too much power into the speaker. The answer is to buy higher powered speakers.
I run a disco and havent ever fried a speaker because I use an amp that matches the speakers.
The only time I have fried speakers is when the amp has gone faulty and put DC into the speakers.
It might be worth having a look at the DC on the output of your amp in case your amp has gone faulty and is outputting DC.
Power handling is thermal management
I would agree with you generally. If you're regularly burning voice coils, then you're pushing your speakers too hard. Either dial it back a bit, or increase capabilities. An easy way to do that is to buy speakers made to handle more power.
The thing is, heat is the problem so getting the heat out is the answer. The way speaker manufacturers increase power handling is with improved thermal management.
Increasing efficiency is the best thing to do to start with, as an efficient loudspeaker converts more electrical energy into acoustic energy, leaving less to be wasted as heat. But even the most efficient speakers turn at least half their power into heat, so even they can be improved with good thermal management.
nigelwright7557 said:
I would agree with you generally. If you're regularly burning voice coils, then you're pushing your speakers too hard. Either dial it back a bit, or increase capabilities. An easy way to do that is to buy speakers made to handle more power.
The thing is, heat is the problem so getting the heat out is the answer. The way speaker manufacturers increase power handling is with improved thermal management.
Increasing efficiency is the best thing to do to start with, as an efficient loudspeaker converts more electrical energy into acoustic energy, leaving less to be wasted as heat. But even the most efficient speakers turn at least half their power into heat, so even they can be improved with good thermal management.
I think you missed the point, look closely at the normalized power tests. There has never been debate that a square wave of the same voltage amplitude has more power than a sine, but that isn't even what we are talking about...
I think the fundamental problem is lack of understanding that the physical laws determines how loud and for how long you can play. Heat and heat transfer is an issue and most closed boxes are filled with some insulation material (where wool and mineral based materials have different heat transfer properties).
The problem: to play loud you have to use equipment that is up to the task. Also be aware of the risks of damaging your hearing, here there is a rather simple connection between SPL and exposure time. Taking drugs as alcohol make things worse. If you have been exposed to high SPL´s please let your hearing rest for up to a couple of days. Even moderate levels exposed to continuously can cause damages. I have learnt this the hard way i.e. running my big motor bike without silencer in a garage or shooting as a kid, without any hearing protection. I have tinnitus and have to take great care not to make things worse. OK, I can play loud for a shorter period but have to take the risk seriously.
Some weeks ago I disregarded my own experiences ( I had fun playing loud and for to long) so now I have to rest more than normally.
My suggestion is that you make some loudspeakers that is up to the task as said. Volt loudspeakers have some drivers that are cooled in an unusual way;radial. Use an amp so it doesn´t clip as others have pointed to.
https://secure.wilmslow-audio.co.uk...th/22?osCsid=bb86c29fa24fadd414e61e21da7d0c33
I use Volt RV3143:s in two subs weighting more than 200 lbs each and although they can play loud , the extreme purity of the bass notes makes it unnecessary to always play loud. Hot voice coils are not the way I want it...And there seems to be no reason to monitor them; no failure in about eight years.Turning the volume up doesn´t change the character of the sound and this is as I perceive it a very good trait.
I mean; does the sound "boomy" muddy exaggerated unnatural bass coming from some cars passing by, windows down, make me happy? Get better bass and enjoy it without any technically problem. 😉 My point of view only! 😎
The problem: to play loud you have to use equipment that is up to the task. Also be aware of the risks of damaging your hearing, here there is a rather simple connection between SPL and exposure time. Taking drugs as alcohol make things worse. If you have been exposed to high SPL´s please let your hearing rest for up to a couple of days. Even moderate levels exposed to continuously can cause damages. I have learnt this the hard way i.e. running my big motor bike without silencer in a garage or shooting as a kid, without any hearing protection. I have tinnitus and have to take great care not to make things worse. OK, I can play loud for a shorter period but have to take the risk seriously.
Some weeks ago I disregarded my own experiences ( I had fun playing loud and for to long) so now I have to rest more than normally.
My suggestion is that you make some loudspeakers that is up to the task as said. Volt loudspeakers have some drivers that are cooled in an unusual way;radial. Use an amp so it doesn´t clip as others have pointed to.
https://secure.wilmslow-audio.co.uk...th/22?osCsid=bb86c29fa24fadd414e61e21da7d0c33
I use Volt RV3143:s in two subs weighting more than 200 lbs each and although they can play loud , the extreme purity of the bass notes makes it unnecessary to always play loud. Hot voice coils are not the way I want it...And there seems to be no reason to monitor them; no failure in about eight years.Turning the volume up doesn´t change the character of the sound and this is as I perceive it a very good trait.
I mean; does the sound "boomy" muddy exaggerated unnatural bass coming from some cars passing by, windows down, make me happy? Get better bass and enjoy it without any technically problem. 😉 My point of view only! 😎
I agree with those recommending a new woofer. Find the nicest highest efficiency woofer that fits your needs and invest.
I am using a pair of Dayton RS 12" in two 2 cubic foot sealed boxes. They are in the corner and stacked so that the cone movement opposes. One fires up and the other down. This made such a huge improvement in vibration it is difficult to describe. I also have the motors mounted on the outside. Essentially the top box is being supported by resting on the frames of both woofers. It is extremely solid. Not only does it look really cool, but it helps with cooling and won't eat up the box volume. Hook up is really simple as these woofers have spring binding posts.
I am running the pair of four ohm woofers in series with 250 watts; 89db/watt. I haven't pushed the amp to complaint yet and let me say that the matrix is awe inspiring. As for drums that kick, that is all located in the midbass. These subs would eat 400 watts apiece when crossed over at 300hz (it was the amp complaining). Now that I have midbass horns running 105db/watt above 70hz, the subs just love it. I think the biggest problem with the low efficiency of that sub was that you were getting low, but you just couldn't play the "high" stuff with authority.
I hope I didn't write too much : )
Good luck and over engineer!
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-464
I am using a pair of Dayton RS 12" in two 2 cubic foot sealed boxes. They are in the corner and stacked so that the cone movement opposes. One fires up and the other down. This made such a huge improvement in vibration it is difficult to describe. I also have the motors mounted on the outside. Essentially the top box is being supported by resting on the frames of both woofers. It is extremely solid. Not only does it look really cool, but it helps with cooling and won't eat up the box volume. Hook up is really simple as these woofers have spring binding posts.
I am running the pair of four ohm woofers in series with 250 watts; 89db/watt. I haven't pushed the amp to complaint yet and let me say that the matrix is awe inspiring. As for drums that kick, that is all located in the midbass. These subs would eat 400 watts apiece when crossed over at 300hz (it was the amp complaining). Now that I have midbass horns running 105db/watt above 70hz, the subs just love it. I think the biggest problem with the low efficiency of that sub was that you were getting low, but you just couldn't play the "high" stuff with authority.
I hope I didn't write too much : )
Good luck and over engineer!
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-464
...as far as I know most standards for power rating of speakers do employ something like a noise signal of which the power is taken more or less correct, but then employ a ON/OFF duty cycle (i.e. 1 minute ON / 3 minutes OFF).
This is fitting to unbelievable 400Wrms ratings with 60mm...70mm voice coils.
Imagine a 60W light bulb, it is bigger than normal voice coils - has to dissipate just 60W - and becomes quite hot.
Even vented coil systems cannot completely ignore obvoiusly giant amounts of heat...
Have a look to some measurements:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=55880&highlight=
Measuring the voice coil temp is a good thing if you drive the system continuously high. Of course a direct measurement is more accurrate than a indicrect, but also indirect can be helpful if you know the relation between the VC and the measured spot.
Furtheron you do not need to shut down completely, you can reduce the input signal softly with a VCA or OTA or LED+LDR or....
This is fitting to unbelievable 400Wrms ratings with 60mm...70mm voice coils.
Imagine a 60W light bulb, it is bigger than normal voice coils - has to dissipate just 60W - and becomes quite hot.
Even vented coil systems cannot completely ignore obvoiusly giant amounts of heat...
Have a look to some measurements:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=55880&highlight=
Measuring the voice coil temp is a good thing if you drive the system continuously high. Of course a direct measurement is more accurrate than a indicrect, but also indirect can be helpful if you know the relation between the VC and the measured spot.
Furtheron you do not need to shut down completely, you can reduce the input signal softly with a VCA or OTA or LED+LDR or....
There are many ways to obtain good sound. So please accept my subjective view. I like clear and clean bass that disappears fast as is intended in the music. Thus I don´t like systems where you have to crank the volume up to enjoy and to experience some dynamics. I have lived with such speakers-amps but now it´s quite different. Listening late at night can be amazing as so little is "lost" compared to high volume listening. And very little background noise and probably cleaner mains add to the amusement. Dynamics I said...amazing!
High volume listening can be a thrill when I have slept enough and neighbors are away.
My way to better bass was: taking care of psycho acoustic knowledge; -maybe. The combination of active filters for the Volt 12" in vented enclosures and 8" Thiel&Partner (Accutone) in closed boxes took some time to get right, but it was clearly worth it. Hope this isn´t to rave about it but nowadays I don´t tend to get impressed while visiting audio fairs.
Room tuning and acoustics is something to learn and it pays dividends to do it.
I still think; if you burn voice coils something is clearly wrong. You don´t have the equipment for sustained high loudness listening.
So I agree to what ChocoHolic wrote. Heat can be a big issue. But I still think it´s up to getting better equipment.
To monitor or not, I say not...Very hot voice coils kill dynamics IMHO. 😉
High volume listening can be a thrill when I have slept enough and neighbors are away.
My way to better bass was: taking care of psycho acoustic knowledge; -maybe. The combination of active filters for the Volt 12" in vented enclosures and 8" Thiel&Partner (Accutone) in closed boxes took some time to get right, but it was clearly worth it. Hope this isn´t to rave about it but nowadays I don´t tend to get impressed while visiting audio fairs.
Room tuning and acoustics is something to learn and it pays dividends to do it.
I still think; if you burn voice coils something is clearly wrong. You don´t have the equipment for sustained high loudness listening.
So I agree to what ChocoHolic wrote. Heat can be a big issue. But I still think it´s up to getting better equipment.
To monitor or not, I say not...Very hot voice coils kill dynamics IMHO. 😉
FWW here is a link to a commercial site and the subject is partly about the negative effects of very hot voice coils. The solution is said to be the use of a servo system. In my opinion servo systems have their drawbacks as well. One may say that it´s always a matter of correcting faults that have already occurred.
http://rythmikaudio.com/memory.html
Sorry; there seems to be a intermittent problem to access this page (although I read it just minutes ago without any problem).
In case you encounter a problem with the above link maybe it is possible to find it at:
http://rythmikaudio.com/products.html
(look for Memory Effects and a full page document)
http://rythmikaudio.com/memory.html
Sorry; there seems to be a intermittent problem to access this page (although I read it just minutes ago without any problem).
In case you encounter a problem with the above link maybe it is possible to find it at:
http://rythmikaudio.com/products.html
(look for Memory Effects and a full page document)
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