Watts are watts, but the AES rating is a band limited voltage applied across the nominal speaker impedance in free air equivalent to the power rating. A "250 watt" AES rated "4 ohm" speaker would get 31.6 Volts RMS applied to it, though in free air, it's average impedance over the frequency range might be as high as 20 ohms. A 20 ohm average speaker with 31.6 volts applied would only use 50 watts.
As has been pointed out, at Fb (box tuning) the speaker's impedance is at minimum, usually close to the DC resistance, so driven at that frequency the coil will draw the full 250 "watts" it was "rated" for, letting out the magic smoke within a short time period, while still passing the AES test.
There are now plenty of music tracks with crest factor even lower (less than 3 dB) than sine waves, so it is not unusual for coils to roast even with amps limited to the speaker's AES rating.
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Weltersys,
Taken from AES2-1984 R-003:
--> The short version of the following: AES standard has RMS voltage 1/2 of peak. So the continuous or "RMS" Power is 6dB down on peak power. Manufacturers quote the peak power.
--> please tolerate my intentionally erroneous use of the "RMS" above.
"2.3 Power-Handling
2.3.1 Test Conditions and Equipment. The driver shall be mounted on an appropriate constant- or expanding-area acoustical load whose initial area is no smaller than that of the driver throat. The manufacturer shall specify the method of loading. The driver shall be excited with a band of pink noise extending one decade upward from the manufacturer’s stated lowfrequency (lf) limit of the device. The noise shall be bandpass filtered at 12 dB per octave, with Butterworth filter response characteristics, and the peak-to-rms voltage ratio of the noise signal supplied to the lf driver shall be 2:1 (6 dB). Refer to Appendix C for recommended method. The manufacturer shall state the upper and lower cutoff frequencies (– 3 dB) of the noise signal."
Taken from AES2-1984 R-003:
--> The short version of the following: AES standard has RMS voltage 1/2 of peak. So the continuous or "RMS" Power is 6dB down on peak power. Manufacturers quote the peak power.
--> please tolerate my intentionally erroneous use of the "RMS" above.
"2.3 Power-Handling
2.3.1 Test Conditions and Equipment. The driver shall be mounted on an appropriate constant- or expanding-area acoustical load whose initial area is no smaller than that of the driver throat. The manufacturer shall specify the method of loading. The driver shall be excited with a band of pink noise extending one decade upward from the manufacturer’s stated lowfrequency (lf) limit of the device. The noise shall be bandpass filtered at 12 dB per octave, with Butterworth filter response characteristics, and the peak-to-rms voltage ratio of the noise signal supplied to the lf driver shall be 2:1 (6 dB). Refer to Appendix C for recommended method. The manufacturer shall state the upper and lower cutoff frequencies (– 3 dB) of the noise signal."
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…. and now for LF drivers (vs HF drivers)
but the answer is the same.
"4.5 Power-Handling
4.5.1 Test Conditions and Equipment. The lf driver shall be mounted in free air so that the direction of motion of the diaphragm is in a horizontal plane and so that there is no appreciable air loading from adjacent structures. The driver shall be excited with a band of pink noise extending one decade upward from the manufacturer’s stated lf limit of the device. The noise shall be bandpass filtered at 12dB per octave with Butterworth filter reponse characteristics, and the peakto-rms voltage ratio of the noise signal supplied to the lf driver shall be 2:1 (6 dB). Refer to Appendix C for recommended method. The manufacturer shall state the upper and lower cutoff frequencies (– 3 dB) of the noise signal.
"
but the answer is the same.
"4.5 Power-Handling
4.5.1 Test Conditions and Equipment. The lf driver shall be mounted in free air so that the direction of motion of the diaphragm is in a horizontal plane and so that there is no appreciable air loading from adjacent structures. The driver shall be excited with a band of pink noise extending one decade upward from the manufacturer’s stated lf limit of the device. The noise shall be bandpass filtered at 12dB per octave with Butterworth filter reponse characteristics, and the peakto-rms voltage ratio of the noise signal supplied to the lf driver shall be 2:1 (6 dB). Refer to Appendix C for recommended method. The manufacturer shall state the upper and lower cutoff frequencies (– 3 dB) of the noise signal.
"
What all the others say is exactly what I was trying to say. see further up.
Only that I could not express it as well.
You seem to be totally unaware of what you are doing to these speakers and possibly your ears as well. That you do not notice any damage or immediate damage doesnt mean it does not exist.
Only that I could not express it as well.
You seem to be totally unaware of what you are doing to these speakers and possibly your ears as well. That you do not notice any damage or immediate damage doesnt mean it does not exist.
It was probably a bit less than 400W at 20Hz. The amp was rated 400W RMS into 8 ohms @1000Hz. Never actually measured it. Kapton was a poor choice for VC former as far as heat dissipation and the "T" shaped pole piece didn't help either. Yes the 100Hz was very loud, for a short time.
I dont play anything like 100hz bass thats much too loud and painful to my ears.
40hz or below is my preference for deep good bass. sounds nicer and less hammering on my ears.
i tested just one. and both subwoofers hooked up and it hits harder with both in series hooked up. rather than just one. it hits cleaner and deeper that way. and less boomy sounding.
shakes my windows more too. I think its more efficient too because it gets louder and the subwoofers both run cooler. run all day long at any frequency too. no overheating coil when run on half power.
40hz or below is my preference for deep good bass. sounds nicer and less hammering on my ears.
i tested just one. and both subwoofers hooked up and it hits harder with both in series hooked up. rather than just one. it hits cleaner and deeper that way. and less boomy sounding.
shakes my windows more too. I think its more efficient too because it gets louder and the subwoofers both run cooler. run all day long at any frequency too. no overheating coil when run on half power.
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took some pictures of the subwoofer (first one)
no idea why theres differences but they both seem to work fine and about about the same after some breaking in on the new one.
pictures taken with old no-serivce samsung galaxy s4 smartphone since its all i had to take some pictures with.
no idea why theres differences but they both seem to work fine and about about the same after some breaking in on the new one.
pictures taken with old no-serivce samsung galaxy s4 smartphone since its all i had to take some pictures with.
From what I see, I find hard to believe that speaker can stand 250W sinewave or pink noise **continuous** for any significant time (say 4 hours or more to mimic some Party environment).
5 minutes? ... no beef about that.
That magnet is relatively small, around 125 to 130mm diameter, decorative rubber ring partly hides plates but from the partially exposed area I estimate some 8 mm thick each.
The voice coil visible through frame vents (only original idea shown so far, and which I like very much) is at least 3X , probably 4x (or even somewhat more) longer than plate thickness, so it´s not that well cooled by it along its full length.
In principle a voice coil is cooled by dumping its heat into the magnetic circuit (that´s why the relatively small one ... compared to claimed specs that is ... does not give me much confidence) which in due time dissipates it into surrounding air.
So: a very long coil is not as powerful as it looks, pecause only one part of it is inside the gap at any time.
And a relatively low mass magnetic circuit can take only so much heat.
Seat of the pants rating, based on own experience speaker manufacturing: with an aluminum former VC that speaker might reach 200W continuous dissipation ... not bad at all.
With Kapton former: I´d hate putting more than 120/150W continuous on it, if that much.
Of course, with a high dynamic ratio unclipped low duty cycle Music program, you could use it with a far larger amplifier ... just set your limiters carefully and never let average power exceed , say, 120W "RMS" or so.
5 minutes? ... no beef about that.
That magnet is relatively small, around 125 to 130mm diameter, decorative rubber ring partly hides plates but from the partially exposed area I estimate some 8 mm thick each.
The voice coil visible through frame vents (only original idea shown so far, and which I like very much) is at least 3X , probably 4x (or even somewhat more) longer than plate thickness, so it´s not that well cooled by it along its full length.
In principle a voice coil is cooled by dumping its heat into the magnetic circuit (that´s why the relatively small one ... compared to claimed specs that is ... does not give me much confidence) which in due time dissipates it into surrounding air.
So: a very long coil is not as powerful as it looks, pecause only one part of it is inside the gap at any time.
And a relatively low mass magnetic circuit can take only so much heat.
Seat of the pants rating, based on own experience speaker manufacturing: with an aluminum former VC that speaker might reach 200W continuous dissipation ... not bad at all.
With Kapton former: I´d hate putting more than 120/150W continuous on it, if that much.
Of course, with a high dynamic ratio unclipped low duty cycle Music program, you could use it with a far larger amplifier ... just set your limiters carefully and never let average power exceed , say, 120W "RMS" or so.
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True about watts and voltage, but AES rating is calculated at the minimal driver impedance, not at the nominal driver impedance:
"2.3.2 Test procedure
...Power shall be determined as the square of applied rms voltage, as
measured with a “true rms” voltmeter, divided by Zmin..."
So, AES watts rating are at least 25% higher than "Wrms" referred to a nominal impedance. That, plus the much higher impedance in the whole tested frequency spectrum (as correctly explained by weltersys) means that AES watts are different (and optimistic) than one would expect from the simple meaning of the "Wrms" rating.
True.
EV was honest enough to claim 2 different power ratings for their EVM Pro/PA speakers for closed and ventilated boxes, the closed one being lower of course.
The Musical instrument amp world must hold the Nobel Prize for WORST thermal design in the whole planet.
Polytone amplifiers enclose a 100W amplifier, including finned heatsinks, and a Guitar speaker inside the smallest volume possible cabinet, just 2" larger than the cardboard box where speaker was shipped in, hermatically sealed and with all walls COVERED WITH 2" THICK FIBERGLASS.
EV was honest enough to claim 2 different power ratings for their EVM Pro/PA speakers for closed and ventilated boxes, the closed one being lower of course.
The Musical instrument amp world must hold the Nobel Prize for WORST thermal design in the whole planet.
Polytone amplifiers enclose a 100W amplifier, including finned heatsinks, and a Guitar speaker inside the smallest volume possible cabinet, just 2" larger than the cardboard box where speaker was shipped in, hermatically sealed and with all walls COVERED WITH 2" THICK FIBERGLASS.
ew fiberglass that stuff is nasty itchy and bad for your health. I wouldn't want to be working anywhere near that stuff!
realflow100 :
" fibra de vidrio que las cosas son desagradables picazón y mal para su salud. ¡No querría estar trabajando cerca de esas cosas! "
I think nobody has died to use it, big brands of speakers used it for many years. Neither is an exposure to radioactivity, a mask and gloves solved the problem ......
The problem exists in many materials, but it is much greater for operators who are continuously exposed during years of work .....
Here we have purchased subway cars (used, from Spain) with high content of asbestos, also considered highly carcinogenic, the problem is for those who travel every day ......
(take it as a joke in bad taste, please ......... 😀😱 )
" fibra de vidrio que las cosas son desagradables picazón y mal para su salud. ¡No querría estar trabajando cerca de esas cosas! "
I think nobody has died to use it, big brands of speakers used it for many years. Neither is an exposure to radioactivity, a mask and gloves solved the problem ......
The problem exists in many materials, but it is much greater for operators who are continuously exposed during years of work .....
Here we have purchased subway cars (used, from Spain) with high content of asbestos, also considered highly carcinogenic, the problem is for those who travel every day ......
(take it as a joke in bad taste, please ......... 😀😱 )
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still the itchiness is really bad with fiberglass insulation.
better polyfill or egg crate acoustic foam for speaker box stuffing.
and yes they have double stitching. i confirmed its real stitching on the back of the subwoofer. not fake stitching.
better polyfill or egg crate acoustic foam for speaker box stuffing.
and yes they have double stitching. i confirmed its real stitching on the back of the subwoofer. not fake stitching.
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