I have a class D audio amplifier powered by a 1 amp 12v DC power supply (cuts off it draws more than 1 amp and tries to restart after a second)
and I have two 30W RMS 120W peak coaxial 4-way speakers hooked up in a ported speaker box and the amplifier is not clipping. they speakers sound clear but I can feel them getting very toasty. all the way up to the cone I can feel a fair bit of warmth from them! and they must be getting only a few watts each and no where near 30W RMS each but they still get warm without clipping or distortion.
If I smell right up to them they smell pretty toasty. smells like heat radiating from a metal surface. no cooked or burnt smell. but pretty warm
I dont know how its possible they can get so warm from 6W RMS each
does anyone have any clue? I know its not clipping because it sounds clean and undistorted at all volumes up to the point the power supply cuts off from overcurrent and restarts itself after a second. if I back it off just a little and play the speakers with a lot of bass songs they get warm after a few minutes and I dont want them to burn up.
and I have two 30W RMS 120W peak coaxial 4-way speakers hooked up in a ported speaker box and the amplifier is not clipping. they speakers sound clear but I can feel them getting very toasty. all the way up to the cone I can feel a fair bit of warmth from them! and they must be getting only a few watts each and no where near 30W RMS each but they still get warm without clipping or distortion.
If I smell right up to them they smell pretty toasty. smells like heat radiating from a metal surface. no cooked or burnt smell. but pretty warm
I dont know how its possible they can get so warm from 6W RMS each
does anyone have any clue? I know its not clipping because it sounds clean and undistorted at all volumes up to the point the power supply cuts off from overcurrent and restarts itself after a second. if I back it off just a little and play the speakers with a lot of bass songs they get warm after a few minutes and I dont want them to burn up.
So there is no way it puts out more than 12W DC so no way to get more than, say, 5W RMS into each speaker
Not sure it is really happening, you always post about VERY unlikely or plain impossible "problems", but IF happening, it can not be caused by your feeding them way less than 5W RMS, NO WAY.
my point
no way
No way.
yes, you are making this up, for unknown reasons.
Lots of similar posts from you.
No way.
I'm not making anything up?? I can feel the cone is really warm near the center when I put my fingers on the surface.
I think the amplifier could be oscillating at a high frequency above human hearing making the speakers get extra hot or something. I don't know any other way it could be heating them up unless the speakers are morbidly over rated
I think the amplifier could be oscillating at a high frequency above human hearing making the speakers get extra hot or something. I don't know any other way it could be heating them up unless the speakers are morbidly over rated
Run a 5W resistor up to full power. It gets pretty hot.
Remember, 30W will be a 2-hour survival rating, based on pink noise in free air.
ie, at 30W continuous input, the adhesives will melt (usually well past 100C). Put the driver in a box, and you ought to derate it accordingly. It might only survive 20W long term.
Combine that with "bass music" that can have content that can be sine-wave-like (ie, low crest factor, so lots of heating with minimal peak voltage swing), and I can see why your drivers might get warm.
No surprises here...
Chris
Remember, 30W will be a 2-hour survival rating, based on pink noise in free air.
ie, at 30W continuous input, the adhesives will melt (usually well past 100C). Put the driver in a box, and you ought to derate it accordingly. It might only survive 20W long term.
Combine that with "bass music" that can have content that can be sine-wave-like (ie, low crest factor, so lots of heating with minimal peak voltage swing), and I can see why your drivers might get warm.
No surprises here...
Chris
100C will be fine for most adhesives, but it will vary. Decent PA speakers go above 200C before any trouble occurs.
Have you got any way of checking the temperature of the coil itself?
I've accidentally had an FE126E up to the temperature where hot smells start. Still working fine, although I did reduce power levels quickly when I noticed.
Chris
Have you got any way of checking the temperature of the coil itself?
I've accidentally had an FE126E up to the temperature where hot smells start. Still working fine, although I did reduce power levels quickly when I noticed.
Chris
It is not at all surprising that a voice coil becomes warm!
The voice coil of a bass/mid speaker is air cooled through its vibration so its temperature rise will remain tolerable under normal operating circumstances.
The tweeter voice coil of your coaxial loudspeaker is more at risk of burning out because of its much lower amplitude of vibration.
Bass drivers driven continuously at their tuning frequency (reflex enclosure) are kept from moving by the resonant action of the port/enclosure. The impedance drops to the dcr of the voice coil while no cooling due to motion takes place...I'm not making this up; my pro sound buddy had JBL 18" 2245 woofers catch fire when some lame *** band just laid on the power. I don't know how he can stand seeing what others are willing to do to his awesome diy rig but now the 8 Labhorns are better able to withstand the abuse.
As the speaker voice coil is basically an inductor as the frequency goes up the impedance of the speaker goes up so its unlikely to be oscillation causing heat.
It might be DC being output and in that case the voice coil is just a few ohms and will cook.
I checked on a friends oscilloscope and the waveform looks completely normal. no DC bias.
Maybe the speakers just suck? they are two 4" speakers coaxial type at 4 ohms each they move at all bass frequencies and dont seem to have any specific peak frequency where they move the most or make the loudest bass
The box is not tuned at any specific frequency. just a square ported box with a hole and port tube in the back of it port seems about 1" wide for tube diameter inside and goes really deep in the box flared at the outside of the box to about 1.5" wide and it also seems flared inside too. seems overkill for a 4" speaker.
Maybe the speakers just suck? they are two 4" speakers coaxial type at 4 ohms each they move at all bass frequencies and dont seem to have any specific peak frequency where they move the most or make the loudest bass
The box is not tuned at any specific frequency. just a square ported box with a hole and port tube in the back of it port seems about 1" wide for tube diameter inside and goes really deep in the box flared at the outside of the box to about 1.5" wide and it also seems flared inside too. seems overkill for a 4" speaker.
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