Saying that an underpowered amp can’t blow speakers with a higher power handling rating is false. The vast majority of “blown speakers” are not blown by amps with a higher power rating than the speakers… Tweeters are much more sensitive to clipped signals when an amp is overdriven. Woofers, except in cheap speakers, are extremely hearty and can handle prodigious power, even beyond their rated capacity. You have to heavily overpower a woofer to cook it. Most people simply don’t have that kind of power in their car or home systems. However, you can cook a woofer with a clipped signal that tells the woofer to hold the cone at the extremes of movement. Do a little online research and you will see that what I am saying is true.
The reason tweeters are so sensitive to clipping is because in normal music and speech, there is so little energy in the upper frequency range and so tweeters are only designed to handle a few watts of power.
If you put heavier gauge wire in the voice coil of a tweeter, you also increase the voice coil’s mass and reduce it’s ability to vibrate at high frequencies, not to mention that the increased inertia reduces the power factor. (real power divided by apparent power or watts divided by AC volt-amps)
“Anyway, the point is that an amp that is rated below the speakers capacity is not going to damage it, even if driven to clipping, period”
Typical “bookshelf” 2-way speaker has a dome or cone diaphragm tweeter that can handle ~5 watts.
That paired with a woofer that can handle 50-100W.
So in a heavy clipping situation a 10W or less power amp wouldn’t damage; but a 50W one could.
Anyway, in my work back in the '80s with home and pro speaker systems I found fast-blow fuses in series and sometimes zener diode pairs in parallel with a tweeter provide some protection.
"Anyway, the point is that an amp that is rated below the speakers capacity is not going to damage it, even if driven to clipping, period"
Wrong…Clipping is a form of waveform distortion that occurs when an amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum capability. Driving an amplifier into clipping may cause it to output power in excess of its published ratings.
BTW…some speakers with lower power handling capabilities does NOT mean it’s cheap or can’t get very very very very loud. Take a look at the wattage ratings of large theater speakers. I’ve seen speakers that are 7’ tall with an wattage rating only 60watts. But they have an efficiency rating of over 110db. At 1 watt they are pumping out 110 db’s…at a mere 30 watts they’ll make your ears bleed.
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@MikeInNH "Clipping by definition is Over driving the AMP. It’s the amp that’s clipping…NOT the speakers. "
Mike look at this statement. You can’t see how I interpreted it to mean the amp was overdriven by the input? You didn’t specify and that is how I interpreted it. It may not be how you intended, but at the first reading, thats what I got.
Also as to sub woofers, most subs today use an amp that is clipped. In fact the output is clipped to an almost square wave. They use class D amplification which is a form of pulse duration modulation. The square waves are at a frequency that is too high for the coil in the speaker to respond to, so a capacitor is put at the output of the amp to store the energy of the square waves until the coil responds and starts conducting.
It essentially forms a filter to turn the high frequency square waves back into a sine wave. This works pretty good for frequencies under 120 Hz. Above that, it probably wouldn’t work as it would be hard to find transistors that could handle the power and switch at the very high frequencies that would be needed.
The inductance of low and medium frequency drivers protects them from the high frequencies produced by clipping. To produce high frequencies with a significant amount of energy, the output would have to be clipped by at least half of its amplitude, and even then am amplifier will not put anywhere near 10% of its rated output into those high frequencies. It takes an almost perfect square wave to get anywhere near that. To get near that, you would have to clip over 90% of the signal.
Mike, I do agree with you that there is a lot more to the quality of a speaker than its power handling capacity. In fact a cheap speaker can have a large power handling capacity simply by adding a bunch of heat sinks. The heat sinks do not add to the quality of the sound, in fact they probably hurt it by fooling the customer that they can use a higher powered amp than they should, and the customer in turn ends up driving the speaker into the distortion (clipping) zone.
That is really my criticism of most boxed surround sound systems. Cheap speakers with heat sinks, over powered amp to get the volume and impress the customer with lots of watts. Watts are cheaper than speaker quality. I much prefer a system with better quality speakers and a lower powered amp. That is why I bought the individual components for my surround system. If I had more money, all of it would have all gone into even better speakers.
It essentially forms a filter to turn the high frequency square waves back into a sine wave. This works pretty good for frequencies under 120 Hz. Above that, it probably wouldn't work as it would be hard to find transistors that could handle the power and switch at the very high frequencies that would be needed.
There are DC to AC inverters that use pulse width modulation to simulate an AC sine wave today. The switch rate is usually around two kHz and they come in sizes large enough to drive 500 HP and higher three phase motors at 460 volts. This technology is rapidly making brushed DC motors obsolete.
They even have the technology to have the drive sink power and return it to the line during coast down or while an elevator car is going down, or during a Tesla’s regen braking.
The semiconductors that handle this kind of current are disks that are clamped between heat sinks, due to their size and shape, they are often called “hockey puck” semiconductors.
In theory, 2k Hz switching could work up to 1k Hz, you would need a high power amp to switch at least 44 kHz for a full range audio amp. I’m sure that technology will come, but as far as I know, it isn’t here yet.
Modern insulated gate bipolar transisters (IGBT’s) can switch at ultrasonic rates and can conduct hundreds, even thousands of amps and can be had with blocking voltages up to 6000 volts. They use these in inverter drives for locomotive traction motors using three phase induction motors instead of brushed DC motors. They have inverter drives for 4160 volt motors now.
The advantage of switching amps is that with the semiconductor either on or off, there is very little power lost in the amp and you don’t need huge heat sinks to keep the amp cool.
All the audiophiles talk about the frequency spectrum but very few put the spectrum into perspective.
To put it in perspective consider that the strings of a violin are tuned 196, 293.7, 440, and 659.25 Hz, (G,D,A,E) when tuned to an even tempered (chromatic) scale and the standard for middle A is 440 Hz.
A guitar’s strings are tuned 82.4, 110, 146.8, 196, 246.9, and 329.6 Hz.
It’s clear now that the bulk of the energy in normal music and speech is below 1 KHz. That’s why tweeters don’t need to be designed to handle a whole lot of power. They mostly give us the hiss of cymbals and the string slap of rockabilly bass players.
“In theory, 2k Hz switching could work up to 1k Hz, you would need a high power amp to switch at least 44 kHz for a full range audio amp. I’m sure that technology will come, but as far as I know, it isn’t here yet.”
Using power MOSFETs switchmode operation at 100khz or higher is not a big deal.
http://www.crownaudio.com/en/product_families/xls-drivecore-series
OK, OK, but so far AFIK the only class D amps are subs. Audio amps are mostly push pull Class AB and a few Class A.
There are lots of full-range class D amps out there, like the one I linked. Do a little searching.
Not the highest fidelity.
I wouldn’t want it at home with the high efficiency speakers I prefer (think Klipsch) I don’t need much power (45WPC stereo).
Zzzzzzzzzzzzzzzz…
You might want to fix that ground loop…
OP was asking for advise concerning 1997 speakers with a 2004 stereo. I’m sure any car audio shop could solve their minor problem. 6 pages of highly technical and conflicting advise is probably not what they were looking for.
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Well, you know it’s critical to have the very best audio components so you can hear what they are saying while you listen to AM talk radio and the news on your way to work.
critical to have the very best audio components so you can hear what they are saying while you listen to AM talk radio
lol …
Some of you folks seems to have a lot of expertise on audio amps and speaker. fyi, there’s a good article on practical build it yourself audio amp design in a recent issue of the magazine “Nuts and Volts”. It shows how actual audio amplifier design engineers do it to get good performance using current mirrors.
Mike, I do agree with you that there is a lot more to the quality of a speaker than its power handling capacity.
Power handling is THEE least meaningful spec. It is always the last thing I look at. It’s only purpose is to do amp matching…It says absolutely nothing on how speaker sounds…absolutely NOTHING. Nor does it say anything on how loud a speaker can get.
Crown made a series of amps that were Class A and Class AB. At low power settings it was Class A…then at higher power settings switched to Class AB…then AB/B
In a typical CAR speaker, it doesn’t really matter if you blow the tweeter or woofer or both. If you blow one, the speaker is junk. Nobody I know is repairing those kind of speakers. The OP is not talking about home audio loudspeakers here…
One other thing, once the amp reaches clipping, it isn't going any louder than that. It has reached B+ voltage and that is all there is, end of story.
I agree with almost everything you said with the above exception. It appears you’re confusing audible output with electrical output power. As the clipping amount increases by continuing to rotate the volume adjustment the output power increases dramatically as the area under the “curve” continues to grow (width of the clipped waveform) There will be no additional audible output but the power being dissipated is increasing…did I misunderstand your point there?