Does this seem suspicious to you?

[agedhorse]

Since I am an engineer (a real one ) and design specifically for this industry, I would suggest that my opinion (expert or otherwise) is pretty well informed as far as following basic engineering principles.

 

I will tell you WHERE the warning aganst "underpowering" a speaker came from though. For many years, biamped systems (I mean bi-amped top cabinets specifically so there's no chance for confusion) were almost non-existant in the MI marketplace. All PA cabinets had a passive crossover, horn drivers were quite fragile (even paper formers) so any amplifier clipping would increase the amount of high frequency power bandwidth to the horn driver (due to the Fourier transform principles of a square wave being composed of a fundamental plus a series of higher ordered harmonics) causing the high frequency driver to fail.

 

This was at a time when large power amplifiers did not exist in the MI market and there was little danger of gross overpowering. This has all changed in the last 15-20 years with improved former materials (Kapton) for HF drivers, better diaphram manufacturing processes and materials (titanium for ex.), active crossovers becoming more common, and most importantly really large power amplifiers becoming really cheap. Now, the problem is no longer to little power causing HF drivers to fail (thermally) but too much power cauusing low frequency drivers to fail mechanically. Look at the Xmax of drivers 20+ years old and you will see very small values (and correspondingly higher sensitivity numbers) with lower power ratings. This was ideal for maximizing performance with lower powered amplifiers. Additionally, manufactures have been "one-uping" each other and there has been specification creep for identical products over the years. Many (though not all) of these spec. increases have come from previously more conservatively rated specs. Things have changed, and so has today's reality of the urban myth.

 

Here's a good bit of reading that represents the real world pretty well and even contradicts their own marketing department somewhat. Note that the IEC rating approximates the "RMS" rating (heating effect) with +3dB for program accomodation and a +3dB peak conversion:

 

http://www.jblpro.com/pub/technote/spkpwfaq.pdf

 

My experience is that for their self-powered products, their engineers limit the power and/or process the signal to adhere to between the "RMS" and "RMS" + 3dB levels. Much of the processing contains time based elements which really help limit the potential for damage.

[Craig Vecchione]

I believe there is possibly a reason for a manufacturer to give such recommendations that is based on reliability and performance considerations. I tend to see a lot of things here that are based on expert opinions that do not often follow very basic engineering principles. But I'll shut up now.

 

 

Perhaps the most basic engineering principle is that you can't damage a speaker by applying *less* than a maximum specification rating. The warning stickers imply that more is better, which is not the case at all.