Reading this article just flabbergasted me with regard to the gross simplification of an amazingly complex topic, simplification to the point of being factually incorrect in both the approach and the assumptions made throughout the article. IMO, if you are going to attempt to tackle a topic like this, you should better understand the depth and breadth of the topic, and present the details in a more accurate and informative way, one that more closely represents the real world better. Folks can not learn from inaccurately presented information.
Just starting with the grossly inaccurate assumption (and simplification) that the RMS voltage is going to be Vpeak/1.414 (or Vpeak x .707). It is in fact about as far from reality as can be. Bass guitar signals are not sinusoids, have never been nor are they likely to ever be (though they are in fact made up as a series of sinusoids represented by a Fourier series). Then, many (if not most) amplifiers being driven hard, ESPECIALLY those using tube preamps, solid state preamps with any kind of overdrive or saturation emulation, software based preamps that utilize overdrive algorithems, any amp that uses any form of dynamics management in conjunction with the above requires power analysis using the area under the curve method (or using a true RMS voltmeter that does not do it's conversion based on a sine wave and peak voltage). For instance, even a dB(power) of dynamics management in conjunction with some overdrive (they should and do go hand in hand in a well manage amp design) can represent a very large deviation between a simplistic and thorough measurement. A 1.5 dB of difference in a 500 watt amp would represent an additional 200 watts that while present if measured using the area under the curve method would not be represented using the inaccurate peak to RMS conversion because the resulting output was never intended to be sinusoid.
The other simplistic assumption that is inaccurate in the context of bass world (both bass guitar as well as bass PA applications) is the notion that a 20msec burst is of any value. Good grief guys, we are talking about 1 cycle at 50Hz. There aren't many bass guitar signals in the real world that has it's critical attack enevlope contained within the 20msec when driven hard (per the intent of the topic). In fact, when designing preamps and power amps around this attack envelope, if you are not focusing on the first 100msec you are missing an incredible amount of the tone and feel information in the context of real world performance and playability. The amplifier's performance needs to track the attack and decay envelopes within the context of the real world, not to some 20mSec burst standard that is utterly meaningless to low frequency signals. While they may make some amplifiers look better on paper, they do not translate to low frequency performance unless thay also perform the same at much longer burst periods. This 20mSec standard has nothing at all to do with the measurement of low frequency signals, it was developed as part of an old IHF standard specifically to represent higher frequency program material. I remember when it came into popularity, when Hitachi introduced class G (2 rail modulated high tier) they needed a way to express the approximate doubling of power for short periods of time for >100hz signal. They were the first to capitalize on it but why above 100Hz? Because AT THE TIME THE STANDARD WAS INTRODUCED, the LF dynamic range was limited by the reproduction medium of the day... LP's. (for those of you young enough not to be familiar with these, they were flat vinyl discs with a modulated spiral groove. The modulations (music) was cut in the master with a mechanical cutter on a record lathe and because of the mechanical limitations, the dynamic range at low frequencies were limited to prevent overcutting and chattering of the cutter in the master. The 20msec standard is only appropriate for characterizing midrange and higher dynamic performance.
Then there's the undisputable fact that some specific amplifier topologies will perform better in inductive load tests using an electro-dynamic load, but these topologies haven't even been discussed nor considered even though most of the amps being brought to the market today use at least some of this technology (including the module JGR is using). Why should any amplifier that utilizes this topology be penalized by not accounting for it's contribution? It is a significant real world contributor, one that must be accounted for if attempting to present an accurate comparison. THIS is the future guys, new designs that address WHY some of the older designs are so well liked by players, then taking the next step to make them "better". When I say "better", I mean where the original designer's might have gone with the approach had the technology been available to them at the time. I mention this because there are a few noteworthy amp designers that hang out here, and while it's easy/convenient to catagorize some of them/us as being stuck in the past, that would be an inaccurate characterization. I spent a little time with Bill Hughes a few years back, and while his legacy was the SVT, a few years back he was, and presumably still is VERY much involved with cutting edge technology and the future of MI amplification. To underestimate the creativity and wisdom of the older designers is to close your eyes to the evolution of our amplification culture. Evolution hinges on thoroughly knowing and understanding the past to take advantage of the future.
I myself have spent much of my professional career (for a variety of amplifier companies) studying and designing around this specific topic and it makes me uncomfortable to see a cpmplex (and important from the player's performace perspective) topic oversimplificated to the point of being misleading, especially when being presented as a way to make commercial comparisons that result in inaccurate results. Each design approach MUST be tested according to the amplifier's specific design approach rather than lumping all approaches together (might as well include PA amps, servo amps, mag amps, shaker table amps etc.). I would rather see more of an explaination/discussion of the hows and whys of topics such as dynamics, harmonics, frequency response, linearity, wave shapes, the engineering behind the wide variety of over techniques, etc. all the way from the bass through the speakers. If nothing else, it might develop an appreciation for the compexity of the topic and maybe stimulate some thinking about how it all applies to us in the real world as players.
