Double down, good or bad?

Ralph,Thank you for that explanation. I agree with your assertion that human hearing is the most important aspect of audio. I have found lately, that the speaker/room relationship or room acoustics may be the second.

I have not thought of or previously read about the "Power Paradigm" vs. the "Voltage Paradigm". It is interesting to view it from the speaker designer's point of view. I used to drive my Eggleston speakers with a Pass XA160 which had constant power to all loads, but I now use the Pass XA100.5 which doubles down as impedance is halved. The speaker's nominal load is 6 ohms, which means that the amps have about the same power. The latter combination sounds much better to me. From your explanation, am I to understand that the XA160 follows the "Power Paradigm" while the XA100.5 follows the "Voltage Paradigm" and that Eggleston probably designed the speaker with the latter in mind? It must sound better to me because the amp is better able to handle the load of the speaker. Or is it also because this paradigm places more value on low distortion, and that sounds better to me? This sounds overly simplified. Pardon me for my ignorance, but I'm interested and would like to better understand the issue. I'm fairly new to the hobby and don't have the technical background. Thanks.

Ralph just thinking off the top of my head.Because most speakers report "nominal" impedance and thier real impedance curve is all over the place, a doubling down amp would create serious spectral balance problems.
Looking at a frequency versus impedance curve like my Martin Logan CLS the high frequencies(2 ohms) would be driven 800 watts where the Low frequencies (8ohms) would be driven at 200 watts. Intuitively this would seem to cause spectral balance problems.
Does this make any sense?

Atmasphere, we're definately on the same page as far as the system-matching aspect of different amplifiers being optimum for different loudspeakers, especially when comparing among various speakers and amplifiers that use very different technologies and design approaches. But, er, well take this statement:

Power Theory (or Power Paradigm) is where the amp seeks to make constant power into all loads. It will not succeed, but that is the goal. The Dynaco ST-70 is a good example, 4,8,16 ohms its 35 watts. Our own MA-2 is another, 4,8,16 ohm 220 watts. Some transistor amps fall into this category.

I'm sorry, but the reasons why a ST-70 and a MA-2 both have constant power ratings into 4,8, and 16 ohms are completely different from each other! Further, a ST-70 has a much lower output impedance than that rated for the MA-2, and thus will interact with the loudspeaker impedance to a much different degree.

To use your B&W 802 example . . . according to Stereophile's measurements, this loudspeaker varies from a low of about 3 ohms in the mid-bass, with a peak of over 21 ohms in the midrange. Looking at my notes from the last time I measured a stock ST-70, it had an output impedance of about half an ohm over most of the audioband, from the 8-ohm tap . . . so I'll take an educated guess and assume it's about 0.29 ohms from the 4-ohm tap, which is what you would use for the 802.

So a ST-70 driving a B&W 802 would thus have about a 0.68dB response peak in the midrange due to the interaction of the amplifier output impedance and the speaker's impedance curve. For comparison, a hypothetical traditional solid-state amplifier (0.05 ohm output impedance) would have a 0.12dB response variation. But the MA-2 (published 1.75 ohms output impedance) would have a peak of 2.3dB! And for the MA-1 and M-60, the deviation is even greater . . . 4.04dB and 5.93dB respectively.

Now we're in complete agreement that the B&W 802 is a bit of an extreme case, and also that it's a poor match to an Atma-Sphere amp. And I'm not suggesting this is an inherently bad thing about Atma-Sphere amps (just a "system misapplication" if you will), or that the Dyna is a stellar match either . . . I'm personally a fan of the ST-70 but am also very familiar with its myriad shortcomings. But the ST-70 can hardly be considered a "Power Paradigm" amplifier because of its comparatively low output impedance.

Let me again re-iterate my original point: The suitability of an amplifier for driving a particular speaker simply CANNOT be inferred from looking at its clipping-power ratings into various load impedances! Ever. Period. It's output impedance that makes the difference.

Two secondary points: First, historically, there has been no Paradigm Shift - common practice loudspeaker design has ALWAYS been about constant voltage with frequency . . . as most vintage hi-fi tube amplifiers (such as the ST-70) have low output impedances, especially when compared to loudspeaker impedance curves of the day. Second, this is NOT a tube/transistor thing . . . there are many examples of solid-state amps with high output impedances in addition to tube amps with low output impedances.

Incidentally I actually commend Atma-Sphere for publishing their output-impedance specifications . . .

Peterayer, you are right, the Eggleston is designed around Voltage Paradigm rules, but some of the Pass amplifiers are not. You can find quite a bit of information on Nelson Pass' website regarding that. BTW his papers on distortion are excellent.

Bob_reynolds, Sure:
A transistor amp will make too much power at high frequencies on an ESL because ESLs have a low impedance at high frequencies, often the difference between the bass and highs can be as much as 8X difference in power response in an amplifier that can double power. Gregadd, this answers your question as well.

In the case of horns, the drivers are highly reactive due to tight gaps in the voice coils, and produce a lot of back EMF. When presented to the feedback network of an amplifier, this back EMF causes the input of the amplifier to misbehave- the voltages at that time do not represent the actual correction that the amp needs. So it tends to make excess harmonics and so sounds shrill.

In the case the the mbl, it is an easy 4 ohm load with an 8 ohm peak on the midrange driver. The designer expects the amp to throttle back its power, but an amp that makes constant power will not do so and so will have excessive upper midrange.

In the case of the B&W, the woofers are in parallel and are 3 db less efficient than the mids and highs. An amplifier with constant power response will drive the woofers with 3db less power than intended.

In all cases it is inappropriate power response. This is the major reason why you get mismatch between amps and speakers, although I would be remiss if I did not point out that distortion in both transistor and tube amplifiers also plays a significant role in what we hear as tonal aberration.