Let’s look at these links as an example which are a couple you frequently drop into your posts, including on this thread which is where I pulled them from:
http://www.atma-sphere.com/Resources/Common_Amplifier_Myths.php
http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php
@Clio9
I put these papers up for the simple reason that I got tired of writing the same thing over and over (for example, the article about common amplifier myths gets linked a lot, as that is a very common myth around these parts). I recently added another article about balanced operation; its a lot easier to drop a link than write 200-800 word explanations all the time. That is the only place I know of where I can host something like that.
Other than that, I *do* walk my talk. Beyond that if there is a statement of error, I offer the correction as I have done here. Normally that isn’t a problem, but in this case I’m getting personally attacked over stuff that is normally pretty easy to understand. While I didn’t intend it that way, apparently my presence here is part of why this thread hasn’t been removed.
I dont like the high output impedance or high distorton. I do like Ralph’s amplifiers better than his paper. I wish he would just drop the paper. Its embarassing.
Can’t he just say what his amps do without having to invent this story?
Loudspeakers that operate under Power Paradigm rules are speakers that expect constant power, regardless of their impedance. Examples include nearly all horns (currently the Avantgarde Trio is the only known exception), ESLs, magnetic planers, a good number of bass reflex and acoustic suspension designs. Horns, ESLs and magnetic planers do not get their impedance curve from system resonance and so benefit from a constant power characteristic and indeed, many of these speaker technologies are well-known as good matches with Power Paradigm amplifier designs.
This paragraph is particularly disturbing. Is he saying ESL speakers are constant impedance?
@ramtubes
I’m not saying the ESLs have a flat impedance curve- far from it. Many vary from bottom to top by about 10:1.
Here is the meat of it right here:
Speakers are not power driven, they are voltage driven. Lets look at the low end resonance. Most speaker climb to 40-60 ohms at resonance (35 hz lets say). The speaker designer does not want the voltage to rise into that peak. He already accounted for that peak with the mechanical damping of his speaker.
I am really curious right now how many times I’ll be explaining this!
While the above quote is mostly true these days, its not actually 100% correct due to exceptions. First of all of course, voltage doesn’t exist without current and current times voltage is power, so obviously all speakers are actually driven by power. The bit about them being ’voltage driven’ is a **charged term or phrase**, similar to the idea of ’RMS power’; see:
https://forum.audiogon.com/discussions/rms-powerOn that thread, we see that the term ’RMS power’ is really something that was created to satisfy FTC rules for testing amplifiers back in the 1970s. Outside of that the phrase is ambiguous. I pointed this out at the inception of that thread. There are other charged terms in audio as well- ’damping factor’ and ’output impedance’ are two that come to mind- they have *very* specific meanings in audio, not so much elsewhere in the electronics industry (IMO/IME, Roger, your use of the phrase ’output regulation’ is more accurate).
This is the case with the phrase ’voltage driven’ as well. In this case, what it means is that the speaker is is intended to be driven by an amplifier that acts as a voltage source.
The reason is that the speaker has a resonance caused by a driver in a cabinet, as we see in the quote from you just above. Since the resonance expresses an impedance peak, if you don’t throttle back the power into that peak (IOW, maintain constant voltage), you get a tonal coloration. In effect, the impedance curve of such a speaker is also a map of its efficiency vs frequency: the higher impedances needs less power, lower impedances needs more. A voltage source satisfies this.
Now an ESL is not a driver in a box. In a nutshell its impedance curve is essentially based on a capacitor. Thus its impedance curve does not also represent its efficiency vs frequency; its not following the same rules. Many solid state amps act as voltage sources; if you put one on a Quad, the result is a loss of bass and way too bright.
Now as I mentioned in my email to you, some speaker designers build their speakers to work with Power Paradigm amps, and so apply a different technique. The driver in the box has a peak, but if you do the math and place the peak at a point in the box such that the box is starting to roll off before the peak, what happens is you can extend the LF response of the speaker down another half octave for a given box size. The Acoustic Research AR-1, the world’s first acoustic suspension loudspeaker, was designed for an amplifier with a 7 ohm output impedance.
You claim that this flies in the face of electrical theory, but you then have to explain a lot! Where did the voltage rules come from? Who introduced them? When did that happen? What was out there before that? I’ve of course told you... multiple times at this point. Its audio history.
Regarding distortion:
About high order harmonics I will ask you. Would you rather have an amplifier with 3% 3rd and 0.01 7th-11th or one with less than 1% 3rd and 0.02 7th -11th? My point is that the high ordered harmonics are rather small. Intermodulation will follow a similar path.
The one with the lessor higher ordered harmonics will sound smoother/more like music to the human ear. Most would prefer that, given a speaker on which both amps make good FR. The ear treats the 3rd very much like the 2nd and in that regard its relatively insensitive. We really should be weighting the various harmonics according to the ear/brain’s sensitivity to them. But our current test and measurement regime pretty well ignores human hearing rules that have been discovered since the 1960s. But if we did that sort of rating, a 0.02% of the 7th would look only fair because its pretty audible.
It is a popular myth that if an amp is high in THD it will also be high in IMD.
This is the inconvenient truth about human hearing; feedback violates arguably the most fundamental rule of human hearing perceptual rules: how we sense sound pressure. This is why SETs have made such a huge comeback in the last 28 years.
But only in high end audio.
High end is fundamentally different from regular audio, the difference being in regular audio its all about the money. In high end its all about seeing how far you can push it, making it sound real instead of like a good hifi. That is where I draw the line- IMO/IME if the speaker requires that the amp employ feedback, it will never sound real, at best it will sound like a good stereo.
