Ralph Karsten posted a link to a paper he wrote titled "Paradigms in Amplifier Design". Here is the link for those who haven't read it and would like to:
http://www.atma-sphere.com/Resources...ier_Design.php
Even though I have been accused of not reading his paper and/or not being able to comprehend it, we will muddle through this and come out with some truth on the other end because I like the truth much better than I like nonsense. Ralph proposes in his paper that amplifiers designed using the "power paradigm" are superior to amplifiers designed using the "voltage paradigm." Voltage Paradigm amplifiers are SS and Power Paradigm amplifiers are vacuum tube based with few exceptions. Ralph goes on to state that the ideal Power Paradigm amplifier "will make the same power into all loads, 4, 8 and 16 ohms." OK. So we all know that we seldom reach the ideal state in the real world, but we should expect we should come close. What comes closest to meeting Ralph's definition of the ideal Power Paradigm amplifier are tube amps with output transformers. Here is an example:
Music Reference RM-9
103.5 watts into 8 ohms
102.9 watts into 4 ohms
96.2 watts into 2 ohms
If we want to extoll amplifiers that have constant power, the RM-9 is a mighty fine example. It also has an output impedance of 0.3 ohms and THD distortion less than .05% in the audio band.
Ralph asked us to take a look at a review of his MA-1 amplifier written by Soundstage which included measurements. Here is the link to the measurements so you know I'm not making this up:
http://www.soundstagemagazine.com/me...ere_ma1_mkii2/
First of all, the review states that the power output specification for the MA-1 is 140 watts into 8 ohms and 135 watts into 4 ohms with no distortion percentage given for these output figures. According to the measurements, here is the real truth:
8 watts at 4 ohms at 1% THD
20 watts at 8 ohms at 1% THD
90 watts at 16 ohms at 1% THD
So the difference in output power between 4 ohms and 16 ohms is over 9dB. I would hardly call that constant power. If you want 10% THD, here are the next measurements:
80 watts at 4 ohms
120 watts at 8 ohms
130 watts at 16 ohms
Obviously there is nothing approaching "constant power" in the MA-1 when rated at 1% THD which is the standard definition for clipping in most amplifier measurements I have read. In order for the MA-1 to come close to approaching the ideal Power Paradigm amplifier and his rated output power for the amp, you have to go with the 10% THD distortion numbers. There is still a difference in output power of 50 watts between 4 ohms and 16 ohms. The output impedance of this amp is also 10.5 ohms.
So if you are going to design and build amplifiers that have 10% THD at near their rated output power (and the MA-1 doesn't make the output power stated in the review at 10% THD), then that would explain why you would say something like this: "It is very easy to tell how an amplifier will sound using measurements based on the Power Paradigm as the measurements are made with regards to understanding and working with the rules of human hearing." Ralph also quotes the following in his paper: "In the 1960s, General Electric's conducted a variety of tests, confirming that amounts of barely hundredths of a percent distortion were not only audible but also irritating to the human ear (conversely, they also found that the ear is quite tolerant of lower ordered harmonic distortion)." So if barely hundredths of a percent distortion are audible and irritating, I wonder what GE would think about 10% THD even if 100% of the 10% THD was low-order?
The bottom line here is that if you buy into the Power Paradigm theory and you like low distortion as well, you best buy a well-designed tube amp with output transformers. The MA-1 does not make equal power from 4-16 ohms, the power increases as the impedance rises. Ideal speakers to mate with an amp like this are very efficient speakers with high impedance. 16 ohm speakers used to be quite common in the 1950s and early 1960s, but I'm pretty sure they are much less common today. That is why I made the original statement that "You are never going to have a flat, uncolored "presentation" from an amplifier with a high output impedance into the majority of all loudspeakers known to man whose impedance changes across the audio bandwidth." Notice I said the majority of loudspeakers on the market today (I didn't say "all speakers" which I was accused of and then in turn was accused of creating a strawman argument when there was none).
So who still believes that OTLs meet the Power Paradigm theory and will be flat and uncolored into anything outside of a resistor strapped to the output terminals on a test bench? No speaker to my knowledge has a pure impedance of 4, 8, or 16 ohms as I said before.
And if someone wants to take exception to what I said, make sure it's what I said and not what you changed it to be. This already happened once and I wasn't amused. Let’s have an open and honest discussion. If someone can clearly point out an error in what I said, I will gladly admit I'm wrong. Until then, I standby the original statement I made in the other thread that started this whole tiff off.
http://www.atma-sphere.com/Resources...ier_Design.php
Even though I have been accused of not reading his paper and/or not being able to comprehend it, we will muddle through this and come out with some truth on the other end because I like the truth much better than I like nonsense. Ralph proposes in his paper that amplifiers designed using the "power paradigm" are superior to amplifiers designed using the "voltage paradigm." Voltage Paradigm amplifiers are SS and Power Paradigm amplifiers are vacuum tube based with few exceptions. Ralph goes on to state that the ideal Power Paradigm amplifier "will make the same power into all loads, 4, 8 and 16 ohms." OK. So we all know that we seldom reach the ideal state in the real world, but we should expect we should come close. What comes closest to meeting Ralph's definition of the ideal Power Paradigm amplifier are tube amps with output transformers. Here is an example:
Music Reference RM-9
103.5 watts into 8 ohms
102.9 watts into 4 ohms
96.2 watts into 2 ohms
If we want to extoll amplifiers that have constant power, the RM-9 is a mighty fine example. It also has an output impedance of 0.3 ohms and THD distortion less than .05% in the audio band.
Ralph asked us to take a look at a review of his MA-1 amplifier written by Soundstage which included measurements. Here is the link to the measurements so you know I'm not making this up:
http://www.soundstagemagazine.com/me...ere_ma1_mkii2/
First of all, the review states that the power output specification for the MA-1 is 140 watts into 8 ohms and 135 watts into 4 ohms with no distortion percentage given for these output figures. According to the measurements, here is the real truth:
8 watts at 4 ohms at 1% THD
20 watts at 8 ohms at 1% THD
90 watts at 16 ohms at 1% THD
So the difference in output power between 4 ohms and 16 ohms is over 9dB. I would hardly call that constant power. If you want 10% THD, here are the next measurements:
80 watts at 4 ohms
120 watts at 8 ohms
130 watts at 16 ohms
Obviously there is nothing approaching "constant power" in the MA-1 when rated at 1% THD which is the standard definition for clipping in most amplifier measurements I have read. In order for the MA-1 to come close to approaching the ideal Power Paradigm amplifier and his rated output power for the amp, you have to go with the 10% THD distortion numbers. There is still a difference in output power of 50 watts between 4 ohms and 16 ohms. The output impedance of this amp is also 10.5 ohms.
So if you are going to design and build amplifiers that have 10% THD at near their rated output power (and the MA-1 doesn't make the output power stated in the review at 10% THD), then that would explain why you would say something like this: "It is very easy to tell how an amplifier will sound using measurements based on the Power Paradigm as the measurements are made with regards to understanding and working with the rules of human hearing." Ralph also quotes the following in his paper: "In the 1960s, General Electric's conducted a variety of tests, confirming that amounts of barely hundredths of a percent distortion were not only audible but also irritating to the human ear (conversely, they also found that the ear is quite tolerant of lower ordered harmonic distortion)." So if barely hundredths of a percent distortion are audible and irritating, I wonder what GE would think about 10% THD even if 100% of the 10% THD was low-order?
The bottom line here is that if you buy into the Power Paradigm theory and you like low distortion as well, you best buy a well-designed tube amp with output transformers. The MA-1 does not make equal power from 4-16 ohms, the power increases as the impedance rises. Ideal speakers to mate with an amp like this are very efficient speakers with high impedance. 16 ohm speakers used to be quite common in the 1950s and early 1960s, but I'm pretty sure they are much less common today. That is why I made the original statement that "You are never going to have a flat, uncolored "presentation" from an amplifier with a high output impedance into the majority of all loudspeakers known to man whose impedance changes across the audio bandwidth." Notice I said the majority of loudspeakers on the market today (I didn't say "all speakers" which I was accused of and then in turn was accused of creating a strawman argument when there was none).
So who still believes that OTLs meet the Power Paradigm theory and will be flat and uncolored into anything outside of a resistor strapped to the output terminals on a test bench? No speaker to my knowledge has a pure impedance of 4, 8, or 16 ohms as I said before.
And if someone wants to take exception to what I said, make sure it's what I said and not what you changed it to be. This already happened once and I wasn't amused. Let’s have an open and honest discussion. If someone can clearly point out an error in what I said, I will gladly admit I'm wrong. Until then, I standby the original statement I made in the other thread that started this whole tiff off.
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