Who will survive? One last table til I die.

Raul- Would love to test it for three months. Everyone else uses their system as their reference point- what is YOUR reference point for your own personal state-of-the-art, zero feedback, solid state amp/pre/phono?

After all, I wouldn't want to start my testing with something less than the same equipment you have so as to be fair. Maybe you could let me know what speakers you have, too, to further reduce trial and error.

Regards
Jim

Raul, anyone who thinks that the location and order of harmonic distortion is "not matters", has no clue of what harmonic distortion is, nor how it affects a musical presentation. Please bone up on it, and try again.

Regarding the 1.8 ohm output impedance of my amplifier, I use 8 ohm speakers which provides a damping factor greater than 4, so it works as well for speaker control and frequency response as any SS amp with any kind of damping factor. Any damping factor greater than 4 is immaterial and makes no discernable difference in the amplifier's ability to control the speaker. The frequency response of my amp is totally unaffected by speaker reactance in my particular system, so it doesn't matter what Stereophile says about amps with 3 ohm output impedance and poorly designed highly reactive speakers. If you notice the Stereophile chart, the impedance peaks that are imposed on the very poor example they chose to use, are at the resonant freq.(F3) of the driver, and at the cabinet tuning point. In the case of my system, my frequency response starts above both of those points, and have no effect in my system. But since you are not a speaker designer(and apparently not an amp designer either) I wouldn't expect you to know about that, any more than you know about the subject we are discussing.

The "very high output impedance" as you put it, has no bearing at all on anything, until you connect a speaker to it. That is when the damping factor is defined, and not until then. If I attached a speaker with a 0.1 ohm load to a SS amp with a 0.05 ohm output impedance, then the damping factor of the SS amp would suck(with that speaker). If you actually knew anything about this parameter, then you would not make statements such as you do.

I actually think that you know very little about audio. You read a few things, and think you know what you are talking about. Your statements give you away.

By the way, we are all still waiting for you to reveal the contents of your "highly musical" solid state system that will be revealing of the "true music" that you think we all are lacking in our systems.

You know, not only are you seriously lacking in audio knowledge, but you are very abrasive, rude, and arrogant. You seem to think that it is ok to ignore anyone else's points, can never debate an opposing position with facts, and simply repeat your own flawed opinions, in the attempt to look important. This is really sad. I like to engage in vigorous audio debate, but I prefer to do so with someone who knows what he is talking about. Unfortunately, you do not.

I'd suggest quite a bit more study before engaging any serious audiophiles here again. You really do need it.

Dear Teres:****" Ultimately, there will never be such thing as a zero-feedback amplifying device, and this includes single-ended triodes (where the electron flow and the space charge are the feedback parameters working in conjunction with the grid-cathode voltage) and transistor emitter-follower configuration (where the flow of minority carriers is the feedback parameter). I agree that a zero-feedback amplifier would be great, but it's not achievable yet."***
Can you read this again?.

There are many amplifiers that don't use global feedback ( use local feddback )¨Krell, Levinson, FM Acoustics, Rowland, etc....

*****" You countered with a number of irrelevant facts (some of which were also wrong) but never came back with any justification for your position. "****

Justification? you can do it for your self: test a tube and a SS amplifier on the subject: in a scientific way and in subjective way, then you can have the answers. I don't have to probe anything for my self. It is almost imposible to do that by writing in this thread, you have to have " live experience ", is the only way. This is not a subject that we can arrange with " words ".

***" But my tolerance for those that impose their views on others is pretty thin."***

I don't try to impose anything, I only give my point of view : tube amplifiers are frequency equalizers.

Chris, if you really think that I'm wrong, why don't try to prove it. Till to now you don't do anything about. Only words that don't prove anything on that subject.
This is not a contest, it is not important who are right, the important issue is that all of us can learn about.
Regards and enjoy the music.
Raul.

Dear TWL:****" Raul, anyone who thinks that the location and order of harmonic distortion is "not matters", has no clue of what harmonic distortion is, nor how it affects a musical presentation. Please bone up on it, and try again."***

The subject that the 2nd harmonics are a " gentle " one, it don't say that there is no distortion. Right?

***"The frequency response of my amp is totally unaffected by speaker reactance in my particular system."****

Do you already measuring?

***"The "very high output impedance" as you put it, has no bearing at all on anything, until you connect a speaker to it."*** Yes, everybody knows that.
****" If you actually knew anything about this parameter, then you would not make statements such as you do."***

Which ones?

***" By the way, we are all still waiting for you to reveal the contents of your "highly musical" solid state system that will be revealing of the "true music" that you think we all are lacking in our systems. "***.

You really think that some " names " can tell you that?, come on you are a wise people.

***"You seem to think that it is ok to ignore anyone else's points.."****

I never ignore anyone else's points: that's the problem.
BTW, till now ( like Chris ) you are not prove nothing on the subjects.

Tom, again, this is not a contest it is not important who is right the important issue is that all of us in this forum can learn about. Now maybe you can feel good if I tell you that you are right and that you are the winner one, Ok: you are the winner and I'm " seriously lacking in audio knowledge ."
Regards and enjoy the music.
Raul.

Here is a very recent article "cut and pasted" from the Audioholics website regarding this very matter.

Damping Factor: Effects On System Response
Monday, August 30 2004

Damping Factor: Effects On System Response

Analysis
Several things are apparent from this table. First and foremost, any notion of severe overhang or extended "time amplitude envelopes) resulting from low damping factors simple does not exist. We see, at most, a doubling of decay time (this doubling is true no matter what criteria is selected for decay time). The figure we see here of 70 milliseconds is well over an order of magnitude lower than that suggested by one person, and this represents what I think we all agree is an absolute worst-case scenario of a damping factor of 1.

Secondly, the effects of this loss of damping on system frequency response is non-existent in most cases, and minimal in all but the worst case scenario. Using the criteria that 0.1 dB is the smallest audible peak, the data in the table suggests that any damping factor over 10 is going to result in inaudible differences between that and one equal to infinity. It's highly doubtful that a response peak of 1/3 dB is going to be identifiable reliably, thus extending the limit another factor of two lower to a damping factor of 5.

All this is well and good, but the argument suggesting that these minute changes may be audible suffers from even more fatal flaws. The differences that we see in figures up to the point where the damping factor is less than 10 are far less than the variations seen in normal driver-to-driver parameters in single-lot productions. Even those manufacturers who deliberately sort and match drivers are not likely to match a figure to better than 5%, and those numbers will swamp any differences in damping factor greater than 20.

Further, the performance of drivers and systems is dependent upon temperature, humidity and barometric pressure, and those environmental variables will introduce performance changes on the order of those presented by damping factors of 20 or less. And we have completely ignored the effects presented by the crossover and lead resistances, which will be a constant in any of these figures, and further diminish the effects of non-zero source resistance.

Frequency-Dependent Attenuation
The analysis thus far deals with one very specific and narrow aspect of the effects of non-zero source resistance: damping or the dissipation and control of energy stored in the mechanical resonance of loudspeakers. This is not to suggest that there is no effect due to amplifier output resistance.

Another mechanism that most certainly can have measurable and audible effects are response errors due to the frequency dependent impedance load presented by the speaker. The higher the output resistance of the source, the greater the magnitude of the response deviations. The attenuation can be approximated given the source resistance and impedance vs. frequency:

where is the gain or loss due to attenuation, is the amplifier source resistance, and is the frequency dependent loudspeaker impedance.

As a means of comparison, let’s reexamine the effects of non-zero source resistance on a typical speaker whose impedance varies from a low of 6W to a high of 40W .

Damping
factor
RG
GdB(MIN)
GdB(MAX)
GdB(ERROR)

¥
0 W
0 dB
0 dB
0 dB

2000
0.004
-0.006
-0.001
±0.003

1000
0.008
-0.012
-0.002
±0.005

500
0.016
-0.023
-0.003
±0.01

200
0.04
-0.058
-0.009
±0.025

100
0.08
-0.115
-0.017
±0.049

50
0.16
-0.229
-0.035
±0.098

20
0.4
-0.561
-0.086
±0.23

10
0.8
-1.087
-0.172
±0.46

5
1.6
-2.053
-0.341
±0.86

2
4
-4.437
-0.828
±1.8

1
8
-7.360
-1.584
±2.9


As before, the first column shows the nominal 8W damping factor, the second shows the corresponding output resistance of the amplifier. The second and third columns show the minimum and maximum attenuation due to the amplifier’s source resistance, and the last column illustrates the resulting deviation in the frequency response caused by the output resistance.

What can be seen from this analysis is that the frequency dependent attenuation due to the amplifier’s output resistance is more significant than the effects on system damping. More importantly, these effects should not be confused with damping effects, as they represent two different mechanisms.

However, these data do not support the assertion often made for the advantages of extremely high damping factors. Even given, again, the very conservative argument that ±0.1 dB deviation in frequency response is audible, that still suggests that damping factors in excess of 50 will not lead to audible improvements, all else being equal. And, as before, these deviations must be considered in the context of normal response variations due to manufacturing tolerances and environmental changes.

Conclusions
There may be audible differences that are caused by non-zero source resistance. However, this analysis and any mode of measurement and listening demonstrates conclusively that it is not due to the changes in damping the motion of the cone at the point where it's at it's most uncontrolled: system resonances. Even considering the substantially larger response variations resulting from the non-flat impedance vs. frequency function of most loudspeakers, the magnitude of the problem simply is not what is claimed.
End

As you can see from these calclulations, a damping factor of 5(1.6ohms/8ohm spkr) provides 0.86db variation in frequency response as a maximum. This falls well within a +/-1db spec. It is inside the +/- tolerance of any loudspeaker, and certainly far inside the tolerances of any listening room. Other factors in the listening system/room will far outweigh this factor, thus making it insignificant in magnitude, even in a low damping case such as 5.

How anyone can make a case that tube amps are "equalizers" from this performance data, is beyond me. I certainly hope that this puts this matter to rest.