So, unless I proof it to you, you do not belief that there exist amps that have no audible difference between input and output? Even if I haven't proven it, you still may belief that it is true of course. Or maybe you are undecided so far? (An entirely logical position).
But do you at least belief that if they would exist, that would be an 'ideal' amplifier as far as faithfull reproduction is concerned?
jan didden
Jan,
Unlike others I do not reject anecdotal evidence.
So, if you told me that you had used a given method (preferably described) to compare input and out of a given (preferably identified) Amplifier and found no difference, I would see no reason to doubt your statement.
Even if you told me your maiden aunt's third cousin had done such a test and you therefore concluded the contention to be true, I would not doubt as such your statement, though I may downgrade the potential for accuracy from tripple A to single C...
However, if you make a definite and positive statement, such as "the best ones [amplifiers] out there have no audible difference between their input and output signals." without presenting any evidence, without even claiming to have done suitable experiments, forgive me for doubting that your statement was based in fact.
Thus your contention that "
I have little use for the religious mode of the human mind which relies, as Saul of Tharsus so charmingly put it "the substance of things hoped for, the evidence of things not seen."
It has been my personal experience so far that no such amplifiers exist. So I am neither believer, nor disbeliever, nor undecided.
I am decided that until I receive better evidence than I had so far I hold the existence of such an amplifier as theoretically entirely possible (just as the Higgs Boson is theoretically possible), yet unproven as of now.
If it was coupled with loudspeakers that also where 'ideal' in the sense of your original contention in my living room and when reproducing recordings made "ideal' microphones and electronics, etc., most certainly.
Sadly, such 'ideal' devices or entities have so far failed to materialise in the realm of human experience (not just in audio) and at some point in time in the past where considered to exist only in the "mind of g*d" (whatever this may signify). As to many Humans the concept of a supranatural or superior being is depreciated we may say that such ideal entities only exist in the realm of Philosophy and Science Fiction novels.
Should, against my better judgement such ideal entities of any kind materialise in the realm of human experience (even if not audio related) do be sure to alert me...
Ciao T
Unlike others I do not reject anecdotal evidence.
So, if you told me that you had used a given method (preferably described) to compare input and out of a given (preferably identified) Amplifier and found no difference, I would see no reason to doubt your statement.
Even if you told me your maiden aunt's third cousin had done such a test and you therefore concluded the contention to be true, I would not doubt as such your statement, though I may downgrade the potential for accuracy from tripple A to single C...
However, if you make a definite and positive statement, such as "the best ones [amplifiers] out there have no audible difference between their input and output signals." without presenting any evidence, without even claiming to have done suitable experiments, forgive me for doubting that your statement was based in fact.
Thus your contention that "
I have little use for the religious mode of the human mind which relies, as Saul of Tharsus so charmingly put it "the substance of things hoped for, the evidence of things not seen."
It has been my personal experience so far that no such amplifiers exist. So I am neither believer, nor disbeliever, nor undecided.
I am decided that until I receive better evidence than I had so far I hold the existence of such an amplifier as theoretically entirely possible (just as the Higgs Boson is theoretically possible), yet unproven as of now.
If it was coupled with loudspeakers that also where 'ideal' in the sense of your original contention in my living room and when reproducing recordings made "ideal' microphones and electronics, etc., most certainly.
Sadly, such 'ideal' devices or entities have so far failed to materialise in the realm of human experience (not just in audio) and at some point in time in the past where considered to exist only in the "mind of g*d" (whatever this may signify). As to many Humans the concept of a supranatural or superior being is depreciated we may say that such ideal entities only exist in the realm of Philosophy and Science Fiction novels.
Should, against my better judgement such ideal entities of any kind materialise in the realm of human experience (even if not audio related) do be sure to alert me...
Ciao T
Ok, but which tube amp with no GNFB is the best you've ever heard ? It can be one or several if there's no clear winner.
Thanks, an opinion supported by arguments - that's exactly what I was hoping for !
I tried searching for "The Vacuum State KT88" but without success.
Can you point me to a link about it ?
Jan, I'm not as shy as Thorsten, so I'll say "Yes". But I would want to see the amps measured on the load they will be driving and see FR, crosstalk, a good spectrum analysis at least every octave from 20Hz-12Khz and some IM measurements as well. Impulse would also be nice to see. If the inputs and outputs look alike on with all that, I'd be super happy.
But I'm willing to bet that 2 amps can sound almost exactly alike and still fail some of the above tests. Some stuff just isn't that important to the ear. I wish I knew better what.
I don't think that a simple difference test will tell us much, either.
Just look at the results of a SINGLE capacitor, compared to a higher quality capacitor, such as a 1uF Teflon in the test that Walt Jung and I did, back in 1985 or so.
A single Mylar cap could give you a -70dB residual, even with compensation for inductance, resistive ESR, and value differences. How can a complete power amp, especially with input coupling caps do any better?
Just look at the results of a SINGLE capacitor, compared to a higher quality capacitor, such as a 1uF Teflon in the test that Walt Jung and I did, back in 1985 or so.
A single Mylar cap could give you a -70dB residual, even with compensation for inductance, resistive ESR, and value differences. How can a complete power amp, especially with input coupling caps do any better?
In this newsletter you find the Vacuum State amp i am talking about. Actually the name is DPA150 but i am bad in remembering numbers. For me it is simply the Allen Wright KT88.
http://www.vacuumstate.com/fileupload/Newsletter_August_2010_Comp.pdf
http://www.vacuumstate.com/fileupload/Newsletter_August_2010_Comp.pdf
Vladimir, there's not a lot with direct google search. Is this it? O.N. Ageev?
"ageev's theorem" - Google Search
I believe it is a red herring - "pure math" results do not have to reflect real world hardware, signal limits - no digital music recording will come close to the conditions, and you may note his formulation doesn't include amplitude limitation of the sum of infinite arbitrary bandwidth limited sines
a known issue that can produce "higher than expected" peaks in a amplitude, bandwidth limited digital waveform is illustrated by the "over 0 dB fs problem"
illustration from: Over The Top?
shows what you can get by deliberate construction, applying the realistic limit that real DAC hardware will amplitude limit so the "run up" to the "over" has to be both amplitude and bandwidth limited
by "eyeball" that isn't an "infinite" slew rate - 2x maybe?
I believe I heard Bob Stuart claim better oversampling audio DACs do use saturation arithmetic in the digital filters and include 3 dB over range for the more common hard clipping of simpler music signals
and some DAW sw is "aware" of the problem and provide tools to view reconstructed signal to avoid the problem in the mastering
Mastering audio: the art and the science - Google Books
a known issue that can produce "higher than expected" peaks in a amplitude, bandwidth limited digital waveform is illustrated by the "over 0 dB fs problem"
illustration from: Over The Top?
shows what you can get by deliberate construction, applying the realistic limit that real DAC hardware will amplitude limit so the "run up" to the "over" has to be both amplitude and bandwidth limited
by "eyeball" that isn't an "infinite" slew rate - 2x maybe?
I believe I heard Bob Stuart claim better oversampling audio DACs do use saturation arithmetic in the digital filters and include 3 dB over range for the more common hard clipping of simpler music signals
and some DAW sw is "aware" of the problem and provide tools to view reconstructed signal to avoid the problem in the mastering
Mastering audio: the art and the science - Google Books
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As statisticly improbable as it is a +crest factor event followed by a -one would be the maximum sample to sample delta one could observe.
Slew Rate
Scott, you are stating the limitations of digital audio sources...
...let's talk about a stylus hitting a rock in an LP groove, as opposed to merely playing the bandwidth-limited music that was recorded on it. Now THAT is some slew rate! And damn it; I want that KAPOW!!! played back with perfect fidelity!!!
Seriously, the actual peak dynamic range and bandwidth of a good LP and playback system far exceeds that of a 16-bit CD. The LP system is much less accurate, and has higher broad-band noise, but has higher resolution and dynamic range. The three versions of Telarc's 1812 Overture demonstrate this beautifully. The cannon shots on the original LP version can send just about any stylus out of the groove onto the label. The compressed LP re-release has 20dB less peak level on the cannons in response to customer complaints. The CD is even more compressed to fit the limited dynamic range of that medium.
You could make a compelling argument that this is an absurd example, yet the limitations of the media stand apart from the argument.
Howie
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
1st on the internet
p.s. on my Tannoy dual-concentric monitors listening extreme near-field I cannot hear that sound on the Jethro Tull song. With the Stax headphones it is low-level, but clear: a "ploik!" sound.
Scott, you are stating the limitations of digital audio sources...
...let's talk about a stylus hitting a rock in an LP groove, as opposed to merely playing the bandwidth-limited music that was recorded on it. Now THAT is some slew rate! And damn it; I want that KAPOW!!! played back with perfect fidelity!!!Seriously, the actual peak dynamic range and bandwidth of a good LP and playback system far exceeds that of a 16-bit CD. The LP system is much less accurate, and has higher broad-band noise, but has higher resolution and dynamic range. The three versions of Telarc's 1812 Overture demonstrate this beautifully. The cannon shots on the original LP version can send just about any stylus out of the groove onto the label. The compressed LP re-release has 20dB less peak level on the cannons in response to customer complaints. The CD is even more compressed to fit the limited dynamic range of that medium.
You could make a compelling argument that this is an absurd example, yet the limitations of the media stand apart from the argument.
Howie
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
1st on the internet
p.s. on my Tannoy dual-concentric monitors listening extreme near-field I cannot hear that sound on the Jethro Tull song. With the Stax headphones it is low-level, but clear: a "ploik!" sound.
This one is close to the subject, although the site content is very badly translated into english, probably by a software translator
Dmitry Vassilyevich Ageev
A subtraction from this site:
The theorem is proved that the arbitrary function of time with a restricted spectrum can have sites (segments) of restricted duration, on which one it can vary as much as fast. This on the first view the theorem, contradicting to common sense, was met " in bayonets ", when was reported by the professor Ageev on All-Union session by him. Now it is used at construction of digital sound systems.
In 1955, Mr.. D. V. Ageev introduced and scientifically substantiated, the basic concepts of spectral analysis. They introduced a new concept - an active band of the frequency spectrum function of time and given way to calculate. D. V. Ageev proceeded from the, . that at any given time span that the main contribution to the formation of functions makes it not the whole spectrum, . but only some "active" part of, . reflected in the well-known in our country monograph "The spectra and analysis of Academician A,
. A. Kharkevich. The new concept was suitable for the analysis of systems that process signals, the instantaneous frequency of which varies slowly enough. Portfolio D. V. Ageyeva in this direction were associated with the work of other scientists: Academician A. A. Kharkevich, as well as American scholars P. Fano and K. Page, who introduced the concept of "instantaneous spectrum", defined as the spectrum of the final segment of the process immediately preceding the given moment.
In 1957. D. V. Ageev proved a remarkable theorem, which can reasonably be attributed words of the famous German writer with. Zweig, "truth is beautiful, seemingly implausible". The theorem reads as follows: Suppose that the interval (t1, t2) given any continuous function U (t) and arbitrary frequency F. Then we can construct a function whose spectrum does not contain frequencies higher than F, arbitrarily close (in the mean-square sense) to U (t) in the interval (t1, t2).
. For example, in the time interval of duration 1 s, you can specify a function that changes its sign a million times, and continue it beyond this period of time so that the spectral width of the extended function does not exceed the value of, say, 0.1 Hz
. On this, at first sight paradoxical theorem in detail wrote in his excellent history book "Signals, noise, errors ... (M.: "Communication", 1978) A prominent national scientists. M. Fink. In particular, he remembers that after the D. V. Ageev in 1957,. the All-Union Scientific Session of the Scientific-Technical Society of. A. S. Popov explained that theorem, most listeners did not believe in its fairness and even try to find errors in the presented proof. Theorem Ageyeva significantly expanded representation of engineers of the laws governing the formation of the spectrum of signals and has found practical application in creating digital sound systems.
In 1939, Mr.. American engineer J. G. Chaffee invented demodulator is a frequency-modulated signals (FM) with feedback on the frequency (demodulator PSD). As is known, the frequency modulation has a threshold. This means, . that for the FM signal demodulator can specify a threshold for the signal: if the received signal has a lower (relative to the threshold) level, . a reception is virtually impossible because of the sharp decline in the quality of reception,
. Experiments showed that the demodulator has a high purity as compared to conventional FM demodulator lower threshold, t. e. it is more resistant to interference. Prior studies undertaken in the STI D. V. Ageev and his pupil I. G. Rodionov (1955), theoretical studies of many complex issues relating to the demodulator PSD, including its sustainability and design, not been conducted. These scientists first developed the theory of tracking receiving FM signals, published in the Proceedings of the STI, but in 1958. - In the monograph "FM radio reception with the servo tuning". Tracking demodulators FM signals are widely used only in the mid 60-ies. in satellite and tropospheric communication systems, for which most pressing problem was to reduce the energy potential of communication lines.
In the results presented in the monograph D. V. Ageyeva and I. G. Rodionova, based later on the witness receive FM signals, the study of large domestic specialists L. YA. Kantor A. S. Winitzki, SW. A. Afanasyev et al
In addition to the significant contribution to the theory of communication, D. V. Ageev with pupils achieved notable results in the field of radio engineering, which is reflected in the book D. V. Ageyeva and C. S. Zelmanova "Fundamentals of the theory of resonance in linear systems". In addition, together with his pupil A. V. Kovich Ageev introduced a new concept of "dynamic resonance - resonance in the oscillator circuit with nonlinear resistance and depends on the amplitude of the fluctuations in its frequency, the phenomenon of resonance in linear systems with variable parameters, . and also developed methods for assessing distortions, . arising during the passage of FM signals through different paths connected,
. Since 1951. D. V. Ageev s. V. Malanova, K. P. Sexually etc.. developed a general theory of GPI amplification of radio signals, which is based on a large number of methods for improving the energy efficiency of amplifying devices. This promoted a way of improving efficiency (for. n. d.) amplifier using pulse-width modulation (PWM), proposed in 1932. major Soviet academician A radio personnel. L. Mintz and Professor C. V. Persson. In accordance with this method to be increased tone in the modulator is converted into a sequence of pulses of constant amplitude with double-sided PWM. The frequency of the pulse sequence substantially higher than the frequency in. A. Nyquist equal 2FB, (FB - the upper frequency spectrum of the amplified signal). Pulses of low power with PWM control switching current flowing through the powerful amplifier tubes. At the load of the amplifier is allocated amplified sound. Since the spectrum of double-sided PWM audio frequency spectral components have significant intensity, then to. n. d. amplifier operating on this principle, is close to 100%. In conventional amplifiers to the same. n. d. is only about 20%.
D. V. Ageev lived long and fruitful life, full of intense creative labor. He and his many disciples were made first-class work in many areas of radio engineering. These results influenced the research carried out later than other domestic scientists, and included in the book, which taught thousands of professionals.
Yet due influence on the development of world science research results D. V. Ageyeva not had since been published on time and in less accessible publications, and thus became known only to a limited circle of specialists. Very rarely they were published in leading professional journals abroad. Unfortunately, he E. V. Ageev paid insufficient attention to the publications of his works.
. Another important reason for the influence of domestic science in the world was not enough, is that for decades it was virtually isolated from the processes of development of world science
. Domestic scholars have generally been denied the opportunity to participate in international scientific conferences, to communicate freely with their foreign colleagues and published in foreign scientific journals. In addition, severely limited the ability of our scientists and strict rules of publication of scientific results in the open press. State policy, leading to a closed society that does not allow the national scientific achievements become part of the global science and, of course, reduces the overall cultural level of the nation. This is the beginning of XX century, wrote convincingly a prominent Russian physicist, H. A. Minds, whose words ring true today: "The political significance of the nation can be strong only under the condition that its cultural level corresponds to its weight lifting. In our time, weapons, courage is not the only factors that ensure success in the struggle of peoples for their development and existence .... If we turn to our country, you realize that we, unfortunately, still largely adopt and borrow and invest very little in the cultural life of mankind. "
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seriously you should look at noise shaped dithered 16/44 CD compared with say 100 cm/s of a really good cart at mid frequency - I think CD still has the LP beat handily - Loudness Wars compression isn't happening due to the "limited dynamic range" of CD as a media
as I read it extended high frequency response beyond 20 KHz (at reduced amplitude, outer grooves only, with high tracking/tracing distortion...) is the only hard spec that vinyl playback can clearly claim superior numbers on
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