Got Distortion?

[pauln]

Distortion!<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

dis·tor·tion (di-stôr'sh?n)
n.

The act or an instance of distorting.

The condition of being distorted.

An undesired change in the waveform of a signal.

A consequence of such a change, especially a lack of fidelity in reception or reproduction.

A statement that twists fact; a misrepresentation.

A change in the shape of an image resulting from imperfections in an optical system, such as a lens.

Electronics

An undesired change in the waveform of a signal.

A consequence of such a change, especially a lack of fidelity in reception or reproduction.

Psychology The modification of unconscious impulses into forms acceptable by conscious or dreaming perception.

With so many threads appearing about SETs, it's high time to have a clearifying analysis, discussion, and maybe a little feuding about distortion. Using the generic term distortion is highly misleading and may lead to misunderstanding. Here are some different types - I'll make names (some of which may be correct) until someone straightens it out. If I am mistaken in my definitions, PLEASE indicate what I left out and got wrong, we are here to learn, and occasionally feud, right?

CLIPPING - that is when the curvy extremes of the wave form begin to be limited so that they appear to flatten like little mesas (and upside down mesas). This happens when the available power of the amp is maxed out but the wave form keeps trying to be bigger. The extreme case is the approach to square waves. What is important here is that the composite frequencies that comprise a square wave have additional higher frequency components compared to the more sine like wave signals. The higher frequencies don't appear and cause the flattening - its the other way around. Clipping sounds bad.

HARMONIC DISTORTION - clipping is an advanced form of this, but it may be caused in other ways. Typically, the nature of the amp topology/circuitry determines how and what harmonics are progressively added to the signal as more power is demanded. Again, in these cases it is not the additional frequencies that cause the modification to the wave, but the other way around. For example, the emergence of the second harmonic in a triode a la SET is a result of the minor imbalance in size between the upper and lower parts of the wave. This shape of wave may be decomposed to represent the presence of an additional frequency component an octave above the original signal, but again - it is not the case that the tube sings an additional tone that shapes the wave - the wave shape just is, but can be deconstructed into frequencies as if there was another tone emerging.

AMPLITUDE DISTORTION - a non-linearity in the amp response, usually a compression of the signal on peaks, but not clipping.

FREQUENCY DISTORTION - this is a deviation from 'flat response' as in an amp that can't play real low or real high frequencies as well as the middle. In some tube amps (and SETs) this can be caused by the operation of the output transformer.

FREQUENCY DISTORTION type II - this is the true generation of additional tones by the amp (but not feedback from instability). Called the Tones of Tartinni after the work of said fellow many years back, its like this - when two different frequencies are simultaneous, there are two additional tones that comprise the addition and the difference of these frequencies. For example. If you have 1000Hz and 1200Hz at the same time, you also have 2200Hz and 200Hz as well, although these are much lower in level. As the number of tones is increased the permutations and combinations increase rapidly. An amp which is prone to this will sound 'off' and lousy. These additional tones are somewhat like the upper and lower side bands of signal theory. Oh, and a single note that starts and stops repeatedly also has sidebands based on how fast the notes are played.

INTERMODULATION - I think this may be limited to mechanical systems (styli and speakers) in which two frequencies are superimposed in the same element so that the higher frequency is alternately raised and lowered (a la Doppler shift) by the lower frequency. This is minimized by low excursion (Klipsch) and emphasized by high excursion. This sounds pretty bad lending a strident ugly character to the sound. Imagine a bass playing low and an oboe playing high through the same speaker cone... the bass will wiggle the paper back and forth - the very same paper on which the oboe notes are playing... some don't believe in this kind of distortion because they claim that the Doppler effect in the cone is opposite and equal to the Doppler effect within the microphone element that caught both the original sounds at the recording time. That could be true, but how much music these days is captured that way... most I think is superimposed in the studio as separate signals, so I guess it depends.

NEGATIVE FEEDBACK - well, for we SET folks this is considered something to avoid, but generally in the amp world it is used to varying good effect in some designs. The way it works is that a sample of the output signal is compared to the input signal using a circuit device called a comparator. The comparator subtracts the output from the input so that any difference between the two (distortion) is provided as an 'error signal'. A small amount of this error signal is inserted back into the input signal as a reverse signal in order to provide a degree of correction. This correction for an unvarying constant signal can be extremely effective in correcting any variances that occur to the input signal on its way to becoming the output signal. The sort of philosophical issue with SET folks and some others is that the feedback loop is not instantaneous but slightly delayed in its effect, which diminishes its operation with changing dynamic music signals, and might even mis-correct because of this delay. Also, the NFB can respond to the back signal from the speakers, and this signal having been through the networks may evoke NFB correction attempts to supposed error signals that have no real correspondence with the actual sound.

CROSSOVER DISTORTION - this is the misalignment of the wave form as it passes from positive to negative in amps that use separate elements to drive the upper and lower parts of the wave. In these amps, the signal is sort of passed back and forth between the elements and both parts get combined to drive the speakers, or in push pull tube, combined in the output transformer windings. Since the slight misalignment is fairly constant it makes up a lesser and lesser portion of the signal as the wave gets bigger and bigger - this is why some amps don't sound so good at real low levels but seem to clean up as you turn up the volume. Since the musical wave form being passed back and forth crosses the zero level somewhat arbitrarily with complex music signals, the crossover distortion has no harmonic relation to the sound and tends to sound like low level noise. (White noise/static)

TUBE / SS DISTORTION - lots has been done on the different distortions of these elements. The triodes tend to have second harmonic distortion which is difficult to hear because it is highly frequency compatible with the original signal. Tetrodes and pentodes have higher harmonic distortions, but these tend to be even harmonics which are somewhat frequency compatible. The SS elements tend to have the odd distortion harmonics which tend to not be frequency compatible with the original signal. This makes them much easier to detect, especially the higher odd orders which lend an edgy sound because they are not harmonically related to the original frequencies. This is why a SET can play at a measured couple of percent distortion (predominately the second) and it sounds clean and clear, while a fraction of a percent in some SS is hard on the ears. The other thing is how quickly the harmonic distortions come into play... Triodes do this very gracefully by first producing the second, then addition higher evens in ascending order. SS tend to bring up the higher harmonics (odd ones) more suddenly, and Op Amps engage them almost all at the same time when pressed to their limit. This is why headroom requirements for SS for good sound tend to need to be pretty robust, whereas tubes and SETs in particular can get away with much less calculated headroom but still sound loud with lots of apparent reserve capacity. This is part of the effect that makes some claim that tube watts are louder than SS watts - the tubes can be driven past their spec without losing their good sound. The SS can produce the higher odd harmonics which serve as loudness detectors at comparable levels (that is the detection or perception of a signal as loud occurs faster/earlier for the SS compared to the tubes).

And best of all, the blue text is back, baby!

Pauln

[NOSValves]

<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

With so many threads appearing about SETs, it's high time to have a clearifying analysis, discussion, and maybe a little feuding about distortion. Using the generic term distortion is highly misleading and may lead to misunderstanding. Here are some different types - I'll make names (some of which may be correct) until someone straightens it out. If I am mistaken in my definitions, PLEASE indicate what I left out and got wrong, we are here to learn, and occasionally feud, right?

CLIPPING - that is when the curvy extremes of the wave form begin to be limited so that they appear to flatten like little mesas (and upside down mesas). This happens when the available power of the amp is maxed out but the wave form keeps trying to be bigger. The extreme case is the approach to square waves. What is important here is that the composite frequencies that comprise a square wave have additional higher frequency components compared to the more sine like wave signals. The higher frequencies don't appear and cause the flattening - its the other way around. Clipping sounds bad.

HARMONIC DISTORTION - clipping is an advanced form of this, but it may be caused in other ways. Typically, the nature of the amp topology/circuitry determines how and what harmonics are progressively added to the signal as more power is demanded. Again, in these cases it is not the additional frequencies that cause the modification to the wave, but the other way around. For example, the emergence of the second harmonic in a triode a la SET is a result of the minor imbalance in size between the upper and lower parts of the wave. This shape of wave may be decomposed to represent the presence of an additional frequency component an octave above the original signal, but again - it is not the case that the tube sings an additional tone that shapes the wave - the wave shape just is, but can be deconstructed into frequencies as if there was another tone emerging.

AMPLITUDE DISTORTION - a non-linearity in the amp response, usually a compression of the signal on peaks, but not clipping.

FREQUENCY DISTORTION - this is a deviation from 'flat response' as in an amp that can't play real low or real high frequencies as well as the middle. In some tube amps (and SETs) this can be caused by the operation of the output transformer.

FREQUENCY DISTORTION type II - this is the true generation of additional tones by the amp (but not feedback from instability). Called the Tones of Tartinni after the work of said fellow many years back, its like this - when two different frequencies are simultaneous, there are two additional tones that comprise the addition and the difference of these frequencies. For example. If you have 1000Hz and 1200Hz at the same time, you also have 2200Hz and 200Hz as well, although these are much lower in level. As the number of tones is increased the permutations and combinations increase rapidly. An amp which is prone to this will sound 'off' and lousy. These additional tones are somewhat like the upper and lower side bands of signal theory. Oh, and a single note that starts and stops repeatedly also has sidebands based on how fast the notes are played.

INTERMODULATION - I think this may be limited to mechanical systems (styli and speakers) in which two frequencies are superimposed in the same element so that the higher frequency is alternately raised and lowered (a la Doppler shift) by the lower frequency. This is minimized by low excursion (Klipsch) and emphasized by high excursion. This sounds pretty bad lending a strident ugly character to the sound. Imagine a bass playing low and an oboe playing high through the same speaker cone... the bass will wiggle the paper back and forth - the very same paper on which the oboe notes are playing... some don't believe in this kind of distortion because they claim that the Doppler effect in the cone is opposite and equal to the Doppler effect within the microphone element that caught both the original sounds at the recording time. That could be true, but how much music these days is captured that way... most I think is superimposed in the studio as separate signals, so I guess it depends.

NEGATIVE FEEDBACK - well, for we SET folks this is considered something to avoid, but generally in the amp world it is used to varying good effect in some designs. The way it works is that a sample of the output signal is compared to the input signal using a circuit device called a comparator. The comparator subtracts the output from the input so that any difference between the two (distortion) is provided as an 'error signal'. A small amount of this error signal is inserted back into the input signal as a reverse signal in order to provide a degree of correction. This correction for an unvarying constant signal can be extremely effective in correcting any variances that occur to the input signal on its way to becoming the output signal. The sort of philosophical issue with SET folks and some others is that the feedback loop is not instantaneous but slightly delayed in its effect, which diminishes its operation with changing dynamic music signals, and might even mis-correct because of this delay. Also, the NFB can respond to the back signal from the speakers, and this signal having been through the networks may evoke NFB correction attempts to supposed error signals that have no real correspondence with the actual sound.

CROSSOVER DISTORTION - this is the misalignment of the wave form as it passes from positive to negative in amps that use separate elements to drive the upper and lower parts of the wave. In these amps, the signal is sort of passed back and forth between the elements and both parts get combined to drive the speakers, or in push pull tube, combined in the output transformer windings. Since the slight misalignment is fairly constant it makes up a lesser and lesser portion of the signal as the wave gets bigger and bigger - this is why some amps don't sound so good at real low levels but seem to clean up as you turn up the volume. Since the musical wave form being passed back and forth crosses the zero level somewhat arbitrarily with complex music signals, the crossover distortion has no harmonic relation to the sound and tends to sound like low level noise. (White noise/static)

TUBE / SS DISTORTION - lots has been done on the different distortions of these elements. The triodes tend to have second harmonic distortion which is difficult to hear because it is highly frequency compatible with the original signal. Tetrodes and pentodes have higher harmonic distortions, but these tend to be even harmonics which are somewhat frequency compatible. The SS elements tend to have the odd distortion harmonics which tend to not be frequency compatible with the original signal. This makes them much easier to detect, especially the higher odd orders which lend an edgy sound because they are not harmonically related to the original frequencies. This is why a SET can play at a measured couple of percent distortion (predominately the second) and it sounds clean and clear, while a fraction of a percent in some SS is hard on the ears. The other thing is how quickly the harmonic distortions come into play... Triodes do this very gracefully by first producing the second, then addition higher evens in ascending order. SS tend to bring up the higher harmonics (odd ones) more suddenly, and Op Amps engage them almost all at the same time when pressed to their limit. This is why headroom requirements for SS for good sound tend to need to be pretty robust, whereas tubes and SETs in particular can get away with much less calculated headroom but still sound loud with lots of apparent reserve capacity. This is part of the effect that makes some claim that tube watts are louder than SS watts - the tubes can be driven past their spec without losing their good sound. The SS can produce the higher odd harmonics which serve as loudness detectors at comparable levels (that is the detection or perception of a signal as loud occurs faster/earlier for the SS compared to the tubes).

And best of all, the blue text is back, baby!

Pauln

Yyyyaaaaawwwwwwnnnnnn obviously written by an avid SET fan. Why wouldn't you include who the author is? or was it you? If so I hit the nail on the head LOL!! I for one have become completely tired of this subject.

[pauln]

I wrote every word of it, and yes I am a SET listener now days. I would like to know how other folks view this whole distortion topic. I tried quite hard to lay it out as I understand it and remain fair so as to keep it open to all others and their thoughts. I'm especially interested in knowing if my ideas are incorrect or incomplete... what do you think about it?

[Duke Spinner]

[Deang]

The following came from: http://www.vac-amps.com/no_se_amps.html

Some audiophiles, drawing on single-ended experience, will assume that a triode amplifier produces vast amounts of second harmonic distortion. Interestingly, the triode vacuum tube in and of itself is the most linear amplifying device yet devised. It produces the least distortion, and that distortion is predominately second harmonic, which is relative musical in sound. By contrast, pentodes produce greater distortion, and the third harmonic tends to dominate. A transistor generally looks like a very bad pentode.

To state the obvious, a single-ended circuit must be Class A1 or A2. A push-pull amplifier may be Class A1, A2, AB1, AB2, B1, or B2. Class A indicates that each output tube handles the full cycle of the audio signal, while AB and B allow some of the devices to cut-off during a portion of the cycle. Subscript "1" indicates that no grid current is drawn by the output tube, while subscript "2" indicates that the output stage enters the grid current region of operation. In the grid current region, the impedance presented to the driver stage is abruptly lower, and drive power is required, not just drive voltage. The grid current region tends to be rather non-linear, and most designers will avoid it. Single-ended and push-pull circuits may be built with triodes, beam power tubes, pentodes, or the latter two in ultra-linear ("partial triode") mode.

In a Class A push-pull circuit, there is a natural cancellation of even-order harmonic distortion products. The cancellation is not complete, of course, but it would be unusual to see large amounts of second harmonic distortion from a push-pull circuit (Radiotron Designer's Handbook, 4th ed., 1954, page 571).

Applying this to the Renaissance Series, the circuit is strictly Class A1, and is push-pull with the exception of the very first 6SN7 triode, which operates under conservative conditions and is thus relatively free from distortion (Moir, High Quality Sound Reproduction, page 264). This single phase splitter triode is interesting, in that the very same electron current flow creates the antiphase push and pull signals, which, given equal impedances within the amp (they are), match exactly. As such, the signal is not being Cuisinart-ed as with most phase invertors, an objection voiced by many single-end advocates.

Note that a push-pull circuit has no significant ability to cancel odd-order distortion products. If low distortion performance is required, one must avoid the generation of odd-order harmonics in the first place. A good triode tube meets this requirement.

Three difficulties are encountered in the design of a single-ended tube power circuit. Firstly, there is no mechanism to naturally cancel even-order harmonic distortions. Secondly, significant new distortions may arise in the output transformer. Thirdly, available power output is greatly limited in a single-ended design, such that it will be spending more of its time in overload for a given volume level.

For background, recall the old children's science project in which a length of wire is coiled around a nail and then connected to a battery. The DC current from the battery flows through the coil to create an electro-magnet. The primary winding in a single-ended output transformer is similar to this, and also creates an electro-magnet. The full DC current for the output tube(s) flows through the transformer primary and strongly magnetizes the core of the transformer. Thus, much of the core's ability to couple the audio signal is used up by the non-audio DC current, and causes the core to saturate asymmetrically with audio signals (Radiotron, page 247). Even below saturation, this DC bias increases distortion, especially at low frequencies (Moir, page 283; Radiotron, page 217). Adding parallel output tubes for more power directly increases the DC magnetization current, thus exacerbates the distortion problem, and requires that more primary inductance be designed into the output transformer.

To deal with this, a less saturable core alloy is often used, but this causes poorer coupling of the audio signal (Radiotron page 207). Alternately, a large "air gap" may be introduced into the transformer geometry, which again causes aberrations in coupling. In most cases, a greater amount of core material is used, which may in turn increase some low level (B-H) non-linearities. The final result is either a higher degree of distortion (all harmonics with the second dominating, increasing with decreasing frequency), a measurably peaked frequency response, or both.

Radiotron summarizes, "...fairly high distortion has the effect of apparently accentuating the bass...It should be emphasized that this is not the same as true bass, and does not constitute fidelity" (Radiotron, page 616) and notes that this trick was used "In small [radio] receivers, in which the loudspeaker is sometimes incapable of reproducing the bass" (Radiotron, page 676).

Since the distortion in the single-ended transformer is asymmetrical, a system based around this type of amplifier might be more sensitive to absolute polarity.

In a fairly complete summary of single ended output transformers, Duncan Kelly concludes, "Direct current is thoroughly undesirable in audio transformers" (Transformer Distortion, Audio, March 1959, page 44).

These problems do not arise in a push-pull amplifier, in which the primary halves are oriented in opposing DC directions (Moir, pages 282-284; Radiotron page 207). The DC magnetization force is thus canceled and is not an issue unless the push and pull output tubes are adjusted to draw different currents. Any imbalance in DC idle current will lead to greater distortion at low frequencies, just as in a single-ended design (Audio Cyclopedia, 2nd Ed., 1969, pages 1449-1450). The Renaissance Series maintain a high degree of DC balance due to the self-correcting nature of 300Bs under individual cathode bias.

Please note that the distinction between push-pull and single-ended Class A triode designs does not stem from the tube itself, but from the natural distortion cancellation in push-pull and from the transformer problems in single-ended. Since a single-ended transistor amplifier may omit the output transformer, it may display yet another set of characteristics.

How the ear deals with the characteristics of a single-ended tube power amplifier is quite interesting. The human ear is a non-linear encoder of information, and excess second harmonic blends in to form the impression of an additional sub-harmonic. This technique was deliberately employed in small radios in the 1940's to create a richer sound, then referred to as "synthetic bass" (Radiotron pages 616, 676). The Radiotron Designer's Handbook notes, "It should be emphasized that this is not the same as true bass, and does not constitute fidelity."

The frequency response errors of some single-ended tube amplifiers tends to create a high frequency boost and a low frequency cut, in one case approximately +/- 3 dB (Stereophile, Jan. 1994, page 108). The subjective effect of the low frequency loss might perhaps be partially offset by the second harmonic distortion.

Earlier I noted that the triode could be the most linear of amplifying devices. I left this small hedge because it is possible to build a rather flawed triode as well. The 300B is a highly linear tube. In fact, the high voltage supplies in the Renaissance Seventy/Seventy do not vary by one volt over the range from idle to clipping, indicating an absence of rectification effect (distortion). The type 845 is also a very linear tube, although requiring higher drive voltages, which can result in more overall distortion. The 211 is a bit more problematic; it requires a large drive voltage and drive power to deliver full output. In such operation (Class A2) the tube is said to "draw grid current." Entering the grid current region may cause a sort of crossover behavior as the driver stage is abruptly called to provide significant power into a suddenly lower impedance load (Moir, page 281; Ravenswood, Fixed Bias, Audio, Feb. 1958, page 48). Amplifiers running subscript 2 operation often may be identified by the use of a power tube (2A3, 300B, etc.) in the driver position. The 211 and 845 also require very high plate voltages (800-1200 VDC), about twice that of the 300B, and desire a higher load impedance, both of which complicate output transformer design.

It has been asserted by some contemporary designers that one can not hear second harmonic distortion of 10% to 20%, such as may be produced by some single-ended tube amps. However, I find no corroboration of this, and in the Renaissance Seventy/Seventy hold the sum of all harmonic distortion, including the second, to approximately 2% at clipping without negative feedback.

It is also worth noting that multi-grid tubes, such as the KT88, connected as triodes often do not exhibit linearity comparable to the 300B, 845, or 211 tube types, although this connection may have some advantages over traditional pentode/beam power operation.

In any event, I do not think that THD as such is actually what we hear. I believe that it shadows something that we do hear in the context of analogue tube equipment. As a case in point, there was a 1987 Journal of the Audio Engineering Society (JAES) publication of a study by Dolby Labs' Louis Fiedler, in which, if memory serves, .005% THD in a digital system was clearly audible to all listeners. Several times this amount would not be detectable in a similar tube analogue set up. Some other measurement likely will be found significant in the context of the a/d/a cycle, and will probably be meaningless when applied to tube amplifiers. At the end of the day, the human auditory system is a marvelously arcane recognizer of patterns, and we are not able to mimic it with our test instruments.

Feedback is another interesting topic. Traditional theory gives feedback high marks, but this analysis changes when we consider that the "error" signal is fed back into a non-linear amplifier. Due to this, feedback may lower the overall level of distortion, but it also multiplies its order. For example, if an amplifier naturally produces second harmonic, feedback will create a second harmonic of that second harmonic, which is the fourth harmonic. If the basic amplifier has second and third, the fed-back amplifier will contain second, fourth, sixth, and ninth. As is well known, the higher orders of distortion are more objectionable to the ear than lower orders, and odd orders more offensive than even orders. Thus it may be possible to lower the level of distortion products and still have the distortion be more audible.

The application of negative voltage feedback also reduces an amplifier's measured output resistance, i.e., it raises the "damping factor." Here again, the measurement fails to capture the essence of things. In the case of a feedback amplifier, better control of speaker motion is said to occur because the speaker's excess motion creates a voltage (the back e.m.f.) which enters the feedback loop via the amp's output terminals. The amplifier then acts in a manner opposite the error signal to correct for it. However, like many theories, this is an oversimplification and, in practice, the opposite result may be obtained. There are several reasons:

1) The motion of a speaker's voice coil former may not match the acoustical output due to cone break-up modes and room acoustics.
2) The motion of the coil former is being sensed by the voice coil. The coil is designed to be a good driver, but is a lousy sensor, primarily due to its high inductance, which will create phase anomalies in the back e.m.f.
3) The back e.m.f. may pass through a cross-over network, which will again alter phase and frequency relations.
4) A differing back e.m.f. from another driver may be summed in via the crossover, making a composite signal that does not match either individual driver.
5) The speaker leads may cause additional phase shifts.

By the time the error signal reaches the power amplifier it is arguably an erroneous error signal. As the power amplifier attempts to correct for this signal, it may actually do the exact wrong thing with respect to the speaker's acoustic output. Subjectively, I have noted that high feedback amplifiers tend to give the bass a one note boom on certain speakers, and tend to create an electronic glaze in the midrange, possibly attributable to this process.

With regard to damping, I suspect the best approach is to design the amplifier to have as low an output resistance as possible in a static sense and use little or no feedback. As it happens, the minimum natural output impedance is obtained from a low mu triode amplifier (Williamson & Walker, Amplifiers and Superlatives, JAES, April 1954, page 79).

None of the foregoing is an endorsement or condemnation of any particular amplifier design. The engineering information seems against single-ended tube amplifiers; to be fair, however, perhaps the added distortion offsets something else in the recording chain, at least under some conditions. Then again, perhaps something we do not yet know how to measure something that is better with single-ended designs. The critical ear will help provide the answer: if, for example, part of the sonic character of a single-ended design is attributable to excess 2nd harmonic distortion, then that amplifier will probably sound somewhat full, mushy, or thick, even on instruments that should be clean and fast. This is the characteristic I perceive in such amplifiers.

Nothing made by the hand of man is perfect. It seems to me that the audio designer's task is to push the frontier of compromise as far away as possible, and then to balance the imperfections in a fashion that serves musical truth.

As we often say, in a battle between theory and the real world, the real world always wins. Or, as Daniel von Recklinghausen once said, "If it measures good and sounds bad, it is bad. If it measures bad and sounds good, you've measured the wrong thing."

[TBrennan]

Everybody will make a case for what they like or sell.

Just enjoy what you like and to the Devil with everybody else. Don't explain, don't rationalize.

[coda]

A little footnote, Valve Amplification Company formed 10 miles away from Cary Audio, very close to Chapel Hill. Their gear is admirable, I've auditioned their stuff on several occasions. My understanding when I spoke with them was that their personal experience with single ended triode designs did not include Wright Sound or Welborne gear.

Have to agree with Tom on the write up.

[JJkizak]

Dean:

You convinced me. I now do not like tubes or transisters. Is there anything else?

JJK

[TBrennan]

That's funny.

[leok]

JJK,

Yes, there IS something else: Pulse Width Modulation.

Leo

[Deang]

I'm having a three channel amp built using the ucd180 with the 8620 opamp. I should have it in about a week or so. Should be interesting.

[NOSValves]

I wrote every word of it, and yes I am a SET listener now days. I would like to know how other folks view this whole distortion topic. I tried quite hard to lay it out as I understand it and remain fair so as to keep it open to all others and their thoughts. I'm especially interested in knowing if my ideas are incorrect or incomplete... what do you think about it?

Paul,

I think that Tom's post is absolutely correct! (did I really say that LOL!) There is no right, wrong or absolutes. The constant search for such just ends in disagreement and flame wars. It just is not worth it one way or the other. I was not trying to offend you with my post. I just want to say the subject of amplifier/topology differences is a huge black hole that has become a yyyyyaaaaaaaawwwwwwwwwwwwwnnnn to me.

"Everybody will make a case for what they like or sell."

[jacksonbart]

I like really good music.

[Deang]

Not me. I want really bad music to sound good.

[oldbuckster]

I like really good music.

MR. JIMI HENDRIX knew how to use distortion.....................Makes no difference how you listen, SET's, VRD's, good old SS high power watts, radio, boom boxes, Vinyl, CD's.....................HENDRIX KNEW HOW TO MAKE DISTORTION WORK FOR HIM.......................................

[leok]

Dean,

I'm interested in your impressions of the USD180 (did I spell that correctly?). By the numbers that one should be hard to beat.

Leo

[NOSValves]

I don't get what is going on with this forum software at all. It makes a post when I'm still writing it and sometimes before I have even entered a word. But I personally am still typing the message. Crazy stuff.

Craig

[NOSValves]

Not me. I want really bad music to sound good.

Well I'm pretty darn sure you have that down to a fine art LMAO !!!!!!!!!!!

[3dzapper]

I like really good music.

MR. JIMI HENDRIX knew how to use distortion.....................Makes no difference how you listen, SET's, VRD's, good old SS high power watts, radio, boom boxes, Vinyl, CD's.....................HENDRIX KNEW HOW TO MAKE DISTORTION WORK FOR HIM.......................................

He sure did! And, I want to reproduce that distortion without distortion.[]

[oldbuckster]

I like really good music.

MR. JIMI HENDRIX knew how to use distortion.....................Makes no difference how you listen, SET's, VRD's, good old SS high power watts, radio, boom boxes, Vinyl, CD's.....................HENDRIX KNEW HOW TO MAKE DISTORTION WORK FOR HIM.......................................

He sure did! And, I want to reproduce that distortion without distortion.[]

And with my untrained ears, and average equipment, that's what I want TOO!!!!!!!!!!!!! Distortion in the right hands is MUSIC to my ears....................