Hi, guys:
I think my Airy2 is finally getting broken in. I've been playing the Cardas sweep record and the process accelerated. I spent last night with the Sheffield Drum record, specifically trying to optimize tonearm/cartridge setup for dynamics, and I was impressed with the improvement. I finished by playing Stanley Clarke's Schooldays, one of my longtime dynamic touchstones, and the dynamic impact was as good as I've had. Then, to see if I had compromised other important parameters, I switched to Ella and Joe Pass on a Pablo (my favorite "unknown/ignored" label) LP, and her voice was silk and his guitar fullbodied with good overtones. I'm going to live with the Airy2 for awhile before making a final decision on changing cartridges, but last night I was pleased.
A quick aside, the VPI JMW arm has the easiest VTA adjustment I've ever had the pleasure of using. It allowed me to quickly and accurately repeat VTA settings for comparisons. Sure beats my old method of using a sparkplug calibration tool to repeat settings.
I was interested in Dougdeacon's comments about the Airy3 dynamics problem with certain tonearms. My HRX, of course, came with the JMW and, since there is no separate armboard, the plinth is drilled specifically for the JMW. Obviously I am reluctant to drill new holes in my pretty new plinth, so it will take a lot to get me to change to an arm that doesn't fit in the JMW mounting holes. (Are there others?) And, as luck always has it, just before stumbling on the HRX buy, I had purchased a brand new Graham 2.2, which I now have sitting in an unopened box.
As to the $3400 tonearm cable question, I think I'm more inclined to put that kind of cash towards a new phono stage first. I was hoping someone would come up with God's greatest tonearm cable for under $1000 but you guys have too much experience with the really good (read, oh my god, does heaven really cost that much?) equipment.
I'm also thinking about a new preamp, possibly a linestage so I could use whatever phono stage I liked best. The Steelhead, though, offers an interesting alternative. Using it as my preamp as well as my phono stage might make it cost effective.
Interesting that Raul mentioned subwoofers, because I've been thinking that should be my next move. I definitely plan to add a pair before even contemplating a main speaker change (Watt Puppy 5.1s, now the oldest component in my chain). I've been looking for Vandersteen 2Wq's as a reasonable costing and sized tryout option.
I do agree with Gregadd about tubes, relying on specs, everything is a filter, etc. Since I am unencumbered by any surplus of technical knowledge, I just plug it in, turn it on, listen, and decide. I was into solid state early (remember the Audio Research SP4?)as the wave of the future but eventually found tubes were more satisfying. I do admit, though, that I have not tried any of the new top solid state gear. |
Gregadd,
Excellent and well-argued post, at least when I read it through my many-colored glasses. ;-)
Suttlaw,
Glad to hear the Airy2 is breaking in well. The choice between it and the Airy3 really is a matter of system synegy and taste. If it gives you ample dynamics then it's presumably a good match for your system. Since your tastes are, "unencumbered by any surplus of technical knowledge", I presume that leaves them free to like what sounds most musical without other prejudices. Sounds like a short path to enjoyment to me. You are living the life! |
Suttlaw: you might want to consider the Aerial SW-12. |
Dear Gregadd: You, like me, have to learn a lot on all those issues.
****" Every component in every system either adds or subtracts something to or from the signal. "****, I agree with you, but that is not the issue:
***" The tube amplifiers can't do it, it is impossible by the physics laws), only can function like an equalizer sound reproducer. All the tube amplifiers change their frecuency response with the changes in the impedance of the speakers and this speaker impedance ( normally ) change with the frecuencies,...."***. The problem with the tube electronics is that these changes are really great against the same issue in SS electronics ( read the frecuency response of tube amplifiers in the tests that Mr. Atkinson ( Stereophile ) do to any amplifier. And that tests is with a constant impedance ( he always use resistors at 8-4-2 Ohms ) that is far from reallity because the impedance of the speakers is always changing. Try to find the review of that Wavac amplifier that send you back 350,000.00 and you and any one can understand what I'm talking about. ). By any standard the tube electronics are the greatest equalizers in the audio world ( I'm not talking here if you like it or not, that is other issue ).
******" Every component in the chain is extremely important, things reproduced properly in one component can be easily lost in another."****, I agree with you, thats why I write:
**" I think that almost all of us have a duty: take care for that the signal sound reproduction be the less degraded signal in our system. "*** The tubes electronics ( at any stage in the audio system ) are the links that degraded more the signal in an audio system ( other than: room and speakers ). You have to know, too, that the tubes function like " signal generators ": the tubes create harmonics that does not exist in the original signal and the problem is that you can hear that harmonics through your audio system.
****" Solid state guys always try to hide behind accuracy. "****. First than all I only be in favor of music and the best technology ( at least for today ) for the music reproduction is: SS electronics, I always be with the technology that can give me the " best " for the music reproduction: when you can understand this then you will be near to the MUSIC.
The problem with many people in this forum is that you never hear a SS based audio system that was build with care and for people that really cares about music. Yes I know that many of you already hear very very expensive ( SS based ) audio system that does not like you: but you don't like it not because the SS electronics but because the owner of that audio system do not really cares about: MUSIC REPRODUCTION or maybe there are no good sinergy on that system. Till you can have that experience it will be very difficult that you can understand of what I'm talking about tubes or cartridges. I'm not against the tubes: I'm in favor of music, I take around 20-30 hours each month for to listen live music. How many hours do you or any of you take hearing live music each month?. I appreciate that all of you give and answer to this question.
Regards and always enjoy the music ( not our system ).
Raul. |
Dear Steve: About the phono cable I recomended: Analysis plus Silver Oval, hard to beat at any price ( 100-150 hours for break-in ).
For the phono stage, stayaway from the Steelhead: use step-up transformer internally that degraded in a high way the critical signal that comes from the cartridge.
For the subs: I know very well the Aerial and I respect to Mr. kelly like a speaker designer ( I use an old Kelly speaker design ), but you have to go for the manufacturer that really knows about subwoofers: Velodyne.
Regards and enjoy the music.
Raul. |
Raul,so what SS amp/preamp/phono do you have? |
Raul,upon reading the same Stereophile article from the 1994 archives, I found this rebuttal letter at the end of the article regarding frequency response variations of tube amplifiers with regard to speaker impedance changes and damping factors.
From the Stereophile archives
"A letter in response appeared in April 1994 (Vol.17 No.4):
Thomas J. Norton's "Questions of Impedance Interaction" in January (p.109) showed that a ghostly echo of a loudspeaker's impedance modulus can be imposed on its frequency response by virtue of an amplifier's source impedance acting as the top limb of a potential divider. Mr. Norton illustrated the effect with some specific graphics, but the data can be usefully generalized by means of a simple rule arising from the ohmic arithmetic.
Assuming a worst-case situation of very large impedance undulations, with, for instance, an LF peak reaching 10 times the value of that characterizing the lower-mid region, the rule runs as follows: To confine frequency-response changes within an amplitude band of 1dB, the amplifier's source impedance (plus the resistance of its connecting cable) must be less than an eighth of the speaker's impedance at the latter's lowest point, and less than a sixteenth for a band of 0.5dB.
These criteria also satisfy damping requirements for practical purposes, since the resistance of a speaker's voice-coil is effectively in series with the amplifier feed, so that once the latter falls below about one quarter of the coil resistance, there can be no worthwhile improvement. Perceived changes in bass "softness" between transistor and tube amplifiers are thus more likely to be due to LF impedance "response ghosts" than to the damping-factor, as such. Huge ratios for this parameter make impressive reading in technical specifications (like ultra-low distortion figures), but are so far along the relevant asymptotic curve as to be useless for audio purposes..—John Crabbe, Todmorden, Lancashire, England "
End of Stereophile excerpt.
So, as you can see, there is no consensus that this lower damping factor in certain tube amps with low/no negative feedback in conjunction with certain speakers will actually have the frequency response effects that you refer to as "equalizers". As long as the damping factor remains above 4, then the "equalizer effects" that you refer to are insignificant according to Mr. Crabbe(and others). Many tube amplifiers have output impedances of less than 2 ohms, and many "tube friendly" speakers have impedance curves which remain at(or above) 8 ohms, so this can provide the necessary damping factors of >4 that are required for linear response within about 1 db.
Additionally, it has been known for many years that adding negative feedback to improve damping factor and reduce measured distortion(which is common in both tube amps and SS amps) can be deleterious to the musical sound quality. When applying negative feedback to a sinewave test tone, it shows reduced measured distortion and also improves damping factor. But when playing music which is non-constant, the feedback loop actually can increase music distortion because the feedback added is actually phase shifted(due to the length of the feedback loop), and adds feedback from a previously played part of the signal to an upcoming part of the signal, thus making a big mess. Now, to be fair, engineers have used short feedback loops and other techniques to minimize this problem, but it still can and does exist. This is why some amp makers are adamant about making "no feedback" amplifiers.
So yes, I understand your concerns about the tube amps becoming "equalizers" in theory, but in practice(with a correctly matched system) this concern is not founded in reality. In a poorly matched system, this could be a problem, but all kinds of problems can arise in a poorly matched system. Your "broad brush" application of this concept to all tube amp/speaker systems is misleading at the very least, and disingenuous at worst.
While SS amps with negative feedback and high damping factors may have certain good aspects, there are also downsides to that type of design, as I have just described. Many SS amp makers make strong efforts to minimize or even eliminate feedback in their amps, so that these problems do not noticeably degrade their amps' performance. I agree that while the naturally low output impedance of SS amps, and even the use of negative feedback, can provide a very impressive damping factor number, the overall benefits of this become "asymptotically small" after a small basic damping factor number(>4) is achieved. The main benefit comes from being able to choose from a wider range of speakers which may exhibit low nominal impedances and low impedance swings that may strain amps with higher output impedances. It can be a useful thing in some circumstances. But, matching the amp to the speaker can and does make the difference, and as long as the user observes proper matching, this "equalizer" phenomenon is not a real concern.
As we now see, there are plusses and minuses to various types of designs, and it is the user's responsibility to configure his system to the best effect.
Regards, and enjoy the music.
TWL
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Raul, If I could listen to 20-30 hours of live music per month I'd sell my stereo and move on.
I enjoy the music and my sytem.
your freind gregadd. |
Raul, I wasn't going to say this, but I do have to respond to your statemnt "I have a lot to learn." Truth is I tracked the rise of the high end over the last thiry years. All these arguments have been made already. While it makes for fun discussions, I have no desire to "prove the world is round again."
If the only thing wrong with tubes is frequency reponse that can easily be fixed. The frequency response of every component, and software for that matter, has had it's frquency respone manipilated.
The faults of transistors seems to be infinite. Usually requiring considerable genuis and money to manipilate.
Harmonic distortion generated by tubes. Heard that argument before. Transistors generate harmonic distortion which is far more objectional.
Yeah I've looked at my share of impedance vs frequency curves. (When I started that was all magazines like Audio did was print measurements.
That's why the salesman tried to sell me a Krell w/my M/L CLS I. M/L has a wicked impedance curve. Technically correct but horrible sound.
"I only care about what makes music the best." If that is true you really should try to stay away from hyperbole like "tubes is clown music." The fact is neither tubes or solid state have been able to get me all the way home. At least in my price range. I even tried hybrids, that did not do it either.
Lastly there is no reason to even respond to the claim that I have not heard the equipment you have unless you want to name that system. If all else fails then fall back on the "goldedn ears" argument. Please, spare me.
Finally I know a musically correct(as opposed to what some call "accurate") system when I hear one. There is no way to prove that. You'll just have to trust me.
Your friend, Gregadd |
Hi TWL:*****" So yes, I understand your concerns about the tube amps becoming "equalizers" in theory, but in practice(with a correctly matched system) this concern is not founded in reality. "****. Here it is the point: my concern about is in practice not theory.
Regards and enjoy the music.
Raul. |
Dear Gregadd: That's exactly the point and where the differences are. Think about it and try to change that situation and you will see that you could appreciate more and more the music reproduction at home. That's the way to grow-up in the world of music reproduction.
BTW, till now you are the only one that give an answer to that critical question.
Gregadd I enjoy the music through my system. I do everything to take care about the music reproduction in my audio system. I'm not in love with it it is only a tool ( a very complex one ) for I can hear the music.
Regards and stay enjoying the music.
Raul. |
Raul,once again WHAT SS AMP/PREAMP/PHONO DO YOU HAVE? |
Uggh, this is suppose to be an analog thread, but I just can't resist countering Rauls outrageous tube amplifier comments. I have designed, built and modified a number of amplifiers, both tube and solid state. So my comments are based on actual listening experience.
Tubes and transistors are both devices that produce gain using similar concepts but with quite different characteristics. Tubes have good linearity (low distortion) but low gain. Transistors on the other hand have very poor linearity (high distortion) and very high gain.
To get around the distortion problems most tube amplifiers and all transistor amplifiers use feedback to eliminate distortion. Here I use the term distortion in a very broad sense, anything that deviates from the original signal including frequency response, noise along, harmonic and IM distortion. More feedback means lower distortion, including the "equalizer" effect that Raul mentioned. Since transistors have very high gain and it is easy to produce lots of feedback and therefore very low distortion, ruler flat frquency response, high damping factor, vanishingly small harmonic distortion, blah, blah. Tube amps on the other hand have much more limited gain and can only produce limited feedback. The result is considerably worse distortion measurments, in spite of the fact that they are lower distortion devices to start with.
But there is a significant hitch to this story. It turns out that feedback has a clearly audible negative effect on sound. To date I don't know of anyone that is able to measure this affect. It does not show up in any of the standard distortion measures. This is part of why there is so much controversy about this topic. I have a lot of first hand listening experience regarding feedback and I assert that this is both real and significant.
So like so many things audio it all boils down to compromise. Feedback brings both good and bad to the table and the optimum balance is both system and taste dependent.
In a given context and a set of personal preferences there will be an optimal balance between feedback and distortion. That optimum balance will not be the same in a different system or with different tastes. So it's never as simple as choice between feedback or no feedback or for that matter tubes or transistors.
The goal for good amplifier design is the lowest possible distortion with the smallest amount of feedback. That means that the amplifier needs to have the lowest possible open loop distortion. Open loop distortion is the level of distortion before feedback is applied. A well designed amplifier implemented with high quality components will require less feedback to arrive at a distortion goal and will therefore sound better.
So if you look at amplifiers from the perspective of levels of feedback the high feedback end of the spectrum is the exclusive domain of trasistor amplifiers. On the opposite end of the spectrum is single ended triode amplifiers with no feedback at all. Each have their strengths and weaknesses.
Personally I find that nirvana is a zero feedback amplifier. But the no feedback path is not for the faint at heart. Everything has to be perfect or you will hear it. Component quality become hugely important. Speaker choices are very limited and there are major speaker/amp synergy issues. Feedback extracts a price but it does make things a lot easier.
Chris |
Audio999- Raul is not going to tell you. Ever. He's not going to tell you the name of the analog testing company he claims he has, either. Ever. Nor will he provide the serial number of the Schroder arm he claims he has to Frank Schroder himself so that Herr Schroder can tell him the details that he wanted to know. Ever.
Jim
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Jim,i think you are right. He didn't anwswer my question about his analog rigs a while ago and i bet too this time.
Raul,don't be shy of your great non-eq. gears !
Just let me know so i can sell all my nasty eq. stuffs to buy like yours!!
Runnnnn..... |
Chris & Tom,
Thanks for the informative (Raul, you understand INFORMATIVE, don't you) posts on feedback & damping. Maybe this will finally put this issue to rest.
Joe |
Wow! Just tuned into this thread. No offence here honestly. so please excuse me here. Ahhh..... Geez Raul.... are you infecting another forum thread here? Preaching your narrow minded,lame and pathetic argument about distortion artifacts and that silly equilizer theory? Hey Pal,enough of your condenscending,self righteous BS already... give it a rest will ya! This is about the music here man... and not your distorted math... that distortion thing is right...right between the ears on your square head. Hey gang... I seriously doubt he has even heard half the stuff you guys are talking about, he doesn't own a schroeder tonearm, will never post his system,or even answer a simple question if it's directed at him. Get a life man! Sorry gang....but someone here had to do it. PS: Hey Raul....you any relation to Didactically? |
Audio999- Fact is that Raul needs to take considerable time to review all of his posts to create a theoretical system that would be consistent with what he has already written. This could take awhile... |
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Dear TWL and Teres:
With respect to the answer given by Mr. Crabbe, he's right when he says that the voice-coil impedance can be considered to be in series with the amplifier's output impedance. However, that's not the point. The ideal amplifier's mission is to work as a perfect voltage source, regardless of the load impedance presented at its output terminals. This ideal can be reasonably approximated using many technologies -vacuum tubes, bipolar transistors, mosfet transistors, etc.- However, using vacuum tubes this task is almost unsurmountable, simply because tube 99.9% of current designs depend heavily on the use of an output transformer that further introduces anomalies, distortions, colorations, saturations, phase shiftings, etc. etc. By the way, perhaps at this moment the word OTL will come to your mind, but I could mention many aggravations they have too, but that is another matter that would be subject of a different thread. Anyway, assuming that all these problems could be solved, tubes generate big amounts of harmonic content not present in the original signals, and I see this as the biggest obstacle in our road to true fidelity. Tubes will always add sweetness to the music, at the expense of accuracy, that to many music lovers as myself means fidelity. Today's solid state devices, on the other hand, have current linearity far more linear and and noise characteristics far more desirable, all in favor of a better musical experience. This is the ultimate goal of listening to music.
And regarding Teres arguments, I have several points I would like him to consider: Tubes are voltage devices, whereas transistors are current devices. Therefore they operate in completely different fashions, not similar. Any electronics designer can confirm that. Although tubes and transistors both present big amounts of distortion if not corrected, transistors have the advantage of having complementary devices, that when properly matched, can virtually eliminate alinearities, harmonic distortion and IM distortion without needing any global feedback. Unfortunately, there are not and will never exist such thing as a complementary tube; they simply can't have this fundamental advantage. So when you say that transistors depend on big amounts of feedback, I can see that you have been simply ignoring the state-of the-art in modern solid-state design, where non-feedback is almost a gospel.
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.
Regards and enjoy the music,
Raul |
"The ideal amplifier's mission is to work as a perfect voltage source, regardless of the load impedance presented at its output terminals"...
"Tubes are voltage devices, whereas transistors are current devices."
Is this an inadvertent mistake or a blatant inconsistency?
"Tubes will always add sweetness to the music, at the expense of accuracy, that to many music lovers as myself means fidelity."
The truth is that distortions of tubes is much less objectional to the human ear becasue it is a "natural device" God is a much better designer than man will ever be. Raul you confuse confuse the absence of euphonic colorations(some disingenuous solid state designers have added that distortion in order to compete with tubes.)with accuracy. The fact is that transistors have added a cold sterile quality to the sound either by adding or taking away something from the music. It reminds of the argument that a vpi motor was noisy and that could be proved by listenig to a tunrtble with a magnetic bearing. Shouldn't we be comparing motors.
..."using vacuum tubes this task is almost unsurmountable" You previously said "impossible". So we are making some progress.
Those of us who have been around for awhile remember that using amplifer specs as a means of evaluation is more of a madison avenue ploy than science. It was an attempt to convince us that transistors must be better than tubes because they measure better.
Raul as indeed your own post which refers us to $350,000.00 amp proves. It is the ss electronics that require major trickery to cure it's inherent problems. Everytime I read about or hear a ss amp that I can live with it is priced way beyond my reach.
As a huge fan of conrad johnson I look forward to auditioning thier Premier 350. It is suppose to achieve low distortion without any feddback. Somtimes that means only no global feedback. Examination of its spec's indicate it does not "double down" like Krell. I have nothing against ss per se.
Enjoy the music and playing with your equipment!(stereo) Thanks to all you guys for whetting my appettite for stereo again. Pardon me while I earn some money to buy some equipment! |
Anybody notice how Raul's English improved about an order of magnitude in that last post? Interesting... |
Raul, I do agree that there are some favorable characteristics to both SS and tube designs.
However, it appears that you are attempting to engage in some kind of "specs race" between SS and tube amps. Distortion Specs are only useful in some regards, and are not indicators of performance in a music system. The methods used to measure them are not the same as the intended use of musical playing, and therefore may have little or no bearing on the actual musical performance of the amplifier. Static sine-wave distortion measurements into a dummy load are not even close to the way an amp produces music. Most informed users do not rely on these specifications. The ear can hear distortions produced by a design that do not show up in any measurement protocol.
Regarding "complementary transistors", they are only applicable in Class AB or B amplifiers(push-pull), which require switching, phase-splitting, or both, and are not the equal of true Class A design(no phase-splitting or switching) for musical reproduction. But I agree that complementary Class AB is nice to use when you need a high power amp that cannot run totally in Class A all the time, for use with certain difficult speakers. But it is obvious that virtually all Class AB SS amp makers bias them as high as possible, to keep the amp in Class A as much as possible. This is simply a "de facto" example that any kind of Class B(complementary or not) cannot compete with Class A sonics of a similar quality level amplifier(maybe even from the same manufacturer). They just do this switching to Class B so they can output more power without as much wasted heat. Not for better sonic performance than Class A.
Regarding your comments on "unwanted harmonic content", which I suppose means "harmonic distortion", you only have to look at harmonic distortion curves of various amplifier designs to see that SS amplifiers have relatively low amplitude harmonic distortion characteristics, but have them all the way up the spectrum, and have them primarily in odd-order content, which makes them much more objectionable to the ear, and therefore they have to be lower to be even listenable. Tube amps, on the other hand, especially Single-Ended Triode amps, have a somewhat higher amplitude harmonic distortion curve, but it is located primarily(almost completely with SET) at the 2nd harmonic interval, and is almost all even-order distortion which is easier on the ear, and also easier to deal with by other aspects of design. Push-pull tube amps are not as good in this regard as SET, and suffer from both odd and even order harmonic distortion, as well as the phase-splitting and complementary amplification things. But they can be good sounding amps nonetheless, if they are designed and built well(typically with some negative feedback that was well applied).
Regarding your discussion about output transformers, this is the crux of your previous discussion that included output impedance of tube amps and their performance with reactive speakers. The tubes have higher output impedances than transistors, and usually must have impedance-matching output transformers to achieve a low enough output impedance to drive a speaker load. This is well-known. I agree that there are problems associated with output transformers. However, very good output transformers achieve a very high level of performance, and mitigate the problems to a large degree. OTL and ZOTL can eliminate these output transformers, but traditional OTL must resort to parallel-ganging of the output tubes to reduce the output impedance to a useful level(which is still usually a bit too high, but works), and only ZOTL allows the use of true SET Class A single-tube output, with impedance matching to the speaker that is under 2 ohms,no output transformers, and devoid of the typical transformer artifacts. As you know, this is a unique circuit from David Berning, and it the circuit used in my personal amplifier. The distortion from this(my personal) amplifier has total harmonic distortion of much less than 2% in the audio spectrum and the predominating location is at the 2nd harmonic(with much much less in the rest of the spectrum). Output impedance with 0 feedback is under 1.8 ohms. The circuit is true Class A(no phase split) and has a single output triode per channel, which negates any need for any "complementary devices". Bandwidth extends to 500khz. It can produce a square-wave anywhere in the audio range. True full-power bandwith is produced down to 2Hz(where a coupling cap intercedes to avoid DC), and this produces very prodigious and fast bass response. Signal-to-noise ratio is better than -100db(quieter than most SS amps). Supersonic(RF)frequencies are used to heat the tubes, for heater noise elimination and long tube life. The amp is 12vdc powered to eliminate line noise. It has choke-loading for improved linearity. Super short signal path. Ultrahigh-speed switching power supply that is very stiff. Overall, this amp is about the most advanced and most musical amplifier that I have ever heard or seen, and it is a tube amp. I realize that specs are not the answer, as I mentioned earlier, but if you want some specs, there they are.
If you want to quibble about the 2% total harmonic distortion spec on my amp, then it would be useful to note that the single-driver speakers that I use have a similar 2% harmonic distortion profile at the 2nd harmonic primarily, and the judicious connection of the speakers at 180 degree phase angle to the amp outputs cancels much of the overall system harmonic distortion, and results in an overall system distortion much lower than any competing SS or tube amp with multi-driver speakers( which have wide ranging additive distortion profiles and cannot benefit from this happy matching). See the articles by amp designer Eduard de Lima on SET amps and single-driver loudspeakers, available with a web search.
I have no "axe to grind" against SS amps in general, and there can be some very nice SS amps. I have owned and heard many. My main purpose for my posting here, is to rebut the premise that you have made, which states that tube amps cannot be serious musical amplifiers. I hope I have done that. Nothing is perfect. Bliss is in the ears of the beholder. |
Dear Twl:*****" The distortion from this(my personal) amplifier has total harmonic distortion of much less than 2% in the audio spectrum and the predominating location is at the 2nd harmonic(with much much less in the rest of the spectrum). Output impedance with 0 feedback is under 1.8 ohms. "****
This is exactly the point: THD 2% is really a high distortion it does not matters if location is: 2nd harmonic. But the output impedance of 1.8 OHms is a heavy problem for your amp can works like a constant voltaje source ( it's almost imposible ). This very high output impedance is the problem.
Now, you can check in your Stereophile's any ( all ) of the tests about, for tube and SS amplifiers,. and you can find the terrible errors that have all the tube amplifiers when they are trying to match the impedance of the speakers. Again, you can hear it.
Gregadd,this is not how it measure it is that any one can hear that big mistakes. The output impedance in the tubes amplifiers, usually, goes from 0.5 to 3 OHms ( high one ) and the output impedance in the SS goes from 0.02 to 0.5 OHms ( very low one. That's is one of the parameters why the SS has a high damping factor ). This is the point and the problem on the subject and you can hear it ( any one ).
BTW, I'm not in love with " specifications numbers " but like in the cartridge/tonearm combo is very important the " number " on the resonance frecuency, here at the amps this output impedance is one of the issues.
Any one that is using tube amplifiers in their system, don't really know how really " sound " their speakers and don't know the true performance of their audio system.
Don't say " NO " for what I'm telling you, till you do a serious test with a whole SS audio system at your home and for at least three months.
Regards and enjoy the music.
Raul.
Regards and enjoy the music.
Raul. |
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Raul,
Yes, I know that tubes are voltage devices. Bipolar transistors are current devices and mosfet transistors are voltage devices like tubes. Yes the theory of operation is different but the application is still very similar. You use a small current or voltage to control a larger voltage or current. And though bipolar and mosfet transistors operate on different principles they end up sounding much the same. And neither has linearity that is even close to that of a vacuum tube. This is all quite irrelevant to this discussion.
The topic of complementary devices is another red herring. It just makes it easy to implement a push-pull topology without using a transformer or coupling capacitor. The push pull topology does cancel distortions but also has it's own set of advantages and disadvantages. Push pull is widely used with both tube and transistor equipment so it has nothing to do with the topic at hand.
You are really in the weeds when you imply that non-feedback is practically gospel. Please name a single commercial transistor amplifier that uses no global feedback. For that matter name a single non-triode tube amp with no feedback. Reduced feedback is an often cited goal but with the vast majority of amplifiers the sound would sound awful without any feedback.
The intent of my post was to counter your outrageous assertion that tube amplifiers are frequency equalizers and therefore unsuitable. You countered with a number of irrelevant facts (some of which were also wrong) but never came back with any justification for your position. If you are going to make sweeping authoritative statements then I suggest that you be ready to defend them.
Personally I love the sound of tubes and in particular single ended triodes with no feedback. So does that give me license to say that transistor amps suck? Or that anyone that likes transistor amps is uninformed and/or can't hear? I have plenty of tolerance and even appreciation for people that have different preferences and views. But my tolerance for those that impose their views on others is pretty thin.
Chris
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Anybody notice how Raul's English improved about an order of magnitude in that last post? Interesting... Indeed. One wonders who actually wrote it. Is some SS amp builder ghosting for Raul? |
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
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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, letÂ’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)
Â¥
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 amplifierÂ’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 amplifierÂ’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. |
And my last post was premised on the damping data alone, and did not even take into account the other important factors that may play into this matter. |
Raul- If you really wanted someone like me to learn, how 'bout trying to teach by example? As you say, this forum is about learning- help me learn by telling me of products that exemplify your points. Maybe even let me know what you have so that I have a clearer understanding of your own point of view. In that way, I can truly learn from you! (That is your stated goal, correct?)
Jim
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Dear TWL: Just checked out your system. Was curious about the Rottweiller tweak. Does it work best between the speakers or on top of them? |
Suttlaw, that Rottweiler "tweak" can go anywhere he wants to! :^)
Typically, he goes right next to the listening chair, since he likes to be close to his "Dad". |
Perhaps we can talk some time about the real weakness of tubes. Diminshed performance at the frquency extremes. Less than optimum perfomance when it comes to transient attack. See, the absolute sound issue 147 "tubes vs transistors" Can you get true dynamics from a two watt amp? What problems do horns or otherwise highly efficient speakers cause?
That's a new thread.
I always learn something from Rauls' comments. Unfortunately it's not always what he was trying to teach me. I think the point he was trying to make is that output impedance can effect spectrum balance. Fair enough! To say that you can't design around that problem in a tube amp goes to far.
Raul is right on another point. Paying attention to specs can help in trying to match components. For example amp and speaker should be thought of as a system in istself. Turntable, tonearm, catridge and preamp should be purchased as a mini system. All too often we go out and by the product of the month and jam it into an incompatible system. Many reviewers and salesman simply don't know how to match components. We also need to avoid the spec of the month club.
Thanks TWL for doing the research for us. I looked at the amp tests in Sterophile. I can see how Raul was misled( or misinterpreted the data.
Raul, keep punching! Converts are won one at a time! |
Gregadd, those frqequency extreme and transient softness issues are also output transformer related. Not necessarily related to tube response. Tubes can provide very wide frequency extremes, and fast speed, when done properly. |
Also if the transformer is eliminated entirely as with tube OTLs.
. |
Hmmm... Audioholics seems to have somewhat contradicted the information that Thomas J Norton of Stereophile presented in his article about amplifier stability / frequency response into various loads. The Stereophile article ( which i've linked to more than a few times ) shows the differences in frequency response between SS, tubed and hybrid designs when fed into the same loads. After looking at those results, it is quite obvious that a "decent" SS amp will maintain a more consistent amplitude linearity over a wider bandwidth than a "typical" tube based amp ( if there is such a thing ). Before making any further comments though, i need to read the entire Audioholics article and study their test procedures and results, not just look at an excerpt.
Thanks to Twl for bringing this to our attention. Sean
> |
Here's a link to the entire article. http://www.audioholics.com/techtips/audioprinciples/amplifiers/dampingfactor.phpI copied the entire 2nd page in my previous post, which related to the issue we were discussing. However, on the first page there is more info regarding the misconceptions of large amounts of overhang or time-delay that has commonly been attributed to tube amplifiers, and found to be not true by these measured results from Audioholics. |
To me, the key here is not whether there may be some slight affects to the amplifer based on speaker reactances, but whether these small effects could even be actually audible, given wider range tolerances in many other parts of the sytem context.
As Audioholics points out, even normal changes in temp, humidity, and barometric pressure in the room makes more of a difference than some of these issues.
Additionally, practically no speaker made is going to have an "in-room" response of within 1db, so all of this brouhaha is virtually immaterial anyway. This output impedance/speaker reactance parameter is nowhere near to defining the outer envelope of system frequency response +/- tolerances in anyone's system. If we want to improve overall system frequency response, we can look elsewhere for the culprit.
If we want to really look for the differences in sound between tube amps and solid state amps, I think it is in the tone. The even-order harmonic distortion profile of certain tube amps(SET) have this profile when playing, not just when clipping. SS amps with wide-rangeing odd-order harmonic distortion profile have this profile when playing, and not just when clipping, too. Since odd-order harmonic distortions are not found in natural musical presentations, even very small amounts can be detected by the ear, and found to be an unconvincing reproduction. There may be other factors too, but I think that this is at the basis of it. Simply my opinion.
Before we jump on the bandwagon about this, is should be noted that push-pull tube amps are also rife with odd-order harmonic distortion, and so are multi-driver loudspeakers with crossovers. So it may not be(is not) just the amp that is causing this in most systems.
I find it interesting that some people want to focus in on a single parameter to back-up their prejudices about tube amps, when it is entirely possible, and even probable that inherent odd-order distortions in transistor amps/multi-driver speakers may be causing far worse sonic problems to real music listening, and they don't even know it. In fact, I find it rather humorous that as they chase a "spec" or "measurement" around, the sonic realism that is provided by a device that "specs worse", and therefore is "not acceptable", could actually be the very thing that they need to give them the convincing musical reproduction that they seek.
Sometimes I just have to wonder. |
Tom mentions ...a device that specs worse... I agree. Esepcially considering how the relevant spec is measured: sine waves. Hardly conclusive regarding complex signals like music! |
I still haven't had a chance to read the articles, but i just want to ask you folks one question. That is, where do you think the technology came from in order to start mass producing solid state devices? I'll give you a hint. They probably didn't find tubes in the inter-galactic time travelling devices at Roswell : ) Sean
> |
If you want to know what kind of frequency reponse your system is getting into your room you will need a spectrum analyzer. If you are getting on in years, you should also have you ears tested(you could be surprised just by taking the sterophile test cd and playing the frquency sweep section and seeing what frequencies you can't even hear). Once you see the huge peaks and valley's in the frequency response of your room, you may rethink the whole notion of flat from 20-20khz. I contend that was always more of an advertising ploy than indication of how equipment sounds.
From time to time,audio reviewers decide that they need to be more objective. Remember when Peter Aczel of the Audio Critic decided the most important thing about speakers was errors in the time domain. I remember when stereophile decided they were going to publish measurements. They, like all hope to find some correlation between the way components measured and how they actually sound. No doubt TJN thought he was on to something. |
Hi: This statement comes from audioholics ( the TWL link ):****" 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 ( amplifier ), the greater the magnitude of the response deviations. "****.
This is my statement in this thread ( the same that I already post on others threads ):
******" The tube amplifiers can't do it, it is impossible by the physics laws), only can function like an equalizer sound reproducer. All the tube amplifiers change their frecuency response with the changes in the impedance of the speakers and this speaker impedance ( normally ) change with the frecuencies,...."***.
As you can see audiholics agree with Mr. Norton, they speak
on the same subject. ( TWL: I never speak of damping factor ).
The problem with this critical issue is that anyone can hear the high degradation on the signal reproduction.
Now, for anyone can " see " how heavy is that signal degradation: you can go to Stereophile tests on speakers and " see " the electrical impedance diagram where you can watch the multiple frecuency deviation that has the speaker: the tube amplifiers has almost that same deviations ( depend of it output impedance ), only the SS amplifiers can do the job with out that signal degradation.
Regards and enjoy the music.
Raul. |
Clear Audio, VPI, Linn, maybe Basis, maybe Walker. Not necessarily in that order. These are the names that will probably? Maybe? Hopefully? survive the next 20 years only because they will make other products to support their turntable line. In the case of Linn this is already true and therefore the least risk of them all for the future. I was told at HE 2004 last May that Walker is going to come out with a CD PLayer. Time will only tell on that one. Forget about anyone other than the factory repairing any of these. Hell, you can barely find a store that has a turntable hooked up for audition or anyone in the store who knows anything about turntables. As for your last purchase based on performance alone, longevity of the company out of the picture, it would be the Walker Proscenium Gold. My absolute all-time favorite turntable with their servo-tracking arm. I have never heard anything, and I have heard every brand I mentioned, that sounds as spectacular as the Walker. I wish I had $30,000.00 to buy it. It's not just my dream table, it's my dream anything. |
I hope this puts an end to this discussion. "...Gregadd,this is not how it measure it is that any one can hear that big mistakes. The output impedance in the tubes amplifiers, usually, goes from 0.5 to 3 OHms ( high one ) and the output impedance in the SS goes from 0.02 to 0.5 OHms ( very low one. That's is one of the parameters why the SS has a high damping factor ). This is the point and the problem on the subject and you can hear it ( any one )."
Raul this is from an earlier post by you. The audioholics does not agree with your conclusion that a tube amp is an ucorrectable equalizer. In fact what they say is,any non zero impedance signal source can affect frequency reponse. Your own admission verifies that an ss amp is not a zero impedance source. They go on to say that as little as +/-.1 db can be audible. However they do not say it is uncorrectable. Or that because of this tubes amps are unacceptable equalizers or inherently inferior to ss.
For a discussion of this issue and how to solve it, See,http://www.transcendentsound.com/amplifier_output_impedance.htm
MERRY CCHRISTMAS |
Dear Gregadd: ***" I hope this puts an end to this discussion. " ****.
Sorry but is not possible. I can see that you are a little
confused.
I don't have time at this moment. Stay tunned. This subject is really important in the anolog sound reproduction.
regards and enjoy the music.
Raul. |
Good grief, Raul, get over yourself. |
