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In Reply to: RE: "break-in" effects always seem to be for the better. posted by SETdude on August 20, 2015 at 11:19:13
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Why should a transformer be different then? Both are metallic and both undergo heating and cooling so physical parameters can easily change and lead to sonic parameters changing as well.
It's a matter of scale. The internals of a tube are many times hotter than a functioning transformer ever gets. Also the metallurgy of the tube elements are directly producing and manipulating the electron flow.
There are volumes of data on tube break in and aging over the past 100 years. And that information has been certified as well.
There is no such formal information on transformer break-in as it relates to audio sonics. And audio transformers have been around for 100 years as well.
"Also the metallurgy of the tube elements are directly producing and manipulating the electron flow. "
And the metallurgy of wire does something less than that? Not to mention the effects of insulation.
"There is no such formal information on transformer break-in as it relates to audio sonics. And audio transformers have been around for 100 years as well."
So, to you if there is no formal information on something then it doesn't exist? Maybe the transformer is the victim of pre-conceived notions and not many people decided to find out if there was a break-in effect?
I have to ask what is the depth of your education and training in electronics or electrical engineering?
It's one thing to question proven theory after you have not only deeply studied the material, but also practiced the science.
But how can you question proven established theory and practice if you do not understand the material?
I have a Ph.D in analytical chemistry, which included quite a fair amount of formal training in electronics. However, my real training came during my Ph.D where I co-designed laser Mass Spectrometer systems. I worked on mechanical design, lasers and optics as well as digital and high voltage (up to 15KV) electronics. I also had a lot of practical experience in the optimization of the signal transmission from the detectors to the high speed oscilloscopes (> 1Ghz) that were capturing the signal. This was because of high capacitance in the dectors and having to pass through the high voltage section, which required blocking caps as well. Because of the high frequencies we had ringing from the signal bouncing up and down the coax cable due to impedance mismatch. This required months of optimization and measuring return loss with a $100K HP network analyzer. We eventually redesigned the circuit to deliver more than 40db return loss (originally was only 6db). Nothing of the actual circuit elements were changed though, only the geometry of the parts layout (funny stuff RF). I also learned how to trouble shoot and repair $500K laser systems when their power supplies blew up. For digital, we designed a digital counter that took inputs from laser light scattering as a trigger to start, to stop and to count down, without interferrence from other scattering events. This required a sophisticated blocking circuit that I designed using differnt logic gates. This was all done with TTL logic chips and originally hand wired (clock speed of 20Mhz). The counter would then latch and could be read by the computer and then a reset command from the computer reset all the locked gates.
Since then my work has taken me to build charge/voltage amplifiers to measure electrostatic discharge on aerosol particles, Charge detection systems for powders (have an internal patent on that one) and some devices for audio (loudspeakers mostly but also my own direct drive TT with servo motion control system using an optical encoder.
However, I am a scientist and not a fully professional engineer (although I have done a fair amount of engineering on very sophisticated equipment) and as such I make measurements for a professional living. Correlation between measurements and a human response is one of the most diffcult things to do and so it is no wonder to me that the correlation between numbers and perception are limited and often contradictory.
So, I am keenly interested in the CORRELATION between measurements and subjective results. This is the final frontier for audio IMO. It is the most difficult part...not designing an amp with "inaudible" distortion numbers.
What is your background? Professional engineer? Wannabe? What is your system? It is not posted. Are you on the SET forum just to cause trouble? If you think SETs are great sounding but that one can't hear subtle things this is more than a bit contradictory.
It seems to me after reading this that a bunch of brilliant chemistry and physics Phd's took on an electronic design project thinking, "hey, we are Phd's, not lowly engineers. Surely we can build this rig ourselves".
Did you have a competent EE on your team? It doesn't look that way to me. These are very basic problems that should have been caught early in the blueprint phase.
" This was because of high capacitance in the dectors and having to pass through the high voltage section, which required blocking caps as well."
So you had to decouple the high voltage DC in that area? OK, the person that design that circuit didn't know that while it was in the blueprint stage?
"Because of the high frequencies we had ringing from the signal bouncing up and down the coax cable due to impedance mismatch. This required months of optimization and measuring return loss with a $100K HP network analyzer. We eventually redesigned the circuit to deliver more than 40db return loss (originally was only 6db)."
This is basic transmission line theory. As an RF engineer myself I find it hard to believe an experienced engineer wouldn't know to properly terminate coax cables in an RF application within the design stage.
"Nothing of the actual circuit elements were changed though, only the geometry of the parts layout (funny stuff RF)."
Yeah, what can I say. RF is tricky yet many engineers have mastered this so called black art.
"So you had to decouple the high voltage DC in that area? OK, the person that design that circuit didn't know that while it was in the blueprint stage? "
Please don't try to reverse engineer what you don't understand, ok? Obviously it was known but what wasn't known was the degree to which we would be having problems with signal reflections. Do you not understand how a Ph.D. is done? We don't have teams of EEs hanging around to sort out every problem (as if professional EEs forsee every potential design issue...LOL!). Let't not think about cost overruns and other issues big companies face or do you have the illusion it is all "first time right"??
"Yeah, what can I say. RF is tricky yet many engineers have mastered this so called black art"
Once again, did I say I was employed as an engineer for Siemens or HP? We sought the help of professional RF engineers...how do you think we got access to an HP network analyzer...it was not as trivial you would like everyone here to believe.
However, I understand a bit more why you are dismissive about audio engineering...nothing more or less than professional arrogance because you think your kind of EE is superior.
I am not dismissive about audio engineering at all. Quite the contrary.But reinforcing claims that 100hr solder connections sound different than fresh solder connections is hardly audio engineering. It falls under "audiophile voodoo".
Ditto that for most of the burn-in theories.
If you are so confident that exist, then prove it. Because the professional audio community as a majority does not subscribe to these claims. That is a fact.
You are just as arrogant to come into a field to which you have no professional experience and try and tell us our 100year old proven theories and concepts are based on shoddy information. Again prove it! Because otherwise nobody in a position of authority in the AV business is listening to you.
Edits: 08/24/15 08/24/15
"You are just as arrogant to come into a field to which you have no professional experience and try and tell us our 100year old proven theories and concepts are based on shoddy information."
THe funny thing is that you think it is me saying...I am getting this information from your own engineering community! I merely read and synthesize the information. I am not doing experiments in my basement laboratory on most of this stuff...just making a DD turntable with optical encoder feedback control at the moment is about it.
I know orthodox views on this stuff...it is the bulk of what's out there. But they were largely wrong about amp design and sound, to my ears, in the last 50 years so I can imagine they are largely wrong about break-in and parts audibility...I can also think of mechanisms for how those things might change...I too do not believe in voodoo but I am more respectful of human hearing than you seem to be...
So now you are saying (to your ears) that audio amplifier desing for the past 50 years is flawed?How?
Explain what lacking improvements are needed?
Now I am not going to be foolish to state amplifiers are perfect. But for PRACTICAL audio reproduction purposes, they are damn near straight wire with today's electronic components.
Also what is so special about an analog audio amplifer that is not relevant in other precision analog applications. Are you saying audio represents the most critical electrical noise and distortion floor?
Edits: 08/24/15
Gusser is right.
Infamous sockpuppet
"So, to you if there is no formal information on something then it doesn't exist? Maybe the transformer is the victim of pre-conceived notions and not many people decided to find out if there was a break-in effect?"
I think there is sometimes a tendency to fantasise that things are more profound and complicated than they really are. It is maybe nice to dream that one's home stereo amplifier is going to reveal deep truths about fundamental electrical principles that have been overlooked by all the EE experts for decades. But maybe a home stereo amplifier really is just the rather simple piece of electronics that others say it is. It doesn't have to deal with the demanding circumstances of high frequencies or high currents that EEs have learned how to cope with in much more challenging areas in electronics. Perhaps it really is just a rather trivial application, after all.
If those who speak of all these subtleties in audio reproduction were able to demonstrate in proper double-blind testing that they could actually hear the effects they claim to hear, then it might be more convincing. But evidence from such tests seems to show that people, even "pros," are hard pressed to distinguish between *any* pair of amplifiers that have reasonably low THD if their frequency responses have been matched if necessary by means of simple RC networks.
Chris
"I think there is sometimes a tendency to fantasise that things are more profound and complicated than they really are."
I disagree. THere is a tendency by engineers to oversimplify when things related to human perception are actually quite complicated.
"that have been overlooked by all the EE experts for decades"
Not overlooked but observed and disregarded because of the oversimplification tendency above.
"But maybe a home stereo amplifier really is just the rather simple piece of electronics that others say it is."
Simple, yes on the surface, but in the details not simple at all. I recently changed the power supply capacitors in my preamp...changed the sound significantly. I didn't measure though before and after to see if there was a measureable difference...maybe there was and maybe not.
"If those who speak of all these subtleties in audio reproduction were able to demonstrate in proper double-blind testing that they could actually hear the effects they claim to hear, then it might be more convincing."
I am a research scientist for a big Pharma company and I can tell you that double-blind is not a suitable test for audio. It is difficult enough to do these studies correctly with human biology let alone to do them correctly with human psychology. Messy doesn't begin to cover it. Perhaps this is what bothers the engineers so much because it is so easy to show repeatable measurements (I should know, analytics is my speciality) but how they relate is another story (we often have difficulty demonstrating In vivo/In Vitro correlation for drug dissolution...you think auido is easier???).
I am a MEASUREMENT scientist and have a lot of experience professionally measuring not only chemical responses with sensitive instrumentation also measuring the performance of the instruments themselves (I co-designed and built some highly sophisticated mass spectrometers). We use high precsion electronics on a daily basis. However, in the pharma industry it is difficult but required to demonstrate some kind of correlation between drug MEASUREMENTS and clinical behavior.
There have been some more recent attempts to correlate audible issues with measured types of distortions with some success. It should be noted that in those more recent attempts it did not come down in favor of the ultra low THD crowd.
Based on your comments it seems that you would favor rather than a SET (this is the SET forum you are commenting in afterall) but rather a ultra low THD SS amp...is that correct? Those are, afterall, "properly" designed based on "known" engineering principles and fully worked out theories, right? Some even measure, for the most part, below "audibility".
Trust me, as a scientist and part-time engineer, I would love to see amps with virtually "zero" distortion sound the best...it would fit with logic as far as the assumption is that non-linear devices can be forced into linearity. However, all is not quite as it seems and this is where the scientist in me takes over and tries to dig into the root causes of sound. This is where the "simplicity" of audio engineering veers away from the "tried and true" path obviously taught in school...it simply doesn't deliver the sonic goods!
Before you go off thinking I only like euphonic sounds and that realism is not what I seek I would refer you to some articles. One is by Keith Howard where he manipulated sound files by computer. He naturally found the unadulterated file to sound the best (this would be the theoretical perfect amplifier that doesn't exist) but he found that certain distortion patterns were far less objectionable than others. You can find the article in Stereophile.
Likewise, Cheever found that a distortion pattern that mimics what he defines as "Aural harmonics" at all levels (it is a level dependent metric...therefore also depends on the speaker attached) will be inaudible as it will be thoroughly masked by the listner's ear/brain mechanisms. Break with the pattern and bad things start to happen.
"I disagree. THere is a tendency by engineers to oversimplify when things related to human perception are actually quite complicated."
Fine. Then go publish a paper with your finding and prove us all wrong!
Your background is quite impressive as written. However I have a problem with your measurement skills as demonstrated here.
If you do perform scientific measurements as stated, then why do you support the idea if skin effect in audio cables? Ditto that for jitter in DAC circuits. Yes both of the phenomena do exist but countless qualified measurements clearly show the effect is well below established human hearing abilities. Furthermore as I pointed out above, Some of the jitter measurements are below the noise floor of most power amplifiers.
So if you have this deep background in precision measurements, why do you seem to have no comprehension of scale when it comes to electrical measurements.
I think what you are saying is the sensitivity of human hearing is grossly under estimated. Again, do some qualified research based on your credentials and publish your findings in accredited journals subject to peer review.
"I am a research scientist for a big Pharma company and I can tell you that double-blind is not a suitable test for audio."Yes, one hears such assertions, but what is the real basis for saying this? A chap claims he hears a "night and day" difference between amplifier configuration A and amplifier configuration B. He's then tested in a double-blind listening, and he fails to be able to distinguish them. What is the flaw in making the deduction that he was imagining the differences in the first place?
"Based on your comments it seems that you would favor rather than a SET (this is the SET forum you are commenting in afterall) but rather a ultra low THD SS amp...is that correct? Those are, afterall, "properly" designed based on "known" engineering principles and fully worked out theories, right? Some even measure, for the most part, below "audibility". "
I like making and using tube amplifiers largely for nostalgic and aesthetic reasons, I suppose. I don't have particularly strong feelings or opinions one way or the other about whether they sound better, or worse, than solid-state amplifiers. According to what one can read (for example in the accounts of the Richard Clark "amplifier challenge"), even alleged experts are unable to distinguish between the sound of a tube amplifier and a solid-state amplifier, provided that neither has particularly large distortion, and provided that the frequency response of (typically) the solid state amplifier is downgraded with simple RC networks (and maybe a series resistor on the output) to match that of the tube amplifier. I have never tried such experiments myself, and so I do not know for sure that I too would fail to be able to discriminate between them, but I have no reason to think I would do any better. Of course, if one knows what one is listening to, it is very easy to hear differences that accord with one's expectations or prejudices, and I have most certainly experienced that myself.
I sympathise with people's desire to imagine an intricate world of ultra-fine nuances in the sound that their favourite amplifier produces. And in fact, it may be that in a sense their imagining these nuances does actually bring them into being, via the incredibly complex interplay of the senses and the human mind. But if theses nuances cannot be demonstrated and verified in objective listening tests, it is surely more honest to recognise them for what they evidently are, namely imagined effects that exist in the mind of the listener?
Chris
PS: My homemade amplifiers are mostly OTL, and one is an ultra-linear push-pull. I'd like to try an SET some time, which is why I like to follow the SET forum too. Some would say, I think, that SET may give distortions, or perhaps colourations is a nicer word, that would exceed the bounds allowed in listening test like the Richard Clark amplifier challenge, and such that even a dyed-in-the-wool objectivist like myself could hear a difference. So I'd be interested to try that.
Edits: 08/24/15 08/24/15
I won't debate double-blind here with you because it has been done ad nauseum. Suffice to say that I don't think it applicable to audio testing and you apparently do think it appicable.
I have heard things that stunned the hell out of people...ones who were totally unbiased or in fact biased towards the amp that sounded attrocious. They were not audiophiles...just seeking my help for a decent system. We first got new speakers and a cd player (they didn't have one) and then we went looking for an amp. After hearing a few and looking at the prices they asked, "Can't we just keep what we have?". I said sure, but let's just have a couple of the ones you liked there for comparison. They hooked up the Cary CAD572SE (nice amp actually) with a Transcendent Sound GG preamp and were groving to the sound. Then we hooked up their Denon integrated...and the smile ran away from their faces...like instantly. The girl, "OMG, that sounds bad!"...the guy "It is so gray and dead". I said nothing, except "should we try the other amp again?" They said yes, music returned and they bought the Carys and Transcendent and gave the Denon away. The speakers were the tube friendly AudioPlan Kontrast IIIs. Nice two-ways, easy impedance moderate sensitivity. I know it's anecdotal but after having SO many of these kinds of experiences with non-audiophiles hearing differences for the first time like that as well as my own extensive experience in Single blind studies (did it with cables and with preamps mostly), I don't think there is much doubt in the difference in the sound of electronics.
"I like making and using tube amplifiers largely for nostalgic and aesthetic reasons, I suppose. I don't have particularly strong feelings or opinions one way or the other about whether they sound better, or worse, than solid-state amplifiers."
You expect me to believe this? I don't. You make them and use them because you obviously prefer the sound to SS amps...or you would be making and using those too, no? Do you even own a SS amp?
"According to what one can read (for example in the accounts of the Richard Clark "amplifier challenge"), even alleged experts are unable to distinguish between the sound of a tube amplifier and a solid-state amplifier, provided that neither has particularly large distortion, and provided that the frequency response of (typically) the solid state amplifier is downgraded with simple RC networks (and maybe a series resistor on the output) to match that of the tube amplifier. "
IMO, once you start modifying the amps to "match" you can call the whole thing off. That would be like me saying "let's add a bit of active compound to the placebo to make them more similar" or some such nonsense.
One should simply use a loudspeaker where the impedance of the speaker is high enough not to impact the FR significantly. You could even have one high and one low sensitivity if you think that this matters.
"I sympathise with people's desire to imagine an intricate world of ultra-fine nuances in the sound that their favourite amplifier produces. And in fact, it may be that in a sense their imagining these nuances does actually bring them into being, via the incredibly complex interplay of the senses and the human mind. But if theses nuances cannot be demonstrated and verified in objective listening tests, it is surely more honest to recognise them for what they evidently are, namely imagined effects that exist in the mind of the listener?"
Stop playing with OTLs, they are apparently too good for your needs.
"My homemade amplifiers are mostly OTL, and one is an ultra-linear push-pull"
I have had both. Neither was fully satisfying so far. I will try SET OTL at some point though just to see. Most PP ultra-liner amps simply don't sound right; either too lean (too much feedback usually) or too warm (transformer saturation) or a combination of the two (both problems). The VAC 30/30 is a really nice sound PP Triode amp though...not too warm and great bass and extension in the highs without glassiness.
THe Trnascendent Sounds were not stable on my Acoustats so they didn't stay long (would oscillate after a few mW). The Silvawelds made the room too hot to stand but were stunning in their transparency. However, they were a bitch to keep biased AND they did not have the coherence of a top SET (of course if you don't accept that these things are audible it is not really possible to discuss this nuance with you). It is perhaps something that is only really an issue with a time coherent, single driver speaker (like my Acoustats). The other issue was that tonally they were somewhat leaner than I hear in real-live concerts (of the unamplified sort). I heard just the other day a small concert with accordian, guitar, violin and bass. I stood 2 meters away. The sound was powerful and harmonically RICH...even a bit lush. No amps or speakers just instruments. It was unlike anything I have heard from a SS amp driven system.
" I think, that SET may give distortions, or perhaps colourations is a nicer word, that would exceed the bounds"
Based on my research, really top SET amps are LESS colored in the ways that are most objectionable to listeners. People are so used to bleached out sound that they think the SET is "adding" euphonic colorations.
"and such that even a dyed-in-the-wool objectivist like myself could hear a difference"
I find it hard to believe you are a "dyed-in-the-wool" objectivist when you use "bad" measuring tube amps.
"You expect me to believe this? I don't. You make them and use them because you obviously prefer the sound to SS amps...or you would be making and using those too, no? Do you even own a SS amp?"
I do have a rather old commercial SS amp (Yamaha something or other, I can't quite remember what); it sounds perfectly fine to me, but I just got into the amplifier-building habit a few years ago (revival of my hobby from younger days). Since then, I've hardly used the Yamaha. I did also build a MOSFET circlotron a couple of years ago; a class A beast with giant heatsinks. It's OK, but somehow the OTLs with 6C33C tubes from MIG fighters create more of a talking-point in the living room! So, do I prefer the sound of the tube amps? No, I don't think so particularly. I do prefer them as objects to enliven the room, though.
"Stop playing with OTLs, they are apparently too good for your needs."
Haha! Nice observation!!!
"IMO, once you start modifying the amps to "match" you can call the whole thing off. That would be like me saying "let's add a bit of active compound to the placebo to make them more similar" or some such nonsense."
Well, I think Richard Clark's point was that any audible differences between one amplifier and another, as long as their THD wasn't too big, could be taken care of with a couple of dollars worth of resistors and capacitors. That's quite a stunning claim, really! And apparently, he put his money where his mouth is, and offered a substantial prize to anyone who could prove him wrong. And nobody managed it.
"I find it hard to believe you are a "dyed-in-the-wool" objectivist when you use "bad" measuring tube amps."
I'm a dyed-in-the-wool objectivist who doesn't believe there's enough objectively audible difference between the performance of reasonably respectable tube vs SS amps to make it worth having strong preferences one way or the other.
"Based on my research, really top SET amps are LESS colored in the ways that are most objectionable to listeners. People are so used to bleached out sound that they think the SET is "adding" euphonic colorations."
The thing is, though, that all the prior N stages in the progress of the audio signal from the recording studio to the listener's living room will have come through solid-state equipment which you would presumably say will have also "bleached out" the sound? If the SET amplifier in the very final stage of the signal's journey ends up making it sound to be not bleached out, then that surely suggests it is *adding* something euphonic? You seem to be saying the SET amplifier can compensate or "correct" for umpteen previous stages of bleaching. There is nothing wrong with that, if it adds enjoyment for the listener. And indeed that's why I'd be quite interested to try one for myself.
Chris
Chris you raise a good point about previous audio stages being SS etc.
The main difference, IMO, is that small signals are not nearly as demanding of an application compared to the large signal's requirements to couple to a mechanical device of varying impedance while maintaining fidelity.
Infamous sockpuppet
"Chris you raise a good point about previous audio stages being SS etc.
The main difference, IMO, is that small signals are not nearly as demanding of an application compared to the large signal's requirements to couple to a mechanical device of varying impedance while maintaining fidelity."
Well, that is a possible explanation. On the other hand, by the standards of what solid-state devices handle in other more challenging situations in electronics, the signals involved in a home stereo amplifier are really pretty minuscule, even in the output stage driving the loudspeaker. It does seem a bit of a stretch to suppose that the solid-state devices in the prior stages in the signal path handle things perfectly well, without "bleaching out" the sound, but that suddenly in the final stage (and the only one that happens to be under the control of the audiophile himself), their ability to handle the signal properly breaks down.
It seems to me that a much more economical explanation (in the sense of needing to invoke fewer additional assumptions of questionable plausibility) would simply be that the SET amplifier "removes the bleached out" sound precisely because it adds in colourations that are pleasing to the human ear. It is, after all, typically rich in second-order distortion, which apparently the ear finds attractive.
Chris
"SET amplifier "removes the bleached out" sound precisely because it adds in colourations that are pleasing to the human ear."
THis has been debunked by Keith Howard in a rather clever experiment involving software manipulation. He found that NO added distortion sounded the best. Given that this does not exist with real amplification devices (he was adding patterns of distortion to a file of music) then there is only worst, less worse and least worst.
So, if an amp sounds less strident, smoother and more harmonically like "the real" thing it is not because it added just the right amount of juju to the recording (otherwise it would not work from recording to recording because the amount of juju would have to change) it is because it is adding less ANNOYING juju to the recording.
2nd order has been shown to be inaudible up to several percent and according to Cheever if in balance with other "aural" harmonics it will remain inaudible. Only when it is out of balance with the other harmonics in the correct pattern and at the correct level will it sound this way. If out of balance and high enough in level to exceed masking thresholds, then it will "warm" the sound. However, correct harmonics is not just an injection of 2nd order to restore balance. It is far better if the ear hears nothing or next to nothing of the distortion.
The goal, until truly linear amplifying devices can be invented, is to put the distortion in the "blind spot" of human perception rather than try to eliminate it, which 50+ years of trying has failed to do from a perceptual standpoint. Why do you think SETs made a fierce comeback? It had little to do with nostalgia I can assure you (I am not nostalgic in the least...I am extremely pragmatic). I like modern televisions, computers, trains, planes and automobiles. I also like modern electronics for measurements and performing scientific experiments. It's not nostalgia that brought back the SET, it was sound quality, full stop.
No we have not eliminated distortion in the past 50 years. But there are class B power amps out there that measure down to 0.008%.
So faced with that the SET fans now claim that's the wrong type of distortion to measure?
SET amplifiers are a cult. They can work well in specific applications that have careful speaker, listening room, and music content selection. But you don't find them in professional applications. There may be a handful of audiophile record labels that use SET amps but hardly the mainstream studios that mix 99% of what is available to the public.
But you don't find them in professional applications
Well, actually there is a strong return to the use of microphones with tube preamps and those are often single ended circuits.
There was an interesting article from the mid 70s where they went hunting for what went wrong with studio sound and they found the main culprit was the switch from tubes to transistors in those studios.
So faced with that the SET fans now claim that's the wrong type of distortion to measure?
Not SET fans at all...and starting way back at the dawn of the use of negative feedback from the likes of D.E.L. Shorter from the BBC, Norman Crowhurst and a few others crying the alarm but an industry not taking heed.
You keep misunderstanding the nature of the problem. It is not the level of distortion (Geddes demonstrates that there is no significant correlation between sound quality and THD and IMD...however, his graphs show a slight NEGATIVE correlation!) but the pattern of that distortion as a function of SPL level.
We have had "perfect" measuring amps for a long time now and many of them simply sound like shit. Otala found a part of the problem but not all and amps designed to minimize slewing often still sound bad.
"SET amplifiers are a cult."
I disagree with this stupid statement wholeheartedly. They are owned people who were drawn to how the things SOUND in an appropriate setup. THat are sensitive to things you are apparently not sensitive to. They probably would have stayed with their SS amps with 0.0001% THD (most probably started there and got dissatisfied...I know I did) if they thought they sounded better...but they didn't because they don't. I especially hate it when people try to put some kind of religious mantle onto what are nothing more than luxury objects to bring people joy when listening to music. No one is being forced to drink the poison coolaid here or to tithe over their bank accounts to serve a demagogue.
With the specific systems they work in they work better than anything else.
"but hardly the mainstream studios that mix 99% of what is available to the public."
I'm sorry, i thought we were listening to high quality recordings and talking highend audio here but apparently you are not. Like I give a crap what the latest Eminem or Beyonce records sound like or how they were mixed. Yes, some good rock music is also poorly recorded but I don't dumb down my system to make it tolerable...I would much rather have a good recording of Beethoven's 9th symphony sound like I am in the middle Zuerich Tonhalle.
The problem with early transistor preamps was lack of dynamic range which tubes are superior by default. Better silicon technology has greatly improved this however I will agree a tube mic preamp is still superior. It's the old question of if modern transistor preamps are good enough. For most pro applications, they are.As for single ended amplification, I was referring strictly to SET power amps. Look at any OPAMP circuit. Sure they are push pull output but the VAS stage is most always single ended. I am not denouncing single ended amplifier stages at all. I am denouncing $10,000 plus SET amplifiers with greater then 10% THD at a few watts of power and poor PSRR to boot! They are only made commercially by very small manufactures and sold in very unique stereo shops - often on special "made to order" policies. Not to many people buy them hence the cult status. Outside of table radios and low cost TV output stages, the audio industry abandoned SET since the 1940s and there is no evidence of it ever coming back en masse.
The Otala feedback theory is a farce and has been denounced many times since it's publication.
The physics and electronic theory is dead on. You cannot correct a fast rise time signal by measuring it after the distortion is applied. TIM can be demonstrated in most any feedback amplifier using a cheap square wave generator. And many audio magazines have shown the scope shots. But for all the electronics genius of Otala, many have overlooked the 800 pound gorilla in the room.
Show me a musical instrument or any natural or man made sound that can produce a fast acoustic rise time at over 10khz in our 15psi atmosphere? Beyond that show me a mechanical microphone that can respond that fast if such a pressure wave was even possible.
While TIM is real and can easily be simulated, no audio amplifier will ever be called upon to reproduce such a signal in sound reproduction. TIM in audio amplifiers is an academic exercise, nothing more.
The real issue with early transistor power amps was crossover distortion caused by early semiconductor limitations. This is no longer a problem for at least the past 20 years.
Otala's work did however bring to our attention stability issues. His work led us to superior feedback compensation design. This is why HF square wave testing is still very important in audio amplifier design, especially with today's commodity wide bandwidth power transistors.
Read Morgan Jones, Douglass Self, Rod Elliot, Randy Sloan for power amp design expertise. I have and my power maps, a 9.2.4 HT system are all DIY. I built some tube ampssp over the years as well.
Edits: 08/25/15 08/25/15 08/25/15
"It's the old question of if modern transistor preamps are good enough."
If the tube pre amp is still better for sound quality (of which we both agree) then how can a transistor preamp be "good enough" when sound quality should be the most important factor in making a recording??
"They are only made commercially by very small manufactures and sold in very unique stereo shops - often on special "made to order" policies. Not to many people buy them hence the cult status"
yes, the are handmade and therefore more expensive...priced a handmade car these days?? Craftsmanship costs...always has, always will. I agree with you though that it is not a guarantee of great sound...they can screw stuff up just like everyone else. The best ones though have been designed by inspired individuals with a deep understanding about the interactions of parts to make a whole.
A bigger problem that is not much discussed, IMO, is what happens with the back EMF pulse from a speaker. If the amp has a feedback loop some of that distorted back EMF pulse will re-enter the amplifier and be amplified along with the signal. It could well explain why some amps are very speaker dependent despite on paper being very load invariant. An amp without negative feedback cannot be impacted this way and might actually be more tolerant of certain types of speakers...especially those with highly reactive behavior like electrostats.
Apogee ribbons behave almost like a pure resistor (at least as close as you are likely to see in a real loudspeaker) and they are actually pretty tolerant of all kinds of amps. Amps seem to give their best with Apogees and I think lack of reactance is part of the reason why. SETs even work well because of the even impedance curve (my friend's Studio Grands are 5 ohms and only vary between about 4 and 6 ohms.).
"The real issue with early transistor power amps was crossover distortion caused by early semiconductor limitations. This is no longer a problem for at least the past 20 years.
"
I disagree, you can routinely see crossover effects in Class A/B amps in stereophile measurements. It is not really any better, or worse than it was for an amp like the Hafler DH500 or Crown Macro Reference (a horrible sounding amp according to several reviewers but measured nearly perfect). Again, the crossover distortion in those older amps was not at a very high level (inaudible most engineers would say...as if they had a clue) and yet it was highly audible because it produced a VERY unnatural pattern of distortion harmonics.
"Read Morgan Jones, Douglass Self, Rod Elliot, Randy Sloan for power amp design expertise."
Been there done that and it all reads very convincing...except where the proof is in the pudding as they say. The amps designed using the best engineering practice don't sound as good as those "antiques". Ever hear a Halcro amp? What about Soulution? Forget the price for the moment, which is ridiculous. Both of these brands measure about as good as I have ever seen for commercial amps. Halcro SOUNDS dead and sterile, Soulution sounds better but still "soulless" and clinical. It doesn't matter which recording and this tells me that it is an amplification artifact and not a source material choice. If you can show me better measuring amps I would love to see them but probably not to hear them.
So, why should this be the case...they are as Douglas Self would say "blameless". And yet I have heard Soulution on about 5 different pairs of speakers and rooms and still come away with the same damning conclusion. I am not the only one. I took my wife with me to the Munich show this year and we went first to the uber-expensive Magico/Soulution room. At first she was impressed with the clarity...it is definitely clear but then with wide dynamic material she noted that the dynamics seemed constricted and that the tone was rather "gray". She is not an audiophile and I said nothing to her about the room in advance because I wanted to run a little "experiment" with her to see which rooms she found natural and those she did not (she is a big fan of live classical and Jazz concerts though).
We went to the Silbatone room and listened to 1930s theater speakers with modern Silbatone electronics (SETs and vinyl of course). On came an opera singer signing in Russian and my wife started to cry! The sound was beautiful and lifelike and utterly moving. For sure the absolute distortion was an order or two in magnitude higher but for delivery of MUSIC it was no contest...Magico/Soulution lose big time.
I could go on but suffice to say the rest of the experiment mirrored this one. On other interesting thing. The room with the Tune Audio Anima horn speaker was very promising except for some sharpness in the lower treble that bothered both of us. When we looked at the system it was all tube except the amp, which was a Modwright SS amp. No other horn system at the show had this kind of sharpness that used a tube amplifier.
I like to do these kinds of experiments with music lovers who are non-audiophiles because there are not the pre-conceived notions. Then you really see when they realize something sounds realistic or not. My ex-girlfriend is a professional violinist (first violinist in a number of euorpean orchestras) and she could tell in about 10 seconds if a room was worth listening to or not. I used to record her and take some of my own recordings as reference material. That usually sorts things out rather quickly.
"THis has been debunked by Keith Howard in a rather clever experiment involving software manipulation. He found that NO added distortion sounded the best. Given that this does not exist with real amplification devices (he was adding patterns of distortion to a file of music) then there is only worst, less worse and least worst."
I'd be interested to read about that; do you have a reference to an article?
Chris
http://www.stereophile.com/reference/406howard/index.html#Gd1Yfp5PBldxyIxA.97
FWIW, I think Hiraga was wrong in claiming a monotonic harmonic pattern is Euphonic...it is not. WHat it CAN be if the pattern matches precisely with the level as per Cheever, is Invisible or at worst less damaging than other types of distortion patterns.
I think this is the article he is referring to.
Infamous sockpuppet
Edits: 08/25/15
no, but that one is also interesting...you should go to the Gedlee website and read the source material for this particular article by Keith Howard. There you can see the plots, the distortion types measured in a lot more detail.
You should also read the Master's Thesis of Daniel Cheever (also found on the web as .pdf) and I found another more recent thesis
http://www.dancheever.com/main/cheever_thesis_final.pdf
http://projekter.aau.dk/projekter/files/9852082/07gr1061_Thesis.pdf
and to expand on the topic.
Infamous sockpuppet
"I think this is the article he is referring to."
Hmm... not sure. Your first link http://www.gedlee.com/downloads/THD_.pdf is to an article by Keith Howard on a new proposed weighting for characterising distortion. The second one you gave seems to be a sort of summary of points in a presentation he gave at an Audio Engineering Society lecture. It has some discussion of how non-linear transfer functions can be used to create specific harmonic distortions, and some related ideas. There is also a link there to some free software he has provided, one of which apparently allows one to introduce any desired harmonic distortions to a .wav file.
I don't see anything there that reports any experiments that "debunk" the idea that SET amplifiers may be creating distortion effects, or colourations, that listeners like.
Chris
"Hmm... not sure. Your first link http://www.gedlee.com/downloads/THD_.pdf is to an article by Keith Howard on a new proposed weighting for characterising distortion."As it turns out it was not the article he was referring to, nonetheless it does touch on the topic by the same author.
The reason for the weighting schemes are (From the article) "higher order nonlinearities (which give rise to high order distortion products in a sine wave measurement) are more aurally objectionable then lower order ones and should be given greater weight in any subjectively relevant measure of distortion level."
Now, we have to surmise that devices (SETs for example) that produce predominantly low, even-order harmonics is going to be producing a more accurate signal, that's just the way it is.
(The beneficial consequence of this is that subtle acoustical textures will become un veiled, this is where the "richness" comes from.)
This doesn't mean it is adding a bunch of fuzz to warm up the sound, on the contrary.
Also keep in mind that all devices are going to produce some sort of distortion or "colorations".Now, this isn't the end of the story, all devices are also going to interact with speaker nonlinearities, however to keep this point succinct, it is better to keep the harmonics low and even ordered before it gets to the speaker. As mentioned before, this is what differentiates the SET power stage vs solid state small signals.
Pretty easy myth to debunk really. The human ear is sensitive to un correlated side-bands produced by harmonics.
It's all about avoiding some IMD to gain a little more accuracy.
Infamous sockpuppet
Edits: 08/25/15
> "The human ear is sensitive to un correlated side-bands produced by harmonics."
Yes.
-------------------------------------------------------------
Big speakers and little amps blew my mind!
Yes SETs are typically "rich" in low even order harmonics.
It might be more accurate to say that the ear is less offended by low even ordered harmonics then it is by higher odd order harmonics typically created by SS gear.
Vanishingly small distortion numbers on SS gear doesn't negate the fact that high odd ordered harmonics have little correlation to the intended fundamental tone.
That is why they stand out so much, despite measuring less then the typical SET.
On the other hand, second even order harmonics resembles the intended material closer, therefor is less noticeable.
What coloration is noticed could be considered an enhancement that fattens up the tone a bit if it is excessive.
There is no doubt that transistors are used in very demanding industrial, mechanical and symbolic digital applications, however handling complex analog audio signals (HiFi) is not their strongest point due to complex inter-modulations created by their inherent distortion spectrum.
(This causes the problems with consonants that I mentioned earlier(Typical SS imparted sibilance))
So IMO it's not a stretch to believe that the last stage has such influence on the sound, as it imparts the biggest change to the signal's voltage level.
It also has to drive a mechanical device in an acoustically believable fashion, without creating excessive amounts of offensive distortion.
It's more about finesse and dexterity then slew rate or outright power handling.
Infamous sockpuppet
"On the other hand, second even order harmonics resembles the intended material closer, therefor is less noticeable.
What coloration is noticed could be considered an enhancement that fattens up the tone a bit if it is excessive. "
Yes indeed. But it would be a mistake for the audiophile to imagine that this colouration is "restoring" some details of the original performance that have somehow been "lost" on the way from the studio. It is more that it injecting some colourations of the same general kind that are typically present in "rich sounding" performances.
Chris
The funny thing is that you think they have all been lost in the recordings. In some cases this is true and it will still sound like that on a good SET...but perhaps not as exaggeratedly bad. With top recordings though it will feel like a real live performance (particularly if it is a very good live recording...but usually not a rock recording).
Yes I would agree with that if the distortion is excessive.If the distortion is not excessive, I would still opine that the relatively unmolested signal from a SET would still sound richer, due to lack of strident sounding distortions found with other typologies.
Infamous sockpuppet
Edits: 08/25/15 08/25/15
"Yes I would agree with that if the distortion is excessive.
If the distortion is not excessive, I would still opine that the relatively unmolested signal from a SET would still sound richer, due to lack of strident sounding distortions found with other typologies."
Perhaps you are right. It really comes down to the question of how much distortion, and at at different orders, is actually audible. I would tend to trust double-blind testing for judging these questions, since I have no vested interest in disbelieving what it reveals.
If tests like the Richard Clark challenge are reliable, then people are actually considerably less sensitive to tiny high-order distortions than is sometimes claimed.
Chris
I agree that SETs are not necessarily as coloured as made out to be.
The strong point in my opinion, is the ability to convey realistic sibilance.
The last few days I had been listening to my SS receiver while I cleaned up a bit.
When I put the SETs back in the system, the improvement in coronal consonants was immediately apparent.
As many have found over the years, despite measuring slightly worse then modern SS gear, the good old SET is still king when it comes to rendering believable acoustical textures.
Infamous sockpuppet
I thought the biggest thing that needs to break-in with tubes is the cathode coating.
As I understand it new tubes have uneven electron emissions until the cathode coating burns in.
I once asked the guy at Jensen transformer about the burn in period for they excellent MC SUTs.
He just laughed.
Tre'
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