I'm just saying that it sounds like a cop-out to say on one hand that they are more accurate but on the other hand that one will only accept one's own listening experiences as evidence of their accuracy, which I hear all the time.>>
Well, it's not a cop out - if I had tons of measurement gear and knew how to use it, I'd gladly do so.
But how do you specifically measure timbre? You can hear it but I don't know how you measure specifically for this. I'd be interested to know.
andy
Well, it's not a cop out - if I had tons of measurement gear and knew how to use it, I'd gladly do so.
But how do you specifically measure timbre? You can hear it but I don't know how you measure specifically for this. I'd be interested to know.
andy
You don't measure timbre, you determine if the preamp is audibly altering the signal that goes through it. That's easy to do with a low impedance source and a bypass test. You do need to carefully level match, but that takes nothing more exotic than a good voltmeter. Again, you may LIKE the way your preamp alters the signal, and that's fine if "sounds good" is a design goal for your preamp. But the preamp cannot be called "accurate" if you can hear any difference in a bypass test.
SY said:
Having a goal, i.e. to achieve timbre close to live instruments intimate knowledge, does not mean that it is actually captured like that in the various recordings, and for venues or mic distances that those took place. Of course accuracy to the recording can be less pleasing day in day out for some (most?) people, than approximating some ideal. So I am with SY when looking for the truth. But what is a successful design in general? There is no success reference system or ways to achieve if we don't determine that. To me the answer is: Whatever design meets its predetermined standards is successful. If monitoring is the standard, then we must use criteria of a certain order. If some certain timbre quality always present in the mix is the standard, criteria change.
andyjevans said:
Please note what I said about accuracy - meaning as SY said, no change from input to output. This is precisely my point - that accuracy (at any point in the chain) and realism of the final product are not the same thing. If in fact DHT's are more accurate, then distortion must be lower. Timbre is nothing mysterious - it's the fundamentals and all the harmonics. If you think it is something magic, then I'll bow out right now.
Like it or not, you are talking about illusion. I don't quite understand why people turn up their noses at this concept. The only thing you can possibly have is, by definition, an illusion.
andyjevans said:
You are making my point for me. The preamp (or amplifier), with the rest of the system, doesn't have to be accurate in the absolute sense, it just has to tickle your senses in a way such that you are reminded of the real thing, and your brain does the rest. I don't think that this is a very exotic concept in psycology. Heck, we've all had the experience of a sensory input that triggers very vivid recall. Ever smell something and been transported to a specific recollection? Get the sound close enough (probably in very specific ways) and it will sound "real". Is this necessarily accurate in the objective sense? I don't think so. Does it matter? No, if you are guided by you own ears and you have found what you like. Yes, if you want to understand the mechanisms and want to be able to design for specific outcomes.
I have no problem with your assertion that DHT's do it for you, and IDHT's don't. I do take issue with this statement: "Clearly the preamp stage is critical - it establishes the sound that then gets amplified through the chain. Lose something and it's lost." How do you reconcile that with the above quote about all the devices in the recording/mixing chain? How can you recover what has been already "lost"? And what is a preamp anyway, but just another amplification stage? Why should it take out information that all that other stuff doesn't? Logically, it doesn't add up.
However, if we postulate that the music needs something to make up for the inherent artificiality of the entire reproduction chain, it's perfectly conceivable that a single component in the chain will do that. More than one might be better. Seems the problem may be a hang up about purity. DHT's are seen by the DHT only crowd as somehow more "pure". The implication that they might actually add some "impurities", however beneficial, just doesn't jive with the orthodoxy. That's no more useful than the orthodoxy that the only good amp is one with wire with gain (which is true for a laboratory amp). If the point is to create an illusion that works for you (and that's the best you will ever be able to do), then relax and accept sin into your life. If it sounds good, do it.
Sheldon
Historically amplifiers have been measured using static measurements. THD, IMD..... they are all measured under static, unchanging conditions. And yes they are fairly easy to do. A good sound card and some (often free) software and you can make these measurements. We can often measure and talk about slight harmonic distortion differences between diferent amplifiers. Are they responsible for what we are hearing? Do we like the sound of a big solid state wall thumper with 1.21 giggawatts of power and .0000000% distortion? Do all of the amplifiers that measure great sound the same? There must be something else going on here.
However as we all know, music is far from static. Can we make dynamic measurements? That is a hard question to answer. There have been numerous attempts, but the results have been inconclusive. When my daughter lived at home, she and her friends played instruments. My daughter played the drums. I made some recordings using a mike and a PC using cakewalk software. Play the recording through a stereo, and record it again with the same microphone. Then compare the WAV files. I can tell you that the sound of a drum stick hitting the rim of a snare gets distorted. The worst offender is not the amp, it is the speaker. Different speakers do different things to this highly dynamic sound.
Unfortunately I did all this about 10 years ago, and lost interest about 9 years ago. The PC with all the wave files is long since dead. My daughter and her drum set (and xylophone) have been gone for 5 years.
So, we do what Kodak did, build some audio Kodachrome! After all what we want is to please our own ears. What good is an amp that measures real good and sounds like an iPOD?
Kodachrome printed on Cibachrome that was the ticket. Unfortunately when I got married I could no longer justify having a 3 bedroom house, 1 bedroom, 1 electronics lab, and 1 darkroom, so the darkroom went away, and I went over to the dark side (digital). At least all of the glowing tube pictures that I post are photographed through Zeiss glass!
SY said:
That is an interesting observation. It seem reasonable, on the surface, as uncorrelated (if it is that) noise can have a distracting effect on our brain and cause us to focus less on the unnaturalness of the reproduction. I don't know if I am doing a good job of explaining that, but I am thinking of a parrallel with jitter of the uncorrelated versus correlated nature.
"Is it worth using anything other than DHTs for preamps?"
Depends: open loop, or NFB?
These small signal DHTs almost always seem to have low u-factors, but with large r(p)'s and small g(m)'s. Does that make a difference?
In the final analysis, if you've got something that you like to listen to, then you done right.
Depends: open loop, or NFB?
These small signal DHTs almost always seem to have low u-factors, but with large r(p)'s and small g(m)'s. Does that make a difference?
In the final analysis, if you've got something that you like to listen to, then you done right.
Bitrex said:
Then you suppose that:
- of any sound that is different valued by the brain ear combination of a certain individual than another sound, it is possible to make that change in appraisal (indirect) visible on an electronic measuringinstrument that is connected to the sound producing "system".
- because the sound is produced in a long chain of different components that interact with each other it must be possible that, if you exchange one or more components, you isolate all kind of causes and effects that occur and also prove that there is a relation with the psychological appraisal of it.
On the challenges of measurement, remember it took around 30 years from mathematically proving that the PSU must be modulated even in small signal situations, to developing techniques to 'measure' this effect.
Or look at the development of Jitter measurements - initially folks couldnt understand why austensibly the same CD player (integrated transport and dac combination), could sound so different... 15 years or so later, and the finger was pointed firmly at an artifact called 'Jitter'
The DHT movement is fuelled by big old beautiful triodes, who provide a very characteristic sound - but there are many old radio gems that were used in the RF and IF stages, and moderate powers are available (up to 750mW) for next to no money.
My prime suspect for the difference - the emission of electrons from the heater surface in an IDHT - each electron displaced takes energy with it - and in an IDHT there is only a radiative link between the heater and the cathode.
That means that there will be localised micro variations in the overall emission levels, that a DHT, because there is no thermal lag, may be avoiding.
There is also the consideration that an IDHT carries artifacts from the heater psu (which is usually just an AC feed) through emission feedback (inside of cathode to heater is a DHT diode remember) - and that is why top end IDHTs have massively engineered heater supplies....
With a DHT, its is very obvious that the heater supply is in circuit, and why the heater supplies tend to be well engineered in the first place.
Just my thoughts on a complex mechanism
Owen
Or look at the development of Jitter measurements - initially folks couldnt understand why austensibly the same CD player (integrated transport and dac combination), could sound so different... 15 years or so later, and the finger was pointed firmly at an artifact called 'Jitter'
The DHT movement is fuelled by big old beautiful triodes, who provide a very characteristic sound - but there are many old radio gems that were used in the RF and IF stages, and moderate powers are available (up to 750mW) for next to no money.
My prime suspect for the difference - the emission of electrons from the heater surface in an IDHT - each electron displaced takes energy with it - and in an IDHT there is only a radiative link between the heater and the cathode.
That means that there will be localised micro variations in the overall emission levels, that a DHT, because there is no thermal lag, may be avoiding.
There is also the consideration that an IDHT carries artifacts from the heater psu (which is usually just an AC feed) through emission feedback (inside of cathode to heater is a DHT diode remember) - and that is why top end IDHTs have massively engineered heater supplies....
With a DHT, its is very obvious that the heater supply is in circuit, and why the heater supplies tend to be well engineered in the first place.
Just my thoughts on a complex mechanism
Owen
This entire discussion is just a subset of a bigger question: why do people like preamps? Arguably the most mysterious and electrically unnecesary in most systems box. Yet, to most of us music sounds better through an active pre and quite clearly despite the addition of noise and distortion. If DHTs sound even better that's fine, no need to prove how much more linear they are
Is it worth using anything other than DHTs for preamps?
For you andyjevans, who appears not to study the engineering behind his builds, and only cares about his own sentiment, and who seems to have reached happiness with his preamplifier, then the answer is a clear 'no'.
For the rest of the world, who want to understand the objective engineering behind the objective and subjective results, then the answer is a clear and resounding 'yes'.
Andyjevans if you can not suggest why your DHT may produce better results than your previous designs then your posts are no more than sentiment driven nonsense and have no value.
Just my opinion.
G.
For you andyjevans, who appears not to study the engineering behind his builds, and only cares about his own sentiment, and who seems to have reached happiness with his preamplifier, then the answer is a clear 'no'.
For the rest of the world, who want to understand the objective engineering behind the objective and subjective results, then the answer is a clear and resounding 'yes'.
Andyjevans if you can not suggest why your DHT may produce better results than your previous designs then your posts are no more than sentiment driven nonsense and have no value.
Just my opinion.
G.
owen said:
You seem to be suggesting a type of compression. If there is any meaningful difference, it would be in favor of the more massive IDHT cathode. Also, compare the temperature transients due to a music signal to the far more massive swings due to an AC heated filament, yet many people prefer AC heated filaments.
owen said:
How does this jive with the assertion that the only connection between heater and cathode for an IDHT is radiative? In the prior case, a weak connection between heater and cathode is asserted. Here that weaker connection increases the influence of the heater PSU on the cathode?
Let's see: "top end IDHT"S have massively engineered heater supplies".
And: "With a DHT, ... supplies tend to be well engineered in the first place".
?
Sheldon
I'm reading this thread with great interest. The postulate that the construction of the filament in DHTs enhances realism is very interesting. Against it is the argument "so how come all acoustic intruments get enhanced in such a way as to sound closer to what appears to listeners to be real instruments?". I haven't really heard a convincing reply to this. Various arguments proposed are that DHTs may enhance some of the effect so as to trick the brain into thinking the sound is closer. Quite a plausible argument - after all a caricature may be closer to a personality than a photo, and we know that listeners prioritise certain aspects of what they hear (I readily hold my hand up to prioritising timbre). And the complex chain of reproduction before the preamp stage makes the effect of one DHT doubtful, so I guess that's another point to "enhancement".
I continue to have difficulty with "measure what goes in and what comes out" because as a few with more technical knowledge than myself have pointed out, measurement as an art/science evolves and we are continually finding both better measurements and better isolated artefacts to measure within any phenomenon. I particularly remember an article way back in time in HiFi News where some Frenchman whose name escapes me (?Jean Hiraga) measured moving coil cartridges and concluded that the EMT for one could be shown to sound more faithful because of its harmonic spectrum. Maybe someone has a reference for this? So is measuring timbre a question of measuring the harmonic spectrum dynamically over time?
The other thing that occurs to me is that with timbre, we may be dealing with extremely tiny changes. Nevertheless, they are audible changes in the sense that highly trained musicians can identify the tiniest changes in timbre - the difference between a Guarnerius and a Stradivarius for instance - and routinely have to blend with other musicians in contexts like orchestras and string quartets.
I hope there are more interesting arguments to come here, and I appreciate the time Sheldon, Sy and you folks have put into arguing this. I launched the thread as a hypothesis, of course, as Sheldon has rightly picked up.
andy
I continue to have difficulty with "measure what goes in and what comes out" because as a few with more technical knowledge than myself have pointed out, measurement as an art/science evolves and we are continually finding both better measurements and better isolated artefacts to measure within any phenomenon. I particularly remember an article way back in time in HiFi News where some Frenchman whose name escapes me (?Jean Hiraga) measured moving coil cartridges and concluded that the EMT for one could be shown to sound more faithful because of its harmonic spectrum. Maybe someone has a reference for this? So is measuring timbre a question of measuring the harmonic spectrum dynamically over time?
The other thing that occurs to me is that with timbre, we may be dealing with extremely tiny changes. Nevertheless, they are audible changes in the sense that highly trained musicians can identify the tiniest changes in timbre - the difference between a Guarnerius and a Stradivarius for instance - and routinely have to blend with other musicians in contexts like orchestras and string quartets.
I hope there are more interesting arguments to come here, and I appreciate the time Sheldon, Sy and you folks have put into arguing this. I launched the thread as a hypothesis, of course, as Sheldon has rightly picked up.
andy
andyjevans said:
OK, but SY specifically didn't limit the measurement to a particular instrumentation view. Remember, you have the option of listening for a difference. To reiterate; pick a low impedance source (ideally the source and pre would have similar output impedance) that you can plug directly into your amp and listen at reasonable volumes. Set the volume control of your pre for unity gain (measure AC voltage in and out to be equal with a single tone, let's say 1kHz). Listen to music with the pre in line, and without the pre. If you hear a difference, the pre is altering the signal. You decide if it's a good thing or not. There is no requirement to define the difference.
Sheldon
andyjevans said:
By the way, to all the non-musician engineer types, sound, after being converted to electrical energy by the ear, travels through the brain stem to the rest of the brain. There is good evidence, contrary to what has been thought for many years, that the brain stem is plastic, and that musical training actually changes how and what we hear.
http://www.soc.northwestern.edu/bra...cuments/Musacchia.Sams.Skoe.KrausPNAS2007.pdf
http://www.soc.northwestern.edu/brainvolts/projects/music/index.php
The point being that just because you can't hear something, does not mean that someone else can't.
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