Sure - I know that amps handle signals. I build amps and I own a fair amount of test gear. I can't put donuts into an amp and get carrots out. 🙂
But the signal that goes in is not the signal that comes out, we hope. Unless we are talking about a unity gain line driver - even then it's not perfect.
I still don't understand why "fidelity to the original sound, not always to the original signal" is such a difficult concept. As I've stated before (but it got no comment) ultimately I don't give a rat's patootie what happens to the signal in the amp or preamp, as long as what I HEAR sounds real. My goal is for the sound reaching my ears to sound real. I want the sound I hear to be faithful to sounds of real voices, instruments, concert halls, etc. If that can be achieved with a perfect signal transfer, great. If the electronics need to alter the signal to convince me the sound is real, so be it. It's the end result that is important to me. The rest of it is just a means to an end.
Really, I don't know how to explain it better. I'm perfectly happy with a perfect signal, IF it gives the desired result. If it doesn't, then why do I want it?
It is not a difficult concept; it just isn't hi-fi.Pano said:
To restore anything lost (i.e. whatever was in the original sound but not in the signal) you need to know exactly what was lost. Only then can you replace it. Equalisation works like this.
An alternative, which satisfies some people, is to add something not in the original sound but which can fake what was in the original sound but now has been lost. Even then you need to have some idea what was removed.
Simply having a distorting system and then asserting that it replaces what was lost is either kidding yourself, or attempting to kid us. It is far more likely that you are just adding something which you prefer. Nothing wrong with that; just not hi-fi.
It's not that the concept isn't difficult, it's that it's very slippery. What does that actually mean? These days, sound has the hell processed out of it. This has always been the case. Back in the olden times, Eight Track promised the convenience of compact cassettes with the fidelity of reel-to-reel. However, sound engineers knew that Eight Track machines were going into cars, not listening rooms, and so didn't give the mastering the attention pre-recorded R-2-R programs got. When Eight Track players began showing up in listening rooms, they sounded "off". It was one of the things that destined Eight Track to oblivion (that and the interruptions in the middle of songs as the heads switched tracks, the improvement in compact cassette sound quality, the size inconvenience of the Eight Track cassettes).
We've seen the same thing regarding the engineering of other recorded media: mastering to cover up for the sonic defects of production, solid state amps that most people use. Does "fidelity to the original sound" mean deliberately making bad amps to hide the defects of bad recordings? By the time you get your hands on that CD, a lot has happened to the "original sound". More and more, what has happened are not good things.
As a designer, how do I account for that? The best I can do is to design for maximum linearity in the open loop performance, and correct the defects with NFB. Of course, I also "voice" my designs (solid state and hollow state) since I "eat my own dog food" and have to live with them. That means that designs like the Vixen and Le Renard work best with Metal and Techno, since that's what I listen to. I've seen over and over that folks who like choral music prefer SE amps running little to no NFB.
The best I can do is to add another twiddle knob on the front panel that adjusts the level of NFB, sort of like a Doug Self "niceness" control.
Sigh.... But that's my whole point - the point I seem not to be able to get across. There is a definition of High Fidelity that demands the signal be strictly adhered to. That is Fidelity to the signal. OK, nice definition - but why is it the only one? Fidelity to live sound before the recording is not valid? Fidelity to everyday reality? Only a slavish devotion to the original signal is valid?
Ah - see? Now we are getting somewhere and I posted this a couple of days ago - it got no comment.
Yes. There are many encode/decode systems, Dolby, RIAA, NAB, PCM, ect. These are known encodings that can be accurately decoded. They have to be decoded, or they'd sound anywhere from a wrong off to dreadful. Do more subtle, unintentional encodings exist? I argue that they do, and are present in almost every recording.
Every piece of recording gear I've ever used or measured altered the signal in some way. Some of the alterations are intentional, many are not. It's the unintentional alterations that are of interest here, as we don't know how to decode them, or even if we should try decode them. But perhaps, to some extent, we can. Alterations to the playback signal may be able to undo some of the damage done in the recording process. Of course, we don't know what they are - so it's hard to put back exactly what's been lost, no argument there. But we may be able to put back some of it. The circuits and faults found in the recording chain are similar from device to device, so it may be possible to restore some of those faults. Success will be inconsistent, since the faults are inconsistent, if they weren't we wouldn't be arguing about it. 😉
Are we fooling ourselves by altering the signal to achieve a more accurate sounding result? Does it matter? The whole thing is an illusion. The whole point is to fool you into believing that you hear Pablo Casals playing or Sammy Davis singing or Scarlett Johansson speaking. The point is the illusion. If the illusion is made more convincing, how can that be wrong?
There is something about this discussion and partly the line of reasoning that escapes me.
I've been working in electronics since the mid 70s. At EE school we were taught about transfer functions and the theory for harmonic, IM and linear distortion. I don't think they are up for arguments or modifications. The ideal amplifier is defined as the ' infamous wire with gain, i.e a circuit with a linear amplification factor with only first order frequency components. Everything else added or altered is defined as distortion of one or more of the known types and mechanisms, - ideally all defined as unwanted bi-products, no matter how weak they are. Therefore, the output signal is the only real value of measure. Sound is hopefully the necesseary result of the signal.....
For years now, there has been a sort of consensus, that the distortion producs were somewhat different between tube and SS, - as a sort of 'signature' of the two topologies. There are a few other major factors that may differ between the two, like output impedance or damping factor and maybe rise time.
You cannot have an output signal that 'sounds good', without having an input that sounds equally good! ?? If that is the case, you have a signal enhancer, which is certainly not HiFi. If one still thinks that is OK, - so be it.... why should someone else decide what I or you like? I'll admit it is not my cup of tea, but still....
A crappy amp is still a crappy amp, and mostly unwanted, but I've often wondered about this slightly hysterical approach to playback og music that you KNOW is recorded through bucket-loads of 741's ( as is most music from the 70's)..... still using a 741 in the playback chain has been sacrilege for 40 years or so.... go figure 🙂
I've been working in electronics since the mid 70s. At EE school we were taught about transfer functions and the theory for harmonic, IM and linear distortion. I don't think they are up for arguments or modifications. The ideal amplifier is defined as the ' infamous wire with gain, i.e a circuit with a linear amplification factor with only first order frequency components. Everything else added or altered is defined as distortion of one or more of the known types and mechanisms, - ideally all defined as unwanted bi-products, no matter how weak they are. Therefore, the output signal is the only real value of measure. Sound is hopefully the necesseary result of the signal.....
For years now, there has been a sort of consensus, that the distortion producs were somewhat different between tube and SS, - as a sort of 'signature' of the two topologies. There are a few other major factors that may differ between the two, like output impedance or damping factor and maybe rise time.
You cannot have an output signal that 'sounds good', without having an input that sounds equally good! ?? If that is the case, you have a signal enhancer, which is certainly not HiFi. If one still thinks that is OK, - so be it.... why should someone else decide what I or you like? I'll admit it is not my cup of tea, but still....
A crappy amp is still a crappy amp, and mostly unwanted, but I've often wondered about this slightly hysterical approach to playback og music that you KNOW is recorded through bucket-loads of 741's ( as is most music from the 70's)..... still using a 741 in the playback chain has been sacrilege for 40 years or so.... go figure 🙂
Pano,
You make good (and valid!) points, but to me different concepts can get confused here.
Firstly to 'easy out' (!), the thread started about "tube sound", thus mainly concerning the electronics of amplifiers tube or transistor. Regarding that, fidelity per dictionary definition can only involve "the original" as the signal entering the amplifier.
Yes, your point of the sound is valid, but one thing at a time! Then another factor slips in: The original as perceived by you. Again no quibble, but it is known that that is experienced differently by different people. You correctly bring in what to you sounds similar to the original. That involves inter alia your memory, and one then runs into the difficulty that unless you were present at the specific original .... I think you will get the point. No wrong answers here, just different ones.
Thus, as I perceive it too many variables in this approach to "fidelity". Preference, yes! Taste yes! But the term fidelity is going to 'hang up' somewhere in this process, to use a PC term. But going back to the thread subject: As Miles suggested, one can only really come back to the concept of fidelity as in: "No difference between the input and the output (signal)" - and per the subject, no difference that will be audibly detected. (We are not discussing instrumentation amplifiers.)
You make good (and valid!) points, but to me different concepts can get confused here.
Firstly to 'easy out' (!), the thread started about "tube sound", thus mainly concerning the electronics of amplifiers tube or transistor. Regarding that, fidelity per dictionary definition can only involve "the original" as the signal entering the amplifier.
Yes, your point of the sound is valid, but one thing at a time! Then another factor slips in: The original as perceived by you. Again no quibble, but it is known that that is experienced differently by different people. You correctly bring in what to you sounds similar to the original. That involves inter alia your memory, and one then runs into the difficulty that unless you were present at the specific original .... I think you will get the point. No wrong answers here, just different ones.
Thus, as I perceive it too many variables in this approach to "fidelity". Preference, yes! Taste yes! But the term fidelity is going to 'hang up' somewhere in this process, to use a PC term. But going back to the thread subject: As Miles suggested, one can only really come back to the concept of fidelity as in: "No difference between the input and the output (signal)" - and per the subject, no difference that will be audibly detected. (We are not discussing instrumentation amplifiers.)
AuroraB!I am amused (bemused?) by the frequent reference to the the "original sound"!
In so many recordings there is NO original sound!
Small ensembles listening through headphones to whatever the guy at the desk feeds them. 20 mics fleshing out each instrument group in a symphony orchestra!
What sound? What the mixing engineer hears? What the conductor hears? What I hear in my premium left of center front row balcony seat? (I can see a pianist's hands!)
OK, one can say that it sounds like a real whatever, that it sounds realistic and exciting. That it sounds great and I like it!
But not like the mythical original. The best I can say is "I like it."
AuroraB,
Perhaps apology for seemingly repeating the same ideas as yourself. We typed simultaneously and I was not aware of your contribution before hitting the 'send' function.
I can only add a small point to your good post, and that is that one is actually concerned with the difference between input and output, not just the output - but I think that is what you have meant.
(Like the quotation in your signature! Have not seen it before.)
Perhaps apology for seemingly repeating the same ideas as yourself. We typed simultaneously and I was not aware of your contribution before hitting the 'send' function.
I can only add a small point to your good post, and that is that one is actually concerned with the difference between input and output, not just the output - but I think that is what you have meant.
(Like the quotation in your signature! Have not seen it before.)
For artificially generated music in the studio, certainly there is no "original sound" to pursue...
I expect this is why there is so much demand for early jazz recordings like the Mono columbia 6 eye recordings where the engineers were trying to be faithful to what went down in the studio. To my ears, if these most natural and unprocessed recordings sound as natural as possible, then the system is doing its job well.
I made comment to a friend the other week that some recent recordings sound worse when you play them on a better system. They seem to have been engineered for nothing more than MP3 and laptop playback, and the better the replay chain, the more the glaring faults in production become apparent. Why would you design a system to make Katie Perry sound good at the expense of good replay of a well recorded jazz trio?
I expect this is why there is so much demand for early jazz recordings like the Mono columbia 6 eye recordings where the engineers were trying to be faithful to what went down in the studio. To my ears, if these most natural and unprocessed recordings sound as natural as possible, then the system is doing its job well.
I made comment to a friend the other week that some recent recordings sound worse when you play them on a better system. They seem to have been engineered for nothing more than MP3 and laptop playback, and the better the replay chain, the more the glaring faults in production become apparent. Why would you design a system to make Katie Perry sound good at the expense of good replay of a well recorded jazz trio?
To repeat, nothing needs to be added to the sound to make it sound "better" - there's enough detail in what was captured originally to create a subjectively satisfying experience during playback. However if this detail is 'smeared', discarded or mangled in the various, typical ways of most audio systems then the listening will be pretty ho-hum. Equalising and suchlike are of no value in 'fixing' this - only sorting out the problems that "dirty" the playback process will be good enough ...
You are obfuscating what I wrote and it appears to be intentional. Reread this post.
Why are you keep omitting the part (bold) quoted below?
Reread the sentences with that word intact and you will understand.
Then talk about speakers and room acoustics, preferrably on separate threads.
Then talk about equalizer, preferrably on a separate thread.
When you say "I want the sound I hear to be faithful to sounds of real voices, instruments, concert halls, etc. ", are you saying you want the sound you hear in a specific recording to be faithful to the real voices, instruments, concert hall, etc., of that specific performance whose recording you are listening to, or are you saying you want it to sound like your idea of what voices, instruments and concert halls generically sound like? The way you phrased it, it seems you are saying the latter.
Leaving aside obvious examples such as the use of universally agreed equalisations like RIAA curves, the notion that the amplifier could introduce distortions that could make each specific recording sound more like the original performance of that specific recording seems highly implausible.
On the other hand, it is more plausible that the amplifier could introduce distortions that make a recording sound more like some "generic" original performance, by adding in some harmonics or whatever that are typical of what the ear/brain may feel is "missing." But then, this is really the process of adding in sound effects that give a generic impression of greater realism. It is not recreating the specific version of realism that is faithful to that specifc original performance.
Chris
Facts:
-Valve physics and circuit topologies tend to result in lower power amplifiers that have a higher THD+N than SS amplifiers, but with distortion largely comprised as low-order harmonic distortion, primarily 2nd-order for SET topologies and decreasing odd n-th order for PP topologies.
-SS amplifiers, due to the almost mandatory use of GNFB, have more interphase distortion. The distortion generated by SS amplifiers is of lower magnitude but listening tests (non-objective) have identified it as being "harsher" on the ears compared to valve amplifiers.
-Due to being lower-wattage, valve amps beget high-efficiency speakers. Class-A amplifiers operating with high-efficiency speakers tend to sound good! Operating in a the "first watt" region (thank you Mr. Pass) most of the time where the amplifier is highly linear. It doesn't matter if it's tube or solid state.
-Any sound reproduction system introduces distortion; room acoustics/gain, nonlinear load characteristics of loudspeakers, speaker distortion, varied nonlinear frequency response of the human ear... amplifier distortion is just part of it.
-The goal of "high fidelity" is to reproduce the recorded signal at higher amplitude. SS amps perform better than valve amps for objective measurements here, because the SS amp's signal (using THD measurement) is closer to the ideal "wire with gain." Discussion of the characteristic distortion from valve amps and their associated topologies is meaningless if the "goal" is a true high fidelity amplifier.
-Psycho-acoustics is real. Knowing (or thinking) that the amplifier is using glowing glass bulbs and transformers and not silicon chips to amplify your sound might be enough to make you think it sounds better. Knowing that you spent $5000 on a 10W amplifier might be enough to make you think it sounds better. You might actually like the large amounts of 2nd-harmonic distortion from a SET. None of it is measurable, but it doesn't mean that isn't a different sound to be had from a tube amp (ABX testing has proven this) and that some people, for whatever reason, prefer it.
Completely made up: Tube warmth, recreating the original sound, voicing instruments, smoothness, liquidity, adding back what was lost in the recording...
-Valve physics and circuit topologies tend to result in lower power amplifiers that have a higher THD+N than SS amplifiers, but with distortion largely comprised as low-order harmonic distortion, primarily 2nd-order for SET topologies and decreasing odd n-th order for PP topologies.
-SS amplifiers, due to the almost mandatory use of GNFB, have more interphase distortion. The distortion generated by SS amplifiers is of lower magnitude but listening tests (non-objective) have identified it as being "harsher" on the ears compared to valve amplifiers.
-Due to being lower-wattage, valve amps beget high-efficiency speakers. Class-A amplifiers operating with high-efficiency speakers tend to sound good! Operating in a the "first watt" region (thank you Mr. Pass) most of the time where the amplifier is highly linear. It doesn't matter if it's tube or solid state.
-Any sound reproduction system introduces distortion; room acoustics/gain, nonlinear load characteristics of loudspeakers, speaker distortion, varied nonlinear frequency response of the human ear... amplifier distortion is just part of it.
-The goal of "high fidelity" is to reproduce the recorded signal at higher amplitude. SS amps perform better than valve amps for objective measurements here, because the SS amp's signal (using THD measurement) is closer to the ideal "wire with gain." Discussion of the characteristic distortion from valve amps and their associated topologies is meaningless if the "goal" is a true high fidelity amplifier.
-Psycho-acoustics is real. Knowing (or thinking) that the amplifier is using glowing glass bulbs and transformers and not silicon chips to amplify your sound might be enough to make you think it sounds better. Knowing that you spent $5000 on a 10W amplifier might be enough to make you think it sounds better. You might actually like the large amounts of 2nd-harmonic distortion from a SET. None of it is measurable, but it doesn't mean that isn't a different sound to be had from a tube amp (ABX testing has proven this) and that some people, for whatever reason, prefer it.
Completely made up: Tube warmth, recreating the original sound, voicing instruments, smoothness, liquidity, adding back what was lost in the recording...
Thanks Johan for taking the time to understand, and to point out the problems.
What I'm saying isn't perfect, but neither is Hi-Fi. If a perfect illusions has been found, I don't know about it yet. Chris makes points very similar to yours.
Very much the latter, Chris. I can't know exactly what the sound was like during the recording unless I was there (that does happen). And I wouldn't expect an exact copy anyway, it always gets manipulated to some extent. I just want a consistently plausible illusion. What I want out of a home audio system is is for it to convince me that what I hear is real, over and over again, across many recordings and musical styles. The system should also allow me to hear the differences in recordings, the ambiance of the venue being a very good clue. Such systems exist and I don't remember hearing any that contained "effects boxes". What a system like that gives me is a strong illusion of reality, that's what I want. And when the recording isn't "real" - say anything from Switched on Bach to Justin Bieber - the results are still plausible, as tho something like that could exist. It's an illusion. I hear people talking and singing every day, I have a good idea what that sounds like. Many audio systems don't reproduce that realistically. I want one that does. Same for guitar, tuba, piano or drums - they should sound real.
As for "Tube Sound" - I've picked Solid State over tube amps in a few blind tests, because I thought the SS had more of a "tube sound." 😱 I.E., more natural, better timbre, less fatiguing, better reproduction of the recording acoustics, etc. Those are things I've often heard tube amps do better than solid state, so that's "tube sound" in my mind. Like many stereotypes, it ain't all that accurate. Certainly other people have other ideas of what tube sound is, that just happens to be mine.
In brief, one amp might be doing all sorts nasty things to the signal, but if I can't hear them, so what? I'll still prefer that amp over another that makes fewer changes, but changes that are audible and annoying. It's the final result that matters to me. What I hear.
If you are saying that what you are really looking for is a modification (or, to put it in a way that sounds a little more pejorative, a distortion) that produces a plausible generic sort of "concert hall sound," then it does seem that you are asking for an effects box that creates the illusion of reality. There's nothing wrong with that, but it would be misleading to claim that the sound was more faithful to "the original," where "the original" means literally what you would have heard had you been present at that specific performance in that specific concert hall. In that sense, it does not seem to meet the criteria for being a particularly "High-Fidelity" rendition, either of the original sound or of the signal coming from the playback medium.
Chris
Because those are terms made up by salesmen to try to convince you that spending your money on a tube amp is worth it. And because psycho-acoustics works (that is to say, you measure the sound you perceive and are not an objective observer), it works. Instruments have different harmonic characteristics. So do microphones and recording equipment. The idea that a single amplifier can "bring back what was lost" from every recording for every instrument just isn't feasible. Unless there was a deliberate equalization compression applied (i.e. RIAA), the amp simply adds harmonic content. Which can be pleasant. Better than interphase content, to my ears.
Don't get me wrong, I spent a good chunk of change building a 6550 SET amp, and I recognize that it sounds different from my LM4780 chipamp; even the triode/UL/pentode modes sound different. I also recognize that that is personal preference, perhaps based on the fact that I put time, money, and effort into building the thing, and I like the way it looks in between my speakers.
Don't get me wrong, I spent a good chunk of change building a 6550 SET amp, and I recognize that it sounds different from my LM4780 chipamp; even the triode/UL/pentode modes sound different. I also recognize that that is personal preference, perhaps based on the fact that I put time, money, and effort into building the thing, and I like the way it looks in between my speakers.
Wouldnt this be more up to the design more than toobs vs SS , you can design SS to have soft clipping ...
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