Sound replay system imaging is a construct. It can be measured but that will be on the components of this construct such as amp distortion, frequency response, dispersion pattern, speaker distortion... etc.
I'll reiterate that speaker distortion is a key thing that comes to mind as something that could break the virtual image. Something like H2 has a fixed relationship with the signal from the channel that caused it, not the summed signals. H2 is twice the frequency, so for any given phase shift that the channels sum to, the distortion is going to be coming in at some other angle. H3 summed will have a different phase angle again. And various crackles and pops from magnetic hysteresis would essentially be noise that is both chaotic and different for each channel.
What may be hard to believe is that the electronics, mainly the amplifier to be specific, can affect speaker distortion. This is regularly discussed in the occasional "current drive" threads, specifically because it's a small subsection of the DIY community trying to gain a better understanding of how and why things like damping factor or output impedance have a direct impact on speaker distortion, as a separate thing from the equation that most people think it is.
The usual, (over simplified) equation:
Total (D)istortion = Electronics D + speaker D
Improved equation:
Total D ~= Electronics D + intrinsic speaker D + excess speaker D from drive mismatch
Where "drive mismatch" is a catch-all term, suggesting that some other damping factor may be more optimal for that particular speaker, at the problem frequency.
Hi abstract,
Absolutely, mechanical transducers can have properties that differ between L & R channels. Better speakers that are not damaged has a much lower problem with this.
The fact remains, and let's not be diverted here, the electronics are more alike by far than speaker systems, and certainly room acoustics. If you change the electronics and the imaging changes, you are imagining it, or the electronics are broken in some way. Period. Your room position changed too. Now what do you think may have the greatest effect on perceived imaging. Your room position or what you may be thinking (assuming)? The only variables that have changed.
Absolutely, mechanical transducers can have properties that differ between L & R channels. Better speakers that are not damaged has a much lower problem with this.
Correct again. However a stereo has two nearly identical channels, or two mono blocks sold and designed as a matching pair. So effects on the speaker is the same, this then drops out of the equation.
Right. Taking things to an extreme here, normal speaker systems and drivers are not designed to be driven via a high impedance source. I spent the first decade of my career designing loudspeaker systems and was a hobbyist for ages before that.
The fact remains, and let's not be diverted here, the electronics are more alike by far than speaker systems, and certainly room acoustics. If you change the electronics and the imaging changes, you are imagining it, or the electronics are broken in some way. Period. Your room position changed too. Now what do you think may have the greatest effect on perceived imaging. Your room position or what you may be thinking (assuming)? The only variables that have changed.
Actually, I would note that usually about half the speaker bandwidth has RLC components playing with the output impedance, with a simple inductor being the bare minimum for most woofers. Nothing extreme about that.
What is still unusual are systems that are both active and multiway at the same time. That's kind-of going against the logical grain, unless specifically using full-range drivers as dedicated woofers or mid-ranges. Otherwise, the benefits from active filters limiting the bandwidth coming into the amplifier, are countered by sound quality losses from the damping factor being too high at high frequencies. The battle for ±0.1dB flat frequency response, regardless of load swings is pointless and damaging.
I don't think Nelson Pass' range of amplifiers would enjoy the popularity they do, if it wasn't for the low damping factors (among other things). And no amount of "euphonic distortion" would necromance tube amplifiers from the dustbin of history, either.
Hi abstract,
Having designed speaker systems from early days when Thiel and Small just released their paper, I'm going to respectfully disagree with you.
Many designs can be called popular when they really are not. Class "A" tube per channel with 300B for example. They sound different, but most people tire of that sound after a bit. They colour everything the same way and it is not musical, it is distortion.
All the silliness of low feedback design, playing with feedback levels along with everything else has gone in cycles. We keep going back to what actually does perform well. Back in the 1920's they figured out that push-pull was the way to go. Nothing of quality in the 1930s was single ended. The entire industry evolved without our help along the lines of improved performance and what sounded the best. These days we can measure it and it does agree with subjective (unbiased) opinion.
As a result, loudspeakers today are designed to be driven from a low impedance. Can you mess around with it and get something that sounds sort of okay but different? Sure you can, but you are fighting the natural design. But to claim that mis-using a part (a loudspeaker driver) is better, well that defies reason. That and it is simply incorrect. You will always find examples of poorly performing equipment no matter what design you chase, but the better, properly designed equipment will smoke a fanciful design backed by a great story only. Every single time.
The real test. All music sounds natural, or the way the recording studio intended it to. If something only sounds good with certain music, it is broken or poorly designed.
Having designed speaker systems from early days when Thiel and Small just released their paper, I'm going to respectfully disagree with you.
Many designs can be called popular when they really are not. Class "A" tube per channel with 300B for example. They sound different, but most people tire of that sound after a bit. They colour everything the same way and it is not musical, it is distortion.
All the silliness of low feedback design, playing with feedback levels along with everything else has gone in cycles. We keep going back to what actually does perform well. Back in the 1920's they figured out that push-pull was the way to go. Nothing of quality in the 1930s was single ended. The entire industry evolved without our help along the lines of improved performance and what sounded the best. These days we can measure it and it does agree with subjective (unbiased) opinion.
As a result, loudspeakers today are designed to be driven from a low impedance. Can you mess around with it and get something that sounds sort of okay but different? Sure you can, but you are fighting the natural design. But to claim that mis-using a part (a loudspeaker driver) is better, well that defies reason. That and it is simply incorrect. You will always find examples of poorly performing equipment no matter what design you chase, but the better, properly designed equipment will smoke a fanciful design backed by a great story only. Every single time.
The real test. All music sounds natural, or the way the recording studio intended it to. If something only sounds good with certain music, it is broken or poorly designed.
Yes, devices such as amplifiers and CD players, but also loudspeakers, and individual parts, like resistors or transistors, have different image sizes.
One way to correct this is to rearrange the speakers. And here I generally advise starting with zero distance between them. And to listen. And then move them apart step by step and listen. Until the sound image tears apart. Then move them closer together again until you have a homogeneous, coherent stage with balanced depth, width and height - height, because I also have some parts that somehow also deviate in terms of imaging height ;-)
One way to correct this is to rearrange the speakers. And here I generally advise starting with zero distance between them. And to listen. And then move them apart step by step and listen. Until the sound image tears apart. Then move them closer together again until you have a homogeneous, coherent stage with balanced depth, width and height - height, because I also have some parts that somehow also deviate in terms of imaging height ;-)
Since individual parts, even of the same batch, sound different - i.e. are perceived by the ear as sounding different...
A simple test is to connect the channel-separated power supplies of the "monoblocks" together.
Then you can think further: if the modern complementary PPs run on two power rails (+ and -), i.e. on separate power supply units, even if these consist of parts from one batch, but the ear...
I'm really sorry, but the ear is the absolute, least reliable thing out there to detect sound. I do measure differences between channels, but at levels far lower than anyone can hear. I have never heard a difference in imaging by changing amplifiers or preamps. Not once.
I've measured equipment that "sounds great" after it was modified elsewhere. It measured terribly by the way. Once normal performance was restored, the owner couldn't believe they thought it sounded good. Not one owner, but all of them across decades. Equipment repaired by "technicians" without measuring equipment often fails spec, and it doesn't sound good either. At the very least, it could perform and sound better.
We all say, "to heck with measurements, it only matter how it sounds to us!". Well, sure. It does. If the measuring equipment lead in the wrong direction you have a point ... but it doesn't. When equipment performs better, people like it better. No shock to people who understand how things work.
I've measured equipment that "sounds great" after it was modified elsewhere. It measured terribly by the way. Once normal performance was restored, the owner couldn't believe they thought it sounded good. Not one owner, but all of them across decades. Equipment repaired by "technicians" without measuring equipment often fails spec, and it doesn't sound good either. At the very least, it could perform and sound better.
We all say, "to heck with measurements, it only matter how it sounds to us!". Well, sure. It does. If the measuring equipment lead in the wrong direction you have a point ... but it doesn't. When equipment performs better, people like it better. No shock to people who understand how things work.
You didnt mention what kind of speakers. Some present a "difficult load" to the amplifier, some do not. So the Taguchi factor "difficult / easy" to drive is in an unknown position. What you're hearing could be an artifact of the different amplifiers struggle to drive the speakers.
Keeping things vague (like Bob Dylan) around the amplifiers tested doesnt help toward a good answer either. Did you switch between ArcWelderZilla with 1000W Ch and 0.0000001 Ohm output impedance and an 8 Ohm transformer coupled output 6BQ5 P-P?
Without such specifics, the question is clickbait for others to pontificate all they know about imaging in a stereo system. Because that's about all you can do without.
By the way: if someones can't hear differences, they shouldn't make audio. And also don't claim to make audio suitable or deny others their hearing experiences and ability;-) And probably also not participate in the audio discourse;-?
Or he should simply start taking a scientific approach. Or make simple basic experiences, such as connecting the psus of mono power amps - if he is able to do so;-) Or start with a reasonable positioning of the speakers - this is not common knowledge either, nor is it - as can be seen and heard everywhere - "expert knowledge".
Someone could take part in the chic of the casings;-)
Or he should simply start taking a scientific approach. Or make simple basic experiences, such as connecting the psus of mono power amps - if he is able to do so;-) Or start with a reasonable positioning of the speakers - this is not common knowledge either, nor is it - as can be seen and heard everywhere - "expert knowledge".
Someone could take part in the chic of the casings;-)
Guest listeners on these panels have included audio engineers[some of best in the UK].
Nelson Pass has spoken extensively about negative feedback and its impact on sound and imaging [specifically].
There are naive subjectivists for certain but there are also naive objectivists who desperately do not what to believe in anything which seems to be beyond the scope of established measurements.Neither is very helpful.
Well, we do know how we determine where an object is. We can measure easily what constitutes "imaging", or being able to place a sound in free space.
Hearing differences? I do all the time. So that isn't it. Most people I know who measure extensively also listen extensively, so there is one assumption out the window, and your argument with it.
Anyway, without differences between channels in the electronics, you can only be talking about differences between the transducers, or maybe the room. The electronics alone cannot create a difference in imaging unless the two channels are not operating similarly. But your brain sure can with something as innocent as a question, comment or idea. An expectation has massive power. Then there is the exact position of your head. These things have a far greater effect on what you "hear".
So to make assumptions like people have on the cause of something like a change in imaging, you're over the cliff in uncharted territory. The other more likely factors have not been controlled, not one little bit. So the experiment is a failure before it gets off the ground. Anyone who has properly tested anything in life should know this.
cumbb, I never assess my own work - ever. I tend to be too critical on myself as many people are about anything they have done. There are people I know who never know what to expect (keeps them honest). I measure what I create or modify to prove whether the intended goal was achieved or not. You can't fudge that.
I did set out the basis of the issues I see in the original assertion that changing amplifiers changes the imaging. I was clear, and what was stated is in fact true. All I ever ask is that you think about it, and if you don't know, look it up in factual texts. That's it, that's all.
Many people don't like testing. They lose money when ambiguity disappears. That my friends is the current high end audio market, or should I say "fashion industry". See any parallels?
Hearing differences? I do all the time. So that isn't it. Most people I know who measure extensively also listen extensively, so there is one assumption out the window, and your argument with it.
Anyway, without differences between channels in the electronics, you can only be talking about differences between the transducers, or maybe the room. The electronics alone cannot create a difference in imaging unless the two channels are not operating similarly. But your brain sure can with something as innocent as a question, comment or idea. An expectation has massive power. Then there is the exact position of your head. These things have a far greater effect on what you "hear".
So to make assumptions like people have on the cause of something like a change in imaging, you're over the cliff in uncharted territory. The other more likely factors have not been controlled, not one little bit. So the experiment is a failure before it gets off the ground. Anyone who has properly tested anything in life should know this.
cumbb, I never assess my own work - ever. I tend to be too critical on myself as many people are about anything they have done. There are people I know who never know what to expect (keeps them honest). I measure what I create or modify to prove whether the intended goal was achieved or not. You can't fudge that.
I did set out the basis of the issues I see in the original assertion that changing amplifiers changes the imaging. I was clear, and what was stated is in fact true. All I ever ask is that you think about it, and if you don't know, look it up in factual texts. That's it, that's all.
Many people don't like testing. They lose money when ambiguity disappears. That my friends is the current high end audio market, or should I say "fashion industry". See any parallels?
I think that frantically searching for scientific proof every time someone "allows" themselves to express their listening experience seems surreal to me, and it also seems surreal to me that "sometime" in an audio forum if you express your listening experiences you are almost laughed at.
And yet no one here has expressed their listening experiences trying to sell something to make money, it's all disinterested, and it should have its validity at least as an experience.
And, in my humble opinion, that he should be respected like anyone else.
No one here has ever asked that what he says would must be accepted as the absolute truth on Earth, but at least simply accepted without pontificating on, precisely.
Since no one, not even those who deny the possibility of being able to perceive the change in the imaging between two amps, has a scientific demonstration that shows what they declare is proven in a scientific way, what would be wrong with expressing your listening experiences in an audio forum? 🙄
For some, an anecdote can be a valuable opportunity to search through learned experience in an attempt to explain it. Others may be happy for it to remain an enigma. So in a sense, there may be a clash of minds, depending on how much 'effort' is put into the observation. Kind-of like trying to steer the outcome of a race with a telescopic zoom lens on the finish line.
@anatech , you missed a good thread on "current-drive". It had lots of measurements, showing clear HD improvements in the order of >10dB. Of course it was only valid for a certain frequency band. So the nuance is in being able to apply that to one range of frequencies without compromising another.
This is not controversial — Klippel has papers showing that speaker inductance can be modulated by factors like cone position or current strength, and the claims are very well supported. Then it's just a matter of stabilizing the 'I' (in amperes) in the f = BIL motor equation. Like a constant current source, a basic current-drive topology 'fakes' a high resistance in series, so that the aforementioned modulation inside the speaker is unable to affect the SPL.
The thing is, that throughout history, people have been doing it with crossovers, and the filtering (I'm looking at the low-pass in particular for woofers and midranges) just so happens to coincide with the cleaning-up of unwanted modulation effects. The smoothness from 'padding' tweeters is also often attributed to merely EQ, without considering that distortion levels may also have changed.
I think I realized what you mean and I believe that perhaps an exchange of ideas and mentalities rather than minds is much better than a clash.
An exchange that of course also include one's mutual experiences and beliefs, albeit with different levels of "validity".
A peaceable exchange without derision, possibly.
That's my whole point.
I have zero issue with listening tests and ideas of what the cause may be. However, when things clash with known facts, I simply speak up.
I started in audio in the mid 1970's professionally. Just about every wacky idea you can imagine has been pushed. Back then, we didn't have the instrumentation to actually see what was going on, so wacky was the rule of the day. I was asked to test speaker wires, signal cables, capacitors - you name it. I got to know this stuff pretty well from a listening and comparison to measurement point of view. As measuring equipment got better, I found measurements agreed with listening impressions. That's if you measured the right things and could interpret the results.
I'm not trying to be right at all. What I was trying to do is have people think, learn. That way you don't waste money. The learning process is long, and you have to let go of ideas you think were true. I know I did.
Do I have formal electronics training? Yes. Is my area audio electronics and also my hobby, again yes. Also electronic instrumentation and a few other things. I did design speaker systems that were sold to the public early on. They weren't too bad, but compared to some today, no contest. Today's speaker systems are much better.
As for speakers, they are designed to be driven by a low impedance source. Current drive is interesting, but it never gave the total performance that what we are using today did. Industry went this way for very good reasons. You can get lower distortion in some instances. We have also experimented with plasma and other transducers, they all have big issues and are therefore not realistic.
Understanding is the goal. Try to avoid a belief system without actual proof, which means if what you think might be happening isn't logical you should sit back and have a think on it.
I started in audio in the mid 1970's professionally. Just about every wacky idea you can imagine has been pushed. Back then, we didn't have the instrumentation to actually see what was going on, so wacky was the rule of the day. I was asked to test speaker wires, signal cables, capacitors - you name it. I got to know this stuff pretty well from a listening and comparison to measurement point of view. As measuring equipment got better, I found measurements agreed with listening impressions. That's if you measured the right things and could interpret the results.
I'm not trying to be right at all. What I was trying to do is have people think, learn. That way you don't waste money. The learning process is long, and you have to let go of ideas you think were true. I know I did.
Do I have formal electronics training? Yes. Is my area audio electronics and also my hobby, again yes. Also electronic instrumentation and a few other things. I did design speaker systems that were sold to the public early on. They weren't too bad, but compared to some today, no contest. Today's speaker systems are much better.
As for speakers, they are designed to be driven by a low impedance source. Current drive is interesting, but it never gave the total performance that what we are using today did. Industry went this way for very good reasons. You can get lower distortion in some instances. We have also experimented with plasma and other transducers, they all have big issues and are therefore not realistic.
Understanding is the goal. Try to avoid a belief system without actual proof, which means if what you think might be happening isn't logical you should sit back and have a think on it.
Hi abstract,
A passive crossover is just a "make it go" thing. It is not what you want to do. That is why we have active crossovers. The best systems do not use passive crossovers.
A passive crossover is just a "make it go" thing. It is not what you want to do. That is why we have active crossovers. The best systems do not use passive crossovers.
If an amplifier/loudspeaker has an unusual frequency response curve, it may allow frequencies that have channel to channel differences to be heard when normally they are masked. Or vise versa.