Understood. My point is just that if we test power amps under non-standard, but perhaps real world conditions, we may find there are some tiny differences that a keen ear can pick out at certain points in musical passages that may go by very fast then they're gone. Down around the thresholds some people hear quite differently from others. @soundbloke has spoken to this, and further stated that some sounds may be inaudible to most people yet most people can learn to notice those little tiny differences. IOW, people aren't necessarily born to hear that way, its learnable by most anyone if they want to practice with larger differences first, then reduce the level of the difference and start learning to hear it at lower and lower levels. Other people have talked about learning to hear too, such as Paul Frindle, who was the chief designer of an early 16-bit recording and mixing console under the Sony brand.
So my real point is that, yes, people can be easily fooled and or easily fool themselves, but people can also learn to be more accurate and hear things that are inaudible to most people. Thus if a member here says they can hear a difference between amplifiers, maybe they can. The only way to be sure is to blind test each individual person for each little sound they may or may not have learned how to hear. Mostly, its not worth all the work and all the cost it takes it do the testing properly. Therefore its seldom done.
Doesn't mean any member is right or wrong, but since its not usually practical to blind test everyone to proper scientific standards, it may be best to give them a pass or else just say "I am skeptical because humans can be wrong or right and we don't have a way to know for sure without expensive individual testing." "Our standard amplifier testing appears to be good enough for the vast majority of the listening population." You know, something like that.
So my real point is that, yes, people can be easily fooled and or easily fool themselves, but people can also learn to be more accurate and hear things that are inaudible to most people. Thus if a member here says they can hear a difference between amplifiers, maybe they can. The only way to be sure is to blind test each individual person for each little sound they may or may not have learned how to hear. Mostly, its not worth all the work and all the cost it takes it do the testing properly. Therefore its seldom done.
Doesn't mean any member is right or wrong, but since its not usually practical to blind test everyone to proper scientific standards, it may be best to give them a pass or else just say "I am skeptical because humans can be wrong or right and we don't have a way to know for sure without expensive individual testing." "Our standard amplifier testing appears to be good enough for the vast majority of the listening population." You know, something like that.
Alike, as these class do not switch, causing an extra challenge for the feedback loop (also addressing other issues like thermal stability and other distortions, left apart the startup & shutdown sequences, which are always tricky).
But Markw4's real world load shown in #37 directs us to the general challenge of audio amplifiers: how to cope with these complex impedance with its own back emf source inside? As if the amplifier is connected to... another amplifier. And that is a very different kind of amplifier, a compound of an electrical system, a mechanical system and an acoustic system.
So, discussing circuit strategies cq topologies, which approach is capable of counting with these kind of (extreme) complex loads?
An audio amplifer is considered an almost perfect (ac) voltage source, but fails on many operative issues actually.
To boil it down to the essence: is an 'all inclusive' topology possible, and/or what approach comes most near to this... divinity?
And this is only the technical, the scientific view. What about the 'audience'? A big sigh...
What other measures do we have? There are 7.000.000.000+ opinions currently available in the world, and they're all true.
Who, off you all out there, has 'good' ears? What's your reference?
Hiking through the forrest, birds, trees, the running waters... human voices, stories, instruments, echoes in a church..
Until the opening of our technical times now, everything is possible, everybody is right. But all is replayed, through the available hooter.
Sorry EdGr, your post crossed mine...
Back in the early 70s there could be amps whose sound quality could be variable, nowadays all possible issues
have been sorted out, basically with three transistors in serial and a convenient OS one get all the required quality,
be it a single ended input + enhanced VAS + dual EF or with an input differential and eventually a triple EF or FET OS
for high powers.
Rest is a matter of technical taste more than anything else, of course practical implementation is very important
and a good design can be made awfull if basic EM compatibilities like accurate groundings are not respected.
have been sorted out, basically with three transistors in serial and a convenient OS one get all the required quality,
be it a single ended input + enhanced VAS + dual EF or with an input differential and eventually a triple EF or FET OS
for high powers.
Rest is a matter of technical taste more than anything else, of course practical implementation is very important
and a good design can be made awfull if basic EM compatibilities like accurate groundings are not respected.
If your speaker load really is that harsh you should simply build the amplifier required to drive it. You can find ones that will handle it - but chances are they were made to run up to four pairs of speakers at the same time. But a “regular” amplifier should be able to drive your basic dual-woofer 2 way - and a lot of the cheapies either turn their noses up at them or operate “properly” but on the edge of destruction.
For the most part with run of the mill speakers and normal listening habits most any competently designed and built amp, made with modern parts and the proper care, SOUNDS just fine. Topology isn’t as important as implementation. When you’re doing “things you shouldn’t be doing” like driving 1-ohm-above-10k electrostats, four pairs of speakers in parallel (at a party), or running 6dB into clip as your baseline level (and go louder when you want energy on the floor) some topologies work better than others. Just because it’s easier to meet the actual requirements. And implementation matters that much more. I don’t hear a difference between my best BGW-inspired beast and a little simple 40 watt per channel capacitively coupled amp I built for the test bench - or even my 6550-based monoblocks, when used within their limitations. What surprised me the most about that was how much the tube amp sounded like a good SS, when designed to the same goals.
For the most part with run of the mill speakers and normal listening habits most any competently designed and built amp, made with modern parts and the proper care, SOUNDS just fine. Topology isn’t as important as implementation. When you’re doing “things you shouldn’t be doing” like driving 1-ohm-above-10k electrostats, four pairs of speakers in parallel (at a party), or running 6dB into clip as your baseline level (and go louder when you want energy on the floor) some topologies work better than others. Just because it’s easier to meet the actual requirements. And implementation matters that much more. I don’t hear a difference between my best BGW-inspired beast and a little simple 40 watt per channel capacitively coupled amp I built for the test bench - or even my 6550-based monoblocks, when used within their limitations. What surprised me the most about that was how much the tube amp sounded like a good SS, when designed to the same goals.
Yes, that certainly defines a 'faulty' amplifier. But amps which don't exhibit that fault can sound different in a number of ways - eg:
* depth, width & height of the sound field they deliver (with the same spkrs used with all the amps)
* bass control of the spkrs the amp is driving (ie. 'tight' ... or 'floppy')
* can you listen for ever ... or do you start losing your enjoyment after an hour or so.
andyr - The hum and noise was on PA equipment and powered speakers.
I have not (in recent memory) heard a high-fidelity amplifier whose performance was poor enough to have audible effects. Other parts of the signal chain are much weaker. I have heard all of the problems that you describe on various recordings.
Ed
I have not (in recent memory) heard a high-fidelity amplifier whose performance was poor enough to have audible effects. Other parts of the signal chain are much weaker. I have heard all of the problems that you describe on various recordings.
Ed
Are, at least, the following properties of compared amplifiers same?
- depth, width & height of the sound field they deliver (with the same spkrs used with all the amps) - Power bandwidth, operating class, noise floor
- bass control of the spkrs the amp is driving (ie. 'tight' ... or 'floppy') - DF and power supply
- can you listen for ever ... or do you start losing your enjoyment after an hour or so. - THD+N, harmonic profile, 19/20 kHz and 32 tone IMD
Perhaps to prevent replies like this, Marcel:
... it would've been better to have written "I think they are never the same on two different amplifiers"?
And I would agree with you.
Has anyone ever heard the differences between power supplies - before the more complex topic of amplifiers is discussed;-?
Many like dual mono power supplies. Simply connect them with a cable and switch in between. And, if you feel like it, simply connect or disconnect the channel-separated power supplies;-) With or without double blind, with or without visitors and listeners or whatever. Whether after months of listening in one position or every few seconds. The important thing is to give your hearing a few moments to remember and adjust, so always pause for at least a few seconds;-)
After this experience, the entire hi-fi, high-end and audio discourse can be rolled up;-)
So, basically, we agree that different sounding amplifiers will not measure the same.... it would've been better to have written "I think they are never the same on two different amplifiers"?
And I would agree with you.
There is no voodoo factor in different sound of different amplifiers.
Yes, I think that most of what people hear with certain amplifiers is the output impedance altering the crossover's frequency response. The effect is easy to replicate on a low-output-impedance amplifier by adding a few tenths of an ohm resistor in series with the speaker.
Ed
However you are talking about correlation, not causation. Standard measurements are still not fully predictive of SQ.So, basically, we agree that different sounding amplifiers will not measure the same.
Speaking of resistors, sometimes adding a 100R non-inductive resistor across the speaker terminals will make the amplifier sound better (for different reasons of course).