General > General Technical Chat
WTF??? Is this valid or a scam to part fools from their money?
james_s:
--- Quote from: rsjsouza on April 14, 2021, 10:14:24 pm ---What he described as a "power regenerator" looks to be almost as if it were an online UPS unit without batteries - where the output is a PWM generated low distortion sinewave that powers your product. Perhaps the term "regenerator" is common along the audiofolk, I don't know.
--- End quote ---
That Kikusui thing? Or are you referring to a different "he"?
The Kikusui box looked to me like a programmable AC power source. I have a much older device of a similar concept made by California Instruments. It's essentially a big class B amplifier driven by a sine wave oscillator and feeding an output transformer. It can deliver something like 0-300V at 20Hz to 5kHz at full rated power of 500VA and will go beyond that range derated. Niche thing but very useful in certain applications. Works great for running British and European discharge lamps and control gear from proper 50Hz power.
Zero999:
--- Quote from: M0HZH on April 15, 2021, 03:48:13 pm ---
--- Quote from: GTA on April 14, 2021, 09:56:27 pm ---I know of a couple of people I have come across that would go gaga over these products.
I remember sitting in an electronics class in the 80's and the instructor was going off topic to tell a story of how people get sucked into buying audio amplifiers that has a bandwidth "up to 100KHz". Using this story and explaining that "oxygen-free, piezo effect, high thermal nuclear reaction conductors" doesn't make $300 speaker cable sound better to these people. In the end, they will still be enticed to buy this crap based on sales tactics and marketing claims.
So yes. In the end, people believe in the placebo effect. :-//
--- End quote ---
Actually ... the bandwidth was related to amplifier slew rate and "speed" errors in the past; a "20kHz" amplifier would be more and more inaccurate past a few kHz which would make even 1-2khz sounds sound bad (by damaging the higher harmonics). Sounds are not sinusoids; a sound with a 1kHz fundamental might even take 10kHz of bandwidth or more.
On top of that, mixing different sounds multiplies the necessary bandwidth. Mix a few sounds at 2-3kHz and their first 3 harmonics, you already need many tens of kHz of bandwidth.
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No, an audio amplifier doesn't need to have any bandwidth beyond 20kHz to sound good. In fact, it's desirable to cut frequencies above 20kHz to reduce interference and protect tweeters.
The slew rate is important, but the full-power bandwidth doesn't need to extend all the way up to 20kHz, because music has a 1⁄f spectrum. In other words, an amplifier capable of an output voltage swing of 10V peak-to-peak, doesn't need to be able to do this at frequencies up to 20kHz, 2kHz is more than enough. Large voltage swings are due to bass, rather than treble.
M0HZH:
--- Quote from: Zero999 on April 15, 2021, 09:07:57 pm ---
--- Quote from: M0HZH on April 15, 2021, 03:48:13 pm ---
Actually ... the bandwidth was related to amplifier slew rate and "speed" errors in the past; a "20kHz" amplifier would be more and more inaccurate past a few kHz which would make even 1-2khz sounds sound bad (by damaging the higher harmonics). Sounds are not sinusoids; a sound with a 1kHz fundamental might even take 10kHz of bandwidth or more.
On top of that, mixing different sounds multiplies the necessary bandwidth. Mix a few sounds at 2-3kHz and their first 3 harmonics, you already need many tens of kHz of bandwidth.
--- End quote ---
No, an audio amplifier doesn't need to have any bandwidth beyond 20kHz to sound good. In fact, it's desirable to cut frequencies above 20kHz to reduce interference and protect tweeters.
The slew rate is important, but the full-power bandwidth doesn't need to extend all the way up to 20kHz, because music has a 1⁄f spectrum. In other words, an amplifier capable of an output voltage swing of 10V peak-to-peak, doesn't need to be able to do this at frequencies up to 20kHz, 2kHz is more than enough. Large voltage swings are due to bass, rather than treble.
--- End quote ---
Do agree on some of your comments, but keep in mind the human ear has a non-linear reponse as well. Combine that with 1/f and you'll get a much flatter response up to 4kHz or so.
Also, I was referring to amplifier phase response rather than amplitude. An amp that has good amplitude response up to 20kHz will actually be quite poor over a few kHz in terms of accuracy.
rsjsouza:
--- Quote from: james_s on April 15, 2021, 08:07:12 pm ---
--- Quote from: rsjsouza on April 14, 2021, 10:14:24 pm ---What he described as a "power regenerator" looks to be almost as if it were an online UPS unit without batteries - where the output is a PWM generated low distortion sinewave that powers your product. Perhaps the term "regenerator" is common along the audiofolk, I don't know.
--- End quote ---
That Kikusui thing? Or are you referring to a different "he"?
--- End quote ---
It was referring to the original video. I did not watch the other one.
xrunner:
But but but ... :rant:
How perfect does it have to be anyway? In most cases the listener wasn't even at the recording or concert, so how do they even know what it's supposed to sound like. You can't say it's a "bad" or "good" reproduction unless you have compared it to the original in-situ recording. Even if it doesn't sound the same, who's to say it isn't enjoyable to listen to - or perhaps even better than the original might have sounded because it isn't exactly the same?
It's all subjective!
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