Different albums, tracks show up different qualities. Two that I always reach for are:
Status Quo - 12 Gold Bars, 800 062-2: Almost any track will tell you a lot, "Caroline" is as good as any. Boogie rock, multiple guitars constantly driving, vocals should appear cleanly in their own acoustic space, and have a soft, almost sweet quality about them. But the most telling is the sound of the cymbals, a splash(?) cymbal is struck almost continually throughout the track: on a just OK system you can barely tell that this is happening, especially with volume up; when system is completely up to scratch that cymbal is perfectly reproduced, has all the qualities of the real thing, beautiful shimmer and all.
Led Zeppelin I, 240 031: This is the original release, none of that remastering rubbish(!). Should have a massive soundstage, everything on this album has a huge, cavernous sound to it. And all the sound elements should be totally clean, even the frenetic drumming should be clear as a bell, perfectly defined. On a lesser setup this album can sound a complete mess!!
At the other end of the spectrum, so to speak:
The Rolling Stones, 820047-2: Pretty rough original release of their first album, this can be hard work: the recording is borderline in many ways, and it takes a good'un, system that is, to make it palatable. Especially the drums. Only reach for when you're really confident!
And as a general call: lots of Motown and similar material is very hard to unravel, plenty of brass and such, and rough and ready recording means a pretty abrasive tone if there are problems ...
Frank
Yes, other end of the spectrum: try AD/DC, "Whole lot of Rosie".
I used that track in a presentation on loudness wars and compression. In Audacity the track absolutely is indistinguishable from white noise, and to tell you the truth, thats how it sounds too . IIRC dynamic range topped out at a whopping 12dB or so.
jan
I used that track in a presentation on loudness wars and compression. In Audacity the track absolutely is indistinguishable from white noise, and to tell you the truth, thats how it sounds too
. IIRC dynamic range topped out at a whopping 12dB or so.jan
Voltage. (i) is defined as 1A peak, which to me implies it is not a current source as such, but rather a voltage source with a current limit.
vac
Why?? Square wave current source with amplitude 1A, quite clear. If you have no problem with square wave voltage source, you should have no problem with square wave current source. +/-1A with infinite output resistance (so open circuit voltage up to infinity), similar as +/-1V with zero output impedance (so short circuit current up to infinity), duality principle.
jan, I'm now going to play hard ball! I was not familiar with that track, so just had a look at it, and there's nothing wrong with it, from my point of view! I've also looked at it in Audacity, and from where I stand there's minimal compression, just about every other contemporary track I've looked at recently is much worse.Yes, other end of the spectrum: try AD/DC, "Whole lot of Rosie".
I used that track in a presentation on loudness wars and compression. In Audacity the track absolutely is indistinguishable from white noise, and to tell you the truth, thats how it sounds too
jan
What it does have is cymbals mixed in at a high, not compressed, level, which is the source of your "white noise". So this track in fact is an excellent test of the resolving ability of a system, because that "white noise" will steadily turn into the extremely realistic sounds of dynamically struck cymbals as the system improves: it will turn into quite a showpiece by the endpoint!!
So, thanks for pointing me to that piece, I definitely will add it to my list of "good ones"!!
Frank
Oh no, we have peak value, average value, rms value etc. Peak value of sinus is its amplitude.
Peak value of square current wave is again its amplitude. It is a square current source of 1A (with 1A amplitude or 1A peak, whichever you like better). Again, it is the same specs description like voltage square wave 1V peak.
Current source gives you a defined current (DC or a waveform) regardless load impedance, i.e. it is able to yield any voltage that would maintain the desired current - that's why it is a CURRENT source.
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Pavel,
We may have to give the peanut gallery another day to look up the basics! Opinions are easy, correct answers not so easy.
ES
And how you have to be talking about the same version ...
The original was recorded in 1977, and this is what it looks like before morons get hold of it:
View attachment 297166
Makes Rickie look like she overcooked it a bit ...
So, apples with apples ...
Frank
Frank, very good, it nicely dovetails with another few slides I showed at that presentation. This were sucessive (in time) re-issues of a song by that S-African band made famous by Paul Simon, Black Mamboso or something.
I showed the same track each time from later re-issues, each time progressively compressed.
Your original 1977 AC/DC looks rather good, compared to my 2003 re-issue which was marked 'remastered and enhanced'. Yeah right.
Again points to the inescapable fact that the CD format gets blamed, unjustly, for lousy mastering and compression. That was my point at the presentation. I own an LP and a CD copy from the Graceland album, first releases, with sequential serialnumbers. The content is in both cases clearly from the same mastertape. I've countless times cued up both, switching between the two and never found anyone who can consistently identify which is which.
jan
CD/LP comparison
This same test can be done between a cassette encoded with Dolby S and a CD with the same results. We did it at an AES show (New York 1989?) and had zero positive identifications of the cassette. Before the inevitable comments start about how the poor listening environment obscured the difference, at that AES both Peter D'Antonio and Doug Sax declared our LEDE listening suite to be the best sounding at the show. So, it should have been good enough to show the difference between a lowly cassette and a CD.
I am under no illusions that there was not a difference, but it was obscured by the unfamiliarity of the participants to the room itself. As has been discussed here ad nauseum, a new environment includes enough new aural and visual data to disorient critical listening. I believe this is the main problem with ABX tests. Do I think the cassette sounded as good as a CD? Within the playback constraints we all know regarding analog tape, yes. The same? No. BTW, Dennis Staats, the Dolby engineer we worked with, was the only one who could consistently tell the difference, proving to me that you can teach yourself to be sensitive to different aural phenomena.
Interestingly after the show, we picked up cassette duplication accounts for DMP, Telarc and Sheffield and others so I guess the tapes didn't sound too bad...
Howie
Howard Hoyt
Dir. of Engineering
AMI, LLC
www.ami-media.com
This same test can be done between a cassette encoded with Dolby S and a CD with the same results. We did it at an AES show (New York 1989?) and had zero positive identifications of the cassette. Before the inevitable comments start about how the poor listening environment obscured the difference, at that AES both Peter D'Antonio and Doug Sax declared our LEDE listening suite to be the best sounding at the show. So, it should have been good enough to show the difference between a lowly cassette and a CD.
I am under no illusions that there was not a difference, but it was obscured by the unfamiliarity of the participants to the room itself. As has been discussed here ad nauseum, a new environment includes enough new aural and visual data to disorient critical listening. I believe this is the main problem with ABX tests. Do I think the cassette sounded as good as a CD? Within the playback constraints we all know regarding analog tape, yes. The same? No. BTW, Dennis Staats, the Dolby engineer we worked with, was the only one who could consistently tell the difference, proving to me that you can teach yourself to be sensitive to different aural phenomena.
Interestingly after the show, we picked up cassette duplication accounts for DMP, Telarc and Sheffield and others so I guess the tapes didn't sound too bad...
Howie
Howard Hoyt
Dir. of Engineering
AMI, LLC
www.ami-media.com
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The High End brings this on itself.
One of my favorite examples:
Matt The Electrician Animal Boy Review By Steven Stone
Despite the reviewer's gushing about the recording quality (the music is terrific), it's incredibly compressed and EQed hot enough to burn your ears off. Running Keith Howard's dynamic range software on it, the analysis looked exactly like Howard's example in the documentation of an overly compressed recording.
But hey, what detail!
One of my favorite examples:
Matt The Electrician Animal Boy Review By Steven Stone
Despite the reviewer's gushing about the recording quality (the music is terrific), it's incredibly compressed and EQed hot enough to burn your ears off. Running Keith Howard's dynamic range software on it, the analysis looked exactly like Howard's example in the documentation of an overly compressed recording.
But hey, what detail!
And there is the unstated assumption that the generator has been on indefinitely. A much more interesting problem, albeit quite tractable with simple differential equations, is when the generator switches on at, say, T = 0, and at 0 volts.
Brad Wood
EDIT: Should say 0 amps .
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Oh no, I take into account the initial condition for T < 0 Igen = 0
for T > 0 Igen = +/- 1A with T = 1ms, 50% duty cycle
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