John Curl's Blowtorch preamplifier part II

[fas42]

Originally Posted by PMA

It just illustrates how subjective might be "long-distance" sound descriptions and assessments ...

The CD 2003 dynamic range is horrible.

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:

Whole_Lotta_Rosie_1977.gif

Makes Rickie look like she overcooked it a bit ...

So, apples with apples ...

Frank

[simon7000]

Originally Posted by vacuphile

7000,

The (i) is ill defined and consequently the rest of the questions is either mundane or plain stupid.

vac

Originally Posted by PMA

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.

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

[jan.didden]

Originally Posted by fas42

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:

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

[PMA]

Originally Posted by simon7000

Pavel,

We may have to give the peanut gallery another day to look up the basics!

ES

Ed,

I agree, it might help

AC Waveform - AC Circuit Theory of Sinusoids

[hhoyt]

Originally Posted by janneman

... I've countless times cued up both, switching between the two and never found anyone who can consistently identify which is which...jan

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

[jan.didden]

Another example.
Which do you think sounds better, LP or CD?
And who's to blame? (Hint: it's not your DAC or the metallic resistor eindcaps ;-)

jan

[SY]

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!

[bcarso]

Originally Posted by PMA

Do not forget time constant and 1ms square input ..

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 .

[PMA]

Originally Posted by bcarso

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

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

[scott wurcer]

Originally Posted by simon7000

Yes and let's see who in the peanut gallery can do it!

And the technique to avoid an infinite series is?

Laplace transform and integral?