I think the key is to have a great speaker. Because with cheap speakers, some amplifiers (tube, class-A) really sound better than others. Once the speaker is "changed", all amplifiers sound (almost) "the same" and the lower the distortion the better the sound. (Of course, there is still some "secrets" with numbers-sound relationship)
Define cheap ? My experience is that power amplifiers have very unique sonic characteristics. They vary enormously... enormous being relative in the way that a £$50 compares to a £$500 compares to £$5000 source component. To an audiophile the differences are large and worth paying for. To someone with little interest in audio reproduction they would be happy with the lesser component and find it little different to the others.
My bad, 711 instead of the 5534.
(During electrical installation work for a hot tub, I gave ritual Japanese suicide a shot with a Stanley blade, starting at the top of my right thumb. A thumping thumb apparently affects my brain activity. Which in my case, shouldn't be much of a surprise to all of you)
(During electrical installation work for a hot tub, I gave ritual Japanese suicide a shot with a Stanley blade, starting at the top of my right thumb. A thumping thumb apparently affects my brain activity. Which in my case, shouldn't be much of a surprise to all of you)
That makes it OK.
My worse was separating frozen ravioli with a razor sharp paring knife while holding them in one hand.
You MIT guys. Sheesh.
I taught freshman pre-calc and calc at a public university; series expansions (Taylor, Maclaurin) came either in the first or second semester, depending on whether you had to have pre-calc or placed out of it. Fourier series were second semester or first semester of soph year, same deal. First semester physics, though, core of Intro to Mechanics.
JJ once mentioned that Calculus was an EE senior year subject at the college near his home. So being the kind of guy I am when I met two of their seniors applying for graduate school I asked them about this. They replied it was a first semester senior year class, but most of them took if second semester junior year to get it out of the way.
As I suspect you need calculus to start any serious EE courses, it did leave me wondering. (Neither was accepted to the graduate school.)
?? Calculus was a senior year high school subject here, but they were Jesuits after all. The infinite series stuff was second semester junior year special topic (picked by the individual). First semester was to develop your own geometry from at most four axioms (pretty basic logic exercise).
Last I heard my freshman algebra teacher was in his 90's still teaching native Americans in South Dakota on some reservation.
EDIT - same now
"Students are placed in one of two "tracks" depending on their math test scores and grade school achievement level. Besides the normal sequence of Algebra 1, Geometry, Algebra 2, and Pre-Calculus math, the Department offers the advanced student an opportunity to enter the accelerated track in which he will take five math courses in four years -- the fifth course being Calculus. Students who successfully complete the courses in the accelerated math curriculum will be able to earn college calculus credit through the AP testing program."
Last edited:
Mr Wurcer, you mean there's still hope, or BS-ing me as it's a hopeless case anyway ?
Math at a-level high school here does an intro differentiating, single integration, and series development, but only the basics.
First year tech-u does the full routine in all four trimesters, soph is numerical math only.
(of course it's the physics guys with the drool prep. stuff library for the exams. some of them even look normal)
Speaking of MIT, here's sad news:
Tom Magliozzi, Popular Co-Host Of NPR's 'Car Talk,' Dies At 77 : NPR
Tom Magliozzi, Popular Co-Host Of NPR's 'Car Talk,' Dies At 77 : NPR
Never
. I was the hopeless case that day, wrapped the hand up and went to dinner before the emergency room. Nerves were cut clean through.
Yes, it is. But then, so is TL071, in fact surprisingly good, probably due to its FET front end.
I find Nat Semi's LF411 almost ideal for a servo due to its unbelievanbly small temp drift over time, something like 2 microvolts a month, or some such. Also a FET front end, but unfortunately, low noise floor is not one of its virtues. As an audio amp, it's best avoided.
Thanks for the flashback Scott.
A thick book full of geometric place (loci?) problems, written by Jesuit monks.
This gave us hard days and long nights during the last two years of high school.
George
Last edited:
Thanks
Just tried listening on headphones with PC volume up full. Most obvious feature is hiss in all but B-B. All the others have faintly detectable music (very very faint) together with some artifact (again faint) that is heard in the first few seconds on all. Hard to describe that one.
The peak level on all your images seems to be around -84 db, very low indeed.
Loudness:
RMS power: -60dB to –75dB
Peaks raise up to –53dB
If you look at the original files, you’ll spot the points where music has a sudden fortissimo and/ or exceeds –6db. That’s at the start at 0.2-0.3s, at 3-4s, at 10-11s, at 14-15s and at 24-26s.
These are the locations where on some diff files you hear the “artifacts”(*)
If these acoustic artifacts were the result of SW misbehavior, they would be present on all the diff files. This doesn't happen.
As a double check I run the diff process on all the original files against themselves (A-A, B-B, C-C, D-D). There is nothing in the resulting diff files (flat line at –140dB for the loudness envelope, empty screen down to –198dB for the freq spectrum), like digital silence.
I would say that what these artifacts are, is the distortion occurring on some of the original files during the fast rising peaks of music. This distortion doesn't cancel when the file is subtracted from another file, thus at these points new spectra content appears in the diff file.
George
(*)
B-A: at 3s, 10s and at 25s
B-C: at 0.3s, 8-10s and 25s
B-D: at 0.3s, at 10s, 15s and 25s
Last edited:
Cheap speakers, almost literally. Low distortion drivers are not cheap. And then details... Low distortion drivers, when not "detailed" will sound muddy with class-B as opposed to with class-A or tube. The amplifiers "control" how the speaker sound.
With speakers, low distortion, wide bandwidth (bass) and details do not come cheap. For woofers, high distortion is the main trade-off for low Fs.
As for commercial amplifiers, it would be a difficult decision for the profit oriented manufacturer to increase the parts budget. Transformer, caps... For me, Black Gate NX or Sanyo Oscon are standard feedback capacitors (I used computer grade Sanyo when thousands of capacitance is required).
- Status
- Not open for further replies.