Hi,
I have encountered binary files that passed the "checksum" test (even extended checksum algorithms as found in Binary Usenet Posts [only legal downloads of course]) and still where corrupt nevertheless. It does not happen often, but it does happen. Unless you do a full direct binary compare you cannot claim the files are identical.
Ciao T
I have encountered binary files that passed the "checksum" test (even extended checksum algorithms as found in Binary Usenet Posts [only legal downloads of course]) and still where corrupt nevertheless. It does not happen often, but it does happen. Unless you do a full direct binary compare you cannot claim the files are identical.
Ciao T
That's EXACTLY what I've been doing for the 20+ years, John. Measurements are fine, and I do like to see them and make them, but in the end, it's my ears which get the last word.
Somebody suggested I used one setup to make the copies, and another for playback - true, I did, and in all cases. I ripped off on my PC, made all copies on my PC, and played them back on dedicated CD players and a BD/DVD playback machine.
So what?
According to some of you, this shuld not matter one least bit (pun intended), because it's all so perfecttly same, so if the original plays without a hirch, so should the copies.
Regarding the state of my lasers, gentlemen, I do maintain my equipment all the way down to my cars. Feel free to drop in and check this out anytime you please. The cops can inspect either one of my cars anytime, they are technically roadworthy at any time, anywhere.
The same goes for my audio. All lasers are cleaned every six months, because I live in a very dusty neighbourhood and don't want to see or hear any skipping or uncertainties in any of it. I actually clean my RCA cinch sockets and plugs every three months with medicinal alcohol and cotton swabs. I am heavily into the regular maintenance trip.
Now, you can write volumes if you please, but nothing you write can change what my eyes see and what my ears hear. Checsums are nice, but they don't explain what I see and hear.
Once again, I quote Technicher Rundschau, Switzerland, 1969:
The difference between theory and practice
Theory is when everybody knows how it should owrk, but it doesn't.
Practice is when nobody has a clue, but it works just great.
Good point Thorsten. I doubt many people are aware as they use their digital equipment how much error detection and correction is going on constantly. For example, hard disk drives are deteriorating steadily, but this is not noticed until it gets terrible (that's when you curse yourself for not having done backup recently).
When Harman advised Toshiba on a three-way system for a celebrated laptop, really the best audio ever heard without external speakers (still terrible of course, but adequate for many small presentations etc. on a conference room table), one of the problems was the transmitted vibration from the single lower-frequency driver to the laptop hard drive. But the symptoms weren't computer hangup/shutdown, just a slowing of response when operations involved extensive drive read/writes. The error detection/correction was insisting on multiple reads, and presumably once in a while even this wouldn't be good enough.
Done that under Linux, bit by bit difference tried a few times and never saw a difference. Also loaded the files into Audition/Cooledit and did one big A-B, all bits exactly zero, you can even view the result and see for yourself. This goes nowhere fast.
Since the digital perfection theme is not getting much of a result, perhaps it's time to spit and spew a little on the Fletcher/Munson curves. It seems many hard line audiophools think those two should be burnt at the stake, because lo and behold!, look mamma, no tone controls, and my sale price is higher by 10% because of that. AND MY HEARING DEFIES NATURAL LAWS, UNLIKE OTHER HUMAN BEINGS, I HAVE A LINEAR HEARING, TOTALLY INDEPENDENT OF VOLUME!!!
As one of the already damned, I think a loudness curve is a good idea, provided it is variable and can be adjusted to specific needs.
I also think tone controls are a GREAT idea, provided they are made for correction and compensation, not blatant boom colouring. This is to say that they must be separate for each channel (because the two loudspeakers are rarely in identical acoustic positions), and should have small increments, say in 1 dB steps, up to a maximum of +/- 6 dB.
Ave Cesare, morituri te salutant!
(For the non-classic students: Hail Ceasar, those about to die salute thee!)
As one of the already damned, I think a loudness curve is a good idea, provided it is variable and can be adjusted to specific needs.
I also think tone controls are a GREAT idea, provided they are made for correction and compensation, not blatant boom colouring. This is to say that they must be separate for each channel (because the two loudspeakers are rarely in identical acoustic positions), and should have small increments, say in 1 dB steps, up to a maximum of +/- 6 dB.
Ave Cesare, morituri te salutant!
(For the non-classic students: Hail Ceasar, those about to die salute thee!)
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Hi,
You should join this thread then:
http://www.diyaudio.com/forums/analog-line-level/194119-high-end-tone-control.html
As far as "loudness" goes, I though the contempary version is called "baffle step correction" (the fallacy of the concept should a BBFO [big blinding flash of the obvious]) and no longer adjustable or defeatable...
Ciao T
You should join this thread then:
http://www.diyaudio.com/forums/analog-line-level/194119-high-end-tone-control.html
As far as "loudness" goes, I though the contempary version is called "baffle step correction" (the fallacy of the concept should a BBFO [big blinding flash of the obvious]) and no longer adjustable or defeatable...
Ciao T
I do hope everyone realizes the CD format is not a normal data format with error correction encoded. It has three time slots, two 16 bit audio, one control slot. It is up to the quality of the reading software to try and correct errors. It is entirely possible for a poor transport and poor rip software not to correctly capture the CD or interpolate the missing data. It is possible that a really old PC with really bad riping software and a bad transport could be so marginal, that background processes are causing read errors. Reading an audio CD is not like reading a data format cd. It does not do retries, it has no checksums. If anyone still has the whitebook, it is worth a read. Once yo have it into a data file format, then you can be pretty sure a copy will be exact.
Thank you, T., I just might, time allowing.
Sadly, agreed on loudness, physiological compensation, or whatever one chooses to call it. Obstinacy seems to be the keynote of our civilization, deny the obvious, the more obvious, the harder the denial.
Insist you have a linear hearing, when no other human being does. Claim sound purity as the reason. Defy logic, deny reality, what the hell do they have to do with anything?
To be fair, much of this is the industry's fault. During the specs race, they overblew it all to truly absurd levels, effectively defeating their original functions. Anyone actually NEEDING a +20 dB boost at 20 kHz is either deaf, has some really low down shoddy gear, or both.
errr, BSC is what we do because of the mechanical configuration of a speaker baffle and where the refractive edges are. It has nothing to do with the quite reasonable need for tone controls of some type.
The F-M curves were already abandoned. There are newer and more general curves. What I have not seen is any sets that show the scatter based on age and gender in the published data, even though the reports acknowledged the differences exist. The curves are totally beside the point that tone controls are to correct recording and room variations so that what you perceive as flat, by your own hearing, is what the next person perceived is flat. The old "loudness" controls were quite handy for background music.
Yes, folks need to realize this and differentiate between truly not an exact copy or "CDR's don't play well on my old CD player". I still remain skeptical since to create a consistent sonic change LOTS of bits would have to be different.
Hi,
Really? Are you listening in empty space with the nearest wall or floor tens of meters distant? If you listen in enclosed spaces, have a look what BSC does to the power response and ask yourself which one you are listening to, on axis anechoic or in room power response...
While there are differences between F-M, R-D and other versions there are two key things that seem forgotten:
1) You must compensate the DIFFERENCE between the curves, not attempt a shape like the F-M curves.
2) Equal Loudness curves result from tests with pure tones and tend to overcompensate when listened with music.
Ciao T
Really? Are you listening in empty space with the nearest wall or floor tens of meters distant? If you listen in enclosed spaces, have a look what BSC does to the power response and ask yourself which one you are listening to, on axis anechoic or in room power response...
While there are differences between F-M, R-D and other versions there are two key things that seem forgotten:
1) You must compensate the DIFFERENCE between the curves, not attempt a shape like the F-M curves.
2) Equal Loudness curves result from tests with pure tones and tend to overcompensate when listened with music.
Ciao T
Yes music CDs have lousy error correction compared to data CDs but they still have very few if any uncorrectable errors (on a undamaged CD). And when ripped by good software to a HDD errors will be reread a number of times to give you even less of these errors. The place this goes south is when you burn a CD, the errors multiply and depend on the burner and blank CD.
T,
Yes, really. Dealing with other problems is not baffle step compensation. Valid and problems, sometimes addressable with step filters, but not BSC.
Topic two, agree on both points.
Scott
I agree, but I am just pointing out it is within the realm of explainable physics. Some old CD players did produce LOTS of errors on CDR's. ( I had a NAD I fitted an error light. On some CDR's, it was more like a pilot light.) So, that could be chalked up to a bad PC, bad rip software, and a bad CD player. Fortunately, all very easy to fix. The NAD problem I resolved with a a trip to e-bay for a Rotel 1070.
Yes, really. Dealing with other problems is not baffle step compensation. Valid and problems, sometimes addressable with step filters, but not BSC.
Topic two, agree on both points.
Scott
I agree, but I am just pointing out it is within the realm of explainable physics. Some old CD players did produce LOTS of errors on CDR's. ( I had a NAD I fitted an error light. On some CDR's, it was more like a pilot light.) So, that could be chalked up to a bad PC, bad rip software, and a bad CD player. Fortunately, all very easy to fix. The NAD problem I resolved with a a trip to e-bay for a Rotel 1070.
He doesn't trust his ears. If he would, he would have no problem doing a controlled test.
jan
When you go to enjoy philharmonic orchestra, which curves do you prefer?
I played a lot with that curves when experimented with synthesizers and guitar effects. My conclusion was, the best sounding "compensating volume control" was one that boosted 12 dB / Oct below Fs of speakers. I.e. that used "free" power to compensate roll-off of speakers when loudness goes down. Th effect is flatter frequency response on lower bass. All other controls that followed F-M curves sounded horrible, like odd timbre change with loudness.
I played a lot with that curves when experimented with synthesizers and guitar effects. My conclusion was, the best sounding "compensating volume control" was one that boosted 12 dB / Oct below Fs of speakers. I.e. that used "free" power to compensate roll-off of speakers when loudness goes down. Th effect is flatter frequency response on lower bass. All other controls that followed F-M curves sounded horrible, like odd timbre change with loudness.
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