John Curl's Blowtorch preamplifier part II

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From the premier AES Digital Audio Conference 1982 I quote from Barry Blesser in the keynote paper. He is discussing the residual expansion A to D, "An error of +- 1 LSB in the 8 bits can be tolerated with no final error". The problem with these is that they need very good stability and drift in the analog residual amplifier chain they are not inherently only 8 bit integral linearity. His example was 8 bit first then the residual at 9 bits.

EDIT - BTW I noticed that by 1982 the absolute necessity of dither was underscored by many.

Scott,

The issue is why do master tapes sound better than CDs. Now virtually everyone I know who does qulity recording believes this. Most of the folks seem to hear a difference when they use better master clocks and record at 96 or 192K. Virtually everyone uses 24 "bits" and dither too.

Now that data error seems to be put to bed by actual tests, there will be those who argue that 16/44.1 is adequate based on "classic" human hearing models. SY of course insists that double blind test are the only way to go.

This is actually pretty much moot. MP3 is the most popular distribution form and is adequate for a large percentage of listeners and occasions. There have been attempts to improve the CD quality and those changes are not always greeted warmly. Now I will continue to use 24/192 files for my critical listening because I have access to them and they sound better to my ears than the music available on CDs.

The answer is simple if whatever is good enough for your, fine. If greening your CDs makes them sound better to you by all means continue. The enjoyment of music is emotional, why would anyone expect such perceptions not be improved by external stimuli?

Now we can debate if greening a CD gives better results than drinking a glass of wine before listening. Of course I have my OPINION on this, others may differ.

Too bad Jan has banned me!

The other issue I raised is that fuses used wantonly in audio gear are a bad idea. Some have mentioned fused power supply rails which is something I dread. One weak blown fuse and it is new woofer time.

Now some have confused this issue with SY's recount of the claim that fuses are directional. I have measured this at a level that is below my 160 db system criterion. So since SY is too lazy to try it himself I will have to consider repairing an ancient computer to get those files. I will if it turns out there is other stuff i need. (I don't plan to redo it as simple as it is, I have way better things to do.)

ES
ES
 
Too bad Jan has banned me!

What, you too ?

Just as I thought, we were getting along just fine.
I'm só sad and lonely, sad and lonely, sad and lonely.

Mr Simon ? Mr Simon, where did you go ?
 

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Most of the folks seem to hear a difference when they use better master clocks and record at 96 or 192K. Virtually everyone uses 24 "bits" and dither too.

As I've said ad nauseum, there's good technical reasons for using high sample, high bit on the recording end. There's just no good evidence whatever that it's necessary for playback following mastering.
 
ES,
There seems to be agreement from those who have worked in or have been in a recording studio that there is a difference between the final master tapes and any cd format we have all heard. Sy says it is because of level matching but I say it is more than that, just from my own experiences. I don't think that level matching can be attributable to all the differences I have heard. Why this is so, I couldn't answer with a concise answer.

I agree that some seem to be completely content with MP3 though I can't listen to that format myself, it makes me cringe. And many of us agree that there are good and bad recordings on cd, no matter what you can do to your equipment, there are just clear differences in quality from one recording to another, but that was always the same in any format, even vinyl has always been that way. We can't control the recording process or the recording engineer and have to select the music that we like and those examples that come up to our personal quality levels.

For you Frank,
I know you will chime in here so I am going to beat you to it. I know you will say that you can take a bad cd and make it sound better on some iteration of a system that you have at one time put together, but I say there are times when I don't care what system some cd's are played on they are just poorly mastered and you cannot fix that. Solder all the connections you want, a poor recording is just that and most people would agree that something just sounds wrong with certain material, it is not system related.
 
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Joined 2005
I dont think that SY said that it was all level (mis)matching, just that few people go to the trouble of doing it precisely. And when one looks at the problem, it's more difficult than it might seem, as it depends on how you measure the levels.

If we run down the list of things that one can readily perceive, in order of ease of detection, level is one, frequency response (sometimes called linear distortion) is usually two. But clearly those two items interact --- if we're using pink noise to drive our systems under evaluation for level matching, the frequency responses will affect the overall level. With loudspeakers in rooms this is a big effect, hence the virtual necessity of presenting the systems via a speaker mover.

Much further down the list in ease of detection is nonlinear distortion, particularly with simple signals and when of low numerical order. However with higher-order distortions, and/or loud closely-spaced tones producing intermodulations, especially when the IM products are in bands of high aural acuity, these are at least less room-dependent.
 
Level of matching is a popular excuse ;)
Just blame it all on level matching.

Well, if you don't do something that basic and well-established as significant, how can anything else you do be taken seriously?

I would urge everyone to try this experiment: create two tracks that are identical except for a 0.2dB level, then tell someone that you want to compare the outputs of two amps, and let them ABX it. If they have sharp ears, you will get comments that the louder track is "cleaner," "more open," "better detail." Human ears just don't perceive small level changes as level changes, that's just how we're wired.
 
As I've said ad nauseum, there's good technical reasons for using high sample, high bit on the recording end. There's just no good evidence whatever that it's necessary for playback following mastering.

And if I get a file at 24/192 there is no reason to reduce it to 16/44.1. CDs are a currently popular method of distribution that for many is outdated.
 
And if I get a file at 24/192 there is no reason to reduce it to 16/44.1. CDs are a currently popular method of distribution that for many is outdated.

I argued in my last Linear Audio article that ALL physical media are outdated. But the point under discussion here is the audible transparency of the CD format, and despite much heat and moving air from hand-waves, no-one has produced a shred of evidence that the medium and 16/44 standard is not audibly transparent.
 
I argued in my last Linear Audio article that ALL physical media are outdated. But the point under discussion here is the audible transparency of the CD format, and despite much heat and moving air from hand-waves, no-one has produced a shred of evidence that the medium and 16/44 standard is not audibly transparent.

When I hold a CD up to my ear I notice a distinct loss of high frequencies.

Are you going to claim a CD reproduced concert is the same as live?

The issues are clear, greening a CD improves many peoples perception of it. Contemplation in a rock garden is one thing arguing with a rock is another.

Dick asked why master tapes sound better. The answer is that many master tapes get processed to make CDs. If you record at 16/44.1 that is not quite adequate for many folks. Recording at 24/192 and reducing to 16/44.1 results in loss of data. So even if 16/44.1 is perfect for reproduction :) mastering errors can affect the final product.
 
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The Harman system moves a stereo pair into the same position as a preceding system in a matter of a few seconds.

Who dare state Harman does not operate at near digital speed level.

(Did you notice I have a bifocal ocular system? One side is green filtered, the other is, well, wino. I can switch from environmentally influenced to obscure, in a fraction of a second )
 
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The answer is simple if whatever is good enough for your, fine. If greening your CDs makes them sound better to you by all means continue. The enjoyment of music is emotional, why would anyone expect such perceptions not be improved by external stimuli?

Now we can debate if greening a CD gives better results than drinking a glass of wine before listening. Of course I have my OPINION on this, others may differ. ES

Again, as much as I hate to admit it, I 100% agree with that Ed!

jan
 
Tell that to the record companies.

You mean the ones that are losing physical media sales to downloads? No problem, they won't exactly be surprised.

Hi res downloads are the exception, but they can be found from time to time. As data transfer rates and physical storage limits continue to expand, I think we'll see more shift to higher res formats than MP3; it's unfortunately also possible that it will assume QWERTY status, since there's a large installed base and the vast majority of people aren't finicky about ultimate fidelity.
 
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