CD Redux
Sorry for posting so late...This whole subject has been driven into the dirt so many times. In a LOT of inexpensive players ripple and trash from the transport (spindle motor/focus/tracking coil amps) can be heard in the noise floor of the audio, this is a flaw in player design. Attempting to fix it with a green pen on the CD is like fixing a broken stylus with a coin on the tonearm.
BTW Jan, the EFM data is encoded in the timing recovered from the transitions from both the pit>land and land>pit. The ONLY way ANY disc related parameters affect the output is in the form of hard uncorrectable errors. Period. All else is corrected by definition. Any jitter in the output is due to internal clocking issues not the disc.
Howie
Howard Hoyt
Dir. of Engineering
AMI, LLC
CD/DVD Replicators since 1993
Sorry for posting so late...This whole subject has been driven into the dirt so many times. In a LOT of inexpensive players ripple and trash from the transport (spindle motor/focus/tracking coil amps) can be heard in the noise floor of the audio, this is a flaw in player design. Attempting to fix it with a green pen on the CD is like fixing a broken stylus with a coin on the tonearm.
BTW Jan, the EFM data is encoded in the timing recovered from the transitions from both the pit>land and land>pit. The ONLY way ANY disc related parameters affect the output is in the form of hard uncorrectable errors. Period. All else is corrected by definition. Any jitter in the output is due to internal clocking issues not the disc.
Howie
Howard Hoyt
Dir. of Engineering
AMI, LLC
CD/DVD Replicators since 1993
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Maybe we've all run out of things to say and people to insult.
Although --- I could invite comments on Art Dudley's recent review in Stereophile of the Ayre AX-5 integrated amplifier, which actually attempts to describe the output stage topology in sufficient detail to allow a schematic to be drawn, I think practically a first for the magazine. I searched and found that Hansen has also talked about it in Audio Asylum, helpfully provides a schematic, and speculates about why it sounds better. Amusingly, Dudley describes it as being an "all-but-forgotten technology". This will come as a surprise to a great many of us who have been using it, albeit not strictly as a final high-power output stage, for decades.
One of the oldest stories is supposed to be:
A lad is eager to marry the daughter of a rich caravan merchant. The merchant disapproves because the lad has no money.
The lad consults a wise man, who counsels him to ask to join the merchants caravan in a lowly position so that he may prove himself worthy. But also when he receives his share at the caravan's farthest stop to offer all his money to buy the merchants soul. Then when he returns he should come back and the wise man will see to it that he can marry the girl.
So the lad joins the caravan, works menial jobs and is tormented throughout the journey. At the far end he receives but a pittance.
He goes to the merchant and makes the offer to buy the mans soul for all of that money. The merchant sees him as a fool and to teach him a lesson takes the money and then explains to him there is no such thing as a soul. You cannot see it, touch it, eat it, nor does it have any other uses and cannot even be traded.
Well that night the merchant does not sleep well. The next day he goes to the lad and offers to give him his money back if he has learned his lesson. The lad refuses.
As the journey back continues, every so of the merchant offers more money to buy his soul back. The lad continues to refuse. Finally the merchant asks why and finds out the wise man's instructions.
So at the end of the journey the merchant and the lad go to see the wise man. The merchant says he has cheated the lad out of his money and wishes to return it, but the lad refuses.
The wise man explains to the merchant that even though he cannot see or feel his soul it is the most valuable thing he owns. If he wishes to get it back he must give half of his business to the lad and now that the lad has money, also to let him marry his daughter.
So there are stories older than John's.
ES
Scott Wurcer,
In the thread where you have your discrete opamp design how would you take that basic premise and use it in a preamp? I have tried to stay up with that thread and was wondering how you would practically implement that design into a working circuit rather than the old obsolete and almost impossible to obtain devices that so many still are designing around?
In the thread where you have your discrete opamp design how would you take that basic premise and use it in a preamp? I have tried to stay up with that thread and was wondering how you would practically implement that design into a working circuit rather than the old obsolete and almost impossible to obtain devices that so many still are designing around?
jcx,
Yes you are correct in that statement. But it would be nice to see designs based on devices that are currently in production and not from someones stash of discontinued devices. Just the name Fairchild tells you that they are not in production anymore as that company has ceased to exist. Just one of many it seems today that were some of the best not that long ago.
Yes you are correct in that statement. But it would be nice to see designs based on devices that are currently in production and not from someones stash of discontinued devices. Just the name Fairchild tells you that they are not in production anymore as that company has ceased to exist. Just one of many it seems today that were some of the best not that long ago.
Fairchild is alive and well. Power Management IC | Mobile Semiconductors - Fairchild Semiconductor
EDIT: Having said that, a visit to their site shows them deemphasizing certain small-signal discretes, particularly ones with leads favored by diy. However, there are substitutes.
I'm afraid we're all going to have to get used to SMD, like it or not.
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On the subject of parts, most are probably aware that Diodes Inc. absorbed Zetex and still support some of their transistors. On Semi, having begun I believe as a company spun off from Motorola discretes, also keeps some of those parts alive, and more recently acquired Sanyo discretes. Some of these parts are key for the sorts of things we do or profess to do in here.
Toshiba continues to make a few things but of course famously discontinued the dual JFETs. If we are going to try to emulate the fully complementary designs of JC and others we will have to hope for success in the efforts at Linear Integrated Systems to make good large-area short-channel P parts.
I went back again to the Fairchild site and found more leaded bipolars, which are also stocked by Mouser with no warnings from either that they are on their way out. The puzzle is why Fairchild makes them so hard to find, as their search map, unless I missed something, omits any mention of the category. This may be an ominous sign or just a blunder. In any case, many of the parts are so cheap that if you need a couple I'd get a hundred pieces. Of course that's why I have a lot of parts
, although not really production quantities.
Toshiba continues to make a few things but of course famously discontinued the dual JFETs. If we are going to try to emulate the fully complementary designs of JC and others we will have to hope for success in the efforts at Linear Integrated Systems to make good large-area short-channel P parts.
I went back again to the Fairchild site and found more leaded bipolars, which are also stocked by Mouser with no warnings from either that they are on their way out. The puzzle is why Fairchild makes them so hard to find, as their search map, unless I missed something, omits any mention of the category. This may be an ominous sign or just a blunder. In any case, many of the parts are so cheap that if you need a couple I'd get a hundred pieces. Of course that's why I have a lot of parts
, although not really production quantities.- Status
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