Well I thought I would post it...
"...submitted for your approval..." Rod Serling
Anyhow, I acquired a 1 year old lightly used DVD player at a hamfest. And, after bringing it home thought, because my venerable Esoteric bit the dust, why not try it as a transport... into my custom PCM63 based DAC... which I did.
Quite astounding, my jaw dropped.
Illusions shattered - almost analog purity of sound, relaxed, free of digititis and electronic aspect. The ******* "holy grail" of digital audio!!
Amazing.
Ok, it did seem to want just the right digital interconnect, which still to this day bothers the heck out of me, but it was good from the start... please keep in mind that my system is just very good and I don't mind saying it, even though I'd say it is only at about 75-80% of what the inherent setup is capable of if optimized in several respects (not important for now). Point is that you can come here, bring your <whatever it is> plug it in and really hear it clearly and immediately - good or bad. No ambiguity. Ok, enough telling everyone how good it is, the only point is that you can hear what is going on quickly and clearly. For better or worse.
So, I figure I have stumbled on something BIG here... a cheap DVD that does magic! Time to get a backup for myself, before I tell the world... after all got to have a backup in case it croaks (as they seem to like to do). In fact that is why I bought the darn thing, because the last two CHEAP DVD players I bought CROAKED quickly for no apparent reason.
I got another on eBay.
With great anticipation, plugged it in, same outlet, same interconnect to the DA, etc...
BAH.
NOT THE SAME.
Not awful, but not magic.
Much more digitalized, thinner "solid statish" bass, harder highs, a bit more grain...
Must be impossible. But there it is. Two seemingly identical units, different sound. Crud.
This weekend I will pull the tops and look at the chipset and the parts to see if there is any variation in the runs or PCBs...
But, two otherwise identical units, different sound.
Bits is bits??
_-_-bear
"...submitted for your approval..." Rod Serling
Anyhow, I acquired a 1 year old lightly used DVD player at a hamfest. And, after bringing it home thought, because my venerable Esoteric bit the dust, why not try it as a transport... into my custom PCM63 based DAC... which I did.
Quite astounding, my jaw dropped.
Illusions shattered - almost analog purity of sound, relaxed, free of digititis and electronic aspect. The ******* "holy grail" of digital audio!!
Amazing.
Ok, it did seem to want just the right digital interconnect, which still to this day bothers the heck out of me, but it was good from the start... please keep in mind that my system is just very good and I don't mind saying it, even though I'd say it is only at about 75-80% of what the inherent setup is capable of if optimized in several respects (not important for now). Point is that you can come here, bring your <whatever it is> plug it in and really hear it clearly and immediately - good or bad. No ambiguity. Ok, enough telling everyone how good it is, the only point is that you can hear what is going on quickly and clearly. For better or worse.
So, I figure I have stumbled on something BIG here... a cheap DVD that does magic! Time to get a backup for myself, before I tell the world... after all got to have a backup in case it croaks (as they seem to like to do). In fact that is why I bought the darn thing, because the last two CHEAP DVD players I bought CROAKED quickly for no apparent reason.
I got another on eBay.
With great anticipation, plugged it in, same outlet, same interconnect to the DA, etc...
BAH.
NOT THE SAME.
Not awful, but not magic.
Much more digitalized, thinner "solid statish" bass, harder highs, a bit more grain...
Must be impossible. But there it is. Two seemingly identical units, different sound. Crud.
This weekend I will pull the tops and look at the chipset and the parts to see if there is any variation in the runs or PCBs...
But, two otherwise identical units, different sound.
Bits is bits??
_-_-bear
bear said:
It would be strange if they sounded the same. There will definitely be different components somewhere.
Similar break-in time?
Cheaply made equipment is commonly not consistent from sample to sample. At the time of the NAD 3020 several of my friends owned a unit and they all sounded differerent. From very impressive to completely mundane. After examining the boards in detail i found 6 different types of components between the samples.
Ok...
- no adult beverages present, different auditioners on different days
- the "stream" has only one reconstruction because it is Reed-Solomon code
- break-in time is unknown, as is IF it could possibly be a factor...
- power supply? dunno, will open up over the weekend and look.
- components? same, will look...
They really do need to sound the same unless there is some real difference in the physical realm...
_-_-bear
- no adult beverages present, different auditioners on different days
- the "stream" has only one reconstruction because it is Reed-Solomon code
- break-in time is unknown, as is IF it could possibly be a factor...
- power supply? dunno, will open up over the weekend and look.
- components? same, will look...
They really do need to sound the same unless there is some real difference in the physical realm...
_-_-bear
bear said:
Could the difference come from "different aging and stress" on otherwise identical components"?
Like maybe one has a dirty/dusty laser,
or in the supply, which is maybe SMPS like in cheap DVDs, one unit is affected with "bulging capacitors", and the other isn't (go figure, maybe different lots in the two players, one luckier than the other)
Or something like that.
But it'd have to be something extreme, where the "stressed" component is quite far from its nominal value/behaviour.
(sorry for this obvious troubleshooting hint...
I'm kinda surprised that someone with your experience is so surprised...
)
Not so much surprised as disappointed...
I will open them up shortly and see what there is to see. Maybe look at things like PS rails, if there is time... Doubt there will be anything glaring or obvious.
The real question is why does the "good one" sound so good!
Not why the other one is merely ordinary.
This is not a troubleshooting issue.
Neither is "broken".
Again, the laser being weak, bad, dirty or whatever plays nil role in the reconstruction of the signal, IF it reads at all. It can't because of the way CDs are encoded to avoid issues of this sort. At least that is what the book says.
My experience? Who says I have any that is worthwhile?? Ask anyone who really knows what they are talking about?
_-_-bear
I will open them up shortly and see what there is to see. Maybe look at things like PS rails, if there is time... Doubt there will be anything glaring or obvious.
The real question is why does the "good one" sound so good!
Not why the other one is merely ordinary.
This is not a troubleshooting issue.
Neither is "broken".
Again, the laser being weak, bad, dirty or whatever plays nil role in the reconstruction of the signal, IF it reads at all. It can't because of the way CDs are encoded to avoid issues of this sort. At least that is what the book says.
My experience? Who says I have any that is worthwhile?? Ask anyone who really knows what they are talking about?
_-_-bear
bear said:
I would disagree with that. There is only so much the error correction can do, it might end up replacing a few dodgy segments with random. CDs aren't all or nothing "digital", the read process is analogue.
Music CDs are different to data CDs, the latter will let you know the data is corrupt, the former will struggle on as best it can until the errors are so frequent that it skips.
richie00boy said:
You are incorrect, afaik.
Read about the encoding method of Reed-Solomon.
The read process itself is analog, but then the digital reconstruction filter is applied. When it skips, the errors have grown to the point that the original data can no longer be reconstructed using the inherent error correction of the code.
_-_-bear
bear said:
Try CRC32 from Cyberdyne; you may download it at http://www.simtel.net/product.php[id]34099[cid]112[SiteID]filebasket
This program compares only the non-silent parts of the wav-files. It is an older program, but works well with Windows XP. There are also some newer programs, of which I don't have the links present at the moment.
Kurt
Comparing two wavs recorded via spdif input is quite simple in audacity - just find some major peak at the begining, time-align both stereotracks, cut at the end for the same length, and subtract (invert one, merge both stereotracks). With a bit of practice it takes under five minutes. Make sure audacity is configured to 44100Hz/16bits before opening the tracks, otherwise the format conversions produce non-zero results.
The resultant wav can be analyzed e.g. using sox, effect stat.
The resultant wav can be analyzed e.g. using sox, effect stat.
bear, i think what the other poster was inferring was that the impact of error correction being called up during playback could be audible.
We know that R-Solomon is mathematically perfect until it skips, what we don't know in every case is if it causes jitter or other nasties when filling in the 'blanks'
We know that R-Solomon is mathematically perfect until it skips, what we don't know in every case is if it causes jitter or other nasties when filling in the 'blanks'
sq225917 said:
I agree we don't quite know. Someone knows though! That person is one who has tested or designed the chip that does the laser control and error correction. Wish one of those people would ever surface.
But I would speculate that due to the nature of the process there is some memory buffer in the chip, and nothing comes out until the errors have been corrected, which requires more than a linear read of data (part of the reason the disc spins fast) and then putting the missing bits in place... so it is unclear to me if there is any difference in jitter assuming no complete read glitch occurs, because otherwise you get the "normal" output of the read/control chip.
Otoh, if this was the cause of the sonic differential, then the problem (whatever it is on the read/error correction side) is going on constantly on one unit and not much on the other, or vice-versa (who knows which way it "sounds better"!!). Curious, eh?
Well, one step further along, one might find discs that have marginal read, or substantial errors (like one from the public library that has been used as a hockey puck??) and see if one reads better or more than the other as a test of the read error theory? I might try that one...
Well by the end of the weekend I hope to have the hood open, and something or nothing to report... I have my eye loupe handy for inspection!!
_-_-bear
Today I was doing heavyweight wrestling against a Subaru Outback... I won... at least for now. I could do the same job next time in half the time or less... heh.
Brakes are still spongy, but the other mechanical problems got fixed. Such fun.
So maybe later or tomorrow I can try to pull them onto the bench and pop the covers.
_-_-bear
Brakes are still spongy, but the other mechanical problems got fixed. Such fun.
So maybe later or tomorrow I can try to pull them onto the bench and pop the covers.
_-_-bear
Ok, yesterday I took the covers off the two units.
Turns out that they were both made in September of 2002. Older than I thought, but whatever. They ought to be identical inside given the mfr in the same month.
Well, they are identical inside.
The only difference I could find so far is that the date codes on the chips are not identical. Same chips, same board.
A BB 1704 (i think it was) surface mount DAC in there...
I have not done any probing with a scope yet.
Nor have I run them into a sound card to see anything that could be seen.
The thingie does have a switchmode PS. This may be sufficient to create a sonic difference due to the residual noise in the PS lines... I am giving some thought to taking the lesser of the two and putting in a linear regulated supply and see what that does to the sound. I'd need the service manual though, since the thingie has digital "wake-up" and removing the sense line (if there is one) that tells it that the switchmode is running might cause it to not function.
At this point, I feel ok with letting the cat out of the bag, so it is a lowly Pioneer DV-250, nothing more.
As I said, the "good one" sounds amazing as a transport, very analog, smooth, silky. The other one sounds good, but "normal" and has somewhat more typical of what I would call that old "solid state" sound, a bit thinner/tight bass, harder overall, and maybe a little brittle on the highs - not bad, just not great. Better than many others.
Let me add that the setup into my DAC did seem sensitive to the SPDIF cable, which I wish was not the case. Might say something about whatever is driving the cable as most other transports so far seemed to be less sensitive than this one, but maybe that is only because it sounded so surprisingly good initially that I played with the SPDIF cables for "best sound".
I can put up pix of the innards, if there is enough interest...
_-_-bear
Turns out that they were both made in September of 2002. Older than I thought, but whatever. They ought to be identical inside given the mfr in the same month.
Well, they are identical inside.
The only difference I could find so far is that the date codes on the chips are not identical. Same chips, same board.
A BB 1704 (i think it was) surface mount DAC in there...
I have not done any probing with a scope yet.
Nor have I run them into a sound card to see anything that could be seen.
The thingie does have a switchmode PS. This may be sufficient to create a sonic difference due to the residual noise in the PS lines... I am giving some thought to taking the lesser of the two and putting in a linear regulated supply and see what that does to the sound. I'd need the service manual though, since the thingie has digital "wake-up" and removing the sense line (if there is one) that tells it that the switchmode is running might cause it to not function.
At this point, I feel ok with letting the cat out of the bag, so it is a lowly Pioneer DV-250, nothing more.
As I said, the "good one" sounds amazing as a transport, very analog, smooth, silky. The other one sounds good, but "normal" and has somewhat more typical of what I would call that old "solid state" sound, a bit thinner/tight bass, harder overall, and maybe a little brittle on the highs - not bad, just not great. Better than many others.
Let me add that the setup into my DAC did seem sensitive to the SPDIF cable, which I wish was not the case. Might say something about whatever is driving the cable as most other transports so far seemed to be less sensitive than this one, but maybe that is only because it sounded so surprisingly good initially that I played with the SPDIF cables for "best sound".
I can put up pix of the innards, if there is enough interest...
_-_-bear
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