| mrfeedback |
"this is true - I predict that after the China Economic Machine and Capitalism is fully entrenched in China - The Consumption Machine (North America & The EU) will go looking for another ripe plum to pick - Ummmm how about Africa they need some factories and jobs.... just my 2 cents. "
A friend of mine imports camping equipment and a few years ago he visited China and inspected the Coleman facory.
He told me that China provides the factory land, the factory building and dormitries and high wall around it in exchange for a percentage of the factory turnover.
After a period (15 years I think) the whole operation reverts to the Chinese government who then inherit the infrastructure and knowledge base.
It seems that when this happens the likes of Coleman will be kicked out or at least prices will go up.
If prices go up production facilities will probably move to the next third world country as has been the experience over time - Japan>Taiwan>Korea>Malaysia etc.
Eric. |
|
|
| Nuuk |
In the UK, it is almost impossible to telephone a company without being dealt with by a call centre in India.
Now, I have no problem with anybody having a job and if they can do it cheaper (although I question the 'cheaper' that accountants speak of) fair enough, but it is very difficult to understand the person that you speak to.
A friend of mine needed to speak to his ISP recently about a problem with his connection but gave up after 30 minutes because he just got tired of asking the guy to repeat what he was saying.
Now, consider this: that call and many, many more are on premium rate call charges so there is a double advantage in going this route. First, you get your staff at lower wages and (better still) your (pound-a-minute) callers are on the line three or four times longer because they can't understand what is being said to them! Accountants, don't you just love them? :whazzat: |
|
|
| Circlotron |
Well, I got my DVD player for AUD$99, then Safeway of all places starts selling them for AUD$85, and then just today I am reading my junk mail (which there is a lot of this time of year BTW) and Aldi has a DVD player for AUD$69. Unbelievable. :xeye:
http://australia.aldi.com/cms/product_01/index.html
 |
|
|
| Christer |
| quote: | Originally posted by Circlotron
Well, I got my DVD player for AUD$99, then Safeway of all places starts selling them for AUD$85, and then just today I am reading my junk mail (which there is a lot of this time of year BTW) and Aldi has a DVD player for AUD$69. Unbelievable. :xeye:
http://australia.aldi.com/cms/product_01/index.html
|
Unbelievable? Why so? It happens all the time with the ordinary
consumer electronics. You think you get a good price, and the
next day it is cheaper.
A copule of years ago, when I still didn't own a scanner, I
saw they sold some model for around 500 SEK (I won't bother
to translate to dollars or anything, since it doesn't matter).
I decided that for that price it was worth buying a scanner
just to see if I would really have much use for one. Of course
they were already sold out when I came to the shop. They
often have just a few so they will go away quickly and people
will end up buying something more expensive instead. The
dealer said that instead he could give me a good price on an
Agfa, that was usually 1490 SEK, but I could get it for 1250. I
knew that was quite a good scanner, but didn't really think
I had much need for one so it wouldn't be worth buying it. I
told him so and after a while he said I could get it for 1100.
When he finally offered to sell it for 1000 I decided to go for
it. Know what? Just a week of two later the normal price of
this scanner was 995 SEK!!! I am sure he even knew they
would lower the price soon when he sold it to me. |
|
|
| millwood |
| quote: | Originally posted by Morse
As far as Chinese products undercutting US ones, that may not be the case much longer - the Yuan has been kept artificially devalued (according to both the Japanese and western business press), keeping their goods artificially cheap, and limiting the ability of the hoped for Chinese consumer economy to buy western goods. It's expected by many that with the nosedive in the value of the USD (due to the mass flight from investments in the dollar), that the Yuan will have to be permitted to float up to a free market value and suddenly the cost differential between a western product and a Chinese one will not be so very great after all. |
that's true in theory but if you have been to China, you will know that in terms of purchasing power there, Yuan is about 1:1 with USD. Economists usually think a 20% appreciation in Yuan is called for if Yuan is allowed to float. I would venture to say that 1) the Chinese government will not allow the Yuan to float against the USD; 2) even if Yuan is allowed to float, the advantage in labor cost will persist as the workers there will simply get paid less in Yuan: there is just such a huge pool of eager laborers. 3) even if Yuan is doubled or quardropled against the USD, there is still a decided cost advantage for producers in Asia.
| quote: | Originally posted by Mikett
True economic wealth in the world is a zero sum game. |
it will never be a zero sum game if people invest in themselves and specialize in things they do best. The problem is that there will always be a portion of the population that refuse to look into themselves and instead try to blame others for their problems.
For those people, I have zero sympathy.
| quote: | Originally posted by mrfeedback
[b]After a period (15 years I think) the whole operation reverts to the Chinese government who then inherit the infrastructure and knowledge base.
|
the time frame is usually 50 - 70 years (70 years by the land law there - a private person cannot own land, but can own the rights to use the land for a maximum of 70 years. The government, as an agent for the people, owns the land). |
|
|
| Mikett |
Millwood, the paradigm about economic wealth increasing has to be questioned. How it is measured is the key. Let's not even consider foreign issues first. So the value of property has gone up over the last say, 50 years; what has happened to the "asset" value of the family unit? When two incomes are needed to pay that mortgage? What has been the cost to society of children not raised properly. In a similar vein, economics does not measure the liabilities and future cost of pollution? You know it's real.
So you're visiting China to source goods. As soon as they get enough capacity they will then send an agent over and you will no longer need to travel there. We'll have no "sympathy" for you then.
How does a poor person who holds a couple jobs to make ends meet invest in themself? Have some empathy man. |
|
|
| Morse |
Hi Christer;
>>>...I saw they sold some model for around 500 SEK...Of course they were already sold out when I came to the shop. They often have just a few so they will go away quickly and people will end up buying something more expensive instead...<<<
That's called "bait and switch" in the US. In theory it's thoroughly illegal. As always, theory and practice are at odds, with practices being de facto illegal only for those without a good enough legal department and campaign contributions operation to ensure that official scrutiny is minimised.
Hi Lyra;
Sorry for going OT occasionally; as someone who's been outsourced and has had to retool his own job skills (an ongoing process at the moment), it's a topic that resonates.
Back on topic, have you tried any tweaks on your ailing Mustek? Or, have you tried to discern the cause for those alarming voltage levels you quoted? I for one would be a bit leery about using any piece of obviously malfunctioning equipment (in which dangerously high levels of AC are sometimes present) unless I thoroughly understood the causation.
Hi Millwood;
I'll admit that my experiences are in Japan, not in China. However, my understanding of Yuan vs Dollar is that while the Yuan will buy locally made goods at about 1:1 with the USD, it will not buy Japanese or western made goods at the same ratio - thus China as a market for the west is not happening the way we were promised, when trade relations were normalised. The business press lately seems to be readying people in Japan for a transition to sourcing parts from countries other than China - perhaps even back home, rather than some other source.
Hi Mikett;
Thinking about it, I don't know as I would have said that wealth creation is a "zero sum" game, but your point is very well taken that there is only a certain capacity to create wealth in terms of the amount of machine tools and raw materials availability. The reason I would have not used that term is that by the allocation of machine tool time to making more production apparatus, one can expand the manufacturing base - thus making a real gain in the future at the expense of current living standard. Unfortunately in the US in particular we're now presented with a kind of pseudo wealth: "intellectual property", the creation of which is being used to justify the trashing of the ability to make real wealth (i.e. "things" like DVD players, TV sets, valves, etc.). Watch for the Open Source movement in India and China to undercut Microsoft's de-facto monopoly in the coming years.
Excellent points about the problems with a floating currency - it's a measuring stick that changes over time by definition and thus is open to all manner of official chicanery in terms of it's "real" value. An example of that in the US with respect to electronics would be the old Dynaco amps. Certainly you can buy amps that are the equivalent of the Dynas today (IIRC wasn't there a UK company that had pretty much cloned the Dyna Stereo 70 a couple of years back?) but you can't buy them for anything like the same money. Even if you compensate for "official" inflation, you'll find that goods of that sort are pricier today (even if made in China) than they were in the 1960's.
How many people think their no-name DVD players will appreciate in time the way the old Dynacos and other "classic" electronics will? Will there be a coterie of hard core hobbyists keeping their no-names functioning years after they've been superceded by newer technologies, or will the only people working to keep their players running be the ones with "name brands"? That's very much the pattern with Open Reel enthusiasts in my experience. Similarly with the shutterbugs; I've seen "classic" cameras from pre-war Germany command a king's ransom, yet humbler cameras do not command either the money or the effort at restoration.
Just some thoughts.
Back completely on topic, has anyone tried Elna Cerafine vs Black Gate vs Nichicon Muse for output caps in their audio stages? I for one would like to hear some opinions before I start sourcing parts on this upgrade to my low dollar Sony.
All the best,
Morse |
|
|
| millwood |
| quote: | Originally posted by Mikett
So you're visiting China to source goods. As soon as they get enough capacity they will then send an agent over and you will no longer need to travel there. We'll have no "sympathy" for you then. |
The most valuable activity in the whole supply chain isn't in manufacturing, which the Chinese does superly today. It is in stead in branding, marketing and engineering. The Chinese aren't there yet. Eventually, they may get there (just see the Japanese and Koreans).
When it happens, I will just have to find another place to invest, and don't forget, capital is the most liquid asset.
| quote: | Originally posted by Mikett
How does a poor person who holds a couple jobs to make ends meet invest in themself? Have some empathy man. |
just ask all those who come from modest families (I am one of them). there must be around wherever you live.
| quote: | Originally posted by Morse
my understanding of Yuan vs Dollar is that while the Yuan will buy locally made goods at about 1:1 with the USD, it will not buy Japanese or western made goods at the same ratio. |
That's the same here in the US. No? when you buy foreign goods, fx gets into the consideration.
| quote: | Originally posted by Morse
thus China as a market for the west is not happening the way we were promised, when trade relations were normalised. |
there are clearly sectors that are less open than others (banking, legal services or insurance for example) but for the most part, the market, espcially consumer market, is open. The problem with western companies in China (and in Japan to a more extent) is that western companies have not adapted and adopted an approach tailored for the local market. And when they do, they are usually very competitive. Take Unilever for example. That's a company that is taking the cooking oil market there by storm. P&G is also doing a good job. not to mention GM (which is exporting engines from China) and Cummins.
Is it ideal? no. Can one play successfully and profitably? yes. Is it opening up? absolutely. |
|
|
| Christer |
| quote: | Originally posted by Morse
>>>...I saw they sold some model for around 500 SEK...Of course they were already sold out when I came to the shop. They often have just a few so they will go away quickly and people will end up buying something more expensive instead...<<<
That's called "bait and switch" in the US. In theory it's thoroughly illegal. As always, theory and practice are at odds, with practices being de facto illegal only for those without a good enough legal department and campaign contributions operation to ensure that official scrutiny is minimised.
|
It seems I was a bit sloppy there. I don't really know if they
do it, but I suspect they sometimes do it that way. I really
don't know what the laws here say about it, but probably
it is illegal if they can be proven to do it on purpose. On the
other hand, they usually write some disclaimer like "limited
amount" or "while stock lasts" so I if they have at least a
few it is probably legally OK. On other occasions they actually
do have tonloads of the stuff they advertise. I got an inkjet
printer with ink cartridge for about the price of a replacement
cartridge that way, and they did have quite a lot of these
printers. |
|
|
| millwood |
| quote: | Originally posted by Christer
On the other hand, they usually write some disclaimer like "limited amount" or "while stock lasts" so I if they have at least a few it is probably legally OK. |
"bait and switch" is hard to prosecute for that same reason. FTC requires proof of intent (on the part of the seller) to deceive, and not to sell the advertised items. Many car dealers for example get around that with a disclaimer like the above or put a stock number / vehicle number on the ad. |
|
|
| net-david |
I have been looking at this fairly cheap DVD player for a while to use as a transport and because it would do DVD-A and SACD. BestBuy sent me a 10% off coupon, so I braved the masses of holiday shoppers and bought one. Opened it up as soon as I got home and here is what I found:
Picture of output board and ps
Switching power supply- there may be room to add a small linear ps for the analog stage, or heck, an external power supply, very high end ;)
One BB DSD1791 dac and two BB DSD1702EG dacs, two 4560 opamps. It looks like the 4560s are buffers/filters for the 1702s, but I thought the 1791 needed an ouput buffer, its outputs are differential?
I may just do some dampening to the chassis and leave the guts alone, I will use it mainly as a transport for my Perpetual Technologies P-3A dac. I already have a good SACD player on my main system, I was just a little curious about DVD-A.
--David |
|
|
| jean-paul |
| Wasn't "dampening" making something wet ? I learnt that in case of vibrations you can spend time "damping" the vibrations.... |
|
|
| Morse |
Hi David;
Thanks for the pic of the Pioneer DV563A's interior! I've thought about buying one myself....
The first thought, before you even look at electronics work, is that the boards can easily be remounted on rubber gaskets or o-rings on either side of the screw holes. The second thought is that the output caps look like they're easy enough to find, assuming those connections on the bottom left of the pic are to the audio and video outs. These can be damped with a single dab of rope caulk along one side (not the top, since those are designed to blow "up" through the top in the event of a catastrophic failure. I wasn't able to find the clock crystal in the pic, but it might just be on the other side of the main board. It's another structure that really benefits from some kind of damping (Jon Risch maintains that the "sandbag tweak" as described at his site is best overall, since blu-tak and rope caulk have internal resonances - I'm just a nervous nellie about allowing sand inside my player!).
I'm not sure how much difference it will make, but I'm planning on buying a sheet of thick vinyl sheeting of the type used for damping auto interiors with my next Parts Express order and applying it to the inside of the cabinet lid of my Sony. Before you do any such thing, I'd run it for a while and make sure that the player does not have any heating "issues" (my first and second gen Panasonic DVD's ran pretty darn hot - *knock on wood* for good luck, my A110 still runs though, at least partially because I've been religious about not stacking anything on it during operation that would let heat build up in the case).
On the switchmode power supply, I've never seen a linear power supply on any US export model of any brand - sometimes they're found on the "Japan only" players towards the top of the line, so I wouldn't hold that against the player in any way (not a bad idea to try a linear regulated power supply, just mean that it's not like the Pioneer was unduly "cheaped out"). I didn't see any ferrite clamps on the AC mains in (could be under a board or outside the view on the pic) so I'd definitely see about fitting something there. Parts Express stocks 'em as does Radio Shack - but PE is cheaper by a factor of 3 (once you order enough other stuff to make up for the S&H charge). There are a couple of tiny ferrite beads in the PS circuitry though - but I've found that with the filthy US AC mains in there's no such thing as too much RFI filtering....
Good luck on your tweaks! If it's not too much bother, I'd love to hear about how they're going for you!
All the best,
Morse |
|
|
| net-david |
Main Entry: damp·en
Pronunciation: 'dam-p&n
Function: verb
Inflected Form(s): damp·ened; damp·en·ing /'damp-ni[ng], 'dam-p&-/
Date: 1547
1 : to check or diminish the activity or vigor of : DEADEN <the heat dampened our spirits>
2 : to make damp <the shower barely dampened the ground>
3 : DAMP 1c |
|
|
| Lyra |
| quote: | Originally posted by Morse
Hi Christer;
>>>.Hi Lyra
Sorry for going OT occasionally; as someone who's been outsourced and has had to retool his own job skills (an ongoing process at the moment), it's a topic that resonates.
Back on topic, have you tried any tweaks on your ailing Mustek? Or, have you tried to discern the cause for those alarming voltage levels you quoted? I for one would be a bit leery about using any piece of obviously malfunctioning equipment (in which dangerously high levels of AC are sometimes present) unless I thoroughly understood the causation.
All the best,
Morse |
Hi...I was not as serious as it might look at first glance;)
I think the alarming output voltages is coming from some kind of fault in the switched powersupply. I can definitely!!! feel it in my fingertips when touching the output, and GND at the same time. I have had a (quick) look inside, but there was no obviosly (burned out) defects.
To me...an old electonics-engineer (who have forgotten a lot I realize when i read some of theese posts), a switched power supply is not good at all used inside equipent made for hifi/ audio. To me this is WRONG !
:att'n: Switched powersupply and audio equipment = NOGO (in my ears anyway).........:att'n:
All the best!
P |
|
|
| Morse |
Hi Lyra;
Glad I didn't offend! I tend to get a little preachy on the whole "we shouldn't lose our capacity to produce real wealth and become dependant on the labour of others" thing....others can and do disagree.
>>>...a switched power supply is not good at all used inside equipent made for hifi/ audio. To me this is WRONG !...<<<
Frankly SMPS can be a real pain to work with - my first thought is that some component has gone a trifle out of spec - since it's not just the primary, but secondary component values that count there (i.e. a capacitor's equivalent series resistance, a resistor's lead reactance, etc). I'm no expert on SMPS by a long shot though, and debugging 'em goes over my head. I read up on 'em enough to find out that it was going to take a while for me to experiment around enough to come up with one for a portable valve amp project I've got on the back burner. WAY on the back burner - some very qualified people (thanks Dhaen! :) ) were helpful in putting it into perspective....
Good luck and all the best,
Morse |
|
|
| Morse |
Hi Lyra;
Almost forgot. Where I was going with that was, if you think the SMPS is problematic, why not convert the unit to battery power from a deep draw gel cell (and of course a charger to be run when you're not playing the unit), or build a linear regulated supply? As an EE, it should be a snap for you. Particularly in the case of battery power, you can expect some significant improvements in sound and picture quality as the RFI on the power lines will be nothing but a memory.
All the best,
Morse |
|
|
| millwood |
| quote: | Originally posted by jean-paul
Wasn't "dampening" making something wet ? I learnt that in case of vibrations you can spend time "damping" the vibrations.... |
| quote: | Originally posted by net-david
Main Entry: damp·en
Pronunciation: 'dam-p&n
Function: verb
Inflected Form(s): damp·ened; damp·en·ing /'damp-ni[ng], 'dam-p&-/
Date: 1547
1 : to check or diminish the activity or vigor of : DEADEN <the heat dampened our spirits>
2 : to make damp <the shower barely dampened the ground>
3 : DAMP 1c |
:)
| quote: | Originally posted by Lyra
:att'n: Switched powersupply and audio equipment = NOGO (in my ears anyway).........:att'n:
All the best!
P |
what harm can a smps do in a mostly digital device with just small output analog buffer?
Again, I would be surprised if anyone can hear the difference. |
|
|
| Morse |
Hi Millwood;
>>>...what harm can a smps do in a mostly digital device with just small output analog buffer?...<<<
RF hash from the switching. It depends on how good the SMPS design is and how good the V+/V- rail filtering is. There's also the issue with SMPS dumping pulses of RF grunge into the AC mains that can pollute the incoming power of other components. That's why even cheapie CD/DVD players have an "X" cap at bare minimum (if they didn't they wouldn't meet Part 15 FCC criteria) - but it only acts as a 6dB/octave reduction in both incoming and outgoing RFI; the addition of a ferrite choke will add yet more filtering.
>>>...Again, I would be surprised if anyone can hear the difference...<<<
As always in audio that's debatable, but I for one have heard the grunge that switching noise can produce, and have cut it by aggressively using "X" caps, snubber caps, ferrite chokes, and even isolation transformers. Personally the best rectification for sound quality I've ever used is valve type rectification, due to it's soft switching.
If you can't hear switching noise and RF grunge, count yourself lucky - it's one less hassle you have to put up with.
All the best,
Morse |
|
|
| Lyra |
| quote: | Originally posted by Morse
Hi Lyra;
Almost forgot. Where I was going with that was, if you think the SMPS is problematic, why not convert the unit to battery power from a deep draw gel cell (and of course a charger to be run when you're not playing the unit), or build a linear regulated supply? As an EE, it should be a snap for you. Particularly in the case of battery power, you can expect some significant improvements in sound and picture quality as the RFI on the power lines will be nothing but a memory.
All the best,
Morse |
Have thought about it but there are to many different voltages, I don't remember exactly but I think +-5V, +-12V, -28V!!! and something with 14-15V on it. Standard computer voltages ++. Just too much job.
BTW I read somwere on the net that the DVD-unit itself was interchangeable with other standard DVD units made for PC's. This would no doubt be an advantage...as the original player is very! little fond of scrathed CD's
I think my other player is a better startingpoint for a decent player....my good old Denon DCD-2560.
Build like a tank, but I havent figured it out yet how to make the outputstage optimal with theese 4 AD-DAC's and oversampling.
Regards...
P |
|
|
| millwood |
| quote: | Originally posted by Morse
RF hash from the switching. |
Is it on the digital out or analog out? Even if it is on the analog out, couldn't you filter it out with an easy rc filter? wouldn't that be a lot easier than putting in a linear supply with all those voltages? |
|
|
| Morse |
Hi Millwood;
>>>...Even if it is on the analog out, couldn't you filter it out with an easy rc filter?...<<<
Can a SMPS be effectively filtered? Absolutely. However, you're going to find that you're going to have a tough time getting the best possible sound by adding parts in the signal stream - better to filter RFI from the power supply before it leaves the power supply. Also, the issue of RFI from a SMPS entering other devices must then be addressed, which is one reason I use such aggressive RF filtering at the AC inlet over here.
However, if you have a player with a malfunctioning SMPS (which is what Lyra posted he believed was the case with his) then it strikes me as easiest to sidestep the whole SMPS issue completely with a DIY linear regulated supply. Easiest of all to replace the unit completely, but to an EE more willing to spend time than money.....
Linear regulated supplies are much easier to design, build, and debug than are SMPS ones - as I discovered when I was doing the groundwork on my (still theoretical) valve type portable headphone amp. Designing a GOOD one is a nontrivial task, unfortunately.
As far as all the different voltages are concerned, for someone from a valve background that's par for the course. My DIY 2A3 uses 2.5VDC, 5VDC, 6.3VDC and 350VDC, all from separate transformers and/or windings.
All the best,
Morse |
|
|
| millwood |
| just a follow-up to this discussion on job migration. yesterday IBM announced that it will outsource close to 5000 programming jobs to India, China and other low cost regions. |
|
|
| chris ma |
| quote: | Originally posted by millwood
just a follow-up to this discussion on job migration. yesterday IBM announced that it will outsource close to 5000 programming jobs to India, China and other low cost regions. |
That is very very sad
Chris |
|
|
| Nuuk |
I bought a cheapo DVD yesterday with the name 'Clairtone' on the badge. It cost 38UKP and sounds quite reasonable playing CD's but I get the ocassional click and silence so I will be taking it back for a replacement or refund.
And I remember the days when factories had a quality control department but that job has now been out-sourced, not to India or China but to the consumer! :xeye: |
|
|
| carlosfm |
| quote: | Originally posted by Nuuk
I bought a cheapo DVD yesterday with the name 'Clairtone' on the badge. It cost 38UKP and sounds quite reasonable playing CD's but I get the ocassional click and silence so I will be taking it back for a replacement or refund.
And I remember the days when factories had a quality control department but that job has now been out-sourced, not to India or China but to the consumer! :xeye: |
:D
I can't say this enough:
THOSE CHEAPO DVDs ARE ****!!!
One of those things you use only once.
Even worst than a condom, at least it works once.:clown:
Nuuk, ask your money back or you'll go to the store every day.
Would you spend 250 Euros tweaking that ****?:rolleyes:
New clock, new op-amps?:eek:
And a dead player before the warranty finishes?
For god's sake, I've seen that film before. |
|
|
| ashok |
| quote: | | I still eat meat..does that make me a mass murderer? |
Bas , you murderer !!
:drink: :drink: .................
Me too !!
:drink: |
|
|
| hottyson |
| quote: | Originally posted by carlosfm
:D
I can't say this enough:
THOSE CHEAPO DVDs ARE ****!!!
One of those things you use only once.
Even worst than a condom, at least it works once.:clown:
Nuuk, ask your money back or you'll go to the store every day.
Would you spend 250 Euros tweaking that ****?:rolleyes:
New clock, new op-amps?:eek:
And a dead player before the warranty finishes?
For god's sake, I've seen that film before. |
This is a good point. What choices are there in the US for current inexpensive DVD players to modify? Is there one that can be found for around $100 worth hot rodding? Or do you have to spend more to get good sound AND good quality? Perhaps there are some that are under $200? Many are modifying the Phillips 963 but I think it costs over $300. |
|
|
| Will |
Lars,
Why didn't you go all the way and install yer Zapfilter in the el-chepo DVD ? Then compare it with the $2000 CDP and see.
BTW what's in the Zap filter ? Care to share the schematics ? |
|
|
| Nuuk |
To bring you up to date with my Clairtone story, I took it back to the store on Wednesday and they replaced it without fuss.
However, when I tested the replacement, I found that I could still hear some noise under the music so I played a digital silence track from a test CD and with the volume turned up, I can clearly hear what seems to be motor noise, probably from the sled motor.
However, that aside, the sound is good and can probably be made quite respectable with a small amount of tweaking. Build quality is poor but again that could be rectified with a bit of DIY.
Now Carlos, I agree that this could become a bit expensive except for the point that you are starting with something that costs so little, 38 UKP in my case.
If I had paid say 100UKP, I would be much more critical of the short-comings of this DVD, but not so at 38UKP.
I still reckon that at the price, it is a reasonable candidate for a good sounding (budget) CD player.
The question now is do I return it for a refund or try and cure the motor noise with a cap? Fortunately, a friend is in the same situation and will hopefully report back on whether the noise is curable. |
|
|
| Lars Clausen |
Will: Here are the schematics of the ZAPfilter 2.
All the best, Lars |
|
|
| carlosfm |
| quote: | Originally posted by Nuuk
To bring you up to date with my Clairtone story, I took it back to the store on Wednesday and they replaced it without fuss.
However, when I tested the replacement, I found that I could still hear some noise under the music so I played a digital silence track from a test CD and with the volume turned up, I can clearly hear what seems to be motor noise, probably from the sled motor.
However, that aside, the sound is good and can probably be made quite respectable with a small amount of tweaking. Build quality is poor but again that could be rectified with a bit of DIY.
Now Carlos, I agree that this could become a bit expensive except for the point that you are starting with something that costs so little, 38 UKP in my case.
If I had paid say 100UKP, I would be much more critical of the short-comings of this DVD, but not so at 38UKP.
I still reckon that at the price, it is a reasonable candidate for a good sounding (budget) CD player.
The question now is do I return it for a refund or try and cure the motor noise with a cap? Fortunately, a friend is in the same situation and will hopefully report back on whether the noise is curable. |
Nuuk, send it back.:dodgy:
This is the most sincere advice I can give you.
The moment you open it, you loose the warranty.
Imagine that you can't cure the motor noise (**** dvd-roms...) with just a cap.
You'll be stucked to that ****, and I assure you that those things don't last long.
My father, after 2 ultra-cheap DVDs, changed to a cheap (120 Euros) Pioneer (my first advice:bawling: before he bought the first one).
My brother bought a 115 Euros:eek: DVD-A/V Panasonic.
Guys, this is miles ahead from that ultra-cheap ****.
I will lose some time with these two players.;) |
|
|
| Nuuk |
Well it was 50/50 but in the end I decided to take it back for a refund.
What swung the decision? Well, I didn't want to have Carlos worried all over Christmas ;) |
|
|
| millwood |
| quote: | Originally posted by Nuuk
Well it was 50/50 but in the end I decided to take it back for a refund. |
peraonally, I am too poor to buy cheap stuff.
At work, I think anything is good at a price.
For 38BP, even if it doesn't work, you can certainly afford to throw it out.
Now, if you paid $1000 for a Sony S7000 in the spring of 1997, like I did, that would be an entirely different story, :) |
|
|
| carlosfm |
| quote: | Originally posted by Nuuk
Well it was 50/50 but in the end I decided to take it back for a refund.
What swung the decision? Well, I didn't want to have Carlos worried all over Christmas ;) |
:D
You did well.
That money has a build quality that the DVD player lacks.:angel:
Save the money for something a little better.;) |
|
|
| Morse |
Hi Carlos;
Thanks for the help over on my TDA2030. I did get one channel working following the advice from you and others and will redo it using miniature circuit boards rather than wiring directly to the pins. This'll have to wait 'til after the holidays though.
>>>...My father, after 2 ultra-cheap DVDs, changed to a cheap (120 Euros) Pioneer (my first advice before he bought the first one). My brother bought a 115 Euros DVD-A/V Panasonic. Guys, this is miles ahead from that ultra-cheap ****. I will lose some time with these two players...<<<
That's pretty much the same experience over here (albeit with other 'no-name' electronics) in the past. I think you're onto something - a brand name guarantees that it won't be complete garbage, since none of the brands wants a reputation for something like that. With the fly-by-nighters it's a total crapshoot as to quality. Frankly, given the prices of most high end players, I've come to regard my Panasonics and Sony as "super cheap" and hadn't even thought of the no-names when I started posting on this thread.
All the best and Happy Holidays!
Morse |
|
|
| TugaTweaker |
Carlos , its true that the €100 made in Slovakia Panasonic s35 DVD-Audio and DVD Video machine its miles ahead of asian cheap DVD players . I will not call **** to the cheap european production , and everything made in Denmark even cheap like Kiss DVD, dIVX player , sure deserves attention and Lars too .
But i think that we may full agree the idea that a cheap
DVD no matter his origin , once we change a few important components , in the power supply mainly , can stand comparison
with the expensive ones , i have been doing this for the last ten
years . I m talking of small amounts of money .
Regards
Martinho Adao |
|
|
| carlosfm |
| quote: | Originally posted by TugaTweaker
Carlos , its true that the €100 made in Slovakia Panasonic s35 DVD-Audio and DVD Video machine its miles ahead of asian cheap DVD players . I will not call **** to the cheap european production , and everything made in Denmark even cheap like Kiss DVD, dIVX player , sure deserves attention and Lars too .
But i think that we may full agree the idea that a cheap
DVD no matter his origin , once we change a few important components , in the power supply mainly , can stand comparison
with the expensive ones , i have been doing this for the last ten
years . I m talking of small amounts of money .
Regards
Martinho Adao |
Hi Martinho.
We are talking here of cheap DVDs for tweaking and playing audio CDs.
In my view that's not the best option.
I would buy a good second hand CD player and tweak it.
Or a serious brand (even cheap) DVD player.
And I don't include the Kiss DVD in the group of cheap DVD players.
After all, its costs more than a cheap Pioneer, Sony, Philips, Toshiba... and it looks like a much more serious device than those 50 Euros:eek: DVD players.
I've been tweaking for many years too, but I wouldn't loose my time and money with these **** things.
This is my advice for you guys, take it or leave it.
:angel:
I just don't like to hit play and break it.:eek: :D
Always liked quality things. |
|
|
| millwood |
some of the apex players are actually CD-ROMs, and I have yet to hear one person insane enough to claim that copies made from a cheap and an inexpensive CD-ROMs are different (assuming of course that both work).
I agree that the analog part of the circuitry can make potentially audible difference but the digital part? sure you can pay more for less but why?
But then again I am not goden-ear enough to hear any of that, ;) |
|
|
| carlosfm |
millwood, a cheap DVD-ROM can make stupid things.
Like the motor noise Nuuk was talking about, or taking 20 seconds:eek: to read a CD's TOC.:dodgy:
Today it's 20 seconds, one month later it's 40 seconds, and finally it stops reading.:bawling:
Ridiculous.
And what about CHEAP switching PSUs on audio devices?
Dreadful.
In a while you'll find out that to tweak this thing you won't even use the box, it's too crappy.:bawling:
Value for money?
Oh please...:clown: |
|
|
| analog_sa |
| quote: | | I have yet to hear one person insane enough to claim that copies made from a cheap and an inexpensive CD-ROMs are different |
Look no further :) |
|
|
| millwood |
| quote: | Originally posted by analog_sa
Look no further :) |
Yeah. on a 2nd thought, Microsoft Office installed from my cheapo Brand A runs doesn't look as sharp as the same package installed from Brand B.
:0 |
|
|
| carlosfm |
| quote: | Originally posted by analog_sa
Look no further :) |
I'm in too.:D
millwood, you won't notice difference on CDR copies made on cheap CDR drives and/or at insane writing speeds (more than x4 for audio CDs) IF YOU DON'T HAVE A GOOD SOURCE.
On a crappy DVD player of course you won't notice.
And the problem is not your ears.;) |
|
|
| millwood |
| quote: | Originally posted by carlosfm
millwood, you won't notice difference on CDR copies made on cheap CDR drives and/or at insane writing speeds (more than x4 for audio CDs) IF YOU DON'T HAVE A GOOD SOURCE. |
I would like to retract my earlier statement. I have indeed noticed that pictures burned on crapy CDRs look positively gray, software packages burnt on crapy CDRs, or through crappy CD burners, or installed on crappy CD-Rom drives, don't look right, and sometimes have missing features.
I am sure you guys have the same experience, don't you?
:) |
|
|
| fdegrove |
Hi,
| quote: | | And the problem is not your ears. |
Are you sure about that?
Cheers,;) |
|
|
| carlosfm |
| quote: | Originally posted by millwood
I would like to retract my earlier statement. I have indeed noticed that pictures burned on crapy CDRs look positively gray, software packages burnt on crapy CDRs, or through crappy CD burners, or installed on crappy CD-Rom drives, don't look right, and sometimes have missing features.
I am sure you guys have the same experience, don't you?
:) |
Is JITTER still such an obscure thing?
At least understanding what is it and how to minimize it?
millwood, we're talking AUDIO CDs.:angel: |
|
|
| millwood |
| quote: | Originally posted by carlosfm
Is JITTER still such an obscure thing?
At least understanding what is it and how to minimize it? |
I have absolutely positively zero idea about jitter. do you know what it is? and specifically how is that such a deficiency in those el cheapo DVD players? |
|
|
| millwood |
on the quality front, even if you buy brand name and supposedly high-end stuff, you can assure yourself of a working units. Marantz AVR for example had audio drop outs on digital inputs; Denon DVD players had lip sync problems, as some pioneer ones.
the differrence between a no-name dvd player and a brand name dvd player is much smaller than that in the analog land (like analog amps).
Everyone is doing this. East Tech is famous for example for OEMing for the likes of ATI and Shoreborn. My Parasound is made in China as my Signature.
BTW, Denon & Marantz and McIntosh is building a factory in China to function as its global manufacturing hub.
We better get used to it and don't hold on the perceived notion of brand names and being taken to the bank by marketers. |
|
|
| Circlotron |
| quote: | Originally posted by millwood
I have yet to hear one person insane enough to claim that copies made from a cheap and an inexpensive CD-ROMs are different |
A =data= CD is sprinkled with lots of extra bits for the purpose of error correction. IIRC the resulting bit error rate is 1 in 10^12 or suchlike. If the CDROM hardware doesn't co-operate to make this happen then your files are going to have problems left right and centre, something that will be immediately obvious. Generally speaking though, even dirt cheap CDROM drives give no problems with data CDs.
An =audio= CD has relatively little provision in the way of error correction - worst case is the error is interpolated or muted and you hardly hear it.
Bottom line is this - I think if you read a data CD then you are going to get an error-free result. If you read an audio CD then the result may depend very much on the disc and the individual player. |
|
|
| mrfeedback |
I read a study somewhere on the net about the cd-rom burner drives being quite important.
Bad burners place jitter on the burned disc, and this becomes audible on replay machines.
Recorded pit depth and transitions quality are factors , and so is disc rotational speed stability during recording of audio discs (1x-4x recomended).
IIRC Plextor drives were rated as best recording drives in terms of playback jitter performance of the recorded disc.
Silver, gold, blue, black etc discs were also rated as giving differing playback jitter performance.
Commercial release (silver) discs have measurably different jitter performance according to pressing plant, mother mastering etc too.
Eric. |
|
|
| mrfeedback |
Originally posted by millwood
I have absolutely positively zero idea about jitter. do you know what it is? and specifically how is that such a deficiency in those el cheapo DVD players?
Jitter is everything.
There is infinite information on this forum and all over the net about jitter- go knock yourself out.
Eric. |
|
|
| carlosfm |
| quote: | Originally posted by mrfeedback
I read a study somewhere on the net about the cd-rom burner drives being quite important.
Bad burners place jitter on the burned disc, and this becomes audible on replay machines.
Recorded pit depth and transitions quality are factors , and so is disc rotational speed stability during recording of audio discs (1x-4x recomended).
IIRC Plextor drives were rated as best recording drives in terms of playback jitter performance of the recorded disc.
Silver, gold, blue, black etc discs were also rated as giving differing playback jitter performance.
Commercial release (silver) discs have measurably different jitter performance according to pressing plant, mother mastering etc too.
Eric. |
Eric,
Once again, on the spot.;) |
|
|
| hifiZen |
Well, I probably shouldn't touch this thread, but I've spent the last 2.5+ years designing DVD players for numerous brand names, and I've seen the industry evolve from the inside... plus I see a lot of misinformed posts in this thread. But, I'll give a brief breakdown of what you get when you buy a higher priced DVD player...
1. Better laser head and transport mechnism (motors, spindle bearings, tray, manufacturing tolerances). Good mechanisms will last longer, be quieter, seek faster and more accurately, and deliver lower bit-error rates during playback. They're also more tolerant of damaged discs. Good lasers will similarly give better read performance, tracking and focus, and they'll last longer too.
2. Better front-end circuitry (laser and motor control servo, read-channel decoding).
1 & 2 are directly reflected in how well the player can do disc detection, the playback error rates, tolerance of surface imperfections on the disc, and speed for things like DVD layer change. I did a fair amount of work with DVD front end design, tuning and so on, and they are difficult to get just right. This is the area where some of the biggest sacrifices are made in cheap DVD players. The R&D effort is just not done - the low-cost OEMs are relying on "prior art", just trusting that it will function.
3. Better MPEG decoder chipset. The low-cost units have no room for a decent chipset. They use the cheapest available, period. More expensive units can use better chipsets, and without going into the details, suffice it to say that DVD decoding is exceedingly complex - better chipsets result directly in better video and audio performance, and better useabilty, because care has been taken to ensure that it's all handled properly. (You wouldn't believe what some player firmware will do with audio samples... :whazzat: ).
4. Much, much better PCB layout and quality. Open up a mid-priced Sony and compare that to an Apex. No comparison. The Sony will likely have a 4 or 6-layer mainboard with very fine tolerances, while the Apex will use a crappy 2-layer mainboard, and 1-layer everywhere else.
5. Much better software QA and assembly-line QA. There is tremendous variance in the QA programs of different manufacturers. The software that runs inside these things is ridiculously complex, and good QA is essential to ensure playability with all the badly authored discs out there. The DVD standard is really too flexible and open, and it's created lots of problems because the title authoring has not been held to the standards that do exist. Chances are, if you have a DVD that plays fine on one machine, but borks on another, the DVD is improperly authored, and there's nothing wrong with the player. That said, a manufacturer with good QA will test each and every "special-case" title they know of, to see that it plays correctly... that's hundreds of different movies that need to be tried out, each with different bugs that may or may not show up, and tehn require subsequent debugging and software patches. Assembly-line QA will keep bad units from winding up in your hands, and also snag engineering problems early in the production phase, leading to improved quality for every player that comes off the line after that. A good rule of thumb: never buy a DVD player when the model is brand new. Wait a month or two, and then buy one. You'll get a better product, guaranteed (many models go into production before software debugging has finished, just to meet the production and delivery schedules).
Of course there's always the obvious stuff, like basic component quality and PSU quality too, but that pretty much covers it. If I had to make a recommendation for a player, I'd say buy a model that's at least a year old... the technology has gone steeply downhill since the introduction of a certain cutthroat Taiwanese chipset brand that made the $50 Apex possible about 8-10 mo ago. Sadly, all of the OEMs were forced to compete on price alone, and features, quality, and usability have all suffered.
There are other things I could talk about, such as why progressive scan deinterlacing should be done in the player, not in the TV set, and why a DCDi badge does not mean you'll get good progressive scan. Actually, progressive scan is one big bag of worms that I don't care to get into. Suffice it to say that there can be staggering differences in the quality of progressive scan conversion (3:2 pulldown, and video deinterlacing) from different DVD players, so if you have a progressive display, then it behooves one to do some research and get a player with the best progressive scan conversion possible. I recommend this excellent resource if you really want to understand the basics of progressive scan: Home Theatre HiFi. Yes, as much material is there, it's only the basics. |
|
|
| millwood |
| quote: | Originally posted by mrfeedback
I read a study somewhere on the net about the cd-rom burner drives being quite important.
Eric. |
I also read on the net that you can use certain kinds of permanent markers to improve your CD performance.
BTW, lots of internet sites talk about why cables cannot make a different.
so do you agree that cables cannot make a difference based on that?
:)
| quote: | Originally posted by mrfeedback
There is infinite information on this forum and all over the net about jitter- go knock yourself out.
Eric. |
that's why we have so many jitter experts who cannot explain what jitter is, what caused it and why it is worse in certain players than others. |
|
|
| millwood |
| quote: | Originally posted by hifiZen
Well, I probably shouldn't touch this thread, |
thanks for such a well written post.
I didn't see you mentioning "jitter". Isn't jitter everything?
| quote: | Originally posted by hifiZen
the technology has gone steeply downhill since the introduction of a certain cutthroat Taiwanese chipset brand that made the $50 Apex possible about 8-10 mo ago. |
I didn't know Apex used those Taiwanese chipset. What chipsets do they use? |
|
|
| hifiZen |
Front-end chipset can have a big influence on jitter level... it gets into some pretty complex details regarding the logic-level internals of the chipset, but there are many different ways to handle spindle speed control and the PLL or PLL-like system that is at the head of this function. Data buffering and intra-IC clock domains play a major role here...
PS - all these cheap DVD players are the reason I no longer have a job... for the sake of the other poor souls still employed by American DVD chipset makers, don't buy these odd-name Chinese players! Get yourself a good one (and a good player will in fact make an excellent platform for audiophile mods) made by a japanese company (I recommend Sony, JVC, and Panasonic models - in their mid to high price range). |
|
|
| mrfeedback |
Hi Chad, thanks for your input.
Can you detail the differences between a good pickup and a bad one?, and what goes wrong with pickups ?.
Eric. |
|
|
| millwood |
during the VCD days, Cirrus had a huge chunk of the Chinese market. and I suspect that they still do today in DVD. Zoran also been an aggressive player in that market.
| quote: | Originally posted by hifiZen
don't buy these odd-name Chinese players! |
That's a pretty high order to accomplish. I don't believe in sanction / boycott. To have sustainable success, one has to have a desirable product at a competitive price. If you cannot do that, nothing can save you or your job.
BTW, is there any data on perfromance benchmarking of various chipsets? |
|
|
| mrfeedback |
Originally posted by millwood
I also read on the net that you can use certain kinds of permanent markers to improve your CD performance.
BTW, lots of internet sites talk about why cables cannot make a different.
So do you agree that cables cannot make a difference based on that? :)
The article I spoke of included jitter measurements, including cd pens making measured differences.
that's why we have so many jitter experts who cannot explain what jitter is, what caused it and why it is worse in certain players than others.
The reason that nobody is explaining to you is that jitter is an elementary concept, and easily researched by yourself on this forum and on the net.
Eric. |
|
|
| millwood |
| quote: | Originally posted by mrfeedback
The reason that nobody is explaining to you is that jitter is an elementary concept, and easily researched by yourself on this forum and on the net.
Eric. |
so how much do you know about such an elementary concept? |
|
|
| hifiZen |
MediaTek started the whole price landslide... and now all the chipset makers have been forced to cut corners (and staff!) to keep up. The bulk of production volume comes from these Chinese OEMs who buy their chipsets based on price alone. Manufacturers used to care about quality, but lately, they're not interested. Features are checklist items now... like progressive scan. They don't care if it works well or not, only that they can put the label on the box!
I recall a trip to an Asian OEM about two years ago, to try and convince their senior engineers that our chipset's progressive scan was technically better than a major competitor's chipset (and it was, IMHO). At the time, our sales depended on securing contracts with technical discussions like this. But in the last year or slightly more, the only thing they want to hear is price... technical sales meetings dried right up.
mrfeedback:
The differences in pickup are mainly the laser and photodiode. It mostly boils down to production quality control and tolerances for optical alignments, at least to my understanding. (You understand, I didn't work on pickup design, I just got to see how well they worked in-system...). But there are some problems that come up... lasers burn out because of bad design or poor power control ciruitry. RF signal can be weak or noisy if the analog circuits in the pickup aren't good. Same thing with various error signals that help with focus and tracking. One key thing that many people don't take into consideration is that an optical pickup (OPU), and the associated front-end circuitry is predominantly high-frequency analog stuff. A lot of cheap OEM designs haven't had all of the analog circuitry properly optimized. Even simple things like bias resistors and reference voltages can get screwed up, just because of the sheer number of different OPU models and RF preamplifier ICs available - each combination of OPU+RF amp requires different discrete circuitry to work together, and it must all be meticulously optimized. There's also a motor driver IC, which needs good S/N performance so that the feedback loops can be tightly controlled, and the cheap chips are just plain noisy. There's a myriad of little things that need care and attention in a front-end circuit. Layout is very very important here too. And, of course, you'd better believe that the motors will have an influence on servo loop performance too. Sled gearing sometimes has some slop in it, which leaves a dead-zone in the servo control, and an ambiguity during seek operations, which can drastically slow them down. Anyway, I could ramble on, but what's the point. Cheap is cheap. You get what you pay for. Joe six-pack just hasn't figure out yet that his little $39 special is a piece of junk... they haven't been on the market long enough for the masses to learn their lesson. Soon enough, the market will reach saturation, and people will begin "upgrading" to better models as they replace their crappy ones. Then, I hope, we'll see the return of some quality. Of course, HD-DVD will be making inroads by then... :rolleyes:
milwood: actually, it wasn't Cirrus, it was C-Cube, my ex-employer. C-Cube created the VCD standard, and pioneered much of the MPEG encoding tech for professional video studios. Today, C-Cube is owned by LSI Logic, and has moved out of the DVD chipset biz, but should be a major player in DVD recorders, which is set to be the next Big Thing(tm). Cirrus has always seemed to be just an "also-ran" in the DVD chipset world. I did a certain amount of competitive product analysis, and have seen pretty much the full gamut of chipsets, but never came across a Cirrus DVD chipset. Zoran, however, has held out fairly well over the last few years. It seems their cost cutting has been more successful than others, and they've more or less retained their Toshiba business. But if you ask me, their chipset is pretty ho-hum. |
|
|
| millwood |
| quote: | Originally posted by hifiZen
But in the last year or slightly more, the only thing they want to hear is price. |
I can attest to that myself, :(.
| quote: | Originally posted by hifiZen
milwood: actually, it wasn't Cirrus, it was C-Cube, my ex-employer. |
you are absolutely right on that. I was wrong. |
|
|
| millwood |
| BTW, Chad, what's your view on the jitter-killing felt-pens? |
|
|
| hifiZen |
| I think it's complete BS. Same with "sonic-enhancing" blue LEDs shining on the disc. I know enough about how optical pickups and the associated circuitry work to be severly skeptical of almost every argument I've heard in their favour. I chalk it up to listener psychology. That said, I haven't done much research or thinking on the subject, so perhaps there's some obscure mechanism of operation I've overlooked. There doesn't seem to be much, if any, solid scientific research on the matter, anyway. Proper double-blind testing would be in order, as would serious technical investigation to correlate any audible effects with measurable parameters... maybe if I'm bored, I'll have a look at mrfeedback's article on cd pens. |
|
|
| alvaius |
This is one of those things I hate to admit works, but I have seen it proven with a error-rate detector that the green pen thing can work..... but not always. One of my friends showed this to me about 8 years ago when working on CD-ROMS. For brand new CD's on a good CD-ROM drive, the effect was minimal, however if the disk was a bit "hazed" from physical abuse, it seemed to make a significant difference. However, on some of the cheaper CD-ROM drives, it sometimes made it better, and sometimes worse! He was not looking at jitter, so I can't make any specific comments on that.
I don't profess to have experience in CD\DVD pickups, but I have a fair amount of experience in optical detectors. One theory on why the blue LED "may" work is that it may actually bias the detector into a better operational range. That said, it may not matter if it is blue or whatever. Blue may work best because very little light is likely to get through the optical filter as opposed to another color closer to the optical cut-off. That said and done, any light that gets through may increase the noise level.
Alvaius |
|
|
| millwood |
| quote: | Originally posted by mrfeedback
Bad burners place jitter on the burned disc,
Eric. |
after re-reading your post, I was curious as to how you perceive jitters work in playback and more specifically recording. or maybe you are talking about different jitters. |
|
|
| Christer |
There seems to be some confusion about jitter. As far as I can
see there are two different and unrelated phenomenae
referred to as jitter. The first is clock jitter in the AD and DA
conversions, which has been discussed extensively and it is
also straightforward from theory that such jitter can affect the
final analog signal. The other type of jitter, which Eric talked
about previously in the thread, is jitter in the process of
reading/writing. There is some jitter when reading the disc and
there is some jitter when writing the disc, where the latter
will be recorded in the digital data and thus add to the jitter
of the reading process itself. However, it is important to note
that this second type of jitter has nothing to do with the first
type, since the data is buffered and it is only the jitter of the
clock reading the buffer that affects the analog signal. The
second type of jitter can, however, cause data corruption of
the digital signal if it is serious enough. That is, it may cause
read errors, which can affect the sound but in a different way
than clock jitter does. |
|
|
| hifiZen |
alvaius:
Consider that the photodiodes are imaging a very tiny laser spot (on the order of a few microns in diameter) over most of their surface area. Almost the full power of the laser (minus reflective and transmissive losses) is focused on this tiny spot, so you may begin to understand that the ratio of laser light to ambient light reaching the photodiodes is quite large. This particular fact makes possible the disc detection/discrimination and focus search operations. I don't think the blue LED will have significant effect on the photodiode biasing. At one time, I'd planned to actually go into the lab with a blue LED and see what I could measure, but never got around to doing more than a quick-n-dirty trial, which turned up nothing useful. As far as I could tell, none of the major signals were affected by the presence of the LED, but of course this was not a very scientific or thorough test.
What I have seen, and heard reported (well before green pens and blue LEDs became fashionable), is camera flashes upsetting playback. Now whether this is due to electromagnetic interference from the flash electronics discharging, and interfering directly with the RF circuits in the pickup, or whether it's due to intense light entering the photosystem, I don't know... but food for thought, anyway. People naturally jumped to the conclusion that it was caused by the flash of light, and hence started focusing attention on optical effects. I personally lean in the direction of an EM burst interfering with the RF circuitry, which isn't always well shielded. It would be nice to believe that there is a universal "fix" (as though something needs fixing :rolleyes: ) for every CDP out there, but in reality, every design will react differently to EM interference and the presence of ambient light or other optical differences. |
|
|
| millwood |
to just add to chad's point, doesn't the laser pick-up have very limited bandwidth and very close focus distance?
so you have to use the same wavelength (mostly red) or focus on the exactly point for the light to be seen by the laser diode. Both are pretty hard to do.
the close focus distance is useful so that smears on the disk or minor cuts don't bother the laser pick-up. |
|
|
| mrfeedback |
Hi Chad,
Thanks for your further info.
My question was mainly related to why pickups fail.
I have replaced hundred of faulty pickups (mostly KSS types) in audio cdp's in my time, but have never been able to get a definitive answer on why/how they fail.
I have had several pickups with no laser light output, but the by far majority seemed mechanically ok, but would either not track at all, or would skip very easily despite optimising servo adjustments.
Notable is that the RF signal is usually quite noisey/jittery with defective/borderline pickups, but then again new pickups that work perfectly fine can exhibit noisey RF output also.
Eric. |
|
|
| hifiZen |
Well, lasers just get old and wear out - like a lightbulb. Eventually, they just burn out. The photodiodes can also degrade over time... lower sensitivity and whatnot. I don't really know all the details myself, as my company didn't make pickups. But, from my understanding, the laser usually has the lowest MTBF. This is also affected by the automatic power control (APC) circuit that servo-controls the laser's light output level. As the laser ages, it's light output falls, and it gets driven harder and harder by the APC to try and keep the light output constant. At some point, the APC circuit may just saturate, and so while the laser is still operating, it's output is too low, leading to poor tracking and focus, disc detection etc.
Older CDPs also relied on purely analog servo loops, and were subject to problems of component tolerances and aging leading to drifting values and part failures (caps, resistors and opamps). Nowadays it's all digital - the RF goes through a high speed A-D, gets processed in DSP, then a DAC spits out the signals to control the tracking and focus coils, sled motor, and spindle. A handful of not-so-critical passives are used to filter signals for the ADCs or DACs. So DSP has taken a big bite out of the component aging problem. I have seen issues related to DAC and ADC performance, though these are generally not considered a "wear item" unless the silicon gets exposed to ESD or some other damaging conditions during it's lifecycle.
It's worth noting that most consumer grade servo loops are a bit marginal in terms of performance, even the best ones. Ever since I first started working with DVD front-ends, I have always been amazed that they work so well for such noisy circuits. The precision required for tracking and focus is quite remarkable! But, profit margin considerations will always ensure that the parts used are just good enough to do the job, without unnecessary cost related to improving that performance beyond what is strictly necessary for proper function. There's a sweet spot, where everything is tuned at manufacture time, and all is well within that sweet spot. But, stray too far, and focus, tracking and spindle control get a bit grouchy, as I'm sure you're well aware. Manufacturers could use better lasers, better optics, better photodiodes, better RF chips and motor drivers etc., but would the average consumer ever know the difference? Not counting performance with damaged discs, the pickup either works, or it doesn't. There's not much in between.
Speaking of servo loop performance, and tying that back to the magic felt pen / blue LED thing, I think a far greater benefit can be realized with improved transport mechanics - simply making the tracking and focus easier. Ultimately, this boils down to vibration control... low vibration (read: quiet) motors and smooth running ball bearings, tight tolerance gearing, rigid frame to hold everything solidly in place and damp resonances, and (i think often overlooked) aerodynamics around the spinning disc. |
|
|
| mrfeedback |
Thanks again........
I only ever had a couple of pickups with no light output, and mostly all others looked to have normal light output level.
The few that did not were able to be adjusted to give normal light output level and RF level.
I found plenty of pickups where the RF output (HF signal) looked fine but would not work in any machine.
Replacing the pickup in these machines cured the problems.
I have also repaired plenty of cdp's by resoldering the servo stages (particularly SMD chips) even though the joints looked fine by visual inspection.
I agree that it seems a wonder that some machines work at all despite the electrically noisey environment and doubtful power and grounding techniques typically used.
A comment made to me regarding modern WM type players with anti-shock buffer memory was that this allowed usage of lousy pickups because of multiple reads - switch the shock buffer to off and these mistrack at the merest bump.
Just some Info from the servicing (20+ years) side.....
Q - do all DVD players run at multiple disc speed when playing audio discs ?.
Eric. |
|
|
| hifiZen |
| quote: | | I found plenty of pickups where the RF output (HF signal) looked fine but would not work in any machine. |
That's odd, indeed. If you're actually getting an RF signal, and A - F diode signals all look OK, then i see no reason it shouldn't work... i mean, in order to have an RF signal at all, the focus, tracking and spindle servo loops need to be locked. So that's a bit of a mystery. Perhaps it has something to do with the actuator coils / suspension wearing out. I dunno... just a random thought.
Regading the anti-shock models, that doesn't surprise me at all.
| quote: | | Q - do all DVD players run at multiple disc speed when playing audio discs ? |
No. In fact, every DVD player I've encountered reverts to plain-jane 1x playback, just like an ordinary CDP. Sidenote: most DVD players have a separate laser just for CD, but cheap players skip this, and use one laser for both DVD and CD. Of course, it won't be the proper wavelength for one or maybe even both types of disc. Back to the point: the reason nobody does higher read speeds is that CD discs don't have any kind of physical data addressing built in, like HDDs or DVDs do. This makes it hard to realign the data streams if there's a jump during playback... you don't know where you are, or where you were in the data stream. Hence, when a CD skips, the playback can resume from just about any random point in the adjacent data. Yes, there's a timecode in Q-subchannel, but that's not very reliable or useful, so it's just ignored. At the root, CD playback almost always relies on a servo loop controlling the spindle speed, in order to keep the RF signal locked to a PLL, and the data flows at exactly 1x... straight to the DACs (or maybe through a buffer).
In contrast, DVD playback is done at higher disc speed than necessary, because the data packets all contain physical addresses that allow easy realignment of the data. When the read-channel buffer is full, the OPU jumps backward and re-reads some data. The DVD front-end is thus slave to the decoder chip, which requests data from addresses as it needs that data, and lets the front end chipset figure out how to deliver it, just like a hard drive. |
|
|
| carlosfm |
I'm out of TIME for this jittery talk now, but I have some CDR discs recorded several years ago on a first generation HP x2 CDR drive, and I can hear it's not perfect.
Bass is not tight.
I've bought some original CDs of those that I have recorded long ago and the difference is amazing.
If I copy a CD now, at home, it will be very difficult to distinguish from the original, but on a cheap CDR drive and/or disc and mainly if you record at more than 4x,you'll muck up the sound.
Of cource, you can only hear the effect playing the disc on a good source.
Low Jitter.
My CDP has an LC-audio XO clock, from 1999 (I must be one of the oldest foreign customers of the LC clock).
Bass is tight, soundstage very good.
If it's not, something's wrong.;) |
|
|
| alvaius |
HiFiZen, perhaps you can answer this question?
A few posts back you stated that the DVD is actually read faster than the data is needed. I knew this was true for movies, but have not been able to confirm it for DVD-Audio/SACD.
I have done some rough jitter measurements on CD-Audio and DVD-Audio on my Pioneer and JVC DVD-Audio players as well as a friends Panasonic. In all cases, the jitter on the clocks for DVD-Audio was better, substantially on the JVC. This sort of leads me to believe that the DVD players are buffering even on DVD-Audio.
One of the reasons I have asked is that I have sort of abandoned building an oversampling CD player and plan to put that effort into upgrading a DVD player. I plan to take my CDs and up-sampling them on the PC (playing around with the algorithms), and then burn them to DVD-Audio disks.
Alvaiusdesign program]. |
|
|
| alvaius |
HiFiZen,
W.R.T. the small spot size and ambient versus laser light, you are thinking from the perspective of the pits. However, when you consider ambient light, you must think from the surface of the CD as well (or predominantly depending on surface condition, ambient light angle, etc).
Remember that the reflective pits are covered by over 1mm of plastic. The pits and focusing spot may be on the order of 1/2*2uM at the surface of the pits, however, at the surface of the disk, the spot is more on the order of 1/2-1mm. That is starting to get fairly large. This is one of the main reasons why CDs are not that susceptible to small scratches.
When we think of a spot size of 1/2-1mm, the possibility for ambient light can become significant.
Alvaius
p.s. I would still lean towards the RF for the photoflash, however, photoflashes have huge optical power levels (not energy). A good camera flash can output several joules in 10's of microseconds for a power level in the 100,000 watt+ range. |
|
|
| millwood |
| quote: | Originally posted by carlosfm
I'm out of TIME for this jittery talk now, |
you are talking about a different kind of jitter, carlosfm. |
|
|
| hifiZen |
alvaius:
Yes, all DVD and DVD-in-disguise (SACD) media is generally treated the same by the front end circuitry. From the point of view of the servo DSP and associated control logic, it doesn't much care what particular data is on the disc - all it sees is the same basic DVD structure at the lowest level. It's up to the back-end (decoder chip) to decide what kind of content it's dealing with, and handle the data accordingly. So only very rarely will you see any difference in how a front-end handles DVD-V vs. DVD-A vs. SACD. Try this test: pop in a DVD-A or better yet, an SACD and start it playing. Then mute your preamp and press your ear to the front of the player. Depending on the mechanism, you should be able to hear little clicks as the laser head jumps back... on my sony NS-500V, the little clicks occur at roughly a 4 - 6 Hz repetition rate, with significant "jitter". ;) You may hear a different rate, depending on the front-end's buffer depth and other factors.
You also raise an interesting point regarding the size of the laser spot on the disc surface. However, your logic is unfortunately flawed... The lens system works just like a camera lens. To continue with this analogy, imagine the photodiodes (very tiny) to be a single tiny grain of dye / silver halide on a piece of film behind the lens. If the lens is properly focused, the laser spot will be a sharp point on the film, just the right size to cover a single grain of dye (in this case, our photodiodes), and we get a good RF signal to decode into data. Anything in the "scene" either in front or behind the plane of focus becomes a large blurry spot on the film plane, thus distributing it's energy over a much larger area than a single grain of dye. This is why scratches and blue light reflected from the surface will not focus to a point concentrated on the photodiodes... both will have a large circle of confusion (out of focus at the film plane). Hence, the energy density will still be very low compared to the laser, which is focused sharply on the photodiodes only. Also, I should point out that the lens system for an OPU has a very large effective aperture. This gives it a very very shallow "depth of field", to use photographic terms.
That was a bit of a rough explanation, but I hope you understand what I meant. The point is that not all light that enters the lens will be focused to a pinpoint on the photodiodes. The large spot on the surface of the disc will become a large spot at the other end of the lens, covering an area much larger than the photodiodes. |
|
|
| alvaius |
hifiZen,
My god, now you are asking me to turn on my optics brain..... :-)
I do, completely see your logic [same logic as if you are taking a picture through a window, get the camera as close to the window as possible so you don't see the dirt on the window], however, I am not sure I completely agree. I think I agree more with you than with myself, though, especially if the effective aperture is large.... yep, blue/ambient should not matter. There will be some dependance on how the light reflects off the surface. If the reflection is diffuse, or essentially spherical radiation, then you are 100% correct. However, if the reflection is specular and the source is far enough away, then you have what is essentially a collimated beam pointing possibly (but not likely) pointing into the lens. [If that sounds really confusing, good, because I confused myself.... think of it more from a ray-tracing standpoint]. However, since people generally mount the blue LED parallel to the disk surface, most of the light should just bounce off.... so you still must be right.
Being a reformed skeptic (ever since I heard the difference between two analog audio cables, not to mention seeing green marker on a disk actually effect bit error rates with my very own eyes), I try to look for ways that something could work before completely dispelling it. You sound very familiar with these optical systems. Is there anyway that light could be "leaking" into the system? The only way I could see a blue LED "helping" would be to bias the detector, so I am trying to think of how the light could get in and do this.
Alvaius |
|
|
| alvaius |
hifiZen,
Thank you for the tip on listening to the DVD mechanism. I hear exactly the same sounds listening to DVD-Audio as to a DVD-Movie, so I guess I can assume that is reading in bursts and buffering.
I think you have probably saved me several hundred hours of no doubt interesting, but possibly unproductive DIY time. I am definately going to abandon my upsampling CD player design. I really didn't want to be an expert on VisualDSP any way. I am going to spend some time on upgrading my DVD player and upsample on the PC my worth listening to CDs to DVD Audio.
I am guessing you will be able to confirm the next item. I figure that DVD-Audio has more robust error correction than CD-Audio. Is this true?
Thank you in advance,
Alvaius |
|
|
| fdegrove |
Hi,
I must say the analogy with how modern hard discs and CPUs work is striking...
Where the HDD is still magnetic, it may well turn into an optical reading/writing system soon...
Cacheing data is already used it seems, read ahead and buffer too....
Interesting really, |
|
|
|
