Banned
Joined 2002
Implementation rather then technology used imo.
What Meridian are doing is unlikely to be a CD Rom with a 12 V and 5 V supply running it. I am sure they have gone to a bit more trouble.
I have generally been a fan of quality well built mechanisms like CDM1, VRDS, CDM9 pro etc. I was gobsmacked when a TACT CD player using a new plastic "designed for audio" VAM12 I think smacked the beautifully put together Levinson 31......
What Meridian are doing is unlikely to be a CD Rom with a 12 V and 5 V supply running it. I am sure they have gone to a bit more trouble.
I have generally been a fan of quality well built mechanisms like CDM1, VRDS, CDM9 pro etc. I was gobsmacked when a TACT CD player using a new plastic "designed for audio" VAM12 I think smacked the beautifully put together Levinson 31......
Meridian adds a second buffer.
This is how I see it.
The 47 Laboratory PiTracer and Teac VRDS are impressive pieces of engineering. As a Garrard 301 owner, I can safely say I appreciate great engineering as much as the next guy. But there's a difference. A turntable benefits from mass, stability and such. Those things are of relatively little concern for a CDM. A CD rotates at various speeds and the information is interleaved.
What you need is a CDM that's "good enough." At best a laser can only read the CD without errors. But because of how the information is stored and because the speed of the CD constantly has to be adjusted, the stream of data will always be off. So the most important part of a CDM has to be the electronics--the FiFo and buffer.
Now, I'm no expert on CDMs. But I believe none of the psychobabble coming from 47 Laboratory and Teac. And the belt-drive CDMs out there are nothing but snake oil as far as I can tell.
The Philips CD-Pro still fills a purpose. It has native I2S support and comes with a remote, nice LED display and more. At €300 it's not cheap. But it's not a rip-off either.
This is how I see it.
The 47 Laboratory PiTracer and Teac VRDS are impressive pieces of engineering. As a Garrard 301 owner, I can safely say I appreciate great engineering as much as the next guy. But there's a difference. A turntable benefits from mass, stability and such. Those things are of relatively little concern for a CDM. A CD rotates at various speeds and the information is interleaved.
What you need is a CDM that's "good enough." At best a laser can only read the CD without errors. But because of how the information is stored and because the speed of the CD constantly has to be adjusted, the stream of data will always be off. So the most important part of a CDM has to be the electronics--the FiFo and buffer.
Now, I'm no expert on CDMs. But I believe none of the psychobabble coming from 47 Laboratory and Teac. And the belt-drive CDMs out there are nothing but snake oil as far as I can tell.
The Philips CD-Pro still fills a purpose. It has native I2S support and comes with a remote, nice LED display and more. At €300 it's not cheap. But it's not a rip-off either.
Well, I am familiar with the VAM12 (trash) and Teac / Pioneer types. Phn, you are correct in that the disc must change speed very quickly to properly track the disc. Both the Teac and Pioneer transports did it wrong. They put them together as if they were turntables. Bad idea.
But, if you look at transports that do not use a "stabilizing platter" you will see some better examples. The best transport I have ever seen was the NEC used in the original Nak OMS-7 and Alpine (first) units. They were way too expensive to manufacture for the standard consumer market. The very best eye pattern ever displayed. They used a single spot (non-Philips) head. The Nak updated with the servo mod is amazing. It just needs a better DAC section (based on SAA7000 chip set).
Other good machines were ones using Sony heads and chip sets. Technics had a nice machine as well, except for the mash nonsense.
The VAM12 series has about the noisiest, jittery, unstable RF pattern I have ever seen. The RF level varies greatly between samples. Pure cheap junk.
The problem I see with CDR units is that the intention is to read the disc into memory. Once in memory you can process it. I don't know what the error rate is. The problem: You are now copying the CD, once in memory you can modify the unit to spit it out in digital format. Copy protection may be a problem here as some CD's incorporate errors deliberately. Fun and games. Buffering does not help these problems at all.
-Chris
But, if you look at transports that do not use a "stabilizing platter" you will see some better examples. The best transport I have ever seen was the NEC used in the original Nak OMS-7 and Alpine (first) units. They were way too expensive to manufacture for the standard consumer market. The very best eye pattern ever displayed. They used a single spot (non-Philips) head. The Nak updated with the servo mod is amazing. It just needs a better DAC section (based on SAA7000 chip set).
Other good machines were ones using Sony heads and chip sets. Technics had a nice machine as well, except for the mash nonsense.
The VAM12 series has about the noisiest, jittery, unstable RF pattern I have ever seen. The RF level varies greatly between samples. Pure cheap junk.
The problem I see with CDR units is that the intention is to read the disc into memory. Once in memory you can process it. I don't know what the error rate is. The problem: You are now copying the CD, once in memory you can modify the unit to spit it out in digital format. Copy protection may be a problem here as some CD's incorporate errors deliberately. Fun and games. Buffering does not help these problems at all.
-Chris
Hi phn,
I'm just trying to draw your attention to the fact that if the data is not decoded properly to begin with, it's garbage. When there is high noise and lock instablility, your data will be corrupt. You can only correct a certain amount, but you have already lost the war by this time.
To have good sound, you need accurate data. To get accurate data, you have to get the information off the media (CD in this case) without errors to start with (as much as possible).
I guess what you would need to do is set up at a bench. Monitor the error flags and the RF pattern from different machines and software. In general, you will see that the more stable, cleaner RF patterns generate the fewest error flags. That is the key to good sound.
The transports with the extra platter will work okay on concentric discs. Their problem will show when the information tracks are off center.
-Chris
I'm just trying to draw your attention to the fact that if the data is not decoded properly to begin with, it's garbage. When there is high noise and lock instablility, your data will be corrupt. You can only correct a certain amount, but you have already lost the war by this time.
To have good sound, you need accurate data. To get accurate data, you have to get the information off the media (CD in this case) without errors to start with (as much as possible).
I guess what you would need to do is set up at a bench. Monitor the error flags and the RF pattern from different machines and software. In general, you will see that the more stable, cleaner RF patterns generate the fewest error flags. That is the key to good sound.
The transports with the extra platter will work okay on concentric discs. Their problem will show when the information tracks are off center.
-Chris
CDRom drives are pretty good at reading error free data, when was the last time that old scratched CDR copy of xyz you have sat on your desk failed to read?
If you drive the output of the buffer FIFO from a stable fixed clock and the FIFO never runs empty then the jitter from the CDRom doesn't matter at all. I think the issue is most still use the clock recovered from the transport rather than a stable reference clock.
If you drive the output of the buffer FIFO from a stable fixed clock and the FIFO never runs empty then the jitter from the CDRom doesn't matter at all. I think the issue is most still use the clock recovered from the transport rather than a stable reference clock.
Hi phn,
Keeping to the basics (things that are important) will make your life simple. Just don't count on "things" working properly.
Good CD's are hard to find so you end up working with defective media.
In the quest for more profit, most manufacturers will try to distract consumers from the truth. There is also a desire to move away from Philips due to poor support issues. A service nightmare and the pain finally reached the boardroom in some companies.
-Chris
Keeping to the basics (things that are important) will make your life simple. Just don't count on "things" working properly.
Good CD's are hard to find so you end up working with defective media.In the quest for more profit, most manufacturers will try to distract consumers from the truth. There is also a desire to move away from Philips due to poor support issues. A service nightmare and the pain finally reached the boardroom in some companies.
-Chris
Hi BlackCatSound,
At the risk of repeating myself .... okay, I will
I have several CD's that are not error free, some are unreadable. CD roms work by retrying the read if the uncorrectable error or dropout flag gets set. The entire concept is that they reread and put much more data in a larger buffer memory than in a standard CD player. They generally read the CD faster than they spin in a regular CD player. You are copying the content into memory, that's where some copywrite schemes cause trouble.
-Chris
At the risk of repeating myself .... okay, I will
I have several CD's that are not error free, some are unreadable. CD roms work by retrying the read if the uncorrectable error or dropout flag gets set. The entire concept is that they reread and put much more data in a larger buffer memory than in a standard CD player. They generally read the CD faster than they spin in a regular CD player. You are copying the content into memory, that's where some copywrite schemes cause trouble.
-Chris
The copyright schemes mess up the audio data anyway, doesn't matter if you read it just once or several times. Also if you're not looking for valid file systems (ie with a computer or an MP3 player) then most of the copy protection schemes do nothing.
Personally I think the creators of these schemes should be shot, but thats another matter
Modern CDRom drives are designed to read CDs at 52x and most of the time they can do it in a single pass.
Most DJ CD players buffer the audio, some as much as 60-120 seconds worth, to allow reverse play etc.. Not yet found a CD that won't play in one.
Personally I think the creators of these schemes should be shot, but thats another matter
Modern CDRom drives are designed to read CDs at 52x and most of the time they can do it in a single pass.
Most DJ CD players buffer the audio, some as much as 60-120 seconds worth, to allow reverse play etc.. Not yet found a CD that won't play in one.
Hi BlackCatSound,
However, you have to focus on not whether the CD plays, but rather the quality of the play. You can get away with all kinds of sonic evils going on one pass. Mute, re insert last data point and interpolation are tools used to do this. Some people are happy with MP3's as well. Not high fidelity.
Things have to get really gruesome before a disc will not play or make noise. That is not what we are about. Both a go cart and a luxury car can both go down the road. It's the getting there that we are interested in. A CDROM drive is the go cart. A bad disc is rain (or snow for us northerners). Which way do you want to travel?
-Chris
We agree on that one. Consumers are being burned again.
However, you have to focus on not whether the CD plays, but rather the quality of the play. You can get away with all kinds of sonic evils going on one pass. Mute, re insert last data point and interpolation are tools used to do this. Some people are happy with MP3's as well. Not high fidelity.
Things have to get really gruesome before a disc will not play or make noise. That is not what we are about. Both a go cart and a luxury car can both go down the road. It's the getting there that we are interested in. A CDROM drive is the go cart. A bad disc is rain (or snow for us northerners). Which way do you want to travel?
-Chris
I dissagree. A CDRom is not a fundamentally worse device for reading data from a CD if used correctly.
You can still perform exactly the same error compensation that a single pass transport would perform, repeat last sample, interpolate missing sample etc.. but you also have the advantage of being able to re-read the bad sector incase you can actually read the data correctly second time around.
Plus if you buffer it correctly you remove the transport completely from the clock equation.
A bad disc is a bad disc no matter what you read it with.
Rip a track to WAV on a number of CDRom drives then MD5 checksum the files.
You can still perform exactly the same error compensation that a single pass transport would perform, repeat last sample, interpolate missing sample etc.. but you also have the advantage of being able to re-read the bad sector incase you can actually read the data correctly second time around.
Plus if you buffer it correctly you remove the transport completely from the clock equation.
A bad disc is a bad disc no matter what you read it with.
Rip a track to WAV on a number of CDRom drives then MD5 checksum the files.
Hi BlackCatSound,
Sadly, some things do matter in our quest for throw away technology. The truth is, sometimes you really do have to spend some money.
-Chris
We disagree completely on this point. Until you actually sit down and play with some transports while watching RF patterns and error flags, you will not understand. I am afraid that there is no way to make the transport not part of the equation unless you accept a very low spec. for data integrity.
Sadly, some things do matter in our quest for throw away technology. The truth is, sometimes you really do have to spend some money.
-Chris
RF patterns is one thing, data integrity is another.. have you actually tried recording spdif outputs from various transports - dvd players, cd players, computer drives - and compare them against each other? you're in for a surprise.. they will all match provided the disc is in reasonable condition.. those using CD-ROM drives in their players are not doing so in order to save a couple of bucks.. regular CD mechanisms are way cheaper than CD-ROM drives.. I don't know what are they doing with them but reading each sector multiple times and picking matching trials seems reasonable, just like EAC works..
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