Hi Richard,
The thing you are looking for is the improved response to a C2 error. That has in fact improved over time. I do believe that it was technically mastered years and years ago, but the tech takes time to filter down to lower end models. As far as response to the C1 flag, that process is etched in stone. It can't change.
The errors are determined by a CRC check, there is no look up table.
DAT equipment has much better error correction than CD does. However, C! and C2 errors still occur. It is a mechanical thing, and tape is ... well, tape.
Hi Jan, Stuart and all,
C2 errors occur reasonably often. That is a fact. However, if you connect an LED, it needs a pulse stretcher in order for you to see it. We look at it on an oscilloscope, and use an analogue-like counter that resets at 7.35 KHz to give consistent numbers. I can't remember where or why the 7.35 KHz signal is all about. That would be a frame containing lot's of data. Anyway, you would see this more active on DAT using something like the Tascam purpose-built transport for the DA-88 / DA-38 or their two channel products. Consumer products were typically worse, partly due to the iffy factory setup.
CD players and discs really start lighting up that C2 flag when they have some running time on them. The die-cast Philips transport Stuart was referring to could be set up pretty closely, but that is a grueling job. The NEC worked better and was just a bit less insane to align. All the other transports are significantly worse in every way. I think the next closest good transport was using the Sony KSS-151A head (linear motor). Only the first Philips transports, and that OMS-7 type NEC allowed you to set the head up in all three axis. The NEC was better in that way. Most other transports only gave you azimuth. Some not even that. Focus? Focus = turntable height. Some tables wobbled.
The normal experience for CD playback is nothing like bit perfect. I wish it was, but it just ain't so.
Hi Alan,
We are discussing this because a member asked a question on it. Others followed.
-Chris
The thing you are looking for is the improved response to a C2 error. That has in fact improved over time. I do believe that it was technically mastered years and years ago, but the tech takes time to filter down to lower end models. As far as response to the C1 flag, that process is etched in stone. It can't change.
The errors are determined by a CRC check, there is no look up table.
DAT equipment has much better error correction than CD does. However, C! and C2 errors still occur. It is a mechanical thing, and tape is ... well, tape.
Hi Jan, Stuart and all,
C2 errors occur reasonably often. That is a fact. However, if you connect an LED, it needs a pulse stretcher in order for you to see it. We look at it on an oscilloscope, and use an analogue-like counter that resets at 7.35 KHz to give consistent numbers. I can't remember where or why the 7.35 KHz signal is all about. That would be a frame containing lot's of data. Anyway, you would see this more active on DAT using something like the Tascam purpose-built transport for the DA-88 / DA-38 or their two channel products. Consumer products were typically worse, partly due to the iffy factory setup.
CD players and discs really start lighting up that C2 flag when they have some running time on them. The die-cast Philips transport Stuart was referring to could be set up pretty closely, but that is a grueling job. The NEC worked better and was just a bit less insane to align. All the other transports are significantly worse in every way. I think the next closest good transport was using the Sony KSS-151A head (linear motor). Only the first Philips transports, and that OMS-7 type NEC allowed you to set the head up in all three axis. The NEC was better in that way. Most other transports only gave you azimuth. Some not even that. Focus? Focus = turntable height. Some tables wobbled.
The normal experience for CD playback is nothing like bit perfect. I wish it was, but it just ain't so.
Hi Alan,
That was impolite.
We are discussing this because a member asked a question on it. Others followed.
-Chris
Hi John,
That was a grim time for audio folk. I used the 301A - decompensated. It wasn't until that super chip, the LM318 came out that I even tried feed-forward compensation. 70V/ uSec - can you imagine that? BGW jumped on those in the 750B/C amps. But the 741 was found in lots of audio stuff. What was really bad was the noise, and keeping the overall output level down. Lots of mic preamps used that chip (741) in consumer stuff. The 4558 isn't that far removed from the 741 either. Then there is that horrible 4136 with its peculiar pinout. That forced people to use only that chip, and that chip was a class B nasty thing. These days I yank them, using an adapter I made, other better chips can be used. Either a pair of duals or a quad op amp. The other catch was the low current the 4136 uses. You can run out of power supply fairly quickly when going to another chip. In that case try the TL072 and TL074 chips for replacement.
-Chris
Exactly! I forget the stability vs gain and slew rates, but the point has been made.
No op amps were until the uA739 / 749. Marantz used the one without the pull down resistor and used a current sink there. Crown used the one with the resistor in some of the DC300 and others.
That was a grim time for audio folk. I used the 301A - decompensated. It wasn't until that super chip, the LM318 came out that I even tried feed-forward compensation. 70V/ uSec - can you imagine that? BGW jumped on those in the 750B/C amps. But the 741 was found in lots of audio stuff. What was really bad was the noise, and keeping the overall output level down. Lots of mic preamps used that chip (741) in consumer stuff. The 4558 isn't that far removed from the 741 either. Then there is that horrible 4136 with its peculiar pinout. That forced people to use only that chip, and that chip was a class B nasty thing. These days I yank them, using an adapter I made, other better chips can be used. Either a pair of duals or a quad op amp. The other catch was the low current the 4136 uses. You can run out of power supply fairly quickly when going to another chip. In that case try the TL072 and TL074 chips for replacement.
-Chris
That's right, and that's exactly how I did it. At the time, there was a nice writeup in HFNRR on the method. I couldn't find any discs that were playable which had C2 errors; fwiw, my player was a 582, which was not terribly expensive but quite nice.
The "active feedback" shown on the datasheet's Fig. 14 is kind of cool.
The 4558 is close to the "standard" topology for VFAs, although the performance is not hugely better than the 741. And there are ones very similar, with just more current in the input stage, like the BA4560 and 4580. Still the standard VFA tradeoffs of limited slew rate. I've used tons of the 4560s.
The 4136 was pure evil in that pinout. What were they thinking?
Locked (already written) data can be read nearly infinitely. Changing SSD
states (writing or re-writing) is what is finite.
Firmware will actually decide which data is "busy" and which is "stagnant" -
and allocate the lazy data to fixed sectors.
"Busy data" always gets many more sectors than it needs and this data is
always shuffled around (so any one sector is not overly abused).
Samsung SSD firmware is 11.5mb versus <1mb for most cd-rom/hdd software(firmware).
My SSD firmware is larger than win98 !!
Edit- this firmware will even cache REAL busy data to the oversized RAM buffer
to save on writes to the NAND. some hybrid HDD's now do this , too
OS
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Chris:
That's interesting. What historical comments & perspective can you offer about Sony transports in machines like the old CDP X779ES that use the KSS-272A?
Thanks,
mlloyd1
That's interesting. What historical comments & perspective can you offer about Sony transports in machines like the old CDP X779ES that use the KSS-272A?
Thanks,
mlloyd1
Hi Stuart,
For me, it is the transport I recognize instead of a model number. The cast Al transports were pretty good at tracking most CDs. Different mechanisms have different faults that they can't handle well. Philips machines were not expensive, but the first few series had excellent transports. Just not repairable transports.
Keep in mind that a C2 error will not cause a skip usually, but a defect that causes mistracking will always create a C2 flag. Every single time.
I think something was off on your test. You should have seen something in the C2 error flag. Especially over a range of CDs. Could you insert a disc that would trigger a C2 without a scratch or reason for the machine to mistrack?
The test disc I used was Pierre Verany (spelling?). It would cause C2 errors without a skip in order to confirm what the servos were doing, and to check the DSP reaction. They very nicely encoded a sine wave tone instead of cheesy music. I feel like screaming if I hear the Philips 5 or 5A test discs! You have no idea what hearing the same cuts all day and every day can do to one's sanity.
Hi mlloyd1,
All I know for sure is that the ES series were often plagued by known problems, like rock hard blue grease and silly stuff like that. The heads were often not a problem.
Sony made cheap transports, and we all laughed at those first ones (KSS-150A). Later they did better on the heads, but also made specific models without sleeve bearings and other cheap moves for the cheap market. The KSS-150A was eventually replaced by the much better KSS-210A. The chassis often was nylon injected over metal. Eventually they got it down to a point where the nylon stopped cracking everywhere. But the replacement parts and entire transport were not extremely expensive. Life was good for Sony owners in general. Other brands used the head, or entire transport. Those were generally repairable.
Now for the kicker. Those cheap Sony mechanisms kept being made until they became one of the better transports out there! I kid you not. So today, I actually want to see a Sony transport. If I could see a picture of the head assy, I would be able to tell you more about it. Everything comes down to the transport and servo circuits. Sony's chip set was better than most as well. Many other brands used heads made just terribly, so don't feel badly about your unit. The original Philips and top of the line NEC transports are a bar set wayyyy to high to compare to.
Ah-ha! Good news for you. It would seem that the KSS-272A was like a KSS-240A on a KSS-151A frame. This means that the preamp for the pickup diodes (6 of them) was mounted on the head. The head attaches via a "flexible PCB" and plugs into the PCB. You have a linear tracking motor which is great. Your machine is very fast to search an lock when skipping songs. So your machine is capable of pretty good performance, better than the KSS-210A. Possibly as good as the KSS-151A head (more adjustments). I would expect you to be very happy with your CD player. Fix it rather than replacing it. That is praise. Here is a link showing your head: JusTone Lasereinheiten. KSS-271A / KSS271A SONY Lasereinheit, Laserpickup, Laserunit, Pickup, Laser, Laserkopf
You may have to copy and paste that link.
-Chris
For me, it is the transport I recognize instead of a model number. The cast Al transports were pretty good at tracking most CDs. Different mechanisms have different faults that they can't handle well. Philips machines were not expensive, but the first few series had excellent transports. Just not repairable transports.
Keep in mind that a C2 error will not cause a skip usually, but a defect that causes mistracking will always create a C2 flag. Every single time.
I think something was off on your test. You should have seen something in the C2 error flag. Especially over a range of CDs. Could you insert a disc that would trigger a C2 without a scratch or reason for the machine to mistrack?
The test disc I used was Pierre Verany (spelling?). It would cause C2 errors without a skip in order to confirm what the servos were doing, and to check the DSP reaction. They very nicely encoded a sine wave tone instead of cheesy music. I feel like screaming if I hear the Philips 5 or 5A test discs! You have no idea what hearing the same cuts all day and every day can do to one's sanity.
Hi mlloyd1,
All I know for sure is that the ES series were often plagued by known problems, like rock hard blue grease and silly stuff like that. The heads were often not a problem.
Sony made cheap transports, and we all laughed at those first ones (KSS-150A). Later they did better on the heads, but also made specific models without sleeve bearings and other cheap moves for the cheap market. The KSS-150A was eventually replaced by the much better KSS-210A. The chassis often was nylon injected over metal. Eventually they got it down to a point where the nylon stopped cracking everywhere. But the replacement parts and entire transport were not extremely expensive. Life was good for Sony owners in general. Other brands used the head, or entire transport. Those were generally repairable.
Now for the kicker. Those cheap Sony mechanisms kept being made until they became one of the better transports out there! I kid you not. So today, I actually want to see a Sony transport. If I could see a picture of the head assy, I would be able to tell you more about it. Everything comes down to the transport and servo circuits. Sony's chip set was better than most as well. Many other brands used heads made just terribly, so don't feel badly about your unit. The original Philips and top of the line NEC transports are a bar set wayyyy to high to compare to.
Ah-ha! Good news for you. It would seem that the KSS-272A was like a KSS-240A on a KSS-151A frame. This means that the preamp for the pickup diodes (6 of them) was mounted on the head. The head attaches via a "flexible PCB" and plugs into the PCB. You have a linear tracking motor which is great. Your machine is very fast to search an lock when skipping songs. So your machine is capable of pretty good performance, better than the KSS-210A. Possibly as good as the KSS-151A head (more adjustments). I would expect you to be very happy with your CD player. Fix it rather than replacing it. That is praise. Here is a link showing your head: JusTone Lasereinheiten. KSS-271A / KSS271A SONY Lasereinheit, Laserpickup, Laserunit, Pickup, Laser, Laserkopf
You may have to copy and paste that link.
-Chris
Hi Brad,
Completely agree on that series of dual op amp. I have also used those same JRC op amps, and they aren't bad at all. The 4556 is one of those similar op amps, but it has a pretty high current output stage. Normally you see it driving headphones.
The 4560 was FET input, wasn't it? One of them was. What I liked best about that series was they made them in SIP format. Mush easier to design a PCB for, for me anyway. Too bad that didn't catch on for our op amps.
If anyone knows why the 4136 was designed like it was, could they let us in on that foul deed? Please? Of course, audio designers had to select a substandard part for use. That is another great mystery. Nothing like making sure people were stuck with junk!
-Chris
Completely agree on that series of dual op amp. I have also used those same JRC op amps, and they aren't bad at all. The 4556 is one of those similar op amps, but it has a pretty high current output stage. Normally you see it driving headphones.
The 4560 was FET input, wasn't it? One of them was. What I liked best about that series was they made them in SIP format. Mush easier to design a PCB for, for me anyway. Too bad that didn't catch on for our op amps.
If anyone knows why the 4136 was designed like it was, could they let us in on that foul deed? Please? Of course, audio designers had to select a substandard part for use. That is another great mystery. Nothing like making sure people were stuck with junk!
-Chris
Was C2 turned off or on?
and, this..... C2 accuracy vs efficiency : are they exclusive ? - Club Myce
THx-RNmarsh
and, this..... C2 accuracy vs efficiency : are they exclusive ? - Club Myce
THx-RNmarsh
Hi Chris,
I am happy you decided to venture your knowledge to this group of sometimes rude and unruly gang of thugs. A lot of real info. The other places I added back up what you learned and have told us.
Now, I know I should get a better CD Player... who makes the best drives now -- what about Sony today?
THx-RNMarsh
Raytheon, if mem serves.whom? the people who used it in designs or the manu?
Alan
4560, 4580, and Rohm/JRC versions of the 4558 were all bipolar I think PNP input diff pair. Good stuff for the money.
Chris is cool (favorite moderator) 
.
This filled me in on what I did not know even as I repaired CD units.
I just did PS's and transports , occasional DAC's and output audio.
I must ask , being digital - the same as PC based audio , why the heck are
we still bogged down with CD players ?
We have had the .WAV / Flac's for over decade.
1- A downloaded FLAC is PERFECT. Don't we want perfect ?
2- A FLAC ripped from a new library CD (or your new one -legal) is
as good as the CD ... and better than what most firmware/dac's
can pull off on a 20th century CD player.
3 - A MP3 (320k) is better than most old CD's in your collection ...
if it was purchased or derived from a better source.
Rip your collections -
No more scratches - degradation
Choose your DAC , mine will be a TI pcm 1794 ... don't have to
parallel them , as I have a perfect digital stream.
CD's are so time consuming - inconvenient ... why ? , we
like imperfection so we can grumble and moan ? (or tinker some more ?)
PS - you lose your CD (or the kids wreck it) ,, I have 3 backups !
OS
.This filled me in on what I did not know even as I repaired CD units.
I just did PS's and transports , occasional DAC's and output audio.
I must ask , being digital - the same as PC based audio , why the heck are
we still bogged down with CD players ?
We have had the .WAV / Flac's for over decade.
1- A downloaded FLAC is PERFECT. Don't we want perfect ?
2- A FLAC ripped from a new library CD (or your new one -legal) is
as good as the CD ... and better than what most firmware/dac's
can pull off on a 20th century CD player.
3 - A MP3 (320k) is better than most old CD's in your collection ...
if it was purchased or derived from a better source.
Rip your collections -
No more scratches - degradation
Choose your DAC , mine will be a TI pcm 1794 ... don't have to
parallel them , as I have a perfect digital stream.
CD's are so time consuming - inconvenient ... why ? , we
like imperfection so we can grumble and moan ? (or tinker some more ?)
PS - you lose your CD (or the kids wreck it) ,, I have 3 backups !
OS
I can think of a couple of reasons - a huge installed base and its a fairly long-lived standard.
If I'd ripped CDs to hard disk from when I first started buying CDs (1980s) the HDD interface at the time was ATA (now referred to as PATA to distinguish it from SATA). I'd probably not be able to read that HDD with current hardware (vanishingly few mobos support it now) even if the disk itself hadn't died. Whereas my oldest CDs are still playable on DVD players (and probably by my Bluray too though I've not tried that).
But EAC for instance DOES go back on the CD again and again in an attempt to read error-less.
I think part of the confusion IS language related.
When we talk about error correction in say power amps, we understand that ec can make the amp more linear, decrease the distortion, that sort of thing, but we know that the distortion will never become 0.0. There will always be a residual error.
This is in contrast with ec in digital reads as we discussed here. There, ec DOES decrease the error to 0.0.
An anology for a C2 uncorrectable error would be a record LP player jumping across a track, which does sometimes happen with bad tracking and huge modulation. When that happens, you can't miss it, even if you don't have a wife in the kitchen, it sounds very distracting. An unrecoverable error on CD read is similarly obvious and can't be missed. The upshot: if you don't hear those unrecoverable errors, the bits are read perfectly with 0.0 errors.
Dick you seem to continue to entertain the opinion that CD ec still passes errors. But please realize that it is just your opinion which is in contrast with reality.
Jan
At the time I was using a counter to count the errors over the CD play time, just accumulation the error numbers. As noted, corrected errors often came above 5,000! Never say C2 errors except with the one purposely damaged CD. Maybe I got lucky.
It is true that manus get smarter to 'cover up' C2 errors and there is no standard for that in the Red Book. Early players just copied a piece of music from the previous section into a section that they couldn't read, but newer players got smarter. BTW C2 ec is also called Error Concealment and that is what it really is of course.
Jan
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