Henry Feilden
Auditioning
- Joined
- Feb 20, 1999
- Messages
- 2
I thought with the interest in Laserdisc on the forum I'd try a sort of FAQ post.I've not covered every possible question.Where dates are involved I've generalized because either I don't know or things changed over a period of time.In no particular order,here goes:
Q:What players can play DTS discs:
A:Any player with a digital output can play DTS Laserdiscs with no modification.The DTS data is encoded on the Left and Right digital sound tracks.The player will read and output this data from any digital out on the rear panel,optical and/or coaxial.
What players can play AC-3/DD sound tracks:
Any player with an RCA jack on the back panel marked AC-3 RF or RF can output the required signal.
The AC-3/DD sound track is encoded on to the right analogue sound track.As all Laserdisc players can read the analogue sound tracks,most can be modified with a simple $75 kit from Precision Laserdisc to output the data.
Q:I have an AC-3 RF output.Do I need anything more:
A:The signal from the player is RF(radio frequency).This has to be converted to a regular digital signal by a Demodulator.Several processors/receivers/decoders have an internal demodulator.If you unit has an RCA jack on the back panel marked AC-3 RF or Laserdisc RF it has an internal demodulator and is ready for direct conection to the Laserdisc player RF output.If your unit has no RF input you need an external Demodulator.These are available from several companys starting around $100.The demodulator is connected to any spare digital input on your surround processor.
Q:What sound tracks are on a Laserdisc:
A:Early discs had only Left and Right analogue sound tracks however most discs you come across these days have the two analogue tracks + Left and Right digital sound tracks.What is on these tracks varies with the disc.
A DD/AC-3 disc will have the DD data on the right analogue track.Occasionally it may have a directors commentary on the Left analogue track.It will have a Dolby Surround/Pro Logic sound track on the digital tracks.If your player or system is not equipped to play DD from Laserdisc,the digital sound tracks will play as normal.
A DTS disc will have both digital sound tracks used to store the DTS data.If the disc has no directors commentary,it will have a regular Dolby Surround/Pro logic sound track on the Left and Right analogue tracks.Any DTS disc with a directors commentary on the left analogue track has no other full sound track except DTS.
Excluding old analogue only discs,all other discs will have both Left and Right analogue and digital sound tracks.These may contain several different things.Most likely would be a regular Dolby Surround/Pro Logic sound track on all tracks.This ensures digital playback discs are playable in older analogue only players.They may contain commentary tracks(on the left analogue track) or old movies may only be in Mono sound.
Old analogue only discs will have either a Pro Logic or stereo or mono sound track.
Q:My player has no Digital outputs:
A:Kits are available to fit digital output to several popular players.It may be time to consider a player upgrade as analogue only players will be quite old.Also they will not have AC-3/RF outputs either.By the time you buy and fit all the upgrade kits,it may work out cheaper to buy a later player with all the outputs you require.The later player will most likely have improved video performance as well.
Q:What is the significance of Comb Filters:
A:Laserdisc is an analogue/composite storage medium. Any display has to have the composite video signal split into Luminance (also know'n as Y.The black and white picture) and Chrominance (also know'n as C. The colour part of the signal). This splitting can be done by a simple notch filter(very cheap and not very good) or by a Comb Filter.All TV's have either a notch filter or a comb filter of some sort as standard. Without one they could not display a picture.Any Laserdisc player with an S-video output also has a comb filter. How you connect the player to the display will depend on which unit has the better comb filter. If you use the players composite output jack, your display will perform the seperation of Y and C. If you use the players S-video output jack,the player will perform the Y/C seperation and the displays notch filter/Comb filter will be bypassed.Both options should be tried as no firm information exists as to what will be better with any given player/display combination.
With the better Laserdisc players its more and more likely that the players Comb filter will be the better. With the CLD-99 Elite player it is very unlikely that your displays Comb Filter will be better as the CLD-99 has a exceptionally sophisticated digital 3D motion adaptive comb filter that is user adjustable.This filter is normally only bettered by high cost external units,and few if any of these have the degree of user adjustable parameters available on the CLD-99.
Q:My player has no S-video output:
A:You do not have any video connection options.Use a composite video cable.If your display has a notch filter or a poor comb filter for Y/C seperation,Laserdisc video will not look good.If your display has a good comb filter,the lack of an S-video output from the player is not a great problem.
Q:What comes out of each rear panel jack:
A:S-video jack/s Pre seperated Y and C video information.
Composite video jack/s Un-seperated video information for seperation in your display.
AC-3/RF jack Dolby Digital sound track in RF form requiring demodulation before decoding.
Digital jacks.Optical and/or Coaxial With a DTS disc,the DTS data.With any other disc,whatever is on the Left and Right digital sound tracks.Normally Pro Logic or digital mono on old movies.
Analogue L/R jacks Either the analogue sound track or the digital sound tracks via the players inbuilt D/A convertors(normal Pro Logic or mono sound only) or commentary tracks if on the disc.
Q:How do I select the required sound track:
A:Excluding older analogue only players,the digital sound tracks and AC-3RF/DD tracks are always output by default.If you wish to listen to a commentary track on analogue Left track,press the button on the remote marked audio,on screen will be displayed various sound track options.Keep pressing the button till you hit somthing like /L on screen.Be carefull doing this as the AC-3 data on analogue right track will produce noise if player via an analogue connection.DTS data will produce very unpleasant noise on some systems.If you want to play the analogue sound tracks of a DTS disc on a none DTS system,its best to mute the decoder before going through the available tracks.
All this assumes what ever decodes your surround information is capable of auto detecting what you want to hear.You may need to force the decoder to one input or surround mode to hear what you want.For example most decoders will default to the AC-3RF input if a signal is detected.If you wish to hear the commentary tracks on the Left analogue track you will need to force the decoder to the input connected to the LD players analogue outputs.
Q:What is the difference between CAV and CLV discs:
A:CAV stands for Constant Angular Velocity.This was the original way laserdisc worked.CAV discs store each frame of the video separately.Up to 54000 frames per side for up to 30 minutes of video per side.CAV discs spin at a constant 1800rpm.
CLV stands for Constant Linear Velocity.These were developed to increase storage to around 60 minutes of video per side.They are often refered to as Extended Play on disc sleeves.CLV discs start at 1800rpm on the inner tracks(start of any side) and gradually slow to 600rpm by the outer tracks.Most Laserdiscs are now CLV.
CAV offers perfect still frame pictures with all players.Some players have a digital frame store for still frames on CLV discs,but not to the same standard a those obtained from CAV discs.
Laserdisc sets of longer movies often have one side of CAV video covering an action sequence or similar where people may wish to look at special effects in extreme detail.This tends to happen when a movie is to long to fit on one CLV disc ie over 120minutes total.The studio may do one disc in CLV and one side of the second disc in CAV.
CAV as a method of storage is slightly better than CLV because of inherently lower crosstalk figures.CAV discs may produce a slight improvement to video quality.A good example of this is Twister.It was released in both CLV and CAV formats at the same time with the same basic transfer.In direct comparison the CAV discs look just that little bit better.
In day to day operation the player will play whatever disc you put in automatically.
CLV discs can be searched by chapter or time in minutes and seconds.CAV discs can be searched by chapter or frame number.When a disc is first spun up,the player reads the discs table of contents,from that point searching is possible.Stopping the player will not clear the memory unless the disc try is opened.You can search from a stand still with most players.Chapter searchs can normally be done from a cold start ie put the disc in hit 5 on the remote and play will start at chapter 5.
Q:How do players work that play both sides of a disc:
A:Both side play ie playing both sides of a disc without taking it out of the player and turning it over,is accomplished by the Laser pick up being run along its tracks taken of the tracks and turned upside down,lifted above the disc and put on a second set of tracks to play side B.Some players use a sort of one piece track to run the pickup along to do the same job.
Average time involved is from 8 to 12 seconds for a side change,depending on the player model.
When you put a disc in the player with side 1 or side A up,side 1 is actually on the bottom.All discs have their lables on to allow this ie side 1 is labled side 2 and side 2 is labled side 1.
Q:How do I hook my player up:
A: I won't get to far into cables as it causes more than a little controversy on this forum. Here are the basic requirements:
AC-3 RF out Use 75ohm well shielded coaxial cable.
Coaxial Digital out As above.
Composite video out As above.
Optical Digital out Use a Toslink type optical cable.
S-video out 75ohm S-video cable terminated with 4 pin Mini Din type connectors.
Analogue audio L/R out Normal analogue audio interconnect pair as per any analogue audio connection.
Good quality Composite video cable has the correct spec for RF and digital use as well as video.S-video cables are in effect a double run of composite video cable.
Q:Which player should I buy:
A:This is a question to ask the forum when you know what you can get.It's generally accepted that Pioneer make the best players.Meny other makes are in fact Pioneer clones.
Possibly the very best models for sensible money are the Pioneer D704 and its Elite version,the CLD-79.Both these offer all possible outputs and have excellent all round performance.
Q:What is Laser rot:
A:Laser rot as has become know'n is oxidization of the reflective layer of the disc.The bit the player reads.It has several causes,the main ones are:Failure of the glue used to bond the two halfs of the disc together,and the fact that laserdiscs are made of Acrylic which is hydroscopic ie it absorbs moisture speeding oxidization of the reflective layer and failure of the glue.
Q:What does Laser rot look like:
A:To look at the disc it is not visible.When played it produces a variety of things depending how bad it is.Most usual is lots of coloured sparklie flecks in the video often most visible in the black bars of a widescreen disc.It will also increase overall video noise and eventually render the disc un-playable.
Q:Can rot be repaired:
A:No.
Q:How seious is rot is general as a Laserdisc problem:
A:Excluding some very early discs and more to the point most Sony pressings,it is a non event.
Sony ie Columbia Tristar movies,had a serious problem with their disc pressing plants.Failure rate of some titles is almost 100%.Sony had plants in the USA,Japan and Austria.USA pressings are very bad.Japan pressings are a little better.Austrian pressings are very good but rare.
Q:How do I identify the discs manufacturer:
A:This is not easy but the following is a few general tips.
All disc ID's are on the part of the disc between the outer edge of the label and the start of the playing section ie on the shiny bit just outside the labels edge.
Sony Disc Id is large and appears printed rather than stamped.Will include 4 large letters like LDVS(digital sound)LDAC(AC-3/DD sound) or LDTX(THX certified pressing) + other variations.Reliability Very poor.
Pioneer Disc ID is stamped lightly. No letters included. Often says made in USA.Biggest disc producer by far.Reliability Very good to Excellent.
Mitsubishi May have either printed ID.Early discs.Or Stamped ID on one side with very heavy stamping pressure.Id always includes the letter M at the end of part of the ID code.Reliability Very good to excellent.
Kurrary Lightly stamped ID always ending with the letter K.Pressed 99% of DTS Laserdiscs.Reliability Total.No know'n failures and the very best quality discs ever maunfactured.
Above are the big 4.There were meny others,but the bulk of the discs you come across will be Pioneer or Kurrary.Mitsibishi pop up every now and again.Sony pressings are mostly limited to Columbia Tristar movies.
Q:The disc I played last night had a few white dropouts near the start.Is this rot:
A: Probably not.The odd dropout is caused by dust particals between the layers.It's poor manufacturing quality control,not rot.These dropouts do happen through out some discs,not just at the start,but its dust not rot.You will know if its rot when you view the disc 6 months later and find its got a lot worse.
End of part one.Expecting a power cut or something to wipe out the lot.
Henry
Q:What players can play DTS discs:
A:Any player with a digital output can play DTS Laserdiscs with no modification.The DTS data is encoded on the Left and Right digital sound tracks.The player will read and output this data from any digital out on the rear panel,optical and/or coaxial.
What players can play AC-3/DD sound tracks:
Any player with an RCA jack on the back panel marked AC-3 RF or RF can output the required signal.
The AC-3/DD sound track is encoded on to the right analogue sound track.As all Laserdisc players can read the analogue sound tracks,most can be modified with a simple $75 kit from Precision Laserdisc to output the data.
Q:I have an AC-3 RF output.Do I need anything more:
A:The signal from the player is RF(radio frequency).This has to be converted to a regular digital signal by a Demodulator.Several processors/receivers/decoders have an internal demodulator.If you unit has an RCA jack on the back panel marked AC-3 RF or Laserdisc RF it has an internal demodulator and is ready for direct conection to the Laserdisc player RF output.If your unit has no RF input you need an external Demodulator.These are available from several companys starting around $100.The demodulator is connected to any spare digital input on your surround processor.
Q:What sound tracks are on a Laserdisc:
A:Early discs had only Left and Right analogue sound tracks however most discs you come across these days have the two analogue tracks + Left and Right digital sound tracks.What is on these tracks varies with the disc.
A DD/AC-3 disc will have the DD data on the right analogue track.Occasionally it may have a directors commentary on the Left analogue track.It will have a Dolby Surround/Pro Logic sound track on the digital tracks.If your player or system is not equipped to play DD from Laserdisc,the digital sound tracks will play as normal.
A DTS disc will have both digital sound tracks used to store the DTS data.If the disc has no directors commentary,it will have a regular Dolby Surround/Pro logic sound track on the Left and Right analogue tracks.Any DTS disc with a directors commentary on the left analogue track has no other full sound track except DTS.
Excluding old analogue only discs,all other discs will have both Left and Right analogue and digital sound tracks.These may contain several different things.Most likely would be a regular Dolby Surround/Pro Logic sound track on all tracks.This ensures digital playback discs are playable in older analogue only players.They may contain commentary tracks(on the left analogue track) or old movies may only be in Mono sound.
Old analogue only discs will have either a Pro Logic or stereo or mono sound track.
Q:My player has no Digital outputs:
A:Kits are available to fit digital output to several popular players.It may be time to consider a player upgrade as analogue only players will be quite old.Also they will not have AC-3/RF outputs either.By the time you buy and fit all the upgrade kits,it may work out cheaper to buy a later player with all the outputs you require.The later player will most likely have improved video performance as well.
Q:What is the significance of Comb Filters:
A:Laserdisc is an analogue/composite storage medium. Any display has to have the composite video signal split into Luminance (also know'n as Y.The black and white picture) and Chrominance (also know'n as C. The colour part of the signal). This splitting can be done by a simple notch filter(very cheap and not very good) or by a Comb Filter.All TV's have either a notch filter or a comb filter of some sort as standard. Without one they could not display a picture.Any Laserdisc player with an S-video output also has a comb filter. How you connect the player to the display will depend on which unit has the better comb filter. If you use the players composite output jack, your display will perform the seperation of Y and C. If you use the players S-video output jack,the player will perform the Y/C seperation and the displays notch filter/Comb filter will be bypassed.Both options should be tried as no firm information exists as to what will be better with any given player/display combination.
With the better Laserdisc players its more and more likely that the players Comb filter will be the better. With the CLD-99 Elite player it is very unlikely that your displays Comb Filter will be better as the CLD-99 has a exceptionally sophisticated digital 3D motion adaptive comb filter that is user adjustable.This filter is normally only bettered by high cost external units,and few if any of these have the degree of user adjustable parameters available on the CLD-99.
Q:My player has no S-video output:
A:You do not have any video connection options.Use a composite video cable.If your display has a notch filter or a poor comb filter for Y/C seperation,Laserdisc video will not look good.If your display has a good comb filter,the lack of an S-video output from the player is not a great problem.
Q:What comes out of each rear panel jack:
A:S-video jack/s Pre seperated Y and C video information.
Composite video jack/s Un-seperated video information for seperation in your display.
AC-3/RF jack Dolby Digital sound track in RF form requiring demodulation before decoding.
Digital jacks.Optical and/or Coaxial With a DTS disc,the DTS data.With any other disc,whatever is on the Left and Right digital sound tracks.Normally Pro Logic or digital mono on old movies.
Analogue L/R jacks Either the analogue sound track or the digital sound tracks via the players inbuilt D/A convertors(normal Pro Logic or mono sound only) or commentary tracks if on the disc.
Q:How do I select the required sound track:
A:Excluding older analogue only players,the digital sound tracks and AC-3RF/DD tracks are always output by default.If you wish to listen to a commentary track on analogue Left track,press the button on the remote marked audio,on screen will be displayed various sound track options.Keep pressing the button till you hit somthing like /L on screen.Be carefull doing this as the AC-3 data on analogue right track will produce noise if player via an analogue connection.DTS data will produce very unpleasant noise on some systems.If you want to play the analogue sound tracks of a DTS disc on a none DTS system,its best to mute the decoder before going through the available tracks.
All this assumes what ever decodes your surround information is capable of auto detecting what you want to hear.You may need to force the decoder to one input or surround mode to hear what you want.For example most decoders will default to the AC-3RF input if a signal is detected.If you wish to hear the commentary tracks on the Left analogue track you will need to force the decoder to the input connected to the LD players analogue outputs.
Q:What is the difference between CAV and CLV discs:
A:CAV stands for Constant Angular Velocity.This was the original way laserdisc worked.CAV discs store each frame of the video separately.Up to 54000 frames per side for up to 30 minutes of video per side.CAV discs spin at a constant 1800rpm.
CLV stands for Constant Linear Velocity.These were developed to increase storage to around 60 minutes of video per side.They are often refered to as Extended Play on disc sleeves.CLV discs start at 1800rpm on the inner tracks(start of any side) and gradually slow to 600rpm by the outer tracks.Most Laserdiscs are now CLV.
CAV offers perfect still frame pictures with all players.Some players have a digital frame store for still frames on CLV discs,but not to the same standard a those obtained from CAV discs.
Laserdisc sets of longer movies often have one side of CAV video covering an action sequence or similar where people may wish to look at special effects in extreme detail.This tends to happen when a movie is to long to fit on one CLV disc ie over 120minutes total.The studio may do one disc in CLV and one side of the second disc in CAV.
CAV as a method of storage is slightly better than CLV because of inherently lower crosstalk figures.CAV discs may produce a slight improvement to video quality.A good example of this is Twister.It was released in both CLV and CAV formats at the same time with the same basic transfer.In direct comparison the CAV discs look just that little bit better.
In day to day operation the player will play whatever disc you put in automatically.
CLV discs can be searched by chapter or time in minutes and seconds.CAV discs can be searched by chapter or frame number.When a disc is first spun up,the player reads the discs table of contents,from that point searching is possible.Stopping the player will not clear the memory unless the disc try is opened.You can search from a stand still with most players.Chapter searchs can normally be done from a cold start ie put the disc in hit 5 on the remote and play will start at chapter 5.
Q:How do players work that play both sides of a disc:
A:Both side play ie playing both sides of a disc without taking it out of the player and turning it over,is accomplished by the Laser pick up being run along its tracks taken of the tracks and turned upside down,lifted above the disc and put on a second set of tracks to play side B.Some players use a sort of one piece track to run the pickup along to do the same job.
Average time involved is from 8 to 12 seconds for a side change,depending on the player model.
When you put a disc in the player with side 1 or side A up,side 1 is actually on the bottom.All discs have their lables on to allow this ie side 1 is labled side 2 and side 2 is labled side 1.
Q:How do I hook my player up:
A: I won't get to far into cables as it causes more than a little controversy on this forum. Here are the basic requirements:
AC-3 RF out Use 75ohm well shielded coaxial cable.
Coaxial Digital out As above.
Composite video out As above.
Optical Digital out Use a Toslink type optical cable.
S-video out 75ohm S-video cable terminated with 4 pin Mini Din type connectors.
Analogue audio L/R out Normal analogue audio interconnect pair as per any analogue audio connection.
Good quality Composite video cable has the correct spec for RF and digital use as well as video.S-video cables are in effect a double run of composite video cable.
Q:Which player should I buy:
A:This is a question to ask the forum when you know what you can get.It's generally accepted that Pioneer make the best players.Meny other makes are in fact Pioneer clones.
Possibly the very best models for sensible money are the Pioneer D704 and its Elite version,the CLD-79.Both these offer all possible outputs and have excellent all round performance.
Q:What is Laser rot:
A:Laser rot as has become know'n is oxidization of the reflective layer of the disc.The bit the player reads.It has several causes,the main ones are:Failure of the glue used to bond the two halfs of the disc together,and the fact that laserdiscs are made of Acrylic which is hydroscopic ie it absorbs moisture speeding oxidization of the reflective layer and failure of the glue.
Q:What does Laser rot look like:
A:To look at the disc it is not visible.When played it produces a variety of things depending how bad it is.Most usual is lots of coloured sparklie flecks in the video often most visible in the black bars of a widescreen disc.It will also increase overall video noise and eventually render the disc un-playable.
Q:Can rot be repaired:
A:No.
Q:How seious is rot is general as a Laserdisc problem:
A:Excluding some very early discs and more to the point most Sony pressings,it is a non event.
Sony ie Columbia Tristar movies,had a serious problem with their disc pressing plants.Failure rate of some titles is almost 100%.Sony had plants in the USA,Japan and Austria.USA pressings are very bad.Japan pressings are a little better.Austrian pressings are very good but rare.
Q:How do I identify the discs manufacturer:
A:This is not easy but the following is a few general tips.
All disc ID's are on the part of the disc between the outer edge of the label and the start of the playing section ie on the shiny bit just outside the labels edge.
Sony Disc Id is large and appears printed rather than stamped.Will include 4 large letters like LDVS(digital sound)LDAC(AC-3/DD sound) or LDTX(THX certified pressing) + other variations.Reliability Very poor.
Pioneer Disc ID is stamped lightly. No letters included. Often says made in USA.Biggest disc producer by far.Reliability Very good to Excellent.
Mitsubishi May have either printed ID.Early discs.Or Stamped ID on one side with very heavy stamping pressure.Id always includes the letter M at the end of part of the ID code.Reliability Very good to excellent.
Kurrary Lightly stamped ID always ending with the letter K.Pressed 99% of DTS Laserdiscs.Reliability Total.No know'n failures and the very best quality discs ever maunfactured.
Above are the big 4.There were meny others,but the bulk of the discs you come across will be Pioneer or Kurrary.Mitsibishi pop up every now and again.Sony pressings are mostly limited to Columbia Tristar movies.
Q:The disc I played last night had a few white dropouts near the start.Is this rot:
A: Probably not.The odd dropout is caused by dust particals between the layers.It's poor manufacturing quality control,not rot.These dropouts do happen through out some discs,not just at the start,but its dust not rot.You will know if its rot when you view the disc 6 months later and find its got a lot worse.
End of part one.Expecting a power cut or something to wipe out the lot.
Henry
Last edited by a moderator:
ossibly yes.Place the disc in its sleeve flat on a hard flat surface.Place a sheet of heavy glass or a piece of 1"+ thick MDF(or both)on top of it.Put some weight on top like heavy books.10>15lbs is recommended,but I have used up to a 56lb weight in extreme cases.Leave the disc like this for at least several days,up to a fortnight.Take the disc out and lay it on a clean hard surface for an hour or two.If it stays flat alfter a couple of houres,it will probably star flat when stored upright as above.Some discs will just re-warp.These are either not going to play or may even damage the player in extreme cases.Discard them.
