Conference cookie::notes$archive:cd_v1

    I'm glad you like your new CD player. I will, however, take exception
    to your statement that music recorded a few years back does not
    sound as good. 
    
    Digital recording began in the early 70s. My impression is that
    the quality of the recording process varies more with the artist
    and the type of music than when the music was recorded. For example,
    "Dark Side of the Moon" was recorded by Pink Floyd in 1972, but
    it was digitally mastered; the CD sounds exceptional (although not
    quite as good as "Brothers in Arms", which I believe is in a class
    by itself). The same could be said for "Synchronicity", recorded
    in 1982. On the other hand, there are artists who will dump anything
    on a CD and not give a damn about the different characteristics
    of the medium.
    
    Ed.
    

It's also possible to do some very fine work with analogue recording equipment
as well.

I found that after I did the polypropylene output cap mod to my Yamaha player,
older discs sounded much less objectionable.  Something about the cheap little
electrolytics was making intermodulation distortion combined with the tape hiss
truly annoying.

/john

    Re .1:
        To the best of my knowledge, "Dark Side of the Moon" was
    an analog recording.  Some of my favorite CDs (including that one)
    were analog recordings.  It just depends on how interested in
    quality the recording engineers were.
    
    					Steve

    re: .2
    
    How big a deal is it do to the mod?  Is it one-one replacement?
     How many caps are involved?  etc.

    Re .4
    
    The mods on any component depends on the design of the unit,
    how good you are with a soldering iron, and your inginuity.
    
    The design of the unit tells you how difficult it is going to be
    to get to the capacitors.  I modified my integrared amp and to get
    to the caps, all you had to do was take the cover off and drop the 
    bottom plate.  Well, I'm doing the tuner now and it's a pain.  I
    have to remove the entire ciruit board to get to the underside.
    
    How good you are with a solding iron tells you if you lift up any
    of the ething of the PC board when you take the caps out.  I
    have not messed up the eching and didn't have to bridge wires across.
    
    The inginuity comes in when you take out the caps and have to replace
    them.  The ones you take out will be electrolitics which are small,
    (the size of a colored thumb tacks).  The ones you are going to
    put back are polypropene which will be the size of your thumb. 
    What you have to figure out is where to put them so they fit and
    don't put stress on you PC board.
    
    I am by no means an expert on the topic, I'm just speaking from
    experience.  I had lots of help from the 2 patient (patient because
    they were very helpful with the loads of questions I had) noters that are
    knowledgable about the subject. 
    
    I can answer one other question you had on how may caps are involved.
    That also depends on the design and how much time you want to put
    into it.  The guys I spoke with suggested to replace the DC coupling
    caps and beef up the power supply first because you get the most 
    amount of inprovement for the $.  After that, it depends on the 
    system if you will hear any improvements from furtur mods.  I stopped
    modifying because I want to get a better sound quality CD player
    and good cables before continueing.  I want to be able to hear the
    difference if I'm going to put the time into it.
    
    One more note to the guys that rag on people who can hear the
    difference between caps.  If you guys haven't tried it then how
    do you know there isn't a difference?  When I first read about mods
    I thought that it was something to try.  Do you guys get off saying
    things are full of it?  Maybe I was educated differently and learned
    that you don't say somethings bull until proven otherwise.  How
    were you guys educated?
    
    Kenney

Re: .0  (what  else?): 

Interesting. I  just  had a long chat with a friend who is a EE whiz and who
claims  that  Digitally  mastered disks sound worse than those from analogue
masters.  He  claims  that  to prevent aliasing you need to apply a low pass
filter  which  chops  out everything above 22KHz, and that the technology is
such  that  most  Digital  recorders  do  this  badly,  causing  phase shift
distortion.  (something  about being hard to make a filter that decayed fast
enough  so  you  don't  lose sounds below 18KHz but don't get anything above
22KHz, which is half the sampling rate, the point at which aliasing occurs).
He  claims  that  he  can  really hear the difference in more newly recorded
disks.  He  also admits there is at least one high quality digital recorder,
made by Sony, which costs $1M so most studios don't use it.

His claim therefore has little to do with CDs, or alternatively applies just
as well to digitially mastered records. He claims he rejects 2 out of 5 
disks because the recording quality is so bad, and won't buy disks at all
any more unless he can listen first.

Can anyone  confirm  this observation (about poor recording quality of newly
made digitally mastered disks)? I can't hear it in the (dozen or so) disks I
have. 

Does anyone  have  observations  about  which  labels have consistantly high
quality recording (or consistantly low quality)?

Does anyone know of stores in the area that let you listen to a disk first?

>Interesting. I  just  had a long chat with a friend who is a EE whiz and who
>claims  that  Digitally  mastered disks sound worse than those from analogue
>masters.  He  claims  that  to prevent aliasing you need to apply a low pass

    Oh no... I can hear the religious tirades rumbling in the distance...

    (seriously, tho... I'm sure this has been non-argued elsewhere in
    either this notesfile or AUDIO...)    

    RE .6
	I have a few dozen discs from the Archiv label.  I have never been
    disappointed by any one of the recordings both musically and sonically.
    If you like music of the baroque to early classical periods, you can do
    far worse than buying an Archiv disc.  The GRP label produces some fine
    sounding Jazz discs as discussed elsewhere in the conference.
	The anti-aliasing filter introduces phase shifts.  But so does
    any velocity sensitive transducer such as a magnetic tape head, or a
    magnetic phono cartridge.   If I remember calculus correctly, any such
    transducer introduces a phase change of 90 degrees regardless of the
    frequency.  That is, a 100 Hz signal is "delayed" by 25 ms where as a
    10 KHz signal is "delayed" by only 0.25 ms when the signals passes through
    a velocity sensitive transducer.   Whether such a delay is audible is
    debatable.  But digital recording technique is not alone in introducing
    phase shifts in the signal.

    re: .6
    
    Your friend is correct.  While awareness exists about oversampling
    in players, few realize its needed in the recorders too.  Those
    13-pole filters introduce 100's of degrees of phase shift just as
    they would in a player.  This distortion would happen anywhere analog
    to digital conversion takes place: digital mastering, digital
    recording, and CD mastering.
    
    Analog to digital converters with 16-bit resolution are expensive.
    Ones fast enough to oversample are really expensive and exotic.
    'Till they get cheaper, nearly all CDs will have such a large phase
    shift.  Forget about seeing good ADCs in consumer DAT players.
    
    Can I hear it?  I'm not sure.  If I were to listen to two identical
    recordings except for phase shift and somebody pointed out something
    to listen for, I could learn to identify it; "yeah, phase manglement"
    Now, I just notice that some CDs sound better than others, and that
    Telarc's are generally worse than the Reference Recordings or Opus
    3's.
    
    Until the ADCs and other electronics in digital recorders improves,
    I won't worry about improving my player any more.  It could be slightly
    better, but its still much better than the recorders.
    

Newer digital recorders introduce a low-level random dither noise into the
low bits to take care of sample error problems.  Earlier recorders, including
the first Sony model, did not do this and the result is distorted high
frequencies that sound harsh to those with golden ears.  Dither noise trades
off better sounding highs for a small amount of background hiss.

--PSW

    .10 mentions a real reason why some of the earliest digital recordings
    may have sounded harsh (at least on low level signals).  Another problem
    is that early recorders probably introduced distortion in their sample
    hold curcuits, and who knows if they were really getting 16 bits or so
    of precision.  Probably more important is that fact that recording
    with a digital system requires slightly different technique than analog,
    and habits picked up compensating for analog recording well result in
    worse sound with digital.  With the right technique, digital will be better.

    Note that oversampling in the A-D converter will result in lower cost,
    not higher, since a small, fast low resolution A-D can be matched with
    some LSI to do the digital filtering.  Such hardware was written up
    by a guy at dbx a year or so ago.  It's only a problem of designing
    for mass production.

    Also, its my belief that phase effects per se are not important.
    The real problem with the passive minimum phase filters is that they are
    hard to align to really flat response, with matched response in both
    channels - but you can do this with the digital oversampling filters.
    So people are really hearing amplitude response variations, and
    possibly frequency dependant interchannel delay (not the same as a
    delay that equally tracks in both channels, such as the constant
    delay in single DAC players - that is sonically unimportant).

    - Jim

    I don't recall early Sony recorders missing dither, but rather
    providing a switch that could disable it.  Probably many of the
    idiot recording engineers thought less hiss=better sound and had
    the dither off, or else couldn't tell the difference anyway.