Pioneer CLD-D925 tip
R Larsson
I've just got the service manual for this player - don't have the player
myself, only curious to see the latest and greatest Pioneer-brains can
think of. Well, the tip is you should always use the S-Video output for
best quality, not the RCA jack's composite output. This thing, "the war of
the comb filters", you probably have read about in a.v.l. (regarding where
the best comb filter is hiding, in your LD player or in your TV set?) don't
apply to the 925.
I take as a given that you use the HQ circuit on, and by that you can't get
past the comb filter in the player (a digital 3-line type), cause an Y/C
signal is needed for this circuit. The HQ circuit consist of an Y/C-to-RGB
chip, an RGB-to-Y/C chip, and an analog luminance noise reduction chip. The
composite output just adds the Y/C signal together again, which then has to
be separated another time in the TV set - a totally unnecessary step if
your TV has an S-Video input.
On the other hand, if you turn off the HQ circuit it seems you get out a
composite signal that has not been separated already - but don't know how
attractive that is, as you then don't get the "High Quality".
Another thing; Videotec in England offers an RGB output mod for this player
I heard. That mod is probably a lot easier than one would assume - I expect
they simply take advantage of the unused outputs on one of the RGB chips
already in the player. Strange Pioneer didn't include those outputs
themselves... when's their next top-of-the-line model out? (and why hasn't
any of these expensive machines a dimmer and a "cinema mode" for the
display, as my 1450 has? :o)
Paul Dossett
R Larsson (rune.l...@everyday.no) said:
<snip - comb filters and the Pioneer CLD-D925>
>I take as a given that you use the HQ circuit on, and by that you can't get
>past the comb filter in the player (a digital 3-line type), cause an Y/C
>signal is needed for this circuit. The HQ circuit consist of an Y/C-to-RGB
>chip, an RGB-to-Y/C chip, and an analog luminance noise reduction chip. The
>composite output just adds the Y/C signal together again, which then has to
>be separated another time in the TV set - a totally unnecessary step if
>your TV has an S-Video input.
>On the other hand, if you turn off the HQ circuit it seems you get out a
>composite signal that has not been separated already - but don't know how
>attractive that is, as you then don't get the "High Quality".
Maybe you don't have a good enough TV to notice the 'HQ' circuit seriously
DEGRADES video quality? Look closely at background detail with the switch on
and off. With it on, the detail vanishes.
The best picture you can get from the 925 with most TVs is S-Video out, and HQ
*OFF*.
--
Paul Dossett | Sony STR-665 receiver, Pioneer CLD-D925 laserdisc,
-------------| Sony SLV-X822 VCR, Mitsubishi DIVA 33" TV, Rambler
Melbourne OZ | L/R speakers, Richter Hydra surrounds, Monster Cable.
Amiga 2000 | ObWebSite : http://netspace.net.au/~astroboy/
R Larsson
astr...@netspace.net.au (Paul Dossett) wrote:
>R Larsson (rune.l...@everyday.no) said:
><snip - comb filters and the Pioneer CLD-D925>
>>I take as a given that you use the HQ circuit on, and by that you can't get
>>past the comb filter in the player (a digital 3-line type), cause an Y/C
>>signal is needed for this circuit. The HQ circuit consist of an Y/C-to-RGB
>>chip, an RGB-to-Y/C chip, and an analog luminance noise reduction chip. The
>>composite output just adds the Y/C signal together again, which then has to
>>be separated another time in the TV set - a totally unnecessary step if
>>your TV has an S-Video input.
>>On the other hand, if you turn off the HQ circuit it seems you get out a
>>composite signal that has not been separated already - but don't know how
>>attractive that is, as you then don't get the "High Quality".
>Maybe you don't have a good enough TV to notice the 'HQ' circuit seriously
>DEGRADES video quality? Look closely at background detail with the switch on
>and off. With it on, the detail vanishes.
>The best picture you can get from the 925 with most TVs is S-Video out, and HQ
>*OFF*.
"You talkin' to me?!" ... uh, I thought I made it clear that I only had
looked at the schematics for the player. You talk a lot, Paul, but do you
listen? ;-) Then maybe you were talking to everyone else... well,
anyways... From what you're saying about the HQ circuit, it's clear to me
now that the internal comb filter is used all the time, and you cannot get
a "pure" composite signal out even if your life depends on it.
I have compared the schematics to one of the best american models, the
CLD-D704, which has completely separate paths for Y/C and composite
outputs; meaning the composite out isn't just an added together Y/C, but
instead has its own D/A converter and a big driver circuit. The reason why
this isn't done on the 925 is because stuff like the Pseudo-PAL and noise
reduction circuitry is done on the Y/C signals. The 704 has its noise
reduction done in the digital domain, and is probably way better at its job
than the apparently useless analog one in the 925.
Paul Dossett
R Larsson (rune.l...@everyday.no) said:
>astr...@netspace.net.au (Paul Dossett) wrote:
>>Maybe you don't have a good enough TV to notice the 'HQ' circuit seriously
>>DEGRADES video quality? Look closely at background detail with the switch
>>on and off. With it on, the detail vanishes.
>>The best picture you can get from the 925 with most TVs is S-Video out, and
>>HQ *OFF*.
>"You talkin' to me?!" ... uh, I thought I made it clear that I only had
>looked at the schematics for the player. You talk a lot, Paul, but do you
>listen? ;-) Then maybe you were talking to everyone else... well,
Um, I must admit I read that bit but didn't pay enough attention (late at
night after work). Apologies. No, wait.. I was talking to everybody else.
Yeah, that's it.
>anyways... From what you're saying about the HQ circuit, it's clear to me
>now that the internal comb filter is used all the time, and you cannot get
>a "pure" composite signal out even if your life depends on it.
Videotec in the UK are working up a fix to get around that. I don't need it
but others might be interested.
>I have compared the schematics to one of the best american models, the
>CLD-D704, which has completely separate paths for Y/C and composite
>outputs; meaning the composite out isn't just an added together Y/C, but
>instead has its own D/A converter and a big driver circuit. The reason why
>this isn't done on the 925 is because stuff like the Pseudo-PAL and noise
>reduction circuitry is done on the Y/C signals. The 704 has its noise
>reduction done in the digital domain, and is probably way better at its job
>than the apparently useless analog one in the 925.
Yeah, but the 925 does a nice job without noise reduction, IMHO, up to the
standards of the cheaper NTSC units I've seen. Probably not as good as say a
704, but then again, it plays PAL discs, doesn't it? And PAL discs were
important to me when I bought my machine. Noise reduction wasn't, and I kind
of believe (maybe mistakenly) that you shouldn't use noise reduction on any LD
player. It just seems that playing around with the signal is cheating
somehow..
Oh, I don't get karaoke either.. :)
--
Paul Dossett | Sony STR-665 receiver, Pioneer CLD-D925 laserdisc,
-------------| Sony SLV-X822 VCR, Mitsubishi DIVA 33" TV, Rambler
Melbourne OZ | L/R speakers, Richter Hydra surrounds, Monster Cable.
Amiga 2000/40| ObWebSite : http://netspace.net.au/~astroboy/
R Larsson
astr...@netspace.net.au (Paul Dossett) wrote:
>R Larsson (rune.l...@everyday.no) said:
>
>>anyways... From what you're saying about the HQ circuit, it's clear to me
>>now that the internal comb filter is used all the time, and you cannot get
>>a "pure" composite signal out even if your life depends on it.
>
>Videotec in the UK are working up a fix to get around that. I don't need it
>but others might be interested.
Busy people at that company... You know, the player already has in its
design a DAC which delivers a composite video signal (in fact the exact
same chip the 704 uses for its composite output), so it may only be a
question of re-routing the signal to the RCA jack. Like getting it through
the On-Screen-Display chip, cause that's now done on the Y/C signals
(unlike the 704, where the on-screen text is handled digitally, with the
same chip that's doing noise reduction). The OSD chip on the 925 has the
required composite in- and output, but they are now unused.
>>I have compared the schematics to one of the best american models, the
>>CLD-D704, which has completely separate paths for Y/C and composite
>>outputs; meaning the composite out isn't just an added together Y/C, but
>>instead has its own D/A converter and a big driver circuit. The reason why
>>this isn't done on the 925 is because stuff like the Pseudo-PAL and noise
>>reduction circuitry is done on the Y/C signals. The 704 has its noise
>>reduction done in the digital domain, and is probably way better at its job
>>than the apparently useless analog one in the 925.
>
>Yeah, but the 925 does a nice job without noise reduction, IMHO, up to the
>standards of the cheaper NTSC units I've seen. Probably not as good as say a
>704, but then again, it plays PAL discs, doesn't it?
Yes, and the complexity of the dual standard players is probably the reason
why our top-of-the-line player is a bit below the US top models. Our
players have the added cost of chunkier chips (yummy) and doubling up on
things there seem to be dozens of, like adjusting points, filters,
oscillators, electronic switches or transistors for selecting these, and of
course the whole conversion circuit for NTSC into Pseudo-PAL. So when
expensive digital processing comes along over here, Pioneer sees the need
to economize on other areas and cuts things like a headphone output,
coaxial output, jog/shuttle wheel, etc.
>And PAL discs were
>important to me when I bought my machine.
We're not exactly spoiled with PAL discs, but there is the odd tempting one
that comes along. I'm gonna get E.T. soon - nice disc with an unbeatable
price.