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Old 26th May 2006, 07:34 PM   #1
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Question laser disc players as cd transport?

hi

ok so my modded t-amps are up and running thanx to many here but now...what about the perfect transport?

read Russ Andrews uses a modded laserdisc player for it's extra stability and general over-engineering for plain ol' red-book cds...but i am ignorant as a rock so,

anyone know what ldps have digital AUDIO output that i can feed into a dac and play cds?

ty from i

miles
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Old 26th May 2006, 07:54 PM   #2
anatech is offline anatech  Canada
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Hi Miles,
I'd use a good CD transport. Laserdisc players are optimized for ..... wait ...... here it comes ....... laserdiscs! A purpose built CD player is a much better bet.

Some of the early NEC transports are great, I also like the KSS-151 (linear motor?) type. Even the lowly KSS-210A and 240A types put out a more stable eye pattern than some of the new ones. Easy to fix too.

-Chris
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Old 26th May 2006, 08:42 PM   #3
phn is offline phn  Sweden
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A CD has nothing in common with vinyl. The information on a CD is interleaved.

The CD mechanism has no influence on CD playback. Vibrations, flutter are irrelevant. The FiFo and buffer take care of that. It's electronics and the laser that matter.

Everything else is maketing.
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Old 26th May 2006, 08:52 PM   #4
anatech is offline anatech  Canada
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Hi phn,
The transport has everything to do with digital errors. No comparison with a turntable has been made.

I can say that the more stable the eye pattern is, and how clear it is directly impacts the quality of the information coming off the disc. You are getting an analog signal that is demodulated into a digital signal. Excessive noise will cause data errors.

-Chris
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Old 26th May 2006, 09:40 PM   #5
moe29 is offline moe29  United States
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I've used my Pioneer CLD-D704 Laser Disc player as a transport for
many years now. It has a Direct CD button for bypassing all video
processing circuits.

I've had no reason to update it, because i think i'd have to spend some
serious money before there would be any improvement.

If you can find one used it might be worth looking into... but i'm sure
they're pretty rare now.

Check out the new Rega Appollo... seems like a really nice CD Player.
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Old 26th May 2006, 10:34 PM   #6
phn is offline phn  Sweden
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Quote:
Originally posted by anatech
Hi phn,
The transport has everything to do with digital errors. No comparison with a turntable has been made.

I can say that the more stable the eye pattern is, and how clear it is directly impacts the quality of the information coming off the disc. You are getting an analog signal that is demodulated into a digital signal. Excessive noise will cause data errors.

-Chris
I remember we had this discussion earlier. I don't have the energy for that. But yeah, that Meridian 808 CD player is really a piece of junk, using a cheapo DVD ROM drive instead of the "audio-grade" Philips CD-Pro CDM.

I'm not exactly sure about what you mean. But there's no noise in a digital signal. There are only "ones" and "zeros." The CDM has nothing to do with the analog signal.

The only times the CDM comes into play is if it's broken or if the vibrations or chocks are severe enough to upset the laser.
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Old 27th May 2006, 12:08 AM   #7
anatech is offline anatech  Canada
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Hi phn,
Been in digital audio service since it started.

If you monitor the C2 flag, you can watch the error flags drop as you align a mechanism. The information comes off the disc (or tape) as an analog signal. If you reduce the amplitude, distort the wave shape or add noise, you increase the digital errors. So the alignment of the laser and pick up diodes is critical. This is seen as a change in the quality of the RF or eye pattern. If it's clean with the correct amplitude and stable, you will be able to extract and decode the information properly.

If you send a demodulator garbage, you will get garbage out. You can try to correct it and reclock it as much as you want. Garbage is garbage. You have to realize that on a properly functioning transport with a good disc, there will be a certain amount of errors. That's called the BLock ERror rate (BLER rate). For other digital systems we can perform a BERT test to quantify the error rate.

What I am trying to explain is that the signal is not a digital one until we demodulate it. What happens in the analog, RF realm is of critical importance if we want good sound.

This means that you can not use a cheap transport and a great DAC and expect the performance the DAC is capable of.

-Chris
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Old 27th May 2006, 01:49 PM   #8
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many thanks, phn

nice clear knowledge is always better than cobbled together information, huh?

what i was hoping was that i could use a cheap, used ldp and it would somehow run more stable with cds because of the higher speeds it has to use reading ld...and maybe an emotional reaction - the whole mech is bigger and beefier and that seems GOOD to my heart!!

'cos i'm into these t-amps at the moment - even though the low power has meant i ran it into clipping and blew my carefully crafted iplacoustic tml's drive units! - i'm in 'bargain basement' mode and want a weird industrial transport to use with a reasonably good dac.

still not convinced that ldp isn't the way to go having drooled a little over Russ Andrew's test system but, ok... what machines have the best transports for, like, zero moolah?
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Old 30th May 2006, 12:03 AM   #9
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I gotta say that my old Sony ES 508esd is a great transport. A great player too. It's built like a brick. The loader is metal as far as I can tell. It plays cdr's. It has more features than I know. It was cheeep, about 40 bucks USD on ebay in pretty new condition w/ orig box, manual.

regards,
Marc
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Old 23rd June 2006, 06:41 AM   #10
ido8bit is offline ido8bit  Australia
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If you are looking at industrial players confirm that they actual play CDs before buying. None of the industrial players that I have seen do not play CDs (even those that will play the digital audio from a laserdisc).

All the domestic Laserdisc players that I have owned that were recent enough to have digital audio also played CDs, but some hi-end Laserdisc players were dedicated unit that only played Laserdiscs.

I would think that many Laserdisc transports may actually be less stable than a decent CD transport when playing CDs as they often designed move to the other side of a Laserdisc to save the user from changing sides halfway through a movie. They also have to accomodate the different spindle sizes of Laserdiscs and CDs.
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