Intro material - references wanted

[gingertube]

G'day from Oz,
First time in this forum BUT have spent a fair amount of time over at the Tube Amp DIY forum.

I'm wanting introductory/expanatory information with a view to modify/replace my Dennon 8 times oversampling etc.etc. CD Player.

I'm an Professional Electronics Design Engineer so before wading into the pros and cons of this and that I'm looking for some introductory material on:
Oversampling
Reclocking
Out board DACs (Digital to Analog Converters)
Transport issues
etc.

That is philosophies behind these various techniques, what they are intended to achieve, what performance benefits they are intended to provide and the like. We can get into cost vs performance issues later.

Can anyone recommend useful sites/books/journals/forum threads.

I also would like to think that there are others too afraid to show their ignorance to ask these basic question - so help us all.

My philosophies:
1/ What everyone knows is probably WRONG (if in doubt go back to first principles)
2/ There is no shame in being ignorant, ONLY in remaining ignorant.

Help!!!
Cheers,
Ian

[Jocko Homo]

Here is one recent thread that got off to a good start. Only one or two nay-sayers.

The digital system - On clocks, x-ports, S/PDIF, DAC's, etc

Might be as good a place as any to get ideas.

Jocko

[gingertube]

Joko,
Thanks for that - I actually gad to do a bit of background research so I could follow that thread.

So back to first principles to make sure I'm understanding stuff as I go along:
- I pulled out the service manual for my Denon DCD-1550AR.

In the top level block diagram it shows the photodetector feeding a "function box" in the "Servo Unit" block.

The Function Box says:
EFM decoder
Error Correction
Interpolation
Digital Servo Control

The coax and optical digital outputs are shown as coming from this "box" .

Does that mean that Error Correction and Interpolation are done before feeding out the digital signal or does the digital output comprise the "Raw" digital data including the Reed Solomon Error Correction data etc?

That same box feeds the Phase Locked Loop and the Alpha Processor Block. Can you give me a brief explanation of what the Alpha Processing Block does?

The Alpha Processor Block Output feeds the Digital to Analog Converters (DACs) in the Audio Unit - I'm back in familiar territory here.


Thanks,
Ian

[danb1974]

Bits read from the cd are passed through the efm decoder and through the error correction block. Errors not corrected after this stage are replaced by interpolation. Only after all that we have the pcm bitstream (16bit/44.1KHz) that can be feeded to the dac or sent to the optical or coax digital outputs.

[rfbrw]

Originally posted by danb1974
Bits read from the cd are passed through the efm decoder and through the error correction block. Errors not corrected after this stage are replaced by interpolation. Only after all that we have the pcm bitstream (16bit/44.1KHz) that can be feeded to the dac or sent to the optical or coax digital outputs.

A lot can happen between the raw 16/44 datastream and the dac. You have the, now dominant, delta-sigma route and its combined digital filter/dac or the standalone digital filter and multibit dac route. You can even have a mix of the two.
Into the gap between the raw 16/44 stream and the dac fits Denons AL24 Alpha Processing, a proprietary standalone digital filter. From memory, Adaptive Level Processing varies the filter algorythm depending on the amplitude of the signal.

[rfbrw]

There is an explanation of sorts at the end of this brochure.
http://www.denon.co.uk/site/download...DCDPMA_SA1.pdf

[gingertube]

Thank You one and all,
This was VERY useful - I now have a basic understanding of the CD player guts and where the various mods/upgrades fit into the scheme of things.

All I need to do now is decide wether to upgrade the "old" Denon or live with it "as is" until I replace it with a SACD/CD unit.

Cheers,
Ian