Please explain SACD to me...

[DrG]

Hi guys.

I'd like to know more about the SACD recording format. Could someone explain it concisely? Or refer me to a good source of information on this?

I understand the copyright-based restrictions on SACD players with digital-outs. But is it possible to modify an SACD player to have a digital output and then build my own DAC/LPF?

Thanks

[OliverD]

The DSD format used in SACD is entirely different from the usual PCM in almost every other digital audio gear. Basically it's the raw output of a delta sigma modulator (after which usually a decimation filter converts the data stream to PCM). Of course you can tap the signals right before the DAC chip in your player, build a line transmitter and get them out to an external DAC.

However, there are few pure DSD DAC chips on the market today, and quality is not that different. Providing the internal DAC of your SACD player with better operating conditions (new, separate PSU, clean clock, clean ground) and swapping the analog signal conditioning circuitry seems the easiest and best approach.

As of today, many SACD players internally convert the DSD format to PCM, which defeats the purpose of having DSD in the first place, but leaves a backdoor to simply tap the I2S lines, add a S/PDIF transmitter and use any standard commercial or DIY external DAC.

It is no secret that I'm not a fan of SACD at all (it actually sucks) and generally recommend buying a decent DVD-audio capable player for tweaking.

[purplepeople]

Originally posted by AMT-freak
As of today, many SACD players internally convert the DSD format to PCM, which defeats the purpose of having DSD in the first place, but leaves a backdoor to simply tap the I2S lines, add a S/PDIF transmitter and use any standard commercial or DIY external DAC.

Which ones?

:)ensen.

[DrG]

AMT-freak, thanks for the info!

Am I correct in the following though: if the DSD data was tapped then all SACD requires is a LPF to get back to analog? Is this correct or is there more to it?

[stefanobilliani]

Originally posted by AMT-freak

It is no secret that I'm not a fan of SACD at all

I am not a fan too.I used for a period a sony scd xb9 (xb 940) and "innovation" and the more simplicity in the treatment of digital signals is not for nothing clear. I have been able to count at least 4 smd crystals for clocks in the main board.

I have tried the Pass D1 output stage balanced, but in along term I listen of, this player was revealed to be much disappointing one.

I am also a lot more interested in the possibility to modify a DVD A too.

[OliverD]

Which ones?

If you expect a complete list, I will disappoint you. Whenever recently I had a look at high rez photos of SACD players in audio mags, all I could see were current Analog Devices or Burr Brown PCM input DAC chips. The only one I remember right now was an Accuphase, but there are others.

I guess they are simply re-using their DAC backends from CD or DVD players. I expect this to change as DSD devices become more popular, but what I don't expect to change is the way of implementing PSUs, clocks and analog output stages. And DSD sucks a whole lot more if you don't do it right.

[OliverD]

Am I correct in the following though: if the DSD data was tapped then all SACD requires is a LPF to get back to analog? Is this correct or is there more to it?

Basically it's as simple as that. Burr Brown's DSD1700 is actually an 8 tap analog FIR filter. That circuit description doesn't sound good, does it?

[Elso Kwak]

Originally posted by AMT-freak
It is no secret that I'm not a fan of SACD at all (it actually sucks) and generally recommend buying a decent DVD-audio capable player for tweaking.

Hi AMT-Freak,
My exposure to SCAD is limited to the Sony SCD-1 of a friend of mine. My back is also remembering the Sony as this machine is really too heavy to lift.
I installed the Allen Wright prints for him and we did a clock shootout. I feel the Allen Wright mod is much better than Sony's circuit but my friend disagrees.
We tried of course the standard SMD clock made by KDS, the LCaudio XO-2, The Tent clock on the small Allen Wright board and the KWAK-CLOCK in its 45 MHz incarnation.
With the latter clock and Allen Wrights prints a stunning realism and incredible depth of soundstage is obtained. SACD has more definition and much more dynamics as subjectively experienced.
I learned that SACD is MUCH clock sensitive than normal CD. I did not like the Sony at all in the original state.
The problem with DVD Audio is that even less titles are available than for SACD.

[OliverD]

I'm quite aware of the software problem ( ) and I don't debate that SACD can beat CD in some respects, but the theoretical/objective performance of the DVD-Audio standard is much better than 2.8 MHz DSD.

There are some nice sound-only DVD-Video discs (yep, it sounds stupid). Chesky records for example. Plus a small selection of DVD-Audio discs that can only be played in one of the few high-qulity DVD-Audio players.

Soon there'll be a DVD-Video player in almost every household in Europe, and I wonder why the industry once more completely screwed it up. (I think it shouldn't have been that much a problem to implement DVD-Audio in the DVD family right from the beginning and urge the manufacturers to build players that accept the complete family of discs.)

[purplepeople]

I have an entry-level SACD player (Sony DVP-NC650V) and the only reason for buying it is that the analog stages are better than similarly priced CD players. That said, I've never believed that SACD or DVD-A will ever become the mainstream format. The general public just doesn't discriminate the quality of audio that well. In fact, the rising popularity of MP3 only indicates that the typical consumer cannot possibly hear what "we" can discern.

One question I've always had is: How does the data rate translate into theoretical sound quality between the two formats?

SACD => 2.8Mbit/sec @ 1-bit 2.8MHz clock
DVDA => 4.6Mbit/sec @ 24-bit 192kHz clock

Yet, my basic digital theory tells me that freq resp for SACD should be 1.4MHz while only 96kHz for DVD-A.

:)ensen.