SACD tech help needed (1 Viewer)

[AngelaG]

I'm in a spot of bother here understanding how SACD works. Previously I was of the belief that if I wanted to enjoy the full range of improvements that SACD has to offer, I'd have to upgrade my amp and speakers.

But now there are players like the DVPN S900V which supposedly will offer some level of improvement my existing amp/speaker set-up (as in, not upgraded), but obviously not all of it.

Now, I've actually tried one of these new players, comparing a CD and SACD of the same album against each other, and I'm pretty sure I heard some level of improvement. I definitely wasn't dreaming or listening to louder playback, that's for sure.

At any rate, now I'm told by some telephone-engineering colleagues that this isn't possible - that the speakers and the amp (which haven't been upgraded) would still filter out any supposed improvement.

Could someone please explain if I'm actually hearing right, or if I really am imagining things?

 

[KeithH]

the speakers and the amp (which haven't been upgraded) would still filter out any supposed improvement

What does this mean? Why should the amp and speakers "filter" anything out? What was the rationale there? Now, SACD requires use of the analog outputs. If you connect an SACD player to an A/V pre-amp or receiver that has digital processing capability (i.e., DACs), it is possible to have analog signals routed through the pre-amp's or receiver's A/D and D/A converters, which are PCM-based. In this case, the high-resolution analog signals from SACDs, which are a product of DSD decoding, would be converted to PCM (the encoding scheme used for CD and DVD-Audio) by the A/D converter before being converted back to analog by the DACs. The way around this is to use a pre-amp or receiver that offers an analog bypass mode. The analog bypass mode bypasses the digital processing section. Thus, analog signals are routed directly to the amps and are preserved.

Another thing that might be an issue here is frequency response. It is true that the spec. sheet for SACD says a frequency response up to 100 kHz is possible. However, you do not have to have an amp or speakers rated to 100 kHz to enjoy the benefits of SACD. The same is true for DVD-Audio. The higher sampling frequency of SACD applies to the entire frequency range, not just information above 20 kHz. In short, everything sounds better on SACD than CD. On mid-fi systems, the benefits of SACD are audible. So, I would not be surprised if you heard an improvement in going to SACD. However, I would be interested to know what amp and speakers you have.

 

[AngelaG]

Okay. This is my telephone engineer colleague blurting his responses to me over the phone, which will hopefully make things clearer in terms of explaining how this works to me.

However, you do not have to have an amp or speakers rated to 100 kHz to enjoy the benefits of SACD.

Under the conventional system, the analogue signal coming out of a regular CD player would be at 22kHz. The amplifier used to amplify that analogue signal would also be at 22kHz. The spec sheets of these amplifiers shows the 3dB roll off point at 22kHz. The same thing is essentailly true for the speakers, so any frequenmcy response improvement offered by the SACD player would in effect be filtered by the amplifier and the speakers.

Supposedly with the SACD you can hear a broader frequancy range of up to 100kHz. If the speaker is not delivering that, what additional improvement could I be possibly listening to?

---------------

There endeth the spiel. My current set-up isn't much to boast about, but I'm using an Onkyo TX DS 676 with Acoustic Energy 209 speakers.

 

[PomingF]

Keep in mind it's the 'quality' of sound well within the 20-20K range that separate the higher quality music formats that some users swear by (whether it's SACD or DVD-A) from redbook CD's. Yes, the quality of your equipment may not have the resolution for the improvement (and this improvement has very little to do with whether an amp or speaker's ability to cover the entire 20-20K at least to a reasonable extend) with stereo but when it comes to multi-channel these two formats are supposed to beat the existing compressed format (DD & DTS) handsdown and that is something even a modest quality multi-channel system should be able to appreciate.

Btw, if your technical colleague is really that technical why shouldn't he bother with things beyond 20K for he wouldn't be able to hear them anyway.

PF

 

[AngelaG]

Btw, if your technical colleague is really that technical why shouldn't he bother with things beyond 20K for he wouldn't be able to hear them anyway.

An apt point, but at the same time he must accept at face value that I've heard some kind of improvement.

Thing is, he's narrowed it down to a point where it can't be greater frequency or resolution I'm hearing, so there must be some other quantifiable value I'm hearing that's amounting to this improved sound.

As an engineer (and therefore a control freak), he really really wants to know what it is that's the cause of this.

 

[KeithH]

Angela, let's put it in simple terms. The minidisc covers 20 Hz to 20 kHz. Does the minidisc sound as good as the CD? No. All CD players cover 20 Hz to 20 kHz, but they don't all sound the same. This is with a common medium, even a common CD. A $130 Sony CDP-XE370 CD player certainly doesn't sound as good as a $3000 Sony SCD-XA777ES playing CDs. They both cover 20 Hz to 20 kHz, but they don't at all sound similar. So, why is it so hard for your technical friends to grasp the notion that the SACD, which uses a different encoding scheme than the CD, could sound better. Frequency response is one factor, not the only factor.

 

[AngelaG]

Okay. If you'll indulge me then, could you explain how the method of encoding and decoding on SACDs will improve the sound?

 

[RicP]

Angela, do a little research on DSD (Direct Stream Digital). That's what separates SACD from CD.
I suppose your "technical" friend would blow a gasket trying to get a handle on why DVD-Audio sounds better than CD.

 

[AngelaG]

Heh. I did that. But he keeps coming back to this mathematical relationship between frequency and... er... something else. Even if you can bypass your amp, he says the speaker will filter any improvement anyway.

Having no idea how speakers work, I can't even guess why he thinks there would be no improvement. Basically what I'm looking for is some technical explanation to prove him wrong.

 

[PomingF]

Angela, I think it's safe to tell him it's the word length & sampling rate (@ least with DVD-A's 24/192) that makes these higher quality format stand out over traditional redbook CD (16/48?). If your engineering friend is to bother you with any more of his techno jargon just invite him over to the forum I am sure we have enough fire power to deal with him.
On the other hand all that matters is that you hear & enjoy the improvement. Have fun.
Oh and don't forget to tell your friend since he's a telephone engineer so 'quality' of sound isn't exactly his area of expertise .
PF

 

[KeithH]

PomingF said:

Oh and don't forget to tell your friend since he's a telephone engineer so 'quality' of sound isn't exactly his area of expertise

That's great!

 

[AngelaG]

Well... that sounds all warm, fuzzy, nice and all, but if I did I'd still be left with a lot of questions. What he says in respect of both speakers and amps being band-limited make sense to me, yet this doesn't reconcile with what's obviously a superior analogue signal being output from the player. There must be some quantifiable feature that he or I are missing that's resulting in the improved sound. Any technical explanation would help - he seems as keen to understand why there's an improved sound quality as well.

 

[John Kotches]

Angela,

With DVD-Audio, higher fidelity is acheived with higher sampling depth (up to 24bits) and sampling rates (up to 192kHz). Maximum sampling rate is a function of channels. 192k is limited to stereo, while 96K can have up to 6 channels active.

With SACD, a different encoding approach is employed. Tell your friend that it employs Delta-Sigma 1-bit encoding, with a sampling rate of 2.8224mHz. So, DSD does lots more samples, with much less accuracy, because the goal is to capture the change in the wave, not necessarily the precise value at a point in time.

In terms of why these sound better, there are a few reasons.

1) The technology pushes noise below the threshold of audibility across our most sensitive region (1-4K). 16bit does not have this level of "quiet".

2) Because the sampling rates are higher, less steep anti-aliasing filters can be used. Anti-aliasing filters have a tendency to cause severe pre and post ringing, as evidenced by square wave performance.

3) There is substantial information above 20kHz, and some studies have shown that there is an effect on our brains at some level with these > 20kHz harmonics. Do a web search for the name James Boyk to find some interesting data on > 20kHz content.

Those are the big reasons.

Regards,

 

[Michael_T]

I think another anology that can be added to this equation is the new debate raging in audiophile circles is that Vinyl on a good vinyl rig can sound better than SACD. And I was at a friends house who owns both an XA777ES SACD player and a REGA 25 with a Dynavector cartridge, and the LP we listened to beat the redbook CD (played on the XA777ES) hands down, and had more depth and presence than many SACDs I have heard.

As we all know, Vinyl reproduction will also only reproduce a sound spectrum from 20 - 20,000, but it still sounded better than the CD, which represents the same 20 - 20,000 frequency range.

The clear answer is not whether your equipment is "filtering" any benefits of the music, but that the incoming analog signal, whether it be from a DVD-Audio player, an SACD player or a quality vinyl rig, has an inherent quality that is superior to redbook CD.

The fact is that the incoming analog signal from the SACD is of a higher represented quality than that of a CD. The signal seems to be more perfectly represented to what was fed into the microphones at one end, so it sounds smoother, warmer, more detailed. Cymbals generally sound like cymbals. Vocals tend to have a smoother, less harsh quality to them. Bass is deeper and more well defined. And this is all within the frequency spectrum that humans can hear 20 - 20,000.

We can talk physics and engineering all day, but when you listen to music your ears are the final test. If SACD sounds better than CD it sounds better - period. It really doesn't matter at that point what any engineer says.

And I, for one, can attest to the fact that SACD sounds better than CD - sometimes subtle, somtimes not so subtle. I can also attest to the fact that DVD-audio sounds better than CD.

I trust my ears. So should you.

 

[John Kotches]

Michael,

Cartridges can (and do) have frequency response out well past 20kHz. The Dynavector carts are rated 20-20K with a tolerance, but I guarantee you they have respose out to 30K (and higher for some models). Take the Te Kaitora from Dynavector which is rated at 20-50kHz (20-20 +/- 1dB).

More reasonably priced? The Shure v15vxmr is "Essentially flat from 10-25kHz". Grado's platinum is rated out to 60kHz as well.

I submit to you that there is information, at low levels on the vinyl, and I'm sure some much better steeped in this format than I can back this up.

So while

we all know, Vinyl reproduction will also only reproduce a sound spectrum from 20 - 20,000

I know differently.

Regards,

 

[RicP]

John's right about the higher freq rate on cartridges. In addition though, an LP really can't have any content below 30hz or so with any real authority unless you have a killer tonearm that wil prevent the needle from jumping the groove.
Of course Angela's "technical" friend will dismiss LP as well because the amp and speakers are still "filtering" the signal.

 

[Michael_T]

John and Ric,
Thanks for the clarification. Most importantly, though, I was trying to make a point that it doesn't matter what the "paper" states about hearing thresholds and physics - although it is important in a certain scheme of things, what matters is what we hear from these sources.
And what I hear sure doesn't sound "filtered" to me.

 

[KeithH]

Michael said:

And what I hear sure doesn't sound "filtered" to me.

Sure SACD is filtered. The digital glare is removed!

 

[John Kotches]

Michael,
Know your audience
The techies want to hear what I said even though I left off my best techie description of DSD
I'd discuss things with a musician completely differently. I'd refer to the "shimmer" of a cymbal, or the bite of a harmon muted trumpet, or the barely there tick of a guitar pick before the chord sounds.
If the person was a PRAT cat I'd be talking about swing, groove and rhythmic impetus.
So a lot of it is understanding the people you're speaking with, and what is likely to pique their interest.
I have to gear presentations towards different audiences in my day gig, so I have learned to approach things differently based on the audience.
Regards,

 

[KeithH]

John, personally, I much prefer the musician-oriented discussion. It's far more interesting to me, as I am in this hobby for the music, not the numbers. I'm a chemist in real life , so I spend plenty of hours per day dealing with technical issues. This hobby is supposed to be fun. Speaking of fun, I always like a good-natured discussion like that of the forthcoming Carole King Tapestry multi-channel SACD. Ah, what sweethearts over there, eh?