Sony SACD noise

I've noticed an odd problem with my Sony DVPNC650V. When I play SACD's or the SACD layer of a hybrid disk, I can hear a faint whirring sound coming from the unit. There is no sound at all when I play CD's or DVD's. This noise is very faint indeed with most disks (Blonde on Blonde, Tubular Bells), but with some it's louder, though still pretty faint (the Stones disks). I'm writing because last night when I played the bonus SACD disk of new Dylan soundtrack, it was much louder, loud enough to be heard faintly from across the room during the quieter parts of the music (especially on the first cut). I thought at first that it was a noise in the background of the recording, but sure enough, it was a relatively high-pitched whirring sound coming from the player.

Has anyone else noticed noises like this with their SACD's in Sony players? Any idea what's causing it or causing it to vary in intensity with different disks? I'm going to try exchanging my Dylan disk today to see if maybe there's a flaw in the disk. It's not loud enough to be a bother with any of my other SACD's.

L.

 

I haven't really noticed this with mine, but I did have a similar problem with a defective CD. It might be an unbalanced disk making the noise. In that case it may be a coincidence that you only hear it with SACDs, or maybe it's because they spin at a higher speed (don't they?)

 

Yes my Sony 775 makes more "noises" when playing a SACD.

I believe its just normal operation.

 

I have the Sony DVP-NS999ES, and it runs very quietly. I had the 333ES before, and the motor was noticably loud. Not sure why though

 

Hmmm.... The mystery deepens.

I do think that it has something to do with the quality of the disks. I exchanged my Dylan disk, and the new copy runs much more quietly, more like a digital purr than a whirring sound. As I said in my original post the sound varies from disk to disk.

L.

 

Louis,

Here's the thing - a channel of audio on the the SACD contains four times the audio data that is on a channel of the same length on a Compact Disc. This will mean that the linear track velocity needs to be about four times faster (allowing for differences in non-audio data) for the playback of an equivalent stereo program - hence a higher spin speed.

Now, as with CD, in order to keep a constant linear velocity, the angular velocity decreases from the inner edge (the beginning of the disc) to the outer edge (the end of the disc). This means that, assuming the data is written from the inside to the outside of the disc, the disc spin speed is greater at the beginning of a disc than it is at the end. If your player has a tendency to be noisy at a high spin speeds then this will be most noticable at the "beginning" of a disc.

I say "beginning" because this is where things get a little confusing! It depends whether you are listening to the stereo or multichannel data as to where on the disc the beginning is to be found. Furthermore, if you are listening in mutichannel mode then the data rate will be roughly twelve times that of compact disc and therefore the player will be operating at roughly twelve times the spin speed.

Confusingly, my 2-channel SACDs do indeed spin fastest at the beginning of the program. Yet, the multi-channel content spins fastest at the end of the program!

This implies that the multi-channel content is encoded from outer edge to inner edge (like a good old vinyl LP!) - the opposite way to CD or SACD 2-channel data.....

This also seems to be the case on DVD video discs. The spin speed is fastest just before layer transition implying that the disc is written from the outer edge to inner edge.....

Now, my SONY SCD-XE670 is quite noisy at its fastest spin speed - I can just about hear it from my sitting position if the music is quiet. In contrast, the SCD-1 is very quiet all the time although you can tell if you put your ear to the machine that the spinning of an SACD in playback is audible whereas the CD operation is dead silent. This makes sense - the more expensive the transport the quiter it should be! However, you may be lucky and have a relatively cheap player with very quiet operation - it's all down to how the thing is designed. My expensive (at the time, although I managed to pick one up a couple of years ago for only £150!!) DVD player - a Panasonic A-350 - ticks away quite loudly near the end of a long layer (60 mins +) so buying expensive gear doesn't guarantee quiet operation!

The bottom line is this, if the audio sounds fine then the player is having no trouble reading the data and therefore is not experiencing a fault. If the noise was due to a problem with the transport then the player wouldn't be able to read the disc properly.

It sounds to me like your SONY DVD player is just a little noisy by design . This is not unusual so don't be too disheartened.

Of, course, if your replacement Dylan disc plays more quietly then that would be very interesting - let us know how you get on.



[during the writing of this post Louis has indeed reported back that the replacament disc plays more quietly - I feel another post coming on.....]

 

Have you checked that you are listening to the same portion of the disc in the same mode (ie 2 channel or multi-channel) as you did with the other Dylan disc you had as the noise in playback will depend on these two factors.

 

Thanks for the information!

Both times I played it in 2 channel (I don't have a multi-channel set-up, so I didn't bother checking to see if the noise was the same--I'll check tonight). I did notice that with the first disk I had the noise was loudest at the start of the 2 channel playback, and this would seem to confirm what you've said.

I'll add that I would swear that the new disk also *sounds* better to me. There seemed to me to be some distortion on the first disk that gave it a somewhat harsh sound. None of the posts on the disussion of this disk made mention of this, and I was surprised. But the new copy sounds smooth and pleasant to me. Perhaps whatever manufacturing flaw caused the whirring, also caused the sound to mess up? Is this what folks mean when they talk about "jitter?"

L.

 

My former Apex SACD/DVD-A player was very noisy playing SACD's; my current Sony 900V is very quiet.

Richard.

 

It's not the motor you are hearing - it's the sound of the laser sled mechanism as the tracking servos try to keep the laser focused on the pit track. As others have noted, SACDs (DVD technology) have much more data - smaller pits, tighter spacing. The player has to work much harder to keep the laser focused than with Redbook.

I believe that variation in manufacturing tolerances means that some disks require servo corrections over a wider range, thus you hear more noise from the laser mechanism.

Take the top off the thing and listen as it spins an SACD - you'll soon hear where the actual noise is coming from, and it's not the motor that spins the disc.

Regards,
Geoff

 

Re: Re: Sony SACD noise

I don't think so.

Regards,
Geoff

 

Geoff,

I'm not sure I agree with you on this one!

While I concede that the sled tracking servo makes some contribution to the mechanical noise on my SCD-XE670, the main contribution comes from the spinning of the disc. The noise from the sled is always at the same volume level whereas the spinning noise increases dramatically from one edge of the disc to another.

On the SCD-1 of course, there is no laser sled. Instead, the laser pick-up is fixed in place and the disc itself is moved across the laser. Now, the SCD-1 is very quiet in operation which may be interpreted as backing up your position. However, on close examination the noise that you can hear on SACD playback is definitely due to the greater spin speed of the disc, whereas the servo moving the disc is not audible during playback.

Take a CD-ROM drive - you're not telling me that the loud noise and associated vibrations that occur at 48X read speed are due to the frantic movements of the laser sled!! In my experience, the situation with noisy SACD and DVD playback is analogous to this (notwithstanding that the CD-ROM drive may operate with CAV) - just to a lesser extent.

Your argument does not account for the decrease in mechanical noise from the inner edge to the outer edge of the disc. The whole point of a CLV drive is to maintain the same bit rate going past the laser at all times. Thus, the disc needs to spin fastest (ie with greatest angular velocity) at the inner edge and slowest (least angular velocity) at the outer edge for the same data rate to be maintained. Thanks to the CLV design, the sled will not have to alter the bulk speed at which it corrects for tracking errors. Therfore, if it were the laser sled contributing the majority of the mechanical noise there would be no change in the ammount heard as the portion of the disc being read changes from one edge to the other. This is in direct contradiction to my experience with every CD/SACD/DVD player I have ever come accross!

All optical disc drives that operate with CLV display an increase in the mechanical noise in direct correlation to the spin speed.

Also, based on my above argumensts, I can only conclude that the multichannel content on an SACD is encoded from the outer edge to the inner edge since the spin speed increases as you play through the program. Can you give me a good reason to believe otherwise?

 

Well stated. You may be right about some things.

I have a modified XA-777ES and it has tracking problem. On some SACDs it will not even read the TOC, and on others, it reads the TOC but cannot then play a track. When it's screwed up like this, I can hear a lot of noise coming from the sled. I have the cover off.

If it plays an SACD right through, the sled makes occasional noises as it readjusts focus, and the better made the SACD, the quieter the whole process is.

Now, as far as multichannel content on an SACD is encoded from the outer edge to the inner edge goes, I must admit I don't have any facts at hand to counter your proposition; I just don't think you are correct, based on a negative - I've never read this anywhere, and I have been following the technology pretty closely.

What I do know is the SACD specification is contained in the Scarlet Book. SACD discs are DVD discs in that they use the same sector size, error correction and modulation as DVD discs and the same file system (UDF plus ISO 9660). I just feel that this rules out the method of reading that you suggested, but I don't have conclusive evidence.

Let's examine your numbers ... "operating at roughly twelve times the spin speed."

The difference in pit size (about half) and inter-track distance (pitch is half) on a DVD is significant, providing some of the extra data. The scan speed has increased from 1.3 m/sec for CD to 3.49 m/sec on a single-layer DVD. This is less than three times as fast - rotational speeds will be proportional. So there's the twelve times - 3 for the speed, 2 for the pitch, 2 for the pit length.

Based on an inner radius of 25mm -> circumference of ~157mm, and a linear speed of 3,490 mm/sec gives a maximum rotational speed of about 22 revs per second, or 1,333 r.p.m.

My reference is Disctronics

Regards,
Geoff

 

My Sony DVP NS 500V works great and the SACDs sound better than CDs (2 channel analog out)

 

Geoff,

Take a DVD-Video disc. Suppose you have a dual layer disc containing a continuous program such as a film - the layer transition normally occurs around the 60 minute mark. We can assume that the reason for the transition is that we are close to the end of one side of the disc. At the transition, the data following on from that on the 1st layer is read from the 2nd layer. From my experience with DVD-video discs I would say that the 2nd layer is written in the opposite manner to the 1st layer. That is to say, if the 1st layer is read from the inner edge to the outer edge, then the 2nd layer is read from the outer edge to the inner edge (this does not necessitate the disc to be spun in the opposite direction if the spiral track on the 2nd layer is configured in the opposite sense to that on the 1st layer). In this way, an (almost ) seamless transition is possible as the laser can pick up the new layer very close to where the previous layer ended.

One of the pieces of evidence that seems to back this idea up is that you are able to fast forward or rewind across the transition point without the laser sled having to suddenly jump all the way across the disc each time the transition point is crossed. My player has a sealed drive unit so it is not possible for me to verify this visually, but going on the sounds emanating from the player, this seems to be the way the discs are encoded.

On a closer examination of the spin speed (using my ears!) during playback of a DVD-Video disc, I now believe that the 1st layer is indeed written, as we both might have expected, from the inner edge to the outer edge (OK, so I goofed in my earlier post ). However, the 2nd layer is, I believe, written from the outer edge to the inner edge thus enabling the smooth transition between layers as described above.

If this is indeed the case, it means that the DVD format allows (if not requires) the 2nd hi-res layer to be written from the outer edge inwards.

Now, onto SACD!

The SACD format allows three variations in disc configuration.

(i) A single DSD layer
(ii) Two DSD layers (dual layer)
(iii) Hybrid disc (consisting of a single DSD layer and a single CD layer)

Out of curiosity, I assessed each of these types of disc and have some very interesting results!

Results:

(i) Carole King / Tapestry - Stereo only SACD

Disc spin speed decreases from beginning to end of DSD layer.


(ii) Thomas Schippers / Pictures At An Exhibition - dual DSD layer disc (Stereo DSD on one layer and Multi-ch DSD on the other)

Disc spin speed decreases from beginning to end of Stereo layer.

Disc spin speed increases from beginning to end of Multi-ch layer.


(iii) Pink Floyd / Dark Side Of The Moon - Hybrid disc

Disc spin speed decreases from beginning to end of CD layer.

Disc spin speed decreases from beginning to end of Stereo portion of DSD layer.

Disc spin speed decreases from beginning to end of Multi-ch portion of DSD layer.


These results seem to back up the following overview of the SACD format:

(i) If only one hi-res layer is used then the DSD data is written to "layer 1" from the inner edge outwards.

(ii) If two hi-res layers are present then the first portion of the DSD data is written to "layer 1" from inner edge outwards and the second portion of the DSD data is written to "layer 2" from the outer edge inwards.

(iii) If a hybrid disc is being made then the DSD data is written on "layer 1" from inner edge outwards and the CD data is written to the CD layer in accordance with the conventional redbook format specification (ie from inner edge outwards).


In the case of the discs used in this exercise it is would seem that on the dual layer hi-res disc, the stereo DSD data resides on "layer 1" while the Multi-ch DSD data resides on "layer 2".

In the case of the Hybrid disc, the stereo DSD data seems to be first on "layer 1" with the Multi-ch data following on the same layer.

I concede that the smaller pit length will indeed reduce the required spin speed to enable a given data rate. However, the smaller track pitch will only enable a larger data capacity on the disc and will not alter the required spin speed to yield a given data rate. Think about it this way - it doesn't matter how wide a road is or how wide the lines painted down the middle of it are, the only things that will determine the frequency at which you pass over the white lines in the middle of the road are your speed and the length of the lines and the space between them. In other words, only the dimension of the pits and lands along the direction that the pit track is read will affect the data rate.

Now, my "twelve times" comment was a rough calculation for Multi-ch playback and I did indeed neglect the different pit geometry on the SACD compared to a CD. Taking this into account (using your factor of two)
I calculate that approximately six times the spin speed of a CD is required for Multi-ch SACD playback. Similarly, my estimate for the spin speed required for stereo SACD playback comes down to just twice that of CD. This sounds about right to me from my listening experiments - thanks for pointing out the pit dimension factor!