The operative word here is JITTER. Jitter is the variability in the timing of the bits coming out the end of the S/PDIF cable from the CD transport. At 44.1kHz sample-rate, the bits frequency is around 2.8MHz. ANY variability in the timing of these bits, one bit to the next bit, will cause the D/A conversion to be distorted. The output voltage will not be at the correct value at each point in time, creating analog distortion. Jitter in a typical CD transport is caused by: 1) inaccurate reads of the pits because of imperfect disk and vibration in the disk while spinning - this can be improved by re-writing on a good CDROM disk and by applying treatments to the disk. Some older disk players used a platter like a turntable to eliminate the vibration. 2) jitter in the internal Master Clock oscillator - selected by the designer 3) power subsystem deficiencies that power the oscillator and associated circuits due to the design 4) imperfect S/PDIF output driver due to the design 5) imperfect S/PDIF cable - get the best one you can afford When one refers to a CD player as a "Transport", it means they are using the digital output over a S/PDIF cable from the device, in conjunction with an external DAC or D/A converter. Here is a typical jitter plot from a transport: http://www.audiocircle.com/index.php?topic=154408.0 Here is how the S/PDIF cable adds jitter to the equation: http://www.audiocircle.com/index.php?topic=154425.0 You can see from these measurements what a Synchro-Mesh reclocker can do to reduce jitter from ANY transport or server. None of the disk treatments are needed if a Synchro-Mesh is used, and it provides galvanic isolation, breaking ground loops. Also, see how good a $275 S/PDIF cable can be. Steve N. Empirical Audio |
I don’t know all the variables involved but I do know from experience that CD transports can and do sound different. Bits is bits? Same bits, different Jitter. Bits are the data, Jitter is in the timing. Steve N. Empirical Audio |
Background scattered light has not been addressed by any manufacturers, at least not to any great extent. So there’s that. And magnetism and static electricity are still problems, there’s that, too. I suspect maybe “jitter” isn’t the do-all end-all for various problems involved with CD playback. There’s also the nagging question of why they can’t make the clear layer in CDs a little more transparent. All of these problems are addressed by two current solutions: 1) reclock the S/PDIF output from the transport 2) design a transport using a CDROM and a computer motherboard and memory. Buffer in memory and spool it out over S/PDIF And JITTER is the THE ONLY issue with the S/PDIF output on a transport, period! I am a EE that has designed digital systems for 42 years and have designed dozens of digital audio interfaces including S/PDIF, AES/EBU, I2S, differential I2S, 6 generations of USB, Ethernet. I know what I'm talking about. There are obviously other issues that come up if you use the D/A inside the player and the analog outputs. Steve N. Empirical Audio |
Frankly if you dont spend $20K on a transport, you will not get the kind of low jitter that the Synchro-Mesh can provide. Even then, I'm not convinced. dCS Vivaldi, dCS Scarlatti, MBL do not publish jitter numbers and neither does PSAudio for their memory player. The dCS has word-clock input, so it can synchronize to the Master Clock in their DAC's. So it's the DAC clock that needs to be low jitter. Simaudio 260D says their "intrinsic jitter" is 1 psec. I think this means their oscillator spec. This is not unusual for a good oscillator, however by the time the signal goes out the S/PDIF BNC or RCA, it will usually have 100's of psec of jitter. My clocks have 1psec of intrinsic jitter, but that's not what I advertise. I advertise the jitter at the end of a 1.5m cable with a 75 ohm termination. Steve N. Empirical Audio |
If I understand you correctly, you are saying that putting the Synchro-Mesh between any transport and DAC, will essentially turn the SQ of the transport (not the DAC) into something roughly equivalent to dCS, MBL, Esoteric, MBL. Is that accurate?
That is accurate. Steve N. Empirical Audio |
Is there any CD transport that can do all that in real time as required? Actually, the PSAudio Memory Player transport might do error correction because it is essentially a computer with CDROM drive. This will not make a big difference in sound quality however, because the difference between corrected reads by this transport and uncorrected reads by a typical non-computer transport is almost zero. In other words, errors are not common and even if they do occur, you will not hear it. It is the jitter that is prevalent and will make one transport sound bad and another one good. Steve N. Empirical Audio |
The jitter effect of all of these "tweaks" can be measured. Most of them make audible changes, but not that significant. The best CD disk tweak is to apply a rubbery coating to the top of the CD to prevent vibration while spinning. This is where the majority of the jitter comes from. The best transport tweak is to use a reclocker. Steve N. Empirical Audio |
How abour MSB's Data CD? They seems to take care of both the "read until right" (CDROM drive and memory buffer) and ”jitter/timing" (proprietary I2S connection by using ethernet network connection) problems? MSB's "Pro I2S interface" is a good implementation, along with being a "computer" CD transport. This locates the Master Clock in the DAC rather than the transport. The Transport has a PLL that synchronizes to the DAC Master Clock. This is the optimum way to do the CD transport protocol. dCS does a similar method, but not I2S. I2S is really not necessary when using this scheme, but it simplifies the DAC to use it. I also put I2S inputs and outputs on my products, as does PSAudio, but they don't do the Master Clock in the DAC like MSB and dCS, with a clock cable going from DAC back to the Transport. Steve N. Empirical Audio |
But 20 grand, are you Nuts? It is a question afterall. This is precisely why you get an Oppo for $1000 and add a Synchro-Mesh for $599. People that have them will tell you it’s a no-brainer. Steve N. Empirical Audio |
Have you ever directly compared the Canare LV-77s and Belden 8281F coaxial cables for jitter? No, but if you send these, I will be glad to make measurements and post it. Here are the ones I had on-hand and compared: http://www.audiocircle.com/index.php?topic=154425.0 Steve N. Empirical Audio
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Stick to an all-in-one-box player and the interface problem is eliminated! OPPO!!!
No interface problem, but you are stuck with this jitter that you can do nothing about: http://www.audiocircle.com/index.php?topic=154408.msg1650944#msg1650944 That is unless you open it up and mod it, and even then, the results will never be as good a an external reclocker. Steve N. Empirical Audio |
Select a DAC that rejects interface jitter and then all that you will hear is the inherent jitter in its own internal asynchronous clock driving the DAC. Absolutely true, and this is precisely the problem. You are trapped with a substandard Master Clock implementation that you cannot improve upon. Steve N. Empirical Audio |
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ASRC (asynchronous sample rate conversion) is the mechanism it uses to lower jitter. I’m not a fan of that - but some like the change in the sound. My problem with ASRC is that it resamples the input with a more accurate clock - but tho the output clock may indeed have less jitter than the input, to do that it changes the data (it calculates the values needed on the output to represent the input signal including it’s jitter) - the input jitter is now encoded in the data and can never be removed downstream. Beside any philosophical issues, this breaks bit perfect playback.. Absolutely true. I also used to believe this was an issue. Then I discovered a really good chip and a good way to implement the circuit. The problem in the past was the chip implementations. Not a problem anymore. Telling the difference between a 44.1 native track and the same 44.1 track output from the Synchro-Mesh is almost impossible. This is a very good chip. This is the reason that my customers don't have any issue with the resampling, and the Synchro-Mesh is so popular. The latest version is much better than the previous version BTW, so older feedbacks are likely about a different product. Steve N. Empirical Audio |
And, if I’m not mistaken, any delta-sigma only DAC will "break" bit perfect PCM playback. So, is R2R the only way to get bit-perfect playback? Almost every DAC does some kind of modification in the D/A in order to effectively filter out artifacts. Steve N. Empirical Audio |
I have a PS Audio DirectStream DAC and transport, interconnected with an HDMI cable over their I2S interface. From what I understand, they reduce jitter (timing errors) with the separation of the bits from the timing on that interface.
Actually, the separation of data, control and clocks in I2S bypasses the S/PDIF receiver and any upsampling that might be in the DAC, so the signal goes directly to the D/A without conditioning or synchronizing of clocks. I2S is the native interface for the D/A chip. This does not actually reduce jitter very much, except for this bypassing. The jitter of the source is what you get to hear, so the lower that jitter is, the better the sound quality. I like this approach because as new sources achieve lower jitter, the same DAC sounds better and better. My own Overdrive SX DAC is like this. If you think the PSAudio transport is good, you should hear my Ethernet Renderer, the Interchange, connected with HDMI I2S cable to your DAC. This will deliver signal with ~15psec of jitter. This can play files from any computer running Jriver or Minimserver. I hope you are using a very good silver I2S cable. This makes all the difference. FYI, I sell one of the best on the market. Steve N. Empirical Audio |
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ozzy - First, you purchased an older model Synchro-Mesh. Not all DACs respond well because some have internal resampling already. It is also critical to use a good output cable. Second, I always refund within 2 weeks if returned within 30 days. Did you return within 30 days? How long did it take to get the refund? Steve N. Empirical Audio |
It would be interesting to know whether there are specific attributes in the spectra besides total jitter that correlate with specific qualities; i.e. wide bass vs natural attack and decay of chimes, bells, imaging, etc. The spectra in this particular plot is only jitter amounts at different frequencies. There is very little jitter below 600kHz in any of the plots. Unfortunately, my tool does not allow me to blow up or zoom in on that section of frequencies. Correlation is very difficult. At least there are some differences there. Steve N Empirical Audio |
What does jitter sound like? What is the actual auditory result?
There are several attributes, including: 1) unfocused instruments and vocalists - wider than natural would be 2) "fill", or echoes between instruments that is not actually present in the recording - some mistake this for ambience or "air" 3) a harder, more brittle sound that tends to be fatiguing over the long term 4) vocalists "S" sounds too hissy to be live 5) inability to distinguish the size and depth of the venue of the recording 6) halos around the instruments and vocalists As for selling, I look at it like helping people understand and I also problem-solve. I also feel it is my job to dispel misinformation for my industry. I don't always recommend my own products, unless I know they are the best solution. I also recommend other products. Just read all of my posts on all of the forums. I spend a lot of time online helping, and as much as I like helping people, I also desire something in return. The alternative is to give thousands each month to advertising and pass this cost on to my customers. Do you really want to pay for advertising? I don't. Steve N. Empirical Audio
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As for the timing of my product production, you need to understand that I wear a lot of hats. I am essentially a one-man show here. Because of this, my customers deal directly with me and I help them on an ongoing basis. I also offer upgrades to most of my products over time, so they are not obsoleted. My extended family sometimes interferes with my work. Most of 2015 I was in another state remodeling my mother-in-laws house. This was the timeframe of ozzys order, the end of 2015. I had a lot of catch-up to do after 9 months away from the business. I build everything to order, but I have boards in stock. If I have a lot of orders backlogged, they are processed in order and this can cause wait-times for some customers. If you ask about the lead-time, I will give you an honest prediction. The majority of my customers are wiling to wait when I have a big backlog because my products are unique in the industry. If you order a Ferrari, you will wait 2 years. I recently received new speakers myself that I had on order for 3.5 years. I waited 3.5 years for these. I have them now and I'm glad I waited. Sometimes the best things in life take time. I have patience. It's a good virtue to have. Steve N. Empirical Audio |
Transports are NOT created equal due to differences in quality of the clocking, power supplies, and support circuitry.
-------> there are BIG differences in SQ amongst different transports No argument here. The thing that makes all transports equal is a good reclocker added to the transport. The things that make the jitter different from all of these transports is differences in the oscillators, power supplies, power delivery, implementation and design. It's the jitter that is different for these reasons. Steve N. Empirical Audio |
RCA obviously. It cannot be terminated properly to any coax. Steve N. Empirical Audio |
As you know, in my case I’m going Oppo>Yggy via **RCA** coax out from Oppo and in to Yggy. Shame on me perhaps, but other than optical this is my only option. Or is it? :) The other option is to use a BNC-BNC cable with 75 ohm RCA adapters. This is better than a cable terminated with RCA's. Like anything there are cables and then there are great cables. You get what you pay for. Technically I could go RCA coax out from Oppo and terminate with BNC coax in to Yggy. So is RCA>BNC coax "better" than RCA>RCA coax? (same coax and all else equal)
Yes, anywhere you can use BNC you should do it. Steve N. Empirical Audio |
