Tuttle et al v Audiophile Music Direct

[The Computer Audiophile]

1 hour ago, PYP said:

Exactly.   Some of these hobbyists (and reviewers) reduce the matter to whether digital is ever used in the process of producing the vinyl record.   To them, the "right" way means digital was never used.   At the simplest level, there is no discussion about whether removing steps in the reproduction process, even if digital is used, results in less distortion (see the quote below).    Meanwhile, the entire recording process that occurs in order to get sound onto tape is seemingly of no importance.  

 

I find this blog about digital vs. vinyl very objective and worth reading:   https://www.grimmaudio.com/blogs/vinyl-versus-digital/    

 

From that blog:

"First of all, no one outside a mastering studio will ever hear the quality of the lacquer. In the process of vinyl production (when pressing >10000 copies of an album), the lacquer is first converted to an intermediate negative copy, from which a ‘father’ is copied, from which various ‘mothers’ are copied, from which stampers are then made that are used in the actual pressing of the vinyl (which is also a copying process). This means there are four mechanical copies between the lacquer and the vinyl record you have at home, and with every copy some details get lost and noise is added."

It seems to be common with many people, to reduce things down to a single black/white issue or decision etc... Life is so much easier when there is no gray and when our decisions can be made based on a single criterion. I get it, life is hard. Making it easier is usually good. But, we, myself included, can go a little overboard. 

[The Computer Audiophile]

15 minutes ago, Norton said:

It would be good  if  there was standard and required labelling  to detail all the known formats, sample rates, bit depths etc that a release had gone through from recording to distribution.  

While this may seem like a good idea, it would really be a disservice. Any transfers or conversions that a release has gone through, are of no consequence to the listener if the product sounds good or sounds how the company releasing it wants it to sound. If we had all the information, every armchair engineer would be spouting nonsense and this would actually create a market for worse products, but products that have a mythical following because people talked good about them.

[The Computer Audiophile]

14 minutes ago, Norton said:

 

For some reason you really, really want this to be something to bash people who enjoy vinyl with and seem to care much more about it than most  MoFi vinyl customers do.
 

Why are boutique vinyl buyers pompous and entitled?  They are just pursuing a hobby that gives them pleasure and I guess have a reasonable expectation that if they pay a premium price for a product of a given (or at least heavily implied) provenance, then that is the product they should receive.  But even given that, there is little evidence that most MoFi vinyl customers are doing anything other than continuing to enjoy their purchases.

+1

[The Computer Audiophile]

Just now, Norton said:

 

Surprised at your approach as the information involved would be much the same as that which is the bedrock of  discussion on this site.  Are you really saying that it would be a bad thing to let people know, for example, that the 24/192  release they are considering buying is just upsampled from RBCD?

 

What I'm saying is that if a chain of provenance is on display, it should provide information useful to consumers. We may think it's useful to know how many transfers a specific tape has undergone or what resampling has been done to a specific digital album, but more often than not this information would only have the chance at causing issues. 

 

It's a popular belief that less is more and recordings without resampling are more "pure" and thus better. Does the original master of Kind of Blue sound different than the safety master? Chances are very high that people would purchase a derivative of the original master before purchasing a derivative of the safety master. What if the safety master was stored properly and the original master was not? What if the safety master sounds better because of its lack of use? That would matter not because people have it in their heads that they know best, know more than the professionals creating this stuff. 

 

Remember SPARS codes? Did they really mean anything, in relation to the final product's sound? No. 

[The Computer Audiophile]

Rather than relying items we think would be helpful, SPARS codes etc..., we should rely on the people with proven track records of producing good products. This comes down to people. 

[The Computer Audiophile]

@Norton I used to be in your camp. I've since come to realize my logic was based on zero factual evidence. 

 

A record company will happily release an inferior remaster of Kind of Blue from the original master rather than a better sounding version from the safety master because the effort involved to attempt to change peoples' minds with respect to a specific master is far too great. Thus, we end up with an inferior product. 

 

I wonder if MoFi wishes it would've released an inferior product (AAA), rather than deal with all that is going on. 

[The Computer Audiophile]

What does provenance tell us about a specific album? Absolutely nothing about the sound quality. 

 

What does it tell us about a specific album when a professional works on it, does whatever s/he believes is best, and puts his/her name on it, as in MoFi? It tells us a lot about the sound quality.

[The Computer Audiophile]

5 minutes ago, Iving said:

 

Perhaps straying from MoFi legal issue but how else to discuss ...

 

Here at AS, as Norton suggests, we discuss endlessly digital math; e.g.s:

 

Over/upsampling vs. NOS per se but also wrt Holo May DAC;

 

HQPlayer - how it dances math-wise with specific DACs;

 

PGGB, "heady brew of math and magic";

 

Digital room correction

 

etc etc etc

 

All of which overlaid on what?

 

A recording/mastering:

- Leave to experts - don't question - they know best - black box - mystery - we shouldn't have audacity to ask

or

- Openness about provenance chain so that we can know and understand how our audiophile hobby math combine with what's mathematically underneath - and we can satisfy intellectual curiosity into the bargain?

 

We had SPARS codes. What did those tell you about a recording's sound quality?

[The Computer Audiophile]

1 minute ago, Norton said:

Isn’t that perilously close to just trusting the little blue light...?

Trusting a blue light is like trusting a SPARS code. It means nothing. 

 

Sure, people can create great products followed by bad products, but on the whole, MoFi has produced great products. Trusting MoFi to continue to produce the best products it can is probably a decent move.

[The Computer Audiophile]

Just now, Iving said:

 

We enjoy a hobby where, at least on this forum, we dig and turnover many information and experience amulets in order to make our own judgements about SQ without fear or favour!

 

Why not provenance. Are we not grown up enough to blend in provenance info.

 

Spars very small and specific category of provenance. 

 

Anyway - can we not make up our own minds.

 

This has nothing to do with making up our own minds or being grown up enough. It's about a mistaken belief that this information tells us anything about the quality of the product. It doesn't. Period. 

 

Look at @JoshM's amazing series The Best Version Of ... That's how you find the best sounding version. Not by looking at provenance. 

 

People are mistaking provenance for sound quality. 

[The Computer Audiophile]

Just now, Iving said:

 

I don't.

 

imo patronising remark

Not sure why you're taking this personal. 

 

What does provenance tell you that you want to know, if not indicative of sound quality?

[The Computer Audiophile]

3 minutes ago, Iving said:

Already explained. I want to understand things so that I can make up my own mind.

 

What does AAA, ADD, ADA, tell you that you can use to make up your own mind? It certainly helps you understand the process a recording went through, but that's only helpful if your collecting recordings that went through a certain process. It has zero to do with listening. 

[The Computer Audiophile]

If I'm not mistaken, we all want the best sounding recordings. I don't think armchair engineers looking over real engineers' shoulders, helps the cause. 

[The Computer Audiophile]

2 minutes ago, PYP said:

I'm curious about provenance, just as I am about knowing more about the recording process.  Where was the album recorded and mastered?  Microphones used and even placement.  Just out of (intellectual?) curiosity and the desire to learn more.  

 

For some recordings, you can tell that there is a difference track to track.  With a little digging, you might find out that they were recorded in different location and/or mastered by different people or places.  I find all of that interesting.  And not because it influences what I hear.  I'm streaming all of this stuff and not purchasing any of it, but if I did purchase a download I wouldn't base a purchase on anything else than my ears.

 

 

I absolutely love this information as well. 

[The Computer Audiophile]

1 minute ago, Iving said:

If I buy a record only interested in digits-free ones, I don't want to know provenance to be assured digits-free. I don't care what MoFi or other hobbyists say about DSD records. I just don't want to buy them.

 

 

Why do you only purchase AAA records? Does AAA tell you something about the sound quality?

[The Computer Audiophile]

4 minutes ago, Iving said:

All experts produce what they produce with the world watching. Many produce to spec. Real experts aren't worried about inspection. They have justifiable confidence.

Not sure I live in the same world as you. 

 

I don't think anyone, other than the engineers working on Beyonce's new album, know how it was made. The world is not watching. The album wasn't produced to any spec. If on the other hand, the world demanded she release an album that was AAA, or they wouldn't purchase it, she would've produced an AAA album even if it sounded worse. 

 

Companies have to sell their goods. If the misguided public likes AAA solely because it says AAA, AAA is what they'll sell. 

[The Computer Audiophile]

Just now, Iving said:

 

Good and fair question.

 

A lot of it is I am a child of my time.

 

Even tho' I wasn't yet born I would rather listen to Dixie Swing off shellac than any digital source.

 

 

Not especially. Analogue is implicit. That's what I enjoy.

Understood. It's great that you enjoy them.

 

 

[The Computer Audiophile]

Just now, Iving said:

 

beyonce a bit hypothetical for me

In the real world, she released a new album.

[The Computer Audiophile]

19 minutes ago, hopkins said:

 

If we make the parallel with equipment, I am sure you would agree that many audiophiles take into consideration design aspects when choosing equipment. Many find it interesting to know what makes a product unique, what problems it's trying to solve, even if we know the proof is in the pudding. At the very least, we want to be reassured that we are getting the best "technology" available. "This sounds good" is never really good enough, many of us are curious to understand what's under the hood. It's rare nowadays for a manufacturer not to share technical information. Why would this be different with recordings (especially those geared towards "audiophiles") ? 

 

I have included at the bottom of this post the product description of the Holo May DAC (which I was recently reading), copied from their website: https://www.kitsunehifi.com/product/holo-audio-may-dac/.

 

You've got to be an armchair engineer to understand any of it! For the many of us who do not understand what all this means, it may still influence us and determine what we pay attention to.

 

They conclude by explaining:

 

 

 

 

So two questions:

- how would you feel if you found out that the technical description of one of the equipment you purchased was intentionally deceiving/false ?

- would you go as far as suggest that manufacturers don't publish this type of information so as not to influence our choices ?

 

--- May DAC description ---

 

Some noted features:

The May DAC (all three models) will also support DSD1024 native and PCM 1.536MHz output! Theoretically it can do DSD2048 and PCM 3.072Mhz however is untested at this time. Also, we have worked hard to reduce the common click noise with all dacs when switching from DSD to PCM. This sound click sound has been reduced significantly with a special circuit design. The May DAC has the new and exclusive USB Enhanced module (L2 and KTE ONLY) which has our FPGA with the new Titanis 2.0  and custom firmware to improve USB Eye Pattern and reduce latency to near zero as well as reduce jitter to very very low levels. The USB module has completely new code written to optimize performance and reduce latency significantly. Low frequency performance (-40db) is also improved. The “enhanced” USB xmos module is twice as powerful/capable as the one that is used in the Spring2.

New improved power supply circuit with high performance multi stage regulation circuit using Rubycon ZLH caps, Panasonic FC, Vishay Caps or L2/KTE models with our exclusive HoloAudio Branded Caps (KTE model unique custom proprietary caps to replace Vishay caps)

We are no longer using common LVDS chipset and are now using a custom 4way circuit that isolates each line which further improves sound quality. such as the MCLK is isolated from data line and this improves jitter spec. Also there are TWO i2s ports in the May dac. Each one can be individually configured pin outs to support all i2s products on the market.

The May and KTE version of the May DAC also is with a CNC machined aluminum remote control! Standard with all three models.

The KTE version has OCC copper wire replaced with 1.5mm pure silver wire. 1.5mm Silver wire is soldered direct to the pcbs with highest grade audio solder. Silver Rhodium Faston connectors used at IEC input.

The May is a DUAL mono DAC. so there is a dedicated Dac Module for Left Channel and a dedicated Dac Module for Right Channel. Also each channel is individually powered by it’s dedicated Otype FLATWIRE transformer found in all three models. We have found after careful testing this new transformer type outperforms ALL transformers we have ever tested to this date. Near zero leakage, improved dynamics and overall spectacular performance. They are handmade for this dac specifically and delivery world class performance you would expect.

May DAC also has a new screen on the front that appears the same as the Spring2 on initial glance…. Font size is bigger than Spring2 but smaller than Spring1. Also you can see the CD track-time information is displayed when using spdif inputs!!!. This is done by extracting additional data from SPDIF. This a part of CD red book standard but nobody notices this and often forgets this cool feature or doesn’t know how to extract the data!. This will lead a fashion for other DAC developer to support this feature… customers will surely love this feature albeit subtle. The screen is much better contrast and viewing angles and one of the first things one may notice.

The May also has a front power button now! It’s been a request by many customers and gone are the days of a good old reach around to get the dac to be turned on! As mentioned before above… The DAC has a soft start circuit!! So don’t fret, it takes a moment for it to charge up and pull power without blowing the fuse!! It actually uses the same exact value of fuse that our Spring1 and Spring2 has! But two transformers! If we don’t have a soft start a couple issues can happen… one being a blown fuse from power surge, and another simply having possible pop noises. No chance of these things happening. We have carefully designed the circuit to have a zero compromise design.

Technical Information about our Custom PLL circuit:-

Now the May is implemented with femto clocks, and also new discrete ultra high performance voltage regulators. It has an advanced PLL (phase lock loop) circuit that is completely custom built for ultra high performance anti jitter performance. Even the highest levels of jitter are near eliminated which delivers world class performance. Using Crystek VXCO clocks that will take any incoming digital signal an reclock it to perfection! This feature can be enabled or disabled to test and prove it’s performance is truly spectacular. Note: this is NOT an off the shelf PLL, but it’s truly the most powerful PLL found in a DAC. Or at least to our knowledge it’s the most powerful PLL ever.. Spdif usually is a not a good protocol because it’s very old and dated! It was designed in 70s together with CD with Sony and Philips. As you may know, It encodes the data signal together with clock signal so it can be transferred by a one-core cable. It makes the cable easy to source, but to encode the data to clock at the transmit side and decode the clock from data at the receiving side, creates jitter. Toslink is a fiber glass version of Spdif. So Toslink adds even more jitter while doing electronic to photo and photo to electronic translation. So people will see clearly that I2S is usually better than SPDIF because I2S has 4 separate signal, 3 clocks 1 data. So it does not have encoding-decoding stuff thus has a better jitter performance. This is important to know this.

A common technique to improve the clock signal from SPDIF is PLL. A PLL is to use a local clock generator to track the source clock. You know jitter is actually a time deviation problem. For example, the fist period frequency is 44101Hz and the following second period is 44099Hz. Thus it has 2/44100 jitter. A PLL is to smooth the time deviation of clock. So after the PLL, it can be 44100.9-44099.1(this is a weak/poor performing PLL). Or it can be 44100.1-44099.9(this is a strong performance PLL). Usually, a SPDIF chip, like AK4118A, has an internal PLL. AK4118A is good chip compared to other Spdif receiver chip and it marks 50ps jitter. It’s the best we can get from a commercial chip. But it’s far from ideal, and definitely not enough for a HiFi standard we are implementing in the May dac. So we need a significantly stronger performing PLL. If the PLL is strong enough, it can smooth the 44101-44009 source clock to 44100.00001-44009.99999(very close to ideal 44100-44100)

But to make a stronger PLL is not easy, it’s actually incredibly difficult. First you need a powerful local clock source. A fixed clock can’t be used because it need to be adjusted to follow source clock rate. A common solution to use a VCO(voltage controlled oscillator). VCO is made by resistors, capacitor and inductors. The cost is low but performance is not so great. So, a better solution is to use VCXO(Voltage controlled crystal oscillator), it uses crystal as oscillator and crystal is a far better oscillator. The VCXO we used in May is Crystek’s CVHD-957. This the best VCXO we can get now.

The second hard problem is, the data need to be synchronized with clock. For example, the source has 44101-44099 clock from Spdif, that also mean it has 44101 samples in first period and 44099 samples in second period. So a good local 44100-44100 clock will have to throw away one sample in first period and lack one sample in second period. An easy fix to it is to use digital filter to smooth the data and it calls ASRC, but ASRC actually modified the data. So after ASRC, the data is modified thus not bit perfect anymore. And digital filter can also generate time domain problems like ringing artifacts. So, a digital filter is not a good way to solve this problem, or you can say, it solve a problem by introduce another problem.

May uses a fifo buffer to store the extra one sample in first period and release it in second period. So it has no harm to data. The difficulty for this design is how to manage fifo buffer. It can be a problem when you have a long-term jitter. And long-term jitter is actually called low frequency phase noise in a frequency domain point of view. To explain it easily, let’s take a example, a long term jitter can be like this, 44101-44102-44103-44104-44105-44104-44103-44102-44101-44100-44099-44098-44097-44096-44095-44096-44097-44098-44099-44100. So you see, it will have 25 extra sample in first ten periods, so the fifo buffer need to able store enough of them and release it in next 10 periods.

So, as a result, May’s PLL’s corner frequency is set to 0.05-0.1Hz in 3-orders. Than means it can reduce a 10s long term jitter by 90%, 1s period jitter by 99%, 0.1s period jitter by 99.9%…… That maybe the most powerful PLL in this industrial. And the most important is, it won’t lose data, it can still locking the source while huge jitter comes in. When you compared other similar PLL in the industrial, you can see it simply unlock the signal when huge jitter comes in. So, in that way, it simply stop you from listening, it tells you there is a problem but not solve it.

I have attached 2 pictures. The AP equipment generate huge jitters to SPDIF(750ns, 1KHz). If the PLL turned off, you will see an very ugly spectrum that means the jitter distorted the analog signal badly. The other picture turn on the PLL, and you can see it beautifully removed almost all the jitters. Compared to other competitors PLL. They won’t remove the jitter so clean, and simply unlock the signal for more than 10ns jitters.

 

More about the May Dac.

The new generation of linear compensation technology solves the accuracy errors caused by resistor
tolerance, after compensation, reaching a variance of 0.00005% tolerance accuracy.

Proprietary anti-jitter technology that provides a full amplitude of anti-jitter without increasing noise floor
and other undesirable effects.

Based on this new generation of technology May “梅” can provide a SINAD of >115dB and a dynamic range
of >130dB, which represents the performance limit reached by today’s most advanced R2R architecture
DAC.

Using the ultimate performance of PLL+FIFO technology, provides 0.1Hz Third-Order low-pass ability to
inhibit jitter. It also uses a high-performance femtosecond VCXO as the PLL clock source. Under the premise
of being almost immune to the front-end jitter, it can also lock up to 1.5us-2us @ 1KHz signal with high
jitter. (It can lock up to 1.5us-2us @ 1kHz signal with high jitter on the premise of almost being immune
front-end jitter).

Dual Mono DAC L/R channels are independently powered by their own dedicated transformer in the PSU
chassis. This provides better channel separation and more accurate sound stage.

Official Support USB and I2S up to DSD1024 and PCM1.536MHz sample rate.

The USB interface uses proprietary firmware with ultra-low latency, a highly reliable data transmission, ideal
USB eye pattern measurements that contributes to 2-4 times higher performance than official firmware.

Two sets of independent HDMI-I2S input interfaces are provided, and each set of I2S has a four-way
independent circuit, as opposed to standard LVDS chip, making I2S clock signals subject to lower
interference and lower jitter. In addition, each group of I2S inputs can be configured with specific pinout
configuration, making it compatible with most of the HDMI-I2S digital devices on the market.

That’s mostly marketing. If you think you can make a good DAC with that information, you’re sorely mistaken. It’s about the people designing and implementing it. 
 

A DAC put together with what armchair engineers consider the best parts, won’t get one very far. It takes skill and experience to understand what’s not in the app notes. 
 

We’ve all seen it happen countless times, where someone believes a specific part should’ve been used in an audio component. They then mod the component with that part. However, they have zero understanding of why the part was used in the first place. If designers had to explain their part choices to everyone, they’d just go with whatever people thought was best, because that’s what would sell, rather than fight the crowd. 

[The Computer Audiophile]

Remember the THD+N wars? Turns out when people got that info, they though it mattered. Manufacturers sacrificed other parts of the design just to get lower THD+N. That’s what armchair engineers thought was important. Turns out, it wasn’t what they thought. 

[The Computer Audiophile]

34 minutes ago, hopkins said:

 

If we make the parallel with equipment, I am sure you would agree that many audiophiles take into consideration design aspects when choosing equipment. Many find it interesting to know what makes a product unique, what problems it's trying to solve, even if we know the proof is in the pudding. At the very least, we want to be reassured that we are getting the best "technology" available. "This sounds good" is never really good enough, many of us are curious to understand what's under the hood. It's rare nowadays for a manufacturer not to share technical information. Why would this be different with recordings (especially those geared towards "audiophiles") ? 

 

I have included at the bottom of this post the product description of the Holo May DAC (which I was recently reading), copied from their website: https://www.kitsunehifi.com/product/holo-audio-may-dac/.

 

You've got to be an armchair engineer to understand any of it! For the many of us who do not understand what all this means, it may still influence us and determine what we pay attention to.

 

They conclude by explaining:

 

 

 

 

So two questions:

- how would you feel if you found out that the technical description of one of the equipment you purchased was intentionally deceiving/false ?

- would you go as far as suggest that manufacturers don't publish this type of information so as not to influence our choices ?

 

--- May DAC description ---

 

Some noted features:

The May DAC (all three models) will also support DSD1024 native and PCM 1.536MHz output! Theoretically it can do DSD2048 and PCM 3.072Mhz however is untested at this time. Also, we have worked hard to reduce the common click noise with all dacs when switching from DSD to PCM. This sound click sound has been reduced significantly with a special circuit design. The May DAC has the new and exclusive USB Enhanced module (L2 and KTE ONLY) which has our FPGA with the new Titanis 2.0  and custom firmware to improve USB Eye Pattern and reduce latency to near zero as well as reduce jitter to very very low levels. The USB module has completely new code written to optimize performance and reduce latency significantly. Low frequency performance (-40db) is also improved. The “enhanced” USB xmos module is twice as powerful/capable as the one that is used in the Spring2.

New improved power supply circuit with high performance multi stage regulation circuit using Rubycon ZLH caps, Panasonic FC, Vishay Caps or L2/KTE models with our exclusive HoloAudio Branded Caps (KTE model unique custom proprietary caps to replace Vishay caps)

We are no longer using common LVDS chipset and are now using a custom 4way circuit that isolates each line which further improves sound quality. such as the MCLK is isolated from data line and this improves jitter spec. Also there are TWO i2s ports in the May dac. Each one can be individually configured pin outs to support all i2s products on the market.

The May and KTE version of the May DAC also is with a CNC machined aluminum remote control! Standard with all three models.

The KTE version has OCC copper wire replaced with 1.5mm pure silver wire. 1.5mm Silver wire is soldered direct to the pcbs with highest grade audio solder. Silver Rhodium Faston connectors used at IEC input.

The May is a DUAL mono DAC. so there is a dedicated Dac Module for Left Channel and a dedicated Dac Module for Right Channel. Also each channel is individually powered by it’s dedicated Otype FLATWIRE transformer found in all three models. We have found after careful testing this new transformer type outperforms ALL transformers we have ever tested to this date. Near zero leakage, improved dynamics and overall spectacular performance. They are handmade for this dac specifically and delivery world class performance you would expect.

May DAC also has a new screen on the front that appears the same as the Spring2 on initial glance…. Font size is bigger than Spring2 but smaller than Spring1. Also you can see the CD track-time information is displayed when using spdif inputs!!!. This is done by extracting additional data from SPDIF. This a part of CD red book standard but nobody notices this and often forgets this cool feature or doesn’t know how to extract the data!. This will lead a fashion for other DAC developer to support this feature… customers will surely love this feature albeit subtle. The screen is much better contrast and viewing angles and one of the first things one may notice.

The May also has a front power button now! It’s been a request by many customers and gone are the days of a good old reach around to get the dac to be turned on! As mentioned before above… The DAC has a soft start circuit!! So don’t fret, it takes a moment for it to charge up and pull power without blowing the fuse!! It actually uses the same exact value of fuse that our Spring1 and Spring2 has! But two transformers! If we don’t have a soft start a couple issues can happen… one being a blown fuse from power surge, and another simply having possible pop noises. No chance of these things happening. We have carefully designed the circuit to have a zero compromise design.

Technical Information about our Custom PLL circuit:-

Now the May is implemented with femto clocks, and also new discrete ultra high performance voltage regulators. It has an advanced PLL (phase lock loop) circuit that is completely custom built for ultra high performance anti jitter performance. Even the highest levels of jitter are near eliminated which delivers world class performance. Using Crystek VXCO clocks that will take any incoming digital signal an reclock it to perfection! This feature can be enabled or disabled to test and prove it’s performance is truly spectacular. Note: this is NOT an off the shelf PLL, but it’s truly the most powerful PLL found in a DAC. Or at least to our knowledge it’s the most powerful PLL ever.. Spdif usually is a not a good protocol because it’s very old and dated! It was designed in 70s together with CD with Sony and Philips. As you may know, It encodes the data signal together with clock signal so it can be transferred by a one-core cable. It makes the cable easy to source, but to encode the data to clock at the transmit side and decode the clock from data at the receiving side, creates jitter. Toslink is a fiber glass version of Spdif. So Toslink adds even more jitter while doing electronic to photo and photo to electronic translation. So people will see clearly that I2S is usually better than SPDIF because I2S has 4 separate signal, 3 clocks 1 data. So it does not have encoding-decoding stuff thus has a better jitter performance. This is important to know this.

A common technique to improve the clock signal from SPDIF is PLL. A PLL is to use a local clock generator to track the source clock. You know jitter is actually a time deviation problem. For example, the fist period frequency is 44101Hz and the following second period is 44099Hz. Thus it has 2/44100 jitter. A PLL is to smooth the time deviation of clock. So after the PLL, it can be 44100.9-44099.1(this is a weak/poor performing PLL). Or it can be 44100.1-44099.9(this is a strong performance PLL). Usually, a SPDIF chip, like AK4118A, has an internal PLL. AK4118A is good chip compared to other Spdif receiver chip and it marks 50ps jitter. It’s the best we can get from a commercial chip. But it’s far from ideal, and definitely not enough for a HiFi standard we are implementing in the May dac. So we need a significantly stronger performing PLL. If the PLL is strong enough, it can smooth the 44101-44009 source clock to 44100.00001-44009.99999(very close to ideal 44100-44100)

But to make a stronger PLL is not easy, it’s actually incredibly difficult. First you need a powerful local clock source. A fixed clock can’t be used because it need to be adjusted to follow source clock rate. A common solution to use a VCO(voltage controlled oscillator). VCO is made by resistors, capacitor and inductors. The cost is low but performance is not so great. So, a better solution is to use VCXO(Voltage controlled crystal oscillator), it uses crystal as oscillator and crystal is a far better oscillator. The VCXO we used in May is Crystek’s CVHD-957. This the best VCXO we can get now.

The second hard problem is, the data need to be synchronized with clock. For example, the source has 44101-44099 clock from Spdif, that also mean it has 44101 samples in first period and 44099 samples in second period. So a good local 44100-44100 clock will have to throw away one sample in first period and lack one sample in second period. An easy fix to it is to use digital filter to smooth the data and it calls ASRC, but ASRC actually modified the data. So after ASRC, the data is modified thus not bit perfect anymore. And digital filter can also generate time domain problems like ringing artifacts. So, a digital filter is not a good way to solve this problem, or you can say, it solve a problem by introduce another problem.

May uses a fifo buffer to store the extra one sample in first period and release it in second period. So it has no harm to data. The difficulty for this design is how to manage fifo buffer. It can be a problem when you have a long-term jitter. And long-term jitter is actually called low frequency phase noise in a frequency domain point of view. To explain it easily, let’s take a example, a long term jitter can be like this, 44101-44102-44103-44104-44105-44104-44103-44102-44101-44100-44099-44098-44097-44096-44095-44096-44097-44098-44099-44100. So you see, it will have 25 extra sample in first ten periods, so the fifo buffer need to able store enough of them and release it in next 10 periods.

So, as a result, May’s PLL’s corner frequency is set to 0.05-0.1Hz in 3-orders. Than means it can reduce a 10s long term jitter by 90%, 1s period jitter by 99%, 0.1s period jitter by 99.9%…… That maybe the most powerful PLL in this industrial. And the most important is, it won’t lose data, it can still locking the source while huge jitter comes in. When you compared other similar PLL in the industrial, you can see it simply unlock the signal when huge jitter comes in. So, in that way, it simply stop you from listening, it tells you there is a problem but not solve it.

I have attached 2 pictures. The AP equipment generate huge jitters to SPDIF(750ns, 1KHz). If the PLL turned off, you will see an very ugly spectrum that means the jitter distorted the analog signal badly. The other picture turn on the PLL, and you can see it beautifully removed almost all the jitters. Compared to other competitors PLL. They won’t remove the jitter so clean, and simply unlock the signal for more than 10ns jitters.

 

More about the May Dac.

The new generation of linear compensation technology solves the accuracy errors caused by resistor
tolerance, after compensation, reaching a variance of 0.00005% tolerance accuracy.

Proprietary anti-jitter technology that provides a full amplitude of anti-jitter without increasing noise floor
and other undesirable effects.

Based on this new generation of technology May “梅” can provide a SINAD of >115dB and a dynamic range
of >130dB, which represents the performance limit reached by today’s most advanced R2R architecture
DAC.

Using the ultimate performance of PLL+FIFO technology, provides 0.1Hz Third-Order low-pass ability to
inhibit jitter. It also uses a high-performance femtosecond VCXO as the PLL clock source. Under the premise
of being almost immune to the front-end jitter, it can also lock up to 1.5us-2us @ 1KHz signal with high
jitter. (It can lock up to 1.5us-2us @ 1kHz signal with high jitter on the premise of almost being immune
front-end jitter).

Dual Mono DAC L/R channels are independently powered by their own dedicated transformer in the PSU
chassis. This provides better channel separation and more accurate sound stage.

Official Support USB and I2S up to DSD1024 and PCM1.536MHz sample rate.

The USB interface uses proprietary firmware with ultra-low latency, a highly reliable data transmission, ideal
USB eye pattern measurements that contributes to 2-4 times higher performance than official firmware.

Two sets of independent HDMI-I2S input interfaces are provided, and each set of I2S has a four-way
independent circuit, as opposed to standard LVDS chip, making I2S clock signals subject to lower
interference and lower jitter. In addition, each group of I2S inputs can be configured with specific pinout
configuration, making it compatible with most of the HDMI-I2S digital devices on the market.

Question for you: Does this tell you anything about how the product sounds in your system?

[The Computer Audiophile]

An additional note: My views on this have zero to do with trusting the man, or supporting companies over consumers or any of that. To me it can be summed up by this, the view from the top is always best. 
 

None of us has the top view on how MoFi creates products. We don’t know why decisions are made. We think we know the best way to do things, but these beliefs are based on what? Most certainly not the album MoFi is working on right now. 
 

There’s a time to trust the professionals and buy the album to see if you like it. 
 

MoFi could use DSD for the sole reason that it’s easier to make thousands more albums, even though it sounds worse. However, people have said these one step albums are the best sounding vinyl records of these releases, ever made. I think the professionals got it right. 

[The Computer Audiophile]

19 minutes ago, hopkins said:

AudiophileStyle is itself a platform for many engineers to provide technical explanations. Do these engineers design their products based on what AudiophileStyle readers think are the right "parts" or "techniques", I don't know either. You would have to ask them. I'll assume they design their products based on what they think is best. 

I know the answer to this question. Sometimes they design it how they want, other times they design it how the customer wants. I know one company that put in a Toslink input just because a reviewer wanted it on a previous product. 

 

19 minutes ago, hopkins said:

Second of all, why would it matter what I would infer from that product description?

That's the whole reason for the discussion. People want more details about MoFi releases or releases in general. I asked why. People believe it tells them something that is useful, but I don't believe it does. That's why I asked you what you can infer from al those marketing descriptors. 

[The Computer Audiophile]

1 hour ago, hopkins said:

 

Reading the content of this forum, it seems pretty obvious that many here take into account product descriptions to some extent. 

 

Whether the technical data is useful,  is a good question, but if it's there, it better be correct and honest, that's my opinion.

 

Whether you believe that full analog is useless, and that those who purchased those albums based on that criteria  got what they deserved does not change the fact that the company in question knowingly deceived its customers. 

 

That being said, you are right in reminding everyone that the end result is what counts. 

To that we agree. 

[The Computer Audiophile]

6 minutes ago, Jud said:

 

I don't know how familiar I am with this story and would be interested to know more if you'd be willing to say something about it.

I messed up the abbreviation. THD wars, not THD+N. 

 

http://www.audiophileaddicts.com/2017/07/lower-distortion-often-doesnt-equal-better-sound-quality/