Researching SD Card Transports

[opus101]

Interesting product - its worth noting that the Chinese blurb says the player needs an external 10MHz clock source to work. Which is the right-hand box in the Taobao pictures.

 

SMA cables are affordable on Taobao, under $1 for 0.5m double SMA terminated.

 

https://item.taobao.com/item.htm?spm=a230r.1.14.31.50f86ec5p1EORo&id=556991964477&ns=1&abbucket=20#detail

[bodiebill]

Interesting indeed. I guess the yen sign is actualy Chinese currency? Approx. $ 150 in that case?

 

Can someone explain why the external 10 MHz reference clock option is not optimal? I happen to have one I do not use (Aune XC1) as it was replaced by an Afterdark Emperor Double Crown.

 

I cannot tell from the pictures whether the 10 MHz connection is 50 or 75 Ohm, anyone knows?

 

Thanks @seeteeyou for your research -- thorough as ever :-)

[opus101]

52 minutes ago, bodiebill said:

Can someone explain why the external 10 MHz reference clock option is not optimal?

 

Given that 10MHz isn't related to either of the sample rate families (44.1kHz and 48kHz plus integer multiples), obtaining the relevant frequencies requires a phase locked loop (PLL) to be applied to the 10MHz input clock. A PLL of necessity calls for a VCO (voltage controlled oscillator) as an integral component that won't be as stable as a fixed frequency crystal. 

[bodiebill]

7 minutes ago, opus101 said:

 

Given that 10MHz isn't related to either of the sample rate families (44.1kHz and 48kHz plus integer multiples), obtaining the relevant frequencies requires a phase locked loop (PLL) to be applied to the 10MHz input clock. A PLL of necessity calls for a VCO (voltage controlled oscillator) as an integral component that won't be as stable as a fixed frequency crystal. 

 

Thanks!

 

Does that mean that every solution with an external reference 10 MHz clock is suboptimal, even with the Mutec Ref10, Cybershaft or Afterdark clocks that people are raving about? (In my setup the Afterdark had a considerable positive impact connected to a Mutec MC-3+ USB.)

[opus101]

I am assuming that the fixed frequency crystal oscillator isn't implemented poorly - then yes, based on my EE knowledge an external oscillator isn't going to decrease jitter compared to an XTAL sited close to the DAC chip. But then again, I might be missing something vital. In my understanding frequency references such as an external 10MHz oscillator are intended for ensuring long-term stability and accuracy rather than short-term. Long-term stability and accuracy aren't really significant issues for audio AFAIK.

[bodiebill]

If the latter is the case and we have to believe our ears, the external reference clock apparently also has some short term impact?

[opus101]

Assuming its not a placebo effect then I so far can't imagine how the short-term performance of a VCO (even a VCXO) can beat out a fixed frequency XTAL. But I'm happy if one of the vendors takes time to enlighten me.

[seeteeyou]

Quote

做工还是百万风格，各人喜欢就行，不喜欢我也没话说。声音自然通透，安定感非常突出，背景漆黑，仿佛喧闹的世界一下子变安静了，让你把注意力都集中在歌曲本身，不像pchifi总想换歌，百万说能赶得上cd，大家意会就行，高端cd还是很难超越的，但是搭配好的话，跟一些几千块的cd比，并不输多少，数播的优点就是后期省了买碟的钱，也不用考虑机器的光头老化，机械部件的磨损，碟片刮花的风险，当然也有仪式感强，乐感上限高的优点，yysy，我还是满意用ndp1搭配我的满血版da1套装，一边听歌一边点了“确认收货”

 

https://img.alicdn.com/imgextra/i3/0/O1CN01F2jWfI1NpXwgZU7sk_!!0-rate.jpg

https://img.alicdn.com/imgextra/i1/0/O1CN01n7ZBy41NpXwYTLO9u_!!0-rate.jpg

https://img.alicdn.com/imgextra/i2/0/O1CN01j6b3071NpXwfrAut3_!!0-rate.jpg

https://img.alicdn.com/imgextra/i4/0/O1CN01Stqnwq1NpXwbTglUs_!!0-rate.jpg

[shendrik]

Take a look at my project. I just finished it. 

Supports wav files 44/16 - 192/24, gapless playback, ID3 tags v.2. IR remote control.

SD up to 2 Gb, FAT32 file system.

Output - SPDIF, I2S.

The highest emphasis was placed on sound quality.

 

[bodiebill]

Intriguing, looks great!

Is the 2Gb limitation chosen for SQ?

Why so many buttons on the remote?

Was it built from scratch or using an existing player? 

[shendrik]

The software and device were created from scratch in about 1.5 years.

The 2 GB limit is dictated by the file system used.

The SD card can store up to 999 albums with 99 tracks each.

The style of the device control is as close as possible to the CD transport.

[bodiebill]

In that case you mean 2TB? As FAT32 only supports files of up to 4GB in size and volumes of up to 2TB in size.

 

Given the maximum numbers of albums and tracks: do they need to be named/numbered according to a certain format?

[shendrik]

Forgive me, of course 2 Tb.

After the SD is inserted, the device creates an index file on the card. This file is in text format.

Each directory is assigned a number from 001 to 999. This number is used to make the selection.

The path length limit is 255 characters, and the file name length is also 255. Any number of subdirectories.

[bodiebill]

Thanks, interesting!

 

Are you aware of this clean usb stick player?

https://www.ecdesigns.nl/nl/blog/upl96etl

It has similar file/directory limitations and naming conventions.

I guess sd card could beat usb stick.

[shendrik]

For example:

 

path

/Deep Puple/Made in Japan/CD1

/Deep Puple/Made in Japan/CD2

 

index   

001 /Deep Puple/Made in Japan/CD1

002 /Deep Puple/Made in Japan/CD2

 

play first track from 002 /Deep Puple/Made in Japan/CD2

press 0021

[bodiebill]

Ah, that is easier than the ECdesigns player.

Seems well thought out!

You like the sound?

[shendrik]

I tried using USB, SD sounds much better. This was a decisive choice for the type of media.

 

[shendrik]

I am very pleased with the sound and proud of the result.

[bodiebill]

Congratulations!

Is it a purely private project or doe you plan to make more and sell?

[shendrik]

I have already sold 3 copies and can make a few more in a short time.

[bodiebill]

OK, waiting for more info... :-)

[shendrik]

I can give it to you for testing if you can guarantee that you will return it to me.

The price for the new one will be around 1200 euros.

[opus101]

3 hours ago, shendrik said:

 

The highest emphasis was placed on sound quality.

 

 

Just a suggestion - since you have 3 toroidals in your PSU that's a lot of capacitance to mains from the secondary side. Consider fitting a common-mode choke to raise the impedance to mains-borne noise.

[bodiebill]

12 minutes ago, shendrik said:

I can give it to you for testing if you can guarantee that you will return it to me.

The price for the new one will be around 1200 euros.

 

Tempting.

My SDTrans384 is currently with @gstew for repair (I hope). Have you heard that? How does it compare?

 

I am now enjoying a Pi2AES (with AES/EBU, spdif coax, BNC, optical and I2S out). For serious listening I use it to play local files and deactivate the network with a remote while playing, so it basically works as a standalone player with only minimal jitter.

 

I assume you are in Russia? Interest there in these types of players is more widespread I believe...

[shendrik]

1 hour ago, opus101 said:

 

Просто предложение - поскольку у вас есть 3 тороидальных элемента в вашем блоке питания, это большая емкость для сети со стороны вторичной обмотки. Рассмотрите возможность установки синфазного дросселя, чтобы поднять сопротивление до уровня сетевых шумов.

Thanks for your hint, I will definitely check it out tonight.