[bButcher]

Hi Kingwa,
 
Can you explain a little bit about the new Nos mode. Figure every one in this forum will very much like to know.

 

[bButcher]

I noticed that the LDO chips on my F-1 reads a little differently: the LDO that powers the 575 clocks reads "LEJ#0Z" and the other 2 LDOs that power the cpld and XMOS reads "L337". Is that the same chips that came with your F-1?

Nice job.
 
The one marked LEJ#0Z is ADP150; the other two marked "L337" are generic 3.3V LDO --- can't locate the brand. I replaced both with ADP150s.

 

[Kingwa]

The poor English let I can't join the discuss more.
In the NOS units, there are no any digital filter built in, all modes are real non- oversampling.
Maybe in future we can try the digital filter built in but still without oversampling.
The nos modes had different arithmetic  to process the data, a Chinese sentence say " all the routes can arrive Rome " , different routes may had different views for the eyes.
In audio world is for the ears.
The most important for all modes are the clock process.
The digital signal transmit , or the source design may exist jitter, the nos unit spend a lot resources to reduce the jitter.

 

[bballas]

@bballas where did you get the oxco clock from? I'm thinking to upgrade my nos clock have you consider crystek femto clock?

 
I use  this one:
https://item.taobao.com/item.htm?spm=a230r.1.14.21.sAIvzU&id=537040862399&ns=1&abbucket=16#detail
But also interested : http://www.taitien.com/ti-products/ultra-low-phase-noise-ocxo-series-na-10m-6800-type
The 100rmb ocxo better than 50rmb tcxo 0.1ppm.
Crystek have 12.000Mhz ?  My nos 7 use that.
Choke (10H) filtered  ocxo better(amazing) than without choke.
External clock power - big improvement.
Different xo-s ....depends on your all system.

 

[Mahdi8]

Where did you get the Crystek 12Mhz from it's available in their product marketing PDF but haven't found a store that stock them

 

[bballas]

I don't have 12M crystek.....

 

[Mahdi8]

Sorry misread your statement. But yeah I saw the 12MHz is available in their marketing material but still trying to find a shop that stock them. BTW what's the voltage input of the Taiten OXCO? is it 3.3v?

 

[bballas]

Altera xo powered externally,other xo switch off.So good!!!

 

[Mahdi8]

and what is the voltage of the external power?

 

[bballas]

  and what is the voltage of the external power?

tcxo 3.3 v
taitien ocxo 5v

 

[gk2013]

  The poor English let I can't join the discuss more.
In the NOS units, there are no any digital filter built in, all modes are real non- oversampling.
Maybe in future we can try the digital filter built in but still without oversampling.
The nos modes had different arithmetic  to process the data, a Chinese sentence say " all the routes can arrive Rome " , different routes may had different views for the eyes.
In audio world is for the ears.
The most important for all modes are the clock process.
The digital signal transmit , or the source design may exist jitter, the nos unit spend a lot resources to reduce the jitter.

 
Thank you Kingwa, for me it is clear, good explanation. 
One question: Is the NOS bypass recommended and supported by Audio-GD?

 

[Mahdi8]

Just want to report the upgrade file is running smoothly Running NOS mode 3 with PLL off and ATT1 ON and Async Mode 2. Really liking this. It's more neutral than the old NOS mode 2 but still have a great timbre. one comment after the upgrade though. Low quality music or old recording sounds cleaner. Like a noise filter has been applied but without reducing the detail

 

[bButcher]

  The poor English let I can't join the discuss more.
In the NOS units, there are no any digital filter built in, all modes are real non- oversampling.
Maybe in future we can try the digital filter built in but still without oversampling.
The nos modes had different arithmetic  to process the data, a Chinese sentence say " all the routes can arrive Rome " , different routes may had different views for the eyes.
In audio world is for the ears.
The most important for all modes are the clock process.
The digital signal transmit , or the source design may exist jitter, the nos unit spend a lot resources to reduce the jitter.

Thanks for the explanation, that clarify things a lot.
 
One more question: Is the 6dB/oct filter implemented in hardware or DSP-1 processor?

 

[Kingwa]

-6DB attenuation is in the analog output , it is less than most designs which is had -12DB even 24DB . -6DB had the least phase distortion in the analog filter design.

 

[bButcher]

  -6DB attenuation is in the analog output , it is less than most designs which is had -12DB even 24DB . -6DB had the least phase distortion in the analog filter design.

I see, so you are referring to the "Reconstruction filter (post filter)" and it is implemented as 1st order analog filter, and both NOS and Master dacs have it since they share the same analog circuit boards. (Sorry I misinterpret your NOS dacs web pages, it kind of give me the impression the -6dB filter is specially designed for NOS dacs)
 
One more thing, when comparing tonal balance between NOS modes (1 & 2) and BYPASS mode, I found in BYPASS mode it matches my Antelope Zodiac (also a NOS DAC) pretty well, yet in NOS modes it seems the high end has a little roll-off. Later I double check with 1k Hz single tone (pure sine wave) and found out it is about 2~3 dB quieter in NOS modes. Since you mentioned no digital filter of any kind has been implemented, so I can only assume the "Jitter management" algorithms implemented in NOS modes cause this effect, or can you shed some light on this observation?
 
BTW, since there is no "jitter management" algorithm implemented in Master dacs, can I assume NOS modes in NOS dacs sound warmer than NOS mode in Master dacs?