Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter

[iancanada]

Originally Posted by qusp

yeah ha look I dunno, I know I asked for it ages ago by email or one of the threads (in May'ish), probably lost in the noise, but I was only parroting it from the datasheet and the Japanese crew so honestly its not really something I should get credit for either. Acko is playing with it also afaik and I have that option on titan, which was also initially designed for an ESS

Do you have link to those Japanese crew ?

Ian

[qusp]

Bunpei san (who always seems to be ahead of most in his ESS experiments), ElectrArt and those guys (mostly in Japanese language forums), Acko has it on his TurboClock etc. sorry just snippets I picked up along the way. I also chatted with the designers of titan about it because its a feature in Titan, i'll see if I can dig up the info.

I havent done any experimentation, not sure I trust my ears to pick up the difference, but it should technically be better for the reason you suggest, that the switching is done more in deadtime in relation to the other signals

[iancanada]

Originally Posted by qusp

Bunpei san (who always seems to be ahead of most in his ESS experiments), ElectrArt and those guys (mostly in Japanese language forums), Acko has it on his TurboClock etc. sorry just snippets I picked up along the way. I also chatted with the designers of titan about it because its a feature in Titan, i'll see if I can dig up the info.

I havent done any experimentation, not sure I trust my ears to pick up the difference, but it should technically be better for the reason you suggest, that the switching is done more in deadtime in relation to the other signals

Thanks qusp,

Ian

[Popolvár]

Originally Posted by iancanada

... No any problem display the FIFO status and frequencies, as well as take over the frequency switching control within the window time.

Hi Ian,

So as I get it, it will be possible to query the status of the FIFO stream (frequency, errors, ...) over the Si570 board serial protocol you mentioned few days ago. It would be handy for some status display. Is this feature/"compatibility" valid also for the actual GBIII FIFO and SPDIF boards?

BTW I think that the chain of modules you provide is probably one the best ways to isolate the audio chain from the noisy PC environment (via optical SPDIF). None from the USB / I2S convertors can provide such isolation as I know.

Daniel

[hochopeper]

Originally Posted by Popolvár

Hi Ian,

So as I get it, it will be possible to query the status of the FIFO stream (frequency, errors, ...) over the Si570 board serial protocol you mentioned few days ago. It would be handy for some status display. Is this feature/"compatibility" valid also for the actual GBIII FIFO and SPDIF boards?

As I understand it, the short answer is, yes the current functionality is compatible with the current FIFO firmware.

The difference is that the controller/display won't query the Si570, it will just be sent a message when an event occurs. This minimises serial communications and noise associated with it. The list of events that will be advertised via this channel is in Ian's serial protocol definition.

[Popolvár]

hochopeper,

Thanks for clarification, no need for query commands for that, events are fine. I am amazed in what detail is this designed. I am thinking about some simple microcontroler that will turn on LCD/VFD and will display the status in case of FIFO status change for some time (error, new stream with new frequency, ...) and then it will put itself into a sleep mode.

[hochopeper]

Originally Posted by Popolvár

hochopeper,

Thanks for clarification, no need for query commands for that, events are fine. I am amazed in what detail is this designed. I am thinking about some simple microcontroler that will turn on LCD/VFD and will display the status in case of FIFO status change for some time (error, new stream with new frequency, ...) and then it will put itself into a sleep mode.

That is indeed the sort of thing that is possible. Though I am thinking web interface and OLED screen for myself. Also hoping to build the control/display unit into the playback device.

[iancanada]

Originally Posted by Popolvár

hochopeper,

Thanks for clarification, no need for query commands for that, events are fine. I am amazed in what detail is this designed. I am thinking about some simple microcontroler that will turn on LCD/VFD and will display the status in case of FIFO status change for some time (error, new stream with new frequency, ...) and then it will put itself into a sleep mode.

It's possible. But an isolated display section is prefered. All display modules including LCD,TFT and OLED are noisy because of the scan. The MCU on clock board just works for very short of time during Fs switching. It will go into deep sleep for the rest time with only 15uA consumption.

Ian

[Bunpei]

Originally Posted by iancanada

Do you have link to those Japanese crew

Hi, Ian and qusp! Did you guys call me?

As for MCLK timing, wktk_smile once posted in the "ESS Sabre Reference DAC (8-channel)" thread as shown below;

Originally Posted by wktk_smile

In the Sabre dac app note, ESS recommends inverted MCLK when that's synchronous, although they only says
"The inverted MCLK ensures that the Sabre noise as low as possible." and there's no further explanations.

Anyone tried these?

As far as I tried myself, (I stolen MCLK from transport via LVDS and made inverted at the LVDS receiver input.)
I felt it's slightly better in SQ, but I can't say surely it's better because I haven't done strict A/B comparison yet.

Besides, I have no skill and equipments to measure noise performance correctly.

I 'm just curious what other people found or felt in synchronous + inverted MCLK.

Bunpei followed his post with this;

Originally Posted by Bunpei

Hi, wktk_smile,

I'm not sure that this information has something to do with your interest.
The following Japanese web page by a DAC designer reported a possible noise. You may understand the contents written in Japanese language.

DAC

In the blog page by Mr. Kakuta of AIT Lab, a garage audio dac vendor in Japan, reported a result of his tuning efforts of the timing of synchronous MCLK for ES9018 showing spectra he obtained.

A.[Top] No tuning < 8.8kHz(?) single sine wave input (It is the worst case spectrum)>

B.[Middle] No tuning < 6kHz = 192kHz/32kHz single sine wave input >

C.[Bottom] Tuned. No spurious peaks.



He said nothing about his measurement devices nor sampling frequencies.
I have no idea on what his spectra mean. However, wktk_smile's post reminded me of Kakuta's report.

Is this information helpful enough?

Bunpei

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[qusp]

yep thats the stuff thanks Angel Bunpei , the information all a bit vague but definitely worth experimentation, I guess they dont mention it in the datasheet for nothing. I tried some time ago with titan and results were inconclusive, in that I have no means of measuring the result