On one of my oscillators there is - the ground plane on the bottom is peeking through the side. The copper is directly above the pad and i can see it touching without too much imagination. I'll probably try to squeeze a thin layer of mica in between.
regal,
It makes sense if your mean feed TDA1541 with 32*Fs I2S is better than 64*Fs I2S. I can see the low 16 bits are meaningless for it and only generate more noise to noise floor. But TDA1541 does accept 64*Fs I2S, as well as original Philips I2S protocol which natively supports both 32 and 64*Fs.
That's why I design the I2S to PCM daughter board with stopping clock mode as one of the main function for NOS DACs, which feeds clock to DAC with exactly the numbers it needs and keeps clock line low for the whole rest of time to make noise floor as low as possible.
Regards,
Ian
Universal I2S/DSD isolator for Amanero and other I2S/DSD sources
I have a WaveIO USB. But I’m not happy with the 2.5ns jitter problem on I2S output caused by XMOS, though it’s no longer an issue working with my FIFO. So, I bought another USB, the Amanero. But I did use it until today because there was not an isolator comes with it. I like PC music, but the PC ground.
I realized a universal I2S/DSD isolator is a must for I2S/DSD sources like Amanero and others. It took me a couple of weeks for prototyping. Now you can see it .
This isolator is nothing special, easier than the FIFO isolator because it just uni-direction not bi-direction. Four isolated signals including MCLK, SCK, WS/DSD1, SD/DSD2. PH2.0 and optional u.fl connectors are available for I2D/DSD signals. MCLK is in u.fl only. Two independent bypassble onboard LDOs for both input and output with LED power good indicator. I attached the schematics.
Almost all kind of 5 channel 16-SOIC-W and 16-SOIC-N isolators are working for this small board, including IL715E, IL715-3E, Si8440BB-D, Si8440BB-D-IS1 and others. 16-SOIC-N on top, or 16-SOIC-W on bottom.
It works perfectly with my Anabero, right away without any hesitation. I’ll try the DSD later on.
Ian
I have a WaveIO USB. But I’m not happy with the 2.5ns jitter problem on I2S output caused by XMOS, though it’s no longer an issue working with my FIFO. So, I bought another USB, the Amanero. But I did use it until today because there was not an isolator comes with it. I like PC music, but the PC ground.
I realized a universal I2S/DSD isolator is a must for I2S/DSD sources like Amanero and others. It took me a couple of weeks for prototyping. Now you can see it .
This isolator is nothing special, easier than the FIFO isolator because it just uni-direction not bi-direction. Four isolated signals including MCLK, SCK, WS/DSD1, SD/DSD2. PH2.0 and optional u.fl connectors are available for I2D/DSD signals. MCLK is in u.fl only. Two independent bypassble onboard LDOs for both input and output with LED power good indicator. I attached the schematics.
Almost all kind of 5 channel 16-SOIC-W and 16-SOIC-N isolators are working for this small board, including IL715E, IL715-3E, Si8440BB-D, Si8440BB-D-IS1 and others. 16-SOIC-N on top, or 16-SOIC-W on bottom.
It works perfectly with my Anabero, right away without any hesitation. I’ll try the DSD later on.
Ian
Attachments
nice job Ian, as usual, but a tiny bit late =) Acko has already designed one made specifically for Amanero, plugs right in on pinheader rather neatly.
except your prototype is ready of course
except your prototype is ready of course
why is it any better? the i2s is isolated then reclocked, certainly it seems as though the ESS prefers the clock domain to be powered/grounded on the dac side. here it makes no difference where it happens as long as its before the reclocking stage.
weve been through all of this. there is a theoretical benefit to isolate the i2s input as well, and then again before the reclocker, but both of these isolate the reclocker from the USB ground, for the same result. isolating the USB is not cheap and does not provide additional benefit as far as can be told.
we cant even prove better, let alone 'much better'
weve been through all of this. there is a theoretical benefit to isolate the i2s input as well, and then again before the reclocker, but both of these isolate the reclocker from the USB ground, for the same result. isolating the USB is not cheap and does not provide additional benefit as far as can be told.
we cant even prove better, let alone 'much better'
IMHO, any I2S isolator will add jitter and there is no reclocking stage into Ian's I2S universal isolator board.
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umm, so what are you talking about? some unnamed random application of the universal isolator unconnected to the subject of this thread?
I presumed since..you are in this thread, you might be talking about some application that had a connection to this thread. the universal isolator, was built as..a universal isolator. a USB isolator, may not be better at isolating i2s at all and is not really very universal as an i2s isolator
its like telling someone who just eaten a really nice chicken dinner that beef might have been more enjoyable
I presumed since..you are in this thread, you might be talking about some application that had a connection to this thread. the universal isolator, was built as..a universal isolator. a USB isolator, may not be better at isolating i2s at all and is not really very universal as an i2s isolator
its like telling someone who just eaten a really nice chicken dinner that beef might have been more enjoyable
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Exactly, used as Ian description: an Universal I2S isolator.
As it is designed now, it doesn't have any reclocker circuit in order to attenuate the added isolator jitter
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It could be readily assumed that since Ian has a fifo + reclocker and oscillator, he is designing for use with his boards. Reclocking before the fifo makes little sense to me. Ian's design works well for his system. Anyway Acko has designed exactly what you describe and there is a GB for that. Ian's isolator isolates and isn't concerned about output jitter because he already has a solution to that.
Why I2S/DSD isolator is better than a USB isolator for digital audio interface
I can see there are two reasons:
1, Most of the USB isolators we can touch currently are for USB2.0 full speed 12MHz, not for high speed which is 480MHz. In this case, it will degrade the performance of many good USB audio interfaces which were designed optimizing for 480Mhz high speed, especially for higher Fs application as 192KHz and 384Khz.
2, Even when high speed USB isolator becomes popular down the road, I2S/DSD will still be the better solution than the USB isolator. The reason is very clear. Since we have to power the isolated section from DAC side, powering half I2S/DSD isolator comes with much less noise than powering a whole USB interface. The USB interface usually needs a couple of clocks with different frequency running at same time, not only drawing more current, but also introducing much more EMI noise from power supply and ground.
Ian
I can see there are two reasons:
1, Most of the USB isolators we can touch currently are for USB2.0 full speed 12MHz, not for high speed which is 480MHz. In this case, it will degrade the performance of many good USB audio interfaces which were designed optimizing for 480Mhz high speed, especially for higher Fs application as 192KHz and 384Khz.
2, Even when high speed USB isolator becomes popular down the road, I2S/DSD will still be the better solution than the USB isolator. The reason is very clear. Since we have to power the isolated section from DAC side, powering half I2S/DSD isolator comes with much less noise than powering a whole USB interface. The USB interface usually needs a couple of clocks with different frequency running at same time, not only drawing more current, but also introducing much more EMI noise from power supply and ground.
Ian
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