iFi audio xDSD- The Official Thread
Jun 14, 2018 at 5:11 PM Post #676 of 2,506
The DSD1793 is fully capable of operating at 768kHz with a 32 Bit input. It's actually in the datasheet (just not on the front page).
.

Ok, I don‘t want to argue, you won‘t disclose what kind of tricks are being used anyway, but here is a link to the full data sheet of DSD1793. There is exactly 0 mentioning of 32 bit input capability. If I‘m mistaken, please point out where this capability is being shown.

http://www.ti.com/lit/ds/symlink/dsd1793.pdf

Thanks.
 
Jun 15, 2018 at 3:13 AM Post #677 of 2,506
Ok, I don‘t want to argue, you won‘t disclose what kind of tricks are being used anyway, but here is a link to the full data sheet of DSD1793. There is exactly 0 mentioning of 32 bit input capability. If I‘m mistaken, please point out where this capability is being shown.

http://www.ti.com/lit/ds/symlink/dsd1793.pdf

Thanks.

I'm with you, to claim this chip is natively capable of 768/32 sounds like marketing speak to me. I don't have any music that is 768/32 though so its not a real issue for me.

32Khz sample rate is mentioned = not the same as 32bit resolution, also 768fs system clock is mentioned = not the same as 768Khz sampling rate.

The xDSD does sound great though that is ultimately all that is important.
 
Jun 15, 2018 at 4:40 AM Post #678 of 2,506
TI did a really good job with this spec sheet, it's unusual to find so much and so detailed information. They are also explaining very detailed how the multi-segment decoding is working, with a 6-18 bit split. Not a slightest sign throughout the whole document that the chip can process 32 bit inputs.
Same goes to the fs(sampling rate). However, I could imagine this chip could have some hidden switches to go to a higher fs, in this case with less oversampling.
So, I see the max. frequency claim less critical, likely it's really possible with some hidden register settings. But the bit depth is fixed to 24 max. according to all the explanations provided by this documentation.
 
Jun 15, 2018 at 5:03 PM Post #679 of 2,506
I get distortion when listening to music while charging - it's not so obvious but I s there. As soon as I unplug the charger distortions disappears... I'm not sure at what point it starts again when plugging the charger back in.

Is it possible its discharging faster than charging? I'm using sennheiser hd650 and micro iusb 3.0 (also to charge it)..
As it stands I'm concerned using it in desktop mode...
 
Jun 15, 2018 at 6:16 PM Post #680 of 2,506
I get distortion when listening to music while charging - it's not so obvious but I s there. As soon as I unplug the charger distortions disappears... I'm not sure at what point it starts again when plugging the charger back in.

Is it possible its discharging faster than charging? I'm using sennheiser hd650 and micro iusb 3.0 (also to charge it)..
As it stands I'm concerned using it in desktop mode...

I only use mine as a desktop DAC/amp, and as long as it stays fully charged (white light), there is no issue for me. It has some kind of charge maintenance feature that holds the full charge when connected to the computer through USB, and plugged in with the charge cable at the same time.
 
Jun 16, 2018 at 5:45 PM Post #681 of 2,506
Trying a different charger or using a USB port from your computer for charging, if it can output sufficient current, might solve the noise issue.
 
Jun 16, 2018 at 6:02 PM Post #682 of 2,506
Trying a different charger or using a USB port from your computer for charging, if it can output sufficient current, might solve the noise issue.
I know from experience that the xDSD does not charge through the USB port on a computer. It only charges through a separate micro USB cord that plugs into something like an Apple iPhone charger. That what works for me. It doesn't charge in the same way the Nano BL does. This is what Support told me.
 
Jun 16, 2018 at 8:00 PM Post #683 of 2,506
It was charging from the usb from my Usbridge easily but most of the time not from the usb port just above which comes directly from the sparky which i believe provides more power!

I manage after many attempts to charge from this port as well so to use the usb from the bridge for music. Everything was powered from an ipower and there was not any noise. Actually, the sound quality seemed to be better. I was a bit confused about this behaviour but I believe with a good power supply should be no noise and probably better sound quality overall.
 
Jun 18, 2018 at 11:52 PM Post #684 of 2,506
My review unit arrived this evening! I put it through some Bluetooth and CCK testing with my iPod touch and thus far I am impressed! Zero issues; It just works! Of course, will report back later when I get a better impression.
 
Jun 19, 2018 at 4:02 PM Post #685 of 2,506
It's here at last, well at least it's landed in the UK and in stock with Futureshop (link below), both micro B and USB C variants. I've ordered one of each :) :)

https://www.futureshop.co.uk/ifi-audio-on-the-go-usb-audio-cable

ifi_otgtypec_square01.jpg
 
Jun 19, 2018 at 4:25 PM Post #686 of 2,506
I get distortion when listening to music while charging - it's not so obvious but I s there. As soon as I unplug the charger distortions disappears... I'm not sure at what point it starts again when plugging the charger back in.

Please open a support ticket.

One possibility is that you are listening at very high volume, your charger isn't able to keep up and drops voltage excessively (this can also be due to a bad cable). When charging, the xDSD does operate on the external power and needs it to be of sufficient quality in order to charge and listen at the same time.
 
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Jun 19, 2018 at 4:30 PM Post #687 of 2,506
TI did a really good job with this spec sheet, it's unusual to find so much and so detailed information. They are also explaining very detailed how the multi-segment decoding is working, with a 6-18 bit split. Not a slightest sign throughout the whole document that the chip can process 32 bit inputs.
Same goes to the fs(sampling rate). However, I could imagine this chip could have some hidden switches to go to a higher fs, in this case with less oversampling.
So, I see the max. frequency claim less critical, likely it's really possible with some hidden register settings. But the bit depth is fixed to 24 max. according to all the explanations provided by this documentation.

It is all in the datasheet. What one needs to do is to be able to read 'between the lines'. As Bob Pease used to say "The information you really need to know is never in the datasheet." At iFi, we consider datasheets mostly advertising copy.

As said, the chip will accept 32 Bit data just fine. Due to the 113dB dynamic range limit, the real analogue resolution that is available for actual audio output is well below 24 Bit, never mind 32 Bit. The rest is down to precise terminology and interpretation thereof.

Until we see a 194dB dynamic range DAC, there is no "true" 32 Bit DAC and any DAC that accepts 32 Bit input thus is a "32 Bit DAC", regardless if this is explicitly stated in the datasheet.

Indeed, until we see a 146dB dynamic range DAC there is no "true" 24-Bit DAC either (nor is it likely we ever will see one), however DACs that accept 24 Bit input are commonly referred to as "24 Bit DAC", even those that have a dynamic range that barely exceeds that of 16 Bit Audio. Go figure.

As stated before, to us the key feature of having 32 Bit compatibility is to stop the Hose (Source) Operating System's sound subsystem re-sampling the audio internally. 32 Bit compatibility provides that and is the main reason for the recent flurry of "32-Bit DAC's" that all fail to offer even 24-Bit equivalent SNR/DNR.

TLDR; we see datasheets inside of datasheets.
 
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Jun 19, 2018 at 4:50 PM Post #688 of 2,506
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Jun 20, 2018 at 1:29 AM Post #689 of 2,506
It is all in the datasheet.
Due to the 113dB dynamic range limit...

Sorry, but I respectfully disagree. The data sheet is giving clear register settings for 16/24 bit operation. No talk about 32 bit operation. Even worse - the usable range for that setting is limited to just 3 bits, and there is not much headrum left even to program something in addition.

Also 113dB is not a limit - it's a soft 'typical' spec, meaning the device could go beyond if some conditions are met or a pre-selection is done.

Generally I do agree that anything beyond 24 bit doesn't make much sense, and even 24 bit are never fully reflected in a possible dynamic range.

But hey, that's you advertising 32 bit feature, not me. And so far I've seen 0 proof this is really possible with the used DAC, only marketing talk...

Please don‘t understand me wrong, I think XDSD is a wonderful product and I will most probably get one for myself, as it does (almost) everything I‘m looking for. A real competitive differentiator would be an addition of LDAC. Aptx HD is not much more than marketing, that’s why I believe it’s absolutely ok it hasn’t been covered, but LDAC is a really nice to have feature, as it really has a bit rate to make a difference
 
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