USB-SPDIF Recommendations

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SeanInBrisbane

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Joined 2014
#1
Do you have any recommendations for a USB-SPDIF converter for use with a Metrum Octave DAC? I considered the Audiophilleo, but it's just too expensive for me. I also looked at the waveIO (ready-made), but my soldering skills are rudimentary and I'm not sure exactly what it is I need to buy to add SPDIF. Any help would be greatly appreciated. Thanks
 
#2
The cheap Chinese units on EBay seem to perform just as well as the higher priced ones- I've done some comparisons between a cheesy $20 cheapie and an expensive HiFace and found zero difference at 48k. Since then, I've upgraded to a $35 Phiree U2 to accommodate 96k and it performs flawlessly.
 
#5
Yes, we are in the realms of basic digital engineering here, not audiophile tomfoolery. Like the hi-ace mentioned earlier I suspect from looking at the Audiophilleo specs that the output rise time (claims to use ECL logic) will be rather high for SPDIF signals and add problems. This was one issue with the aforementioned Hi-Face. Converting digital signals like this is basic stuff, I would go with Sy's recommendation, especially as he has sold out and gone up-market now🙂
 
#7
marce said:
Yes, we are in the realms of basic digital engineering here, not audiophile tomfoolery. Like the hi-ace mentioned earlier I suspect from looking at the Audiophilleo specs that the output rise time (claims to use ECL logic) will be rather high for SPDIF signals and add problems. This was one issue with the aforementioned Hi-Face. Converting digital signals like this is basic stuff, I would go with Sy's recommendation, especially as he has sold out and gone up-market now🙂
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Hi Marce,

Is it a question of Clock frequency ? Just for the SPIDF? Sorry to the OP if off topic.

In a case of an USB to I2S with e.g. only the needs of a 22.xx or 24.xx crystal (16 or 18 bits multibit DAC) is the lower speed better than the USB to I2S devices with 49.xx & 51.xxx (for those same "low" speed DAC chips) which use dividers ? Does all those speeds create problems between all the pcbs between the pc and the final DAC coare board in spite of uf.l connectors ?
Is the BLCK sended by the first USB device on the spidf or I2S is involved (32 fs; 64 fs, 128 fs...) is involved ?

Sorry if a confusion between oversampling frequencies and high frequencies about the substrate (pcb)... lacke myself of understanding !
 
#9
Yep, i know it. Unfornatuly this Xmos has a dafault 128 fs BLCK : don't know if it's compatible with a 16 bits/44 or 48 hz ?

The most expensive has an isolator chip. See my thread in the digital line section... I try to list such devices...

need an other device to rectify the fs...
 
#10
Its the signal rise time, here is a decent explanation:
RISE TIME: Signal Integrity | EE Times
and a bit more in depth:
http://www.sigrity.com/papers/EMC-IEEE-BK/si_chapter.pdf
Basically there is some belief that a fast rise time (and so squarer square wave) is better, this is not true, the faster rise time adds more harmonics of a higher frequency and so increases the possibility of reflections and their severity, thus increasing the chance of signal integrity problems. A more benign rise time commensurate with the clock frequency is much better.
 
#13
Fs, clock speed, and dacs

marce said:
Its the signal rise time, here is a decent explanation:
RISE TIME: Signal Integrity | EE Times
and a bit more in depth:
http://www.sigrity.com/papers/EMC-IEEE-BK/si_chapter.pdf
Basically there is some belief that a fast rise time (and so squarer square wave) is better, this is not true, the faster rise time adds more harmonics of a higher frequency and so increases the possibility of reflections and their severity, thus increasing the chance of signal integrity problems. A more benign rise time commensurate with the clock frequency is much better.
Click to expand...

hi Marce,

I'm not clear what the significance is of Fs, but if I understand correctly, if I want my tda1541 to do higher resolution file playback, eg 192Khz or 384Khz, then all I need is a higher clock speed. Higher clock speed however may cause signal integrity problems. Where do I start in understanding how to configure my clock?

Lets assume I want to play 192Khz files, I think I have some of these, and I want the minimum clock speed as I don't want signal integrity problems, then what should my clock speed be, and then how do I select an crystal?

I have spent hours reading about this stuff on diyaudio, but I can not find anything regarding clock speeds and how to work out what I need to buy to get my dac going.

I guess my basic configuration at this stage will be an appropriate usb interface ---> Ians I2S to PCM board ---> tda1541 NOS dac. Any links or advice would be helpful🙂

cheers Luke
 
#14
Eldam said:
Thanks Marce for the links.

Did you have time to finish your Subbu Dac own Layout revision ? You don't come with us with the RyanJ TDA1541 GB ? ... To much pcbs and different layout ?😉🙂
Click to expand...

I am on a customers site at Wimbourne during the week, so have a 6 hour drive Sunday and the same Thursday evening (after work) to get home. I am also in little B and Bs with hardly any internet access. Apart from Saturday running round with the family I don't have much of a life outside work at the moment!
 
#15
Wow... that's the problem and the privilege both of the people like you who can not be swaped by an other personn ! Btw I like very much your english TV entertainment about cars named Top Gear. We don't look at too much the TV, but I find this one refreshing in relation to our too serious equivalent !

It was just for curiosity... Family & rest are much more important... (and you have to replace one pair of speaker too😉 : By chance I heard the last Avantgard speaker with the look à la Geedle : active but an horrible boomy mid-bass and bass 😱 !)

have a good week Marce, thank you to share a little of your time here.

@ Luke : you can have a look also at the TDA kit thread and the thread I open to ask twice your question : I have exactly the same about fs. My understanding is the fs of the first device is fixed but some have jumper to change it : I don't know for the SPIDF device of Ian but maybe someone can answer you on the dedicated thread ? Your welcome on mine : we talk about the TDA inputs conf !
 
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