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USB to I2S 384Khz - DSD Converter

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gentlevoice

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Joined 2007
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Hi DIY'ers & MisterRogers,

Hope things are well in your part of the world ... ;)

Might it be an idea to ask Domenico to add this information to the first post? The first posts in the threads I've started remain editable so maybe this information and other key information could be added there?

This leads me to my reason for posting here now: Anyone interested in starting a separate thread for suggestions/wishes for the combo384? I have a few suggestions/wishes myself and maybe others have some as well - could be interesting to see what they are and also have them gathered in one thread ...
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Yep, I'd agree that would be an excellent idea. Domenico's been busy of late; when he circles back I'll give him a nudge.
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Yet, since the idea is there now I think I'll just start off airing a wish of mine (feel free to comment all of you should you have comments):

The Wish (I know it's not Christmas but might happen anyway :p): To be able to allocate which output goes to which pin on the output section of the combo384. This would allow the outputs to align with the inputs on the D/A thus allowing for equal lengths of the combo384-to-D/A wires. If I am not mistaken 1 ps of timing difference corresponds with 0.3 mm wire length difference (with wire propagation at light speed 300.000 km/s). Thus even a few millimeters of wire length difference would cause a constant timing difference between the data streams of several picoseconds.

Although I guess crystal jitter is of a less permanent nature might this be audible?

Greetings,

Jesper
 
G

gentlevoice

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Joined 2007
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.... And then I have another couple of questions that I hope one of you can answer: Will it damage the combo384 - or make it not work - if the powersupply voltages for the combo384 are:

1. up to their rated value a bit later than the USB signal (e.g. ~1 second), or

2. on permanently even if there's no USB signal?

Insights appreciated ;-)

Jesper

... Found this in an earlier post (1174):

Amanero board must be fed after plug USB. The best way to obtain this is one relay driven by +5v of USB. This relay connect (USB plug) or disconnect (USB unplug) your external supply to Amanero board.
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. So I guess this answers my question.
 
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G

gentlevoice

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@grufti:

Differences in wire length do not matter for the integrity of the I2S signal at the typical length involved in these circuits, totally completely not at all, trace impedance matters.
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Thanks for replying ... but so that I may relate to what you write relative to my own knowledge and experience (e.g. what I wrote) can I then ask you to write why it is so? I am familiar with the impedance considerations.

Best regards,

Jesper
 
G

gentlevoice

Member
Joined 2007
Paid Member
@grufti:

The wavelength of 50 MHz is 6 meters in vacuum [about 5.7 meters in copper traces]. 1 cm difference in length is a small fraction of that and most important of all constant. All current DACs that I'm aware of deal with that offset between signals without any impact on performance.
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Thanks again for replying ... I'll just ponder and see how it adds up with everything else ;-)

Greetings,

Jesper
 
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