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Old 5th November 2012, 04:27 PM   #351
chaparK is offline chaparK  Luxembourg
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Quote:
Originally Posted by qusp View Post
I wouldnt assume we wanted to slave the dacs at all, that would actually be the worst choice, to slave the DSP would be much preferred, the clock for the dac outputting sound should have its clock as local as possible, particularly as there is no controlled impedance method to supply clock to anything, or clock buffer/s
Quote:
Originally Posted by dahlberg View Post
And over the spdif outputs the dacs are clocked by the onboard clock and there an is alternative to reclock it or..... ?
No worries: there's a master clock input. If you select this option, it will clock everything on board - including SPDIF outs.
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Old 5th November 2012, 04:30 PM   #352
Ryssen is offline Ryssen  Sweden
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Put me down for 1 board with volume chip.
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Regards Åke
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Old 5th November 2012, 04:41 PM   #353
qusp is offline qusp  Australia
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nice, thanks it sounded like thats what you were suggesting (that this would be possible) its always best to have the masterclock close to the final stage, then you have less issues with jitter. it demands a certain speed of clock though still yes? in order for the filters to be correct?
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Old 5th November 2012, 06:35 PM   #354
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Quote:
- Analogue audio will be AD converted using that external clock.
- SPDIF will be rate converted to the system rate
- I2S input data will bypass the sample rate converter because it's expected to be at the rate of the supplied external clock.
And how will this masterclock affect the usb reciver ? Will it in any way limit the usb recivers input compatibility ?

Last edited by dahlberg; 5th November 2012 at 06:43 PM.
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Old 6th November 2012, 09:48 AM   #355
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Device sourcing USB has buffer, and software controlling it needs to keep it from underflow/overflow.

Andrew
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Old 6th November 2012, 10:03 AM   #356
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Let me rephrase that last question.
Lets say that I will go for 24/192 on the digital outputs, that's the systemrate right ?
Since the samplerateconverter for I2s will be bypassed am I then forced to (software)
resample all to 192khz or is this (usb reciver output samplerate) set by the new master clock ?
It doesn't seem that Wave IO resamples anything by itself but if I'm reading it right the dsp
will be in need of a fixed samplerate that's the same as the systemrate.
Or is the systemrate something else then the set output samplerate and
that's set by the master clock?
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Old 6th November 2012, 04:20 PM   #357
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Chapark: You can just forget this last isssue. I will go for the onboard clock to
start with anyway and most likely it will work just fine. Any external clock will
be in a far away future anyway. Lets leave it at that for now.

Best regards. Bengt Dahlberg
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Old 7th November 2012, 12:11 PM   #358
chaparK is offline chaparK  Luxembourg
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Quote:
Originally Posted by Ryssen View Post
Put me down for 1 board with volume chip.
That's cool, cheers!

Quote:
Originally Posted by qusp View Post
it demands a certain speed of clock though still yes? in order for the filters to be correct?
There's actually some flexibility in this regard for dividing/multiplying the supplied clock, more details to come when this function is implemented.

One sure thing is that if you need a sampling frequency multiple of 44.1 kHz, then your external clock must be related somehow to 11.2896 MHz.
Likewise if you need a sampling frequency multiple of 48 kHz then you must supply an external clock related to 12.288 MHz.
You were probably expecting this.

Quote:
Originally Posted by dahlberg View Post
I will go for the onboard clock to start with anyway and most likely it will work just fine. Any external clock will
be in a far away future anyway.
That's cool, thanks Bengt. Any other question please ask.
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Old 7th November 2012, 02:02 PM   #359
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I found another one
How about "Double precision mode", how will this work ?
You wrote earlier that if needed you can switch from 24bit to 48bit precision.
Is this something that will be by user choise and how will that effect other
aspects of the XO ?
As an example, I could imagine that there could be a reduction in available
eq-bands or something like that.

Comments ?
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Old 7th November 2012, 02:08 PM   #360
chaparK is offline chaparK  Luxembourg
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Na, double precision is my very own prerogative
As the programmer, I'm the one who's deciding when it's required to switch to double precision. So this "switching" happens in the code and is not user selectable.

One less thing you need to worry about
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