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Old 8th July 2006, 12:40 AM   #521
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Default Listening session

Hi Dutchman,

I am really sorry about that,


I just send you an invitation by email, your patience is rewarded. You are the first diyaudio member that can listen to the new I2S setup.
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Old 8th July 2006, 04:09 PM   #522
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Default Clocking the PCM63p dac...

Hi all -

I've had this question in my mind for the past couple of days, and have just come across ur clocking-at-dac & clock-slaved-back-to-transport discussions..
{sorry, I don't mean to hijack the thread here}

If I use a Trichord clock'3' module at the Burr Brown PCM63 dacs, do I just inject the 16.9--- Mhz frequency to Bit clock / Master clock....or should it be divided down to a lesser frequency ?

As these dacs IC's are in a one-box unit {Copland 288} I have no worries about cable length back to the transport (6 inches).

I noticed that Wadia sport this kind of setup with the main clock driving the Dacs first, then linked back to slave the transport !


Many thanks for your enlightenment
(I posess very little digital knowledge- as you can tell!)

Warmest regards,

-Andy-
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Old 8th July 2006, 04:49 PM   #523
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Doesn't Wadia use ST fiber optic cable to pass clock & signal separately between transport & dac? Curious whether ST FO transceivers (much superior to toslink) might be an interesting alternative to SPDIF or I2S. I wouldn't dismiss ST FO out of hand, tho it is less popular now than years ago. A friend of mine who was using it with his Wadia heard differences between ST cables--possibly due to variability in the quality of polishing on the cable ends.

Dave
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Old 8th July 2006, 11:14 PM   #524
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Quote:
Originally posted by Terry Demol
Personally I run a slaved transport with master oscillator in DAC. This is theoretically even better than I2S because the XO is -right at the dac- reclocking all signals. Also the interface is less important.
I also slave the CDP to DAC clock. Rather than reclocking the jittery, asynchronous signals that come out of the S/PDIF receiver, I strap the 8412/4 in mode 1 and shift the bits out of the receiver with the same clock that shifts them into the DAC chips. That way all asynchronous signal transitions are confined to the bi-phase decoder.


RE: Linear Interpolation

I did a lot of modeling, simulating, and testing of interpolation for a previous project. For NOS data streams, linear interpolation was not very rewarding. I had much better results with non-linear interpolation. I used 16 DACs per channel. The data and word clock were shifted into separate 64-bit registers and each DAC could get its data and word clock from any of the 64 taps.
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Old 9th July 2006, 06:27 AM   #525
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Default Non linear interpolation

Hi Ulas,

Thanks for your reply [post524]

The 64 bit register setup for data and word clock with taps, is in the universal timing chain diagram [post#442], it already has 63 usable taps and can drive 32 DAC chips.

Read [post#151] very carefully, it already proves that I tried similar setups, but sound quality degraded, since the time interval between samples has to remain constant.
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Old 9th July 2006, 06:42 AM   #526
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Hi NjoyTHEMUSIC,

thanks for hijaqcking this thread [post#522]

I looked up some specs about the copland 288, it uses 8 times oversampling and a digital filter (pacific microsonics-100). So if I am not mistaken, the DAC clock equals the master clock, so it doesn't need to be divided. (44.1KHz * 48 * 8 = 16.9344 MHz)

The question about how to route the master clock is difficult to answer, each setup can have it's advantages. I think the best way to find out is just to try both setups (switch between the two if possible) and use the one that you like. A third option (since you use a short 6" cable) is locating the masterclock halfway using 2 (thin coax) cables with the same length, routed from the master clock to both DAC and transport.


cheers,

John
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Old 9th July 2006, 08:54 AM   #527
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Quote:
Originally posted by Ulas




RE: Linear Interpolation

I did a lot of modeling, simulating, and testing of interpolation for a previous project. For NOS data streams, linear interpolation was not very rewarding. I had much better results with non-linear interpolation.
What weighting did you apply to the samples?
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Old 9th July 2006, 09:03 AM   #528
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Default Re: Clocking the PCM63p dac...

Quote:
Originally posted by NjoyTHEMUSIC
Hi all -

I've had this question in my mind for the past couple of days, and have just come across ur clocking-at-dac & clock-slaved-back-to-transport discussions..
{sorry, I don't mean to hijack the thread here}

If I use a Trichord clock'3' module at the Burr Brown PCM63 dacs, do I just inject the 16.9--- Mhz frequency to Bit clock / Master clock....or should it be divided down to a lesser frequency ?

As these dacs IC's are in a one-box unit {Copland 288} I have no worries about cable length back to the transport (6 inches).

I noticed that Wadia sport this kind of setup with the main clock driving the Dacs first, then linked back to slave the transport !


Many thanks for your enlightenment
(I posess very little digital knowledge- as you can tell!)

Warmest regards,

-Andy-

Two things. The PCM63 has no master clock. Dacs of its type don't. Next the PMD100 uses a burst clock and that has to be taken into account in any clock tweaking scheme.
Presumably, there is a clock that provides mclk to the PMD100 and the rest of the player. I'd try replacing that with the Trichord and leave everything else alone.
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Old 9th July 2006, 01:29 PM   #529
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Hi ecdesigns,

Since you are planning to implement USB for the Octal DAC, here is an interesting link on different USB implementations written by John Swenson:

http://www.audioasylum.com/forums/pc...ges/13336.html

Sounds complicated. How will you implement yours?
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Old 9th July 2006, 03:51 PM   #530
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Default Split the clock signal ?!!!!!?

Hi John (ecdesigns) -

Hijack ? Are you calling me 'Robin Hood' ?!?!

Ah come on ....you guys are sooo , and u know it !! - That's why I came to you for help (!)

Actually...respect to you all for your kind suggestions (including Lars!)

But John, seriously.....do you have a crystal ball or something???
You even predicted (& answered) my next question - about feeding the
transport and dac stage midway !!!!! Damm ur good !

BUT- Will feeding/splitting the output clock signal from the Trichord module between the transport servo pcb and HD100 IC have any delerious effect on the integrity of the clock signal ?

I'm gonna have me some fun, and also get Elso's Kwack-7 clock to compare with the Trichord'3 ' - I'll let you know how I get on ...

L8R, -Andy-
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