QA-550 SD card 16/44.1 WAV transport - Page 2 - diyAudio
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Old 28th August 2009, 09:16 PM   #11
EUVL is offline EUVL  Europe
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> I am thinking of removing the 74HVC04 and replacing it with an LVDS driver

What would that do ?
Is it not better to reclock all lines with D-Fliflops ?

BTW Holger, I did finish that discrete opamp phono.


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Old 28th August 2009, 11:57 PM   #12
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Quote:
Is it not better to reclock all lines with D-Fliflops ?
Maybe, this is also an option. In this case, you don't care for signal quality and refresh the signals at the and of the line. The other possibility is not to let the signal quality go down. As I see it, the best error correction is not to let the error happen - but this is theory.
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BTW Holger, I did finish that discrete opamp phono.
Great! BF862 still the way to go?
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Old 29th August 2009, 04:36 AM   #13
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If the biggest contributor to jitter is the uP (the 440ps mentioned above), then there is little you can improve by changing a logic downstream, and I doubt a LDVS is a significant improvement to VHC.

BF862 is the greatest thing since sliced bread.




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Old 29th August 2009, 09:40 AM   #14
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I don't know a lot about reclocking but I've looked for schematics and found the one below. Would this be a reasonable way to go about it in this case? If so, which clock and clock frequency should I use?
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Old 29th August 2009, 10:00 AM   #15
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Any D-Flipflop will do in principle. The QA550 has 3.3V digital outputs, so you can also use LVDS as well as VHC.

As to the clock, I presume you might want to keep the original one, in which case you can use the MCK output from the I2S of QA550 to drive your Flipflop.

Don't be shy to ask Clark of QLS. he knows his stuff, and is quite willing to help.

If you really want expert advise, go to the other place and ask Jocko or Elso.


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Old 29th August 2009, 10:10 AM   #16
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Patrick -

Thanks for your advice.
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Old 1st September 2009, 11:44 PM   #17
jonners is offline jonners  United Kingdom
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Has anyone else actually listened to one of these yet?
I've now housed the DAC directly under the transport so the I2S connections are as short as possible.
Sound quality is excellent. It betters my 'Shigaclone' transport, and I'm getting the best digital playback I've yet had in my system.
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Old 1st September 2009, 11:53 PM   #18
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Mine is connected to an Audio Research DAC7 these days, and I am quite pleased with the sound. Will do a comparison with iPod Classic plus Wadia 170i shortly.
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Old 2nd September 2009, 04:42 AM   #19
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We tried both SPDIF (not Toslink) and I2S, and I2S is better as you would expect (w 1543). Are going to try reclocking and external clock but this will take a while.


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Old 2nd September 2009, 08:03 AM   #20
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One of the shortfalls of that device is the lack of gapless playback. But perhaps they will fix it by a firmware update.

For that price it's a real bargain.
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