Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 17th May 2009, 09:36 AM   #121
SunRa is offline SunRa  Romania
diyAudio Member
 
Join Date: Aug 2004
Location: Romania
super, we will wait the kit..

hope it won't cost an arm and a leg though..

I found very informative posts in this thread, thank you!
  Reply With Quote
Old 17th May 2009, 10:21 AM   #122
diyAudio Member
 
Join Date: Nov 2004
Location: Udine
Hello,
also EiAj is supported (TDA1545, AD1865 etc.)? or only I2s?
I belive in a fair kit price, may be with two options:standard ( high quality)and premium( super quality) parts.
Ciao
Guglielmo
  Reply With Quote
Old 17th May 2009, 10:26 AM   #123
Tolu is offline Tolu  Germany
diyAudio Member
 
Tolu's Avatar
 
Join Date: Mar 2007
Hi John

please put me on the order list!

Have you seen my post #109 and#110?

The main difference will be that the QA-550 is universal mid-fi design and John does real high-end!

If you look closely at the picture of the QA-550 there is a funny mistake with the labeling! Who has seen it?
  Reply With Quote
Old 17th May 2009, 12:03 PM   #124
jkeny is offline jkeny  Ireland
Banned
 
Join Date: Feb 2007
Location: Dublin
Yes John,

The advantages of avoiding any mechanical moving parts
- no spurious PS current draws from servos & motors which bleed back into the clock PS (but logic gates firing can also cause PS glitches - so your DSP chip could also introduce some PS noise. I noticed you have avoided DSP processing as much as possible by supporting only WAV)
- no need for the error-correcting/extrapolation of real-time CD laser readers (& the associated problems)

In doing that you've addressed the main shortcomings of mechanical transports.

Your implementation of the clock signal distribution is interesting BUT I still think that you need to check the jitter at the DAC in order to prove that you have achieved your goal.
  Reply With Quote
Old 17th May 2009, 01:38 PM   #125
diyAudio Member
 
Join Date: May 2002
Location: Madison, WI
Quote:
Originally posted by Tolu


If you look closely at the picture of the QA-550 there is a funny mistake with the labeling! Who has seen it?
Are you talking about the constant power draw caused by the "NO/OFF" button?


__________________
www.buyoutdickvitale.com: Pledge money to enable ESPN to get Dickie V off the air
  Reply With Quote
Old 17th May 2009, 03:58 PM   #126
jonners is offline jonners  United Kingdom
diyAudio Member
 
jonners's Avatar
 
Join Date: Jan 2007
Location: Cheltenham
Quote:
Originally posted by Javin5
Is anything known about the contact reliability of these SD-cards? How many times can they be inserted?

They appear to be rated typically for 10,000 or more insertion/removal cycles.
  Reply With Quote
Old 18th May 2009, 11:21 AM   #127
diyAudio Member
 
-ecdesigns-'s Avatar
 
Join Date: May 2006
Hi jkeny,

Quote:
Your implementation of the clock signal distribution is interesting BUT I still think that you need to check the jitter at the DAC in order to prove that you have achieved your goal.
I attached a block diagram that may clarify the problem (cumulated jitter) and a possible solution (time correction). Best comparison would be that of feedback in an analogue circuit

I have been trying to say that sample timing jitter (DAC output) is most important parameter, low master clock jitter alone is not the solution (top block diagram). So inserting a low jitter master clock is fine, but basically provides only marginal improvement since DAC jitter contribution is usually much higher as that of the master clock, followed by flip-flops / counters and clock buffers.

Sample timing jitter (DAC output / during D/A conversion) translates to audible digital artifacts, by using selected highly critical test tracks, the effects of sample timing jitter can be magnified. Without time correction these digital artifacts remain audible. With the time correction enabled, these audible digital artifacts vanish completely.

Measuring these extreme low jitter levels is difficult (here it can only be measured at a NOS DAC unfiltered output using a suitable test signal). Modern DACs are problematic as they don't provide a suitable feedback signal (integrated switched-capacitor filters). Connecting a test probe already affects measurement too (capacitive load + introduced ground loop).
Attached Images
File Type: jpg tc.jpg (70.4 KB, 1811 views)
  Reply With Quote
Old 18th May 2009, 11:27 AM   #128
diyAudio Member
 
-ecdesigns-'s Avatar
 
Join Date: May 2006
Hi Tolu,

Quote:
Any progress with gapless playback?
I think we might have a solution, this puts some restrictions on track names and requires an identifier file (gapless.txt) to be included in the directory that holds the tracks (WAV files) that are part of a gapless album.
  Reply With Quote
Old 18th May 2009, 11:31 AM   #129
diyAudio Member
 
-ecdesigns-'s Avatar
 
Join Date: May 2006
Hi jonners,

Quote:
They appear to be rated typically for 10,000 or more insertion/removal cycles
The card holder will wear-out first, so I made it replaceable (separate PCB).
  Reply With Quote
Old 18th May 2009, 12:20 PM   #130
diyAudio Member
 
Join Date: Nov 2004
Location: Udine
Hello,
also EiAj is supported (TDA1545, AD1865 etc.) or only I2s?
Ciao
Guglielmo
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 10:55 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2