Synchronous Reclocking Idea - diyAudio
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 11th March 2006, 03:49 AM   #1
Nerull is offline Nerull  United States
diyAudio Member
 
Join Date: Oct 2005
Exclamation Synchronous Reclocking Idea

Alrighty. I have an idea about synchronous reclocking my DAC. Firstly, I use an AD1896 to asynchronously reclock (24.576 MHz) and feed that to a 74HC74 flip-flop for reclocking the s/pdif line in my cd player. Is it feasible if I connect the two using a coaxial cable (to prevent interference) or is that not a sound plan? If so, how would I go about doing so (making the two synchronous)?

Thanks!

~Tom
  Reply With Quote
Old 11th March 2006, 06:08 AM   #2
A 8 is offline A 8  Sweden
diyAudio Member
 
Join Date: Mar 2003
Location: Gothenburg


Perhaps you want to read that again and then think about how you can change it so that the lesser gifted of us can understand what it is you're trying to get to.
  Reply With Quote
Old 11th March 2006, 06:38 AM   #3
Garbz is offline Garbz  Australia
diyAudio Member
 
Join Date: Dec 2003
Location: Brisbane
Send a message via ICQ to Garbz Send a message via MSN to Garbz
The CDplayer's S/PDIF is being reclocked via a D-Type Flipflop circuit directly from the master clock and then fed directly to the back to reduce it's jitter.

The CDplayer's internal clock is sent to a separate jack on the back of the player.

Both S/PDIF and clock are then fed into the DAC. The S/PDIF to the receiver, the clock to the AD1896 to be resampled to the systemclock required by the DAC. Thus bypassing all the jitter induced in clock recovery.

http://www.tnt-audio.com/clinica/diginterf2_e.html Normal configuration + Clock circuit.
  Reply With Quote
Old 11th March 2006, 02:57 PM   #4
diyAudio Member
 
Join Date: Dec 2005
Location: Rostov-on-Don
Yet another way to do it (and a better one, I admit) is to have a clock generator in a DAC module (somehere closer to reclock). Then you fed clock (through RS485 line or something speedy and balanced) into CD player.

In a pro audio equipment there is yet another modification of this technique. You can adapt both of yours DAC and CD transport to be a "master"-"slave" pair.
DAC is acting like a master device, providing clock for transport unit, as a CD transport (slave) has no internal generator.
Use two spdif lines - one from DAC to CD - clock one, and CD->DAC - data one.
Advantage of the "pro" technique - you can use pro- equipment with any of your transport or DAC. Yet another advantage - you may use any kind of frequency dividers/multipliers on the CD side because of good syncronous reclock on the DAC side.

I'm planning to use such way to connect external 24bit/96kHz DAC/ADC module to my Envy sound card. The only difference there will be no spdif - balanced ECL lines rulez forever.

PS: 74hc stuff sucks. Better use 74abt574 instead of 74hc74.
  Reply With Quote
Old 11th March 2006, 02:57 PM   #5
Nerull is offline Nerull  United States
diyAudio Member
 
Join Date: Oct 2005
Sorry! Garbz is correct. Must not have been thinking last night...
  Reply With Quote
Old 11th March 2006, 03:43 PM   #6
diyAudio Member
 
Join Date: Oct 2001
Location: .
Quote:
Originally posted by igdrassil

In a pro audio equipment there is yet another modification of this technique. You can adapt both of yours DAC and CD transport to be a "master"-"slave" pair.
DAC is acting like a master device, providing clock for transport unit, as a CD transport (slave) has no internal generator.
Use two spdif lines - one from DAC to CD - clock one, and CD->DAC - data one.
Advantage of the "pro" technique - you can use pro- equipment with any of your transport or DAC. Yet another advantage - you may use any kind of frequency dividers/multipliers on the CD side because of good syncronous reclock on the DAC side.

That is not quite correct. In the pro arena everything is slaved to a Sync Pulse Generator like the Isochrone OCX or Tektronix SPG600
  Reply With Quote
Old 11th March 2006, 05:43 PM   #7
A 8 is offline A 8  Sweden
diyAudio Member
 
Join Date: Mar 2003
Location: Gothenburg
  Reply With Quote
Old 11th March 2006, 08:35 PM   #8
diyAudio Member
 
Join Date: Oct 2001
Location: .
  Reply With Quote
Old 11th March 2006, 10:49 PM   #9
Garbz is offline Garbz  Australia
diyAudio Member
 
Join Date: Dec 2003
Location: Brisbane
Send a message via ICQ to Garbz Send a message via MSN to Garbz
A 8 Incase you're lost we're talking about how to interconnect digital equipment without any loss of jitter. In consumer equipment this presents a great problem. In pro equipment there is a separate and dedicated clock external to all devices which everything else is synched to.

igdrassil your technique is the same as Nerull's only that the DAC is acting as the master instead of the CD. As long as the clock line is carefully transmitted it wouldn't make much of a difference to jitter characteristics would it? Afterall as mentioned by rfbrw in pro gear the clock is external to everything.

Also can you elaborate why the 74HC series does not make for a good reclocking device? Is it propegation delay or what? I know one is CMOS the otherone BiCMOS but what does this mean to the S/PDIF line?
  Reply With Quote
Old 12th March 2006, 07:07 AM   #10
diyAudio Member
 
Join Date: Dec 2005
Location: Rostov-on-Don
External clocks are used in a studios.
I mentioned pro- (or prosumer if you like) devices as an example. They can be used as a master-slave pair. Or they both can be externally synched with clock clock generators.
Anyway, you can modify your digital source for a "slave" job adding spdif reciever and some clock dividing circuitry (to convert mck from spdif to a frequency you need in a CD player).
Also it is indeed better to place clock in a DAC module, near to reclock. In that case jitter of a cd->dac (data) and dac->cd (clock) lines are no matter to discuss.
When clock is on the CD side, jitter of the clock line became sufficient.
  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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Decoder output: how jittery, worth reclocking? And "double" reclocking hollowman Digital Source 0 17th July 2009 01:39 PM
Duelund synchronous crossover angel Multi-Way 7 8th November 2008 12:02 PM
synchronous buck converter SwedishWings Power Supplies 5 24th April 2008 07:00 PM
How to implement synchronous clocking regal Digital Source 2 20th August 2006 02:57 AM
AC PSU for synchronous motor jo-briggs Analogue Source 11 22nd May 2005 06:08 AM


New To Site? Need Help?

All times are GMT. The time now is 02:19 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