ACG VRDS T-1 reclock - is it still worthwhile?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Disabled Account
Joined 2005
A while ago I stumbled across a series of documents posted on the Audio Crafters Guild website describing a re-clocking circuit the Digital Output One and it's implementation in the VRDS 7 and T-1.

http://www.audiocraftersguild.com/AandE/DOO1.1b.pdf
http://www.audiocraftersguild.com/AandE/doo11rev1.pdf
http://www.audiocraftersguild.com/AandE/teac-doo.pdf

I've been interested in building one, but as time passes that becomes a more and more difficult task. The key chip MC10216P for instance is now EOL'd but can probably still be be sourced.

I'm wondering if it is still worth the effort of sourcing the "hard to find" parts or has the design been rendered sufficiently obsolete by more recent developments not to be worth the effort?

cheers
Paul
 
spzzzzkt said:
A while ago I stumbled across a series of documents posted on the Audio Crafters Guild website describing a re-clocking circuit the Digital Output One and it's implementation in the VRDS 7 and T-1.

http://www.audiocraftersguild.com/AandE/DOO1.1b.pdf
http://www.audiocraftersguild.com/AandE/doo11rev1.pdf
http://www.audiocraftersguild.com/AandE/teac-doo.pdf

I've been interested in building one, but as time passes that becomes a more and more difficult task. The key chip MC10216P for instance is now EOL'd but can probably still be be sourced.

I'm wondering if it is still worth the effort of sourcing the "hard to find" parts or has the design been rendered sufficiently obsolete by more recent developments not to be worth the effort?

cheers
Paul

Hi Paul

There are more clocks, commercially available, some of them even include SPDIF reclocking.

best
 
Disabled Account
Joined 2005
Hi Guido,

thanks for the response. I'm aware of the plethora of commercial clocking kits, and some - like the tentlabs XO clocks - do look very tasty indeed. :D

I'm attracted to the ground-up diy aspect of the DOO, which does have a reclocked S/PDIF, and I think I can source the majority of parts still.

Some minor hurdles are a MOQ of 3 pieces imposed by Scientific Conversion on the S/PDIF-interface transformer, and difficulty in sourcing some of the improved components, notably the CY74FCT2244CTPC (or substitute) mentioned in the Rev1 document.

Out of interest, what level of improvement would an xo3 offer over the DOO in terms of jitter reduction?


cheers
Paul
 
XO3 setups follow questions

Guido,

what I am missing regarding XO3:

- how do you deal with sync of the SPDIF signal and the masterclock (see http://www.audiocraftersguild.com/AandE/teac-doo.pdf where you see a clear description how the sync must be checked and applied). May this depends also on the just master clock freq. while higher clock rates would give you a smaler latch window.

- the master clock signal output level (spec's) given to the related CD drive circuit.

HpW
 
Re: XO3 setups follow questions

HpW said:
Guido,

what I am missing regarding XO3:

- how do you deal with sync of the SPDIF signal and the masterclock (see http://www.audiocraftersguild.com/AandE/teac-doo.pdf where you see a clear description how the sync must be checked and applied). May this depends also on the just master clock freq. while higher clock rates would give you a smaler latch window.

- the master clock signal output level (spec's) given to the related CD drive circuit.

HpW


Hi

XO3 feeds the CDplayer and the SPDIF generated is in synch with the players master clock. The timing on the XO3 very seldomly goes wrong (I have solved such problems with 3 customers only)

The XO boards put out 5V, HCMOS compaible signals.

best
 
really no checks?

>> The timing on the XO3 very seldomly goes wrong (I have solved such problems with 3 customers only)

Really no checks!

See in the teac-doo.pdf file how close the edges are!


> The XO boards put out 5V, HCMOS compaible signals.

Hopfully there will be no signal overshout's given to the sensitive xtal input caused by the masterclock line!


All for this, a high speed scope and a low cap. prope should be used what is usal not avaiable...


Cheers

HpW
 
Re: really no checks?

HpW said:
>> The timing on the XO3 very seldomly goes wrong (I have solved such problems with 3 customers only)

Really no checks!

See in the teac-doo.pdf file how close the edges are!


> The XO boards put out 5V, HCMOS compaible signals.

Hopfully there will be no signal overshout's given to the sensitive xtal input caused by the masterclock line!


All for this, a high speed scope and a low cap. prope should be used what is usal not avaiable...


Cheers

HpW


like I said, no significant timing problems for my boards. Overshoot isn't a real problem either, I use series termination, and th bit of overshoot (say 10%) won't excite the internal clamping diodes (as these are on silicon, they start conducting at say 1V)

98% of my customers have no scope at all but working applications.......

best

Guido
 
Disabled Account
Joined 2005
Ok, seeing I got no negative (or positive for that matter) feedback on the DOO, I'm going to push on and build one.

I've managed to source a few MC10216P and 74FCT244P - the 74FCT2244 seems to be unobtanium in thru hole. MOQ's on the amidon multibeads and scientific conversions parts mean that I'll end up with "rare" parts for 3or4 x DOO.

Over the break I'm going to take a look at re-doing the layout of the boards to incorporate changes described in the DOO11rev1 document, and will get a few boards done early next year.

If anyone is interested in a set of "rare" parts and a board let me know ;)

cheers
Paul
 
Disabled Account
Joined 2005
Hi Guido,

I haven't seen any figures either, so I guess it's a case of building and listening/find someone with the gear to measure. I'll make allowance on the pcb to replace the ECL oscillator with an XO module. I seem to be accumulating enough parts to build a couple of these modules, so it could be an interesting exercise.

cheers
Paul
 
Disabled Account
Joined 2005
Rather than redo the artwork from scratch I've used Illustrator to alter the artwork in the DOO1.1b.pdf to reflect the changes discussed in the other two pdfs referenced above.

The changes described in teac-doo.pdf are:

Then I cut off some traces on the pcb so only one of the eight buffers where left
driving the S/PDIF interface transformer. This should improve the noise level further and also improve jitter performance as eight buffers will not turn on and off at the very same instant, se also [2]. Here is how I did it: Pin 9 on flip-flop U3 shall only be connected to the buffer input on pin 8. So I cut of the pcb trace leading to the other inputs (pin 2, 4, 6, 11, 13, 15, 17) and connected them to ground at resistor R23 with a piece of lead cut off. Resistor R22 shall only be connected to the buffer output on pin 12 of U4. So I removed the pcb-trace connecting pin 3, 5, 7, 9, 14, 16 and 18 with pin 12.

Hopefully the changes I've made to the layout reflect this ;)

cheers
Paul
 

Attachments

  • doo1.1rev1pcb.png
    doo1.1rev1pcb.png
    49.1 KB · Views: 111
Disabled Account
Joined 2005
I have managed to organize the last of the parts for the DOO, so it looks like I'm on track to build a nice "vintage" reclocker :D

I'm sure there are better devices out there, but at least the theory behind DOO is well documented and I'm definitely learning more than blindly following how to instructions or undocumented schematics.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.