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

[spzzzzkt]

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

[Guido Tent]

Originally posted by spzzzzkt
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

[spzzzzkt]

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.

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

[HpW]

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

[Guido Tent]

Originally posted by HpW
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

[HpW]

>> 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

[Guido Tent]

Originally posted by HpW
>> 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

[spzzzzkt]

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

[Guido Tent]

Originally posted by spzzzzkt
Hi Guido,

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


cheers
Paul

I have no clue as there are no measured results on the DOO

best

[spzzzzkt]

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