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Old 16th September 2006, 01:25 PM   #1
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Default X-RAY maybe a really stupid question.

hi all,

I'm looking at the circuit board for the Musical Fidelity x-Ray, version 1 not the v3, chosen because it looked mod friendly and even if not, its supposed to have very low jitter. Which (finally) brings me to my point.

The base player takes the digital info / power et al through a ribbon cable to a separate board for the D-A conversion ans analogue bits. First thing that happens to the digital info is it dissapears into a 74HC175 quad flip flop where its buffered before dissapearing into the BB pcm1716 DAC

question 1 - is that what s known by the digital wonderkind as reclocking?
question 2 - is that a valid method of doing it? (heck it could be the ONLY way of doing it how would I know!)
question 3 - why isnt it done more often if its a great idea? The man Michaelson doesnt seem to normally add in extra components for a laugh.

Apologies if this is really basic but i have no 'feel' for whats a good idea, and whats not, when it comes to digital cicuitry so ANY comments are useful.

cheers then

Andy
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Old 16th September 2006, 05:08 PM   #2
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1.Yes though outside audio it has been referred to as pipelining or registering. Unless it's a delay.
2.Yes but I suppose you could always use BC109's
3a)Have you seen a statistically significant number of schematics to make that a valid claim?
3b)A well thought out PCB can remove the need.
3c)The PCM1716 needs all the help it can get.
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Old 16th September 2006, 06:00 PM   #3
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Hi, thanks for the quick response, nice when you're struggling with a 'HUH?' moment

But regarding 3a

I take it you mean MF's 'value for money' approach? They do seem to shout about it. And yes I have quite a bit of their gear. Most of which gets nekkid if not tweaked.

I should point here out that over time I seem to have settled on MF's equipment, so maybe not the most objective point of view.

BUT For this application it seems (to the uneducated eye) like a neat way of getting the data to switch at the same time. Stick it in a flip flop and send it all to the dac at the same moment. At least thats what the 175's data sheet claims, but 16.9Mhz seems awfully quick

The reason for the query was, in this cd player you have the dac and audio on one board so its ideal for a complete replacement. i.e rip it out and start again. And that strikes me as a better optiion than a standalone DAC through SPDIF...

But i'm intrigued by this methodology. If the data were moving any distance OK, but the cable's maybe 7cm? I didn't think this would be a 'necessary' step, but for the cost of a flip-flop, are there any downsides? I'm reasonably willing to think that if the pro's though it was required then that should be the start of my board too.

anyway I've stuck a board picture to this post. - thats the whole d/a + analogue stage.

one more thing - off topic really, can anyone say what the connector is called? do these things have a name thats RS or farnell compatible?

cheers

Andy
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Old 17th September 2006, 10:16 AM   #4
zanash is offline zanash  United Kingdom
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can't see a pic ?


The Mf gear [all I've poked around in ] is built down to the cost of a fish supper. I find just by swapping the caps for say panna fc's etc you can greatly improve the performance even before you hack the curcuit to bits. Add a set of schottky's for rectification and these units begin to sing.
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Old 17th September 2006, 11:25 AM   #5
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Default Techcnology can be a beautiful thing

oops failed to attach it. Heres the pic.

BTW exactly my point about MF gear, easy to tune! I'd rather buy my own components. If they bunged in the expensive bits to begin with I'd never get the chance to buy 'em

...Yes those are Jamicon Caps and Philips NE5532's

Still looking for the conector too, 'Ribbon' and 'PCB' gets me quite the wrong thing

Andy
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Old 17th September 2006, 12:41 PM   #6
zanash is offline zanash  United Kingdom
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If you can take a pick of the psu area too .....!
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Old 17th September 2006, 12:42 PM   #7
zanash is offline zanash  United Kingdom
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do you mean the ribbon connector at the bottom right ?

is it the cable or thesocket your after ?
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Old 18th September 2006, 01:49 AM   #8
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The socket.

I'd like to remove this board and replace it with something else. (eventually) but if I cant get hold of the connector, I need to think about a plan B

I've checked the online version of farnell, RS, Rapid and Dgikey with no luck. I'm guessing / hoping that I'm using the wrong search string(s).
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Old 18th September 2006, 05:53 AM   #9
zanash is offline zanash  United Kingdom
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just desolder it and as a last resort hard wire the cable in
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Old 19th September 2006, 08:14 AM   #10
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desolder it!!

Sorry, not brave enough to risk a dead player. I've seen that movie...

although when I think about it, this is a pretty standard thing, I wonder if i have one somewhere else that can be de-soldered.

Not in a hurry to get the bits either so I've time to search, by the time I get to the point its required it'll be christmas

Cheers

Andy
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