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Discrete Low Jitter Clock GB

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#226
hi there

beautiful work - proper value for once instead of multi 100'ssss for a clock!!
i have a sony runs at 45mhz on the schmatic, if this is not possible i can source my own

i would like an ac kit if possible if not a pcb if you've still got any im in england

thanks
james
* possible third group buy going up - haha *
 
#228
Hi All,

I'm back from holiday, had a great time. I hope everyone else enjoyed the holiday break.

I still have plenty of PCBs, but there are no kits left. If you'd like some PCBs, please PM me how many and which country you live in, and I'll get back to you with a total cost.

@glowing vinyl: Some Sony players do use a 1024fs clock (45.1584MHz). The crystals for this value are harder to get, but there is the option of using the original if it's a standard HC49 crystal. What player are you modifying?

Anton
 
#230
That's a perfectly valid point. Many crystals over 30MHz are third overtone, but as far as I know most of the Sony players using a 1024fs clock use a fundamental mode oscillator. That's why I asked glowing vinyl which particular player he's working on. I've attached an example, from a Sony CDP-X5000, a fairly typical Sony XO working in fundamental mode.

For those out there who are wondering what third overtone is all about, it's a different operating mode. A crystal operated in third overtone will vibrate roughly (not exactly) three times faster than when it operates in its fundamental mode. Third overtone crystals are the same as fundamental ones, but are cut to vibrate at a particular frequency when operated in their third overtone mode, and marked with their third overtone frequency.
 

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  • Sony CDPX5000 XO.jpg
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#231
hi anton

thank you for the reply and thank you s3tup for the possibly very important point.😱

now i understand what the clock signal does but am just getting into dac and i/v operation - so please bear with me.

I have a sony xb 740 which seems close to xb 940 in the schematics/service manuals - i can provide these to you if you want. (940 has much more complicated audio path after dac out but otherwise are very much the same). the player has two chips one on the transport/drive and one on the processing board they both seem to use the crystal pictured in 1 & 2. I have just found a second crystal but this on the display driver board and does not have individual part number - i don't think this is important to audio.(pic 3)

i have attached snapshots of the dac and crystal listing in the manual - pic 1 &2 also pic 4 is camera shot of crystal in player.

P.S.
i am thinking of replacing the output section with a valve preamp and am starting to learn about dac current output + filtering + I/V conversion - but does anyone understand why this dac has 4 outputs per channel, i understand they give out balanced signals - this is very good and i intend to take advantage of this - but why pair the outputs ??

thanks for anyones time and input 😀😀
james

View attachment xb740 dac.pdfView attachment xb740 crystal.pdfView attachment display driver.pdfIMAG0128.jpg
 
#232
I've had a look a the CDP-XB740, and it seems to use a fundamental mode 45.1584MHz crystal. It should be possible to take that crystal out of the player and install it into this clock, but I can't make any guarantees that it would work, I've not tested the clock at anything over 33.8688MHz. What test gear do you have? I wouldn't try this without an oscilloscope.
 

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#233
Hi Anton

One question about crystal parts, I've noticed you prefer HC49 from Citizen.
Have you tried other good supplier ?
Second question concerns crystal pads. I've seen you use it in your built.
Using them is usefull to avoid crystal desoldering operation.
Where do you get that part, BTW which ref ?
Regards

Phil
 
#235
hi anton

thanks alot for the reply.
i have not got an oscilloscope at the moment and have not got the funds for a proper one but... i have found small handheld ones on ebay - link below - will these do the job or is it just hong kong/chinese nastiness. i can solder/desolder quite well but have never needed to test at a level more than a multimeter.
Is the problem it may not work at all or is there harmonics/unstable signal problems that i do not know about/jet understand ?

thanks for being supportive

P.S. in regards to the question regarding the dac outputs is there anybody on this forum that you can suggest that i might talk to? (if you don't know yourself i do realise it's off topic in this thread)


ARM DSO Nano - Pocket-Sized Digital Oscilloscope New | eBay
 
#236
@korben69: It's more about just finding a reputable manufacturer from who I can get of the shelf crystals in CD player frequencies. I've not compared crystals from other manufacturers.

I used this as a crystal socket. It worked well, while it probably adds some inductance I didn't experience anything adverse while using it.

@andrea_mori: Where did you find information that showed the CSA309 type to be better the the HC49?

@glowing vinyl: If I were pushing the limits of the clock, I'd want to have an oscilloscope. If you plug in the used 45.1584MHz crystal and it works, then great, but if it doesn't you'll be completely lost without a 'scope.

The portable version you linked to won't be useful for this application, it's far too slow. You're going to be looking at a 45MHz signal, so you're going to need something with quite a bit more bandwidth than that. Ideally 200MHz, 100MHz minimum. For cheap, you'd probably be better off with a used analog 'scope, something like this one (though I only had a quick look, you'll need to do your due diligence before you buy).

The output stage questions are a bit off topic here. Start a new thread in the Digital Source forum, you'll get better advice there.
 
#239
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