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Old 21st July 2004, 01:12 PM   #1
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Default TubeDAC from Sheldon Stokes with PCM63

Hi Folks!

I built years ago the TubeDAC from Sheldon Stokes. It use two PCM63-K Burr Brown DAC and 6DJ8 at output stage.

What should do we it? Trash it , use components to build something else or tweak it to obtain something better?
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Old 21st July 2004, 02:26 PM   #2
VT67 is offline VT67  Belgium
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Hi Stef1777

I also have built Sheldon's Big Dac in the past and until today I like the sound verry much. As an experiment I replaced the SRPP output stage with a Mu-Stage (input tube 30 and top tube D3a) and this was a great improvement in soundstage and detail.
I would not scrap it, it's a good piece of equipment.

Happy listening

Walter
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Old 21st July 2004, 03:30 PM   #3
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Default Re: TubeDAC from Sheldon Stokes with PCM63

Quote:
Originally posted by stef1777
Hi Folks!

I built years ago the TubeDAC from Sheldon Stokes. It use two PCM63-K Burr Brown DAC and 6DJ8 at output stage.

What should do we it? Trash it , use components to build something else or tweak it to obtain something better?
Hi

Don't trash

Sheldon's design is OK, to my opinion it deserves attention at jitter, look at

http://httpd.chello.nl/%7em.heijlige...tml/dactop.htm

or

http://www.tentlabs.com/Products/DAC...ACUpgrade.html

best regards
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Old 21st July 2004, 05:14 PM   #4
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Smile Re: TubeDAC from Sheldon Stokes with PCM63

Quote:
Originally posted by stef1777
Hi Folks!

I built years ago the TubeDAC from Sheldon Stokes. It use two PCM63-K Burr Brown DAC and 6DJ8 at output stage.

What should do we it? Trash it , use components to build something else or tweak it to obtain something better?
Hi Steff,
You can improve the digital inputreceiver by placing an AD8561 in front of it. And using the Wildmonkeysects loopfilter for the PLL of the CS8412. Also using a low noise analog supply for the PLL. You can also install my Asynchronous Reclocker. Schematic available on request. And last but not least you can modify the DAC to NON-OS. This will require a 74HC164 to get a normal sound output.
The combined effect of these measures will amaze you!
Though I prefer the TDA1543, the PCM63 is a good DAC similar in sound to the AD1865.
Cordialement,
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Old 21st July 2004, 05:24 PM   #5
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Default Tent VCXO jitter specs ?

Guido,
"3ps rms, 3-sigma."
What does your spec actually mean? Isn't rms a 1 sigma number?

Thanks,
Richard
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Old 21st July 2004, 05:57 PM   #6
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Default Re: Tent VCXO jitter specs ?

Quote:
Originally posted by rlim
Guido,
"3ps rms, 3-sigma."
What does your spec actually mean? Isn't rms a 1 sigma number?

Thanks,
Richard

No

sigma relates to distribution of Gausian ditributed phenomena, like noise

rms refers to a "weighting method" method in order to retrieve the enrgy from a random signal

cheers
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Old 21st July 2004, 07:12 PM   #7
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Smile See also....

Hi Steff,
See also:
http://db.audioasylum.com/cgi/m.mpl?...te&r=&session=
Salutations,
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Old 21st July 2004, 07:52 PM   #8
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Default Re: Re: Tent VCXO jitter specs ?

Quote:
Originally posted by Guido Tent



No

sigma relates to distribution of Gausian ditributed phenomena, like noise

rms refers to a "weighting method" method in order to retrieve the enrgy from a random signal

cheers

Please look up this pdf document and let me know what you think. Unless the pletronics is wrong in their analysis, 1 sigma without deterministic jitter sure sounds like an rms number to me.
http://www.pletronics.com/pdf/Determine%20PK.pdf

Perhaps you can let us know how you did the jitter measurement. That will clarify a lot of my confusion.

Thanks,
Richard
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Old 22nd July 2004, 03:52 PM   #9
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Thanks for all answers.

I can see that I'll have a lot to tweak when my VRDS10 and DEQ2496 will be finished....
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Old 23rd July 2004, 09:16 AM   #10
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Default Re: Re: Re: Tent VCXO jitter specs ?

Quote:
Originally posted by rlim



Please look up this pdf document and let me know what you think. Unless the pletronics is wrong in their analysis, 1 sigma without deterministic jitter sure sounds like an rms number to me.
http://www.pletronics.com/pdf/Determine%20PK.pdf

Perhaps you can let us know how you did the jitter measurement. That will clarify a lot of my confusion.

Thanks,
Richard

Hi Richard

I now see your point
it should be 1 sigma, I'll dig up the typo at the website

thanks
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