[time-nuts] disciplining sound card

[Bill Dailey]

Tips on this process if anyone wants to do this.  From the cards I have
there are 2 different types of oscillators/resonators... one is SMD with 4
pads and the other was a through hole crystal.  The right sided hole when
reading the label is the one you want..  With the SMD (most of the
oscillators that I have looked at of this caliber).  The upper right pad is
the RF out.  So... simply remove the oscillator, find a convenient ground
nearby (I used a nearby pad that I verified to be ground)  pre-tinned the
shield and center conductor and the hole/pads, applied a little liquid
flux.. touched both with the iron and done.  A little hot glue to hold
everything in place.. Bulkhead connector through a hole in the box (for ext
usb) or in a pci cover (for pci cards).

I searched and searched for a card that would take 10MHz and they aren't to
be found.  I didn't want to invest in a word clock that may have oddball
timing issues that I don't understand so I went this route.  It seems to
work very well and is a simple modification.  The only problem is the
24.576 MHz.... I have tried to find a board that was plug and play but the
frequency is not a nice one to play well with 10MHz.  There are numerous
ways to get 24.576 disciplined but since I am not an electronics guru it
appears the best for me is the valon synthesizer.  If someone wants to
build a better mousetrap.. I have a nice VCXO that is begging to be put in
a PLL and would probably give better phase noise performance.   I have
considered injection locking it with the synthesizer but can't get my head
around how to get that done.  To me that would provide the best of both
worlds although it may introduce some injection-locking phase noise nearby
the carrier (from what I have read).

I am getting incredible performance and have phase stable audio in spectrum
lab without any calibration which is what I was trying to achieve.  Also,
it seems to make the audio better when listening to music although I can't
verify this claim and don't want to start another audiophile thread.

-- 
Doc

Bill Dailey
KXØO