[art]

Here's some more stuff to chew on. I know there are lots of guys modding these things and making money at it. I hope that they already tried these ideas but in case they haven't:

You are free to use these ideas, just as long as you are honest in admitting "Yeah.....I wish I had thought of that first. I didn't. Some goober from Texas on some forum gave me the idea."

You won't have to say "Thanks", but it would be nice.

OK.......first problem........

I shouldn't be hard on the guys who designed this thing. They had to shove a lot of stuff into a small space, and not break the bank in the process. But, we don't have those constraints.

First to go/get corrected:

The oscillators. Two in the same chip. Yuk. Two in the same chip, running at the same time! Double yuk.

OK, easy to fix, just takes space.

Build a separate oscillator for 44.1 and 48 kHz operation. Disable the one that is not being used. (Or better yet.......if you aren't going need it, don't build it!) Run it on it own low-noise power supply. Not the noisy switcher inside the unit. In order for an oscillator to be low noise (and therefore, low jitter), it has to be supplied from a very quiet supply. That does not mean a 3-terminal regulator. You can find schematics for oscillator supplies on most any DIY site.

And make sure that you don't have both on at the same time!!!!!!!!!!!

If you do this mod, you will obviously have to take on the crystal and the cap on either side of it to ground. Just stick the quiet oscillator signal into the right input pin on the gate where it was originally.

Or better yet.........assuming the 44.1 kHz works the same as the 48 kHz. (It might, but hard to see, and I am not about to unsolder the chip to find out.)

The 48 kHz uses pins #1 & 2 for the oscillator. Pin #2 goes to #3, to form a buffer. More stuff gong on inside of a chip....the more jitter you get. Ground pin #1, cut the trace from pin $4, and put the clock signal to the far end of the cut trace. Less jitter, better sound that way.

All for now.............

Pat

[Rob F]

Thanks for the suggestion Pat, there isn't a lot of room in these boxes however. One of the Tent Lab's oscillators may fit though. The difficulty may be more in fitting a regulated supply to feed the oscillator.

Rgds,
Rob.

[art]

You could build a small enclosure to mount outside of it. Yeah, may not win awards on looks, but.......

You could run the Tent XO on +5 V. If you have a really clean +5 V supply, think about what else you can do:

Use 2 complementary gates, instead of 1, to drive the output. Now you have 6 dB more signal to play with. That will allow you to further isolate the transformer from the line, and keep the impedance closer to 75 ohms resistive.

Use the Tent XO to reclock the SPDIF signal coming into the output driver.

OK, you would have to make a pad to lower the XO to the Squeeze-thingie. Unless the FPGA is +5 V compliant. You may have to do some level shifting or such to make the +5 V gates work properly with a 3.3 V drive.

You get the idea, though. I think.

Pat