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Flea for ESS9038 dac clock

T

timH

pfm Member
So I’ve added ALWSRs everywhere I can with this board (+ and - 15v for the opamp, separate 3.3v’s for AVCC-L and AVCC-R and DVDD)
Next step Is a clock upgrade. DIYAudio recommend a CRYSTEK CCHD-575-100-50 which is fitted to the board directly but this involves scraping away the ground plane and just spells danger to me. So I have a flea fitted in an unused CD player which I can use. I can get 3.3v by replacing the LED with two zeners. Pin out of the CRYSTEK is the same as the Tentlabs XO plus it’s a smaller footprint so definitely possible.
My question is should I keep the ferrite beads on the flea which are recommended by Tentlabs?
 
Yes, keep the ferrite.

You'll get better performance from the flea by running it at unity gain with a higher voltage reference - use two red LEDs in series as the reference, then replace R6 with a wire link, remove R7 and C6. Long ago I noted it works better also with lower series impedance in the filters, so reduce R1, R3 to 1K or 2.2K say and use larger filter caps - 10-100uF electrolytic will fit (it'd be convenient to re-use C6 for C3 position, minding polarity - the tant needs to be -ve term to the ground plane)
 
Well I’ve done the twin red LED and R6,7 mods and boy do those leds shine bright. But I’m getting 3.7v out and the CRYSTEK clock I’m thinking of using needs 3.3v +- 0.3v input. It’s quite expensive so I don’t really want to risk it at 3.7v. I’m thinking of a 3.3v zener?
 
You can easily divide-down the reference voltage.

Just add a resistor across the filter cap c3: to get 3.3v from 3.7 you need this to be 9x (or nearest lower value) of the value of the resistor you’ve used in the reference filter.

Eg if your filter resistor is 2K2, adding 18k across c3 will set the output voltage at (18/(18+2.2) ) x 3.7 = 3.30v

:)
 
I haven’t modded the filters yet so they still have 10k fitted. So I’ve fitted 100k across C3 and I’m getting 3.36v out. :)
Next step is to do the filter mod so I’ll choose resistors to suit
Thanks again Martin
 
Still waiting for the clock. In the meantime I’m playing with a Raspberry Pi and an AK4493 HAT with Moode audio :)
 
I have a pair of crysteks in my battery powered pi dac stack. A decent upgrade from the stock clocks. Let us know how you get on with them.
 
Finally got round to this. The Flea is modded to 3.3v as Martin suggested. I checked it before fitting into the dac and whilst there was 3.3v into the clock it only measured 1.5v out. I had no idea if this was a problem so I decided to connect it up anyway :D Bugger me it worked! And cleaned up the sound all round. Well worth doing.
Here’s a pic
F9-F39302-B173-456-C-8-FA1-B95310-B30-B1-B.jpg
 
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