Modding the DirectStream DAC MKI

What cap value do you use with the Lundahls? Was it 6800?

Yes

The Directstream is a fascinating and original design. However, it seems from reading these pages that the bottleneck of performance is always going to be the output transformer.
I was wondering, if we were willing to give up a balanced output and just use RCA, could we not replace the transformer with a coil, having the same inductance as the transformer for filtering? Perhaps I have overlooked something (is it filtering some DC?) but I would be keen to hear your thoughts.

It was mentioned on the forum that Ted has not been 100 percent healthy in the near past.

Thanks yes, I read that remark, but I understood that was already quite a while ago and he’s well again since some time…let’s hope so!

The transformer does a number of good things: it’s part of the low-pass filter for raw DSD, it makes differential output easy, it has comfortably low output impedance, and it eliminates any DC offset issues.

I think it’s pretty clear that the cost of the transformer is the bottleneck. Ted’s original proof of concept DAC was built around an ideal transformer that was way too pricey for high-volume productisation by PSA. The DS DAC had to make do with something off-the-shelf at a much lower cost.

I’m not aware of anybody who upgraded to one of the aftermarket transformers specifically designed for the DS and didn’t find it a dramatic improvement.

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You did a great job on the analog board!
Now, you hear more of everything… including more noise from the digital part.
Now, you owe it to yourself to improve the digital.

I have just replaced the diodes for Schottky ones, and WOW! This dramatically improved micro-dynamics! I’m amazed how clean the background and the quietest ambient sounds are there so effortlessly!
Everything became way more focused and holographic! Last time I heard this kind of improvement when swapped [Edcor 4400 without Vocm mod] for [APS with Vocm mod].

Which diodes?

Diodes VSSB410S

Hmm, seems easy enough. You used VSSB410S?

What was the amp rating for the diodes you used?
Do you have a link to the ones you used. Interested in replacing them as well.

https://www.mouser.com/ProductDetail/Vishay-General-Semiconductor/VSSB410S-E3-52T?qs=HSPD0Bff7ib64J9oD9YilA%3D%3D&gclid=CjwKCAiA3aeqBhBzEiwAxFiOBgkuJENOC8h13PDE6BkCoauY9ZDR_yoF_uBrPjn9y6zqkD1Ttqmg9BoC5WMQAvD_BwE

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If anyone wants to use Sparkos regulators in DirectStream DAC or on any other devices, it’s a good time to stock up on those!
They have a Black Friday - Cyber Monday sale

“Use coupon code BlackCyber30 to get 30% off damn near everything on our website.”

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Long-shot here. Is it possible that hobbyist or third party developers could create new Mk 1 firmware? There’s no replacing Ted, yet he has moved on.

Is Ted no longer with PS Audio?

I think point meant was PSA and Ted have moved on from reprogramming the MKI.

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My interpretation of the non-communicated situation is:

Nobody could ever imagine, how much and at which times Ted works and how he additionally communicated to an extent in the forum with us, that it could be a job alone. Such things have to be sorted some time.

He might have completely different reasons or other health topics, but that’s my assumption.

gents, please could you advice where can i order 4 rectifier diodes D1-D4 for DS MK1 original PSU board?
Their markings are FAE12 ES2D .
I had unpleasant accident with my old MK1 and would need to replace those to get it running again.
Although I could find few ES2D fast rectifiers on the net (without reference to FAE12), but would like to avoid fakes, or other less than ideal parts, thanks! :pray:

I just replaced mine with these as Anton suggested and it’s working great:

https://www.mouser.com/ProductDetail/Vishay-General-Semiconductor/VSSB410S-E3-52T?qs=HSPD0Bff7ib64J9oD9YilA%3D%3D&gclid=CjwKCAiA3aeqBhBzEiwAxFiOBgkuJENOC8h13PDE6BkCoauY9ZDR_yoF_uBrPjn9y6zqkD1Ttqmg9BoC5WMQAvD_BwE

I believe I still have the original ones, they are marked JH44
ES2D

If I do have them your more that welcome to them.

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thank you ! mine are FAE12 ES2D , I have quite old board (from kit) so possibly some older revision.
I’ll grab 'em on Mouser