Modding the DirectStream DAC MKI

Audio Components DACs
5169

Thanks sincerely, Elk, but it’s still a total needle in a haystack for a guy like me. While not doing the work myself, I plan to have a tight plan for my modder and parts purchased. Several things were being done by several users at the same time, so it’s hard for those reasons. It’s so stale now, it’s a pain for people to revisit, and they don’t need to order parts, like I might.

Thanks, @jazznut. Perhaps folks like me bought up all those mouser parts, leaving me with unobtainium until May/June.

5170

I fully understand.

1 Like
5171

I did the same to distribute the heat across all 4 heatsinks.
The heat sinks here are thermally coupled and electrically insulated.
(However, after removing the Bridge-card this was in my case no longer necessary)

image
image589×556 33.9 KB

2 Likes
5172

Ok now I understand, JK‘s idea was to bridge, not so much to enlarge surface.

With Bridge installed, bridging has to be different.

5173

No sorry i was not clear.
In my case, I wanted to distribute the heat across all the heat sinks.
So by making the coupling I create a larger cooling surface.

(by bridge i meant the Bridge card that i no longer use)

5174

Is VOCM mod surface mounting?

Ugh…if so, my modder said he’s out.

5175

No, not necessarily SMD. On my first attempt I used Nichicon Muse Caps (UES1A470MEM1TD). These use the solder joints from R6 and can be installed without issues. Don‘t know if there are differences in SQ between the different cap types.

image
image2433×2547 944 KB

2 Likes
5176

Thanks for that, I’ve ordered a couple different caps, with a few to spare in the event that others here need them later.

About to get in on the final order with @jkrichards for my mk1! Thanks a ton gents.

5177

It’s better and faster to use SMD.
close

2 Likes
5178

My buddy’s worried about the SMD work, but he’s got good skills. Anything worth mentioning/having for this specific board work, that would make his life easier? I know from the first set of mods on these boards, that higher than normal temps were used. I’ll buy him a new tool or whatever to make his life easier.

1 Like
5179

Do you recommend changing out R5&6 or just the cap on R6 best when using your transformers?

5180

After all that was discussed here and what seems necessary to consider, I would not recommend letting someone do the work who’s not used to SMD soldering on such multilayer boards and who doesn’t exactly know himself what to consider.

1 Like
5181

Only R6 is required by @jkrichards for the new transformers, and they are piggybacking the existing SMD.

5182

Just want to clear this statement up. Cap over all R6 is the VOCM mod and will work with any transformer.

5183

Wouldn’t APS transformers fail without the VOCM mod? I might have that wrong.

5184

Maybe some misunderstanding happens now:

My knowledge so far…

If resistors are changed (which makes sense according to the discussions so far, although JK didn’t hear too much difference), then both, R5 and R6. Cap is only necessary over R6.

In case the new APS transformer changes anything of this, JK can clarify.

5185

Thank you,
That’s all I have ordered and will install this weekend.
Just wanted clarity since there were so many variations mentioned.
Cheers,
Gregory

1 Like
5186

Nah, they’re completely independent but high-impact mods.

The VOCM mod reduces noise/distortion on the input to the transformer.
The replacement transformer is simply of higher quality than the factory one.

1 Like
5187

VOCM mod has nothing to do with transformers. However both make a big difference in sound quality.

1 Like
5188

Actually the VOCM mod fixes an issue with the common mode power supplied to the opamps. It lowers the impedance as the opamps used were changed from the original which would have been fine in this circuit.

Was originally designed for AD8139 however an AD8132 was used.

1 Like