Directstream Mk 2 observations

The ground tabs you are speaking of are the metallic strips that mount on the top cover not the tiny gold plated ones that have to be on target with the paintless spots on the back panel. I am unsure of the purpose of those are. I think they could avoid having to worry about the lining up of the small paintless circles if they just made a wide strip mask that ran across the back panel.

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The MK1 used copper tape with conductive adhesive on digital inputs. I know from replacing transformers. If your system can’t tell the difference be happy. The fear of resale value is for the anal retentive of us audiophiles. Your on the wrong website it you bought PSA for resale value. Shake u the loose parts and use the copper tape or if the tabs don’t bend enough to reach the masked grounding areas or fall out. Most likely sealing the gaps with copper foil will sound better than the tabs if you have lots of RF and EMI emissions

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sixpack, The guys at PS Audio had to do a minor redesign of the digital board to fix the problem with the tiny gold plated tabs that were falling off of the board. They did not have to fix a problem with the metal strips that mount on the top cover. I think they know which tabs were falling off the board and what the purpose of those tabs is…

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I never even thought about the cabinet grounding strips as having anything to do with the gold ground tabs. I just thought that masking tiny circular targets was the very cause of the tab issue, that and the interference of the i2s plastic locators. As far as I am concernd both are a very easy fix. Trim the plastic locator so it does not get into the way of the ground tab and mask the whole area of the back panel about 1/2 inch wide across the whole width than you have no small target to to aim for. Neither require any board redesign. I was told they were bending the tabs to line up with the paint free spots.

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John, It looks like PS Audio is trimming the the plastic on the HDMI sockets.

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someone said they got a new digital board when they send in too.

Brain, See the quote in my post above.

No, @tonyplachy is correct. This is the piece I’m referencing. Stealing pic from above…

image

The size and placement of these is VERY intentional. With such high frequencies, the closer it is to the input, the more effective it is.

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Oh, I would never have guessed that was the purpose of that tab. I am glad I got the contact locations cleared of paint. It may not have much impact of sound but will keep the noise down anyway. Thank you for explaining that.

Thanks for explaining James!
A follow up query: Are we talking about the same or different RF noise that’s been discussed over the JA review?

I believe he is speaking of noise radiated by the DAC not the noise floor.

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Yes, I can see that, but are they somewhat related or utterly unrelated? So much noise created within, isn’t solely and completely radiated without. At least remnants must remain visible/audible inside.
Is that too simple a logic?

I feel like these are things said after an exorcism.

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Never thought it would take that to improve the MK2, but why not?
No mountain high enough!

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Please feel free to add to this if you feel I have not gotten it right.

There are two kinds of noise when it comes to digital gear ( ADCs and DACs ).

There is real noise ( EMI and RFI are examples of real noise ) and there is renamed noise. Let’s talk about the real noise first. Things like DACs and ADCs create electromagnetic radiation due to the high switching rates ( caused high by sampling rates (01001101011 etc. ). This is referred to as EMI and RFI. This noise radiates from the source and can be carried by unshielded metal. Most governments have regulations about how much EMI/RFI can come from audio gear. Thus the need to make the case act like Faraday cage. This link maybe of interest: Faraday cage - Wikipedia.

Renamed noise is really quantization errors that may or may not have had dither added to them. Both the quantization process ( ADC ) and the reconstruction process ( DAC ) have quantization errors. Some people find it easier to refer to these errors as noise. Noise shaping can take the errors from the audible band to the ultrasonic band. Ted’s new Massive firmware moves the ultrasonic “noise” in the Mk2 DAC to above 100 kHz. If you really want to go crazy on this Ken Pohlman’s “Principles Of Digital Audio” has several chapters on noise shaping.

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Thanks for explaining the differences in where they stem from.
Could you please also elaborate on whether the EMI noise may trigger quantization errors (as I feel Ken Pohlman’s book won’t cover that), or not?
Then I can put this topic to rest with additional understanding (if only partly). :wink:

There was some discussion, including quite a bit of criticism, on this board earlier about Stereophile’s review of the Directstream Mk 2. One quirk of Stereophile is that you don’t know the grade (or class rating) a piece of equipment receives until the next Recommended Components issue comes out.

I got one such issue in the mail earlier this week. The highest class for digital processors is A+. The Directstream Mk2 was placed one step down in the A class.

Of course, their assessment was rendered obsolete by the latest firmware upgrade. IIRC, Stereophile revised the class rating of the Mk1 after listening to it again with new firmware. Maybe they can be persuaded to do the same with the Mk2.

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Sure some want to see their equipment (whatever they buy) on top, but there must be some room for the up to 300k$ DAC‘s, even if it’s just the „+“ :wink:

I think magazines already care enough for placing everything as high as possible for their readers…hard to get any valuable information anyway due to that.

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The Absolute Sound comes to mind as the most egregios offender in that regard. I consider hifi component reviews somewhere in the realm of a distraction or a minor entertainment.

agreed, might add valid, honest, ego-less