Modding the DirectStream DAC MKI

Polyglot said

Indeed it would. One can argue to put something like an iFi iTube but considering the cost of good interconnects and the fuzziness of another add on (I already have the must-have-Regen hanging out on the back), I would gladly pay a grand more (retail) for a version with tube buffer.

Something like a built-in tube pre-amp (aka ModWright Logitech Transporter mod)? The power supply must be completely redesigned in this case. The closest would be that new PSAudio tube pre-amp, but definitely more expensive than one grand. Plus interconnects, etc.

Personally I have the sneaking suspicion that installing one of the old VSE Level 6 modules inside of a DS to bypass the output transformer would be a significant sonic improvement. But unfortunately I canā€™t try this mod without voiding my warranty. Were it not for this fact, I would have scrapped my old dead VSE modified Sony SACD player to salvage my VSE Level 6 modules long ago.

Iā€™d be happy to let Ted try this out on a prototype unit if he was willing. But he has shown no interest to date when I have offered. So this idea is going nowhere until my warranty finally runs out.

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Where is your sense of adventure?

I generally only work on gear after the warranty has expired. This is especially true when something is really expensive, and I have concerns about potentially bricking it with future firmware updates.

TarnishedEars said Personally I have the sneaking suspicion that installing one of the old VSE Level 6 modules inside of a DS to bypass the output transformer would be a significant sonic improvement. But unfortunately I can't try this mod without voiding my warranty. Were it not for this fact, I would have scrapped my old dead VSE modified Sony SACD player to salvage my VSE Level 6 modules long ago.

Iā€™d be happy to let Ted try this out on a prototype unit if he was willing. But he has shown no interest to date when I have offered. So this idea is going nowhere until my warranty finally runs out.


Just for what itā€™s worth. Weā€™re fairly lenient about this. If you perform some work that does not damage the DAC and something else in the DAC fails, weā€™ll still cover it. You just have to use a bit of common sense with this liberal policy. For example, someone covered the inside of a DAC with some sort of Audiophile goo and sticky crap and then sent it back for warranty. The goo and sticky stuff didnā€™t harm the DAC but made it impossible to work on and we refused to do so.

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TarnishedEars said I generally only work on gear after the warranty has expired.
I live much more dangerously. I had parts waiting in my garage with which to mod my Z06 even before it was delivered. If the item needs a mod, it gets it. I however do not do the work unless I know what I am doing.
Paul McGowan said We're fairly lenient about this. If you perform some work that does not damage the DAC and something else in the DAC fails, we'll still cover it.
Very kind and fair.
. . . someone covered the inside of a DAC with some sort of Audiophile goo and sticky crap and then sent it back for warranty.
I have not heard of potting an entire piece of equipment. Ugh.

It wasnā€™t exactly potted. I think it was some sort of EMI covering - silver paper glued to components. Maybe this ERS stuff?

The poor fellow had purchased the DAC used and hadnā€™t any clue as to what had been done other than being told it had been ā€œtricked outā€. When something went amiss he innocently sent it in for repair and we freaked out. I felt bad having to charge him for the repair but we couldnā€™t fix anything on the board and had to replace it instead.

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Poor guy.

Iā€™ve been using USB since I got the DS DAC. Recently, I added the Audiobyte Hydra Z usb to sp/dif bridge with impressive results, and will likely stay with this combination. Iā€™ll post some notes on this in due course.

My understanding is all of the inputs on the DS DSAC are simultaneously active, and I take it the USB processor is spinning away even when it is not being used. Questions:

Is this a source of high frequency noise/jitter in the sensitive input area of the DS DAC?

Is there a way to easily disable the USB input e.g. cut the power or the clock to the USB processor?

Concerns over warranty etc. understood.

Thanks

Lonan

1234 said . . . there are servers but be careful some do not do well with the ds

my Krell connect is one for sure although itā€™s not USB.

I have a connect and it is in no way a server..it is a renderer that functions quite well with lower quality recordings. The ds has trouble with anything less than 128kbs if you go below 64kbs it plays mainly noise...I am not sure if you have a DAC equipped Connect or digital only but either way you can the Connect and its GUI to search and play all your music and pass the digital to the DS via coax or optical and it will stream even dsf via those but for reason Krell Never activated the dsf in its Sabre ess dac that is in the connect which would have been a nice addition

Wow, that is one very unexpected warranty policy! I may just have to crack the lid on this unit after allā€¦

lonan said My understanding is all of the inputs on the DS DSAC are simultaneously active, and I take it the USB processor is spinning away even when it is not being used. Questions:

Is this a source of high frequency noise/jitter in the sensitive input area of the DS DAC?

Is there a way to easily disable the USB input e.g. cut the power or the clock to the USB processor?


Most of the noise from the USB input comes in on the USB cable. The FPGA does the same thing with itā€™s USB input whether the USB chip is running or not. The USB subsection runs on itā€™s own power so if the USB parts make noise on their power supply that noise is still somewhat isolated from the rest of the digital card. The DS was designed to isolate the USB from the rest of the design. So all in all thereā€™s not as much to be gained by disabling the USB chip as one might expect. I donā€™t know what the UI software would do if it didnā€™t get what it expected from the USB chip, thatā€™s not a well tested path either in normal use or when upgrading software.

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Iā€™ll wait for Tedā€™s official answer on this one, but I donā€™t think itā€™s an issue. The USB processor is active and waiting for something to connect, though I think the visual image of it ā€œspinning awayā€ causing noise and problems if left unattended might be not accurate. Itā€™s pretty well isolated and thought out to not have an impact if not in use. But, Iā€™ll defer to Ted.

Ted, Paul

Many thanks for feedback.

The switch to I2S was driven by a wish to get away from USB and its attendant processing, in the belief that I2S was simpler and was the native mode of the Directstream. I expected to hear more notable differences between inputs. Itā€™s a testament to the engineering on the Directstream that all of the inputs are high quality and the differences between them are minimal. I was also surprised that the I2S and SP/DIF inputs were fairly indistinguishable and it took careful listening to make a choice. In the end I did find a clear preference for I2S.

Iā€™ve followed the firmware changes from 1.2.1 to Pikeā€™s to Yale, which I felt had a residual tendency towards brightness. As Iā€™ve cleaned up the USB signal source, the Directstream is never exhausted and is always able to reflect the improvement in sound. Iā€™m now hearing a delicacy and timing from Yale that I didnā€™t hear before - very musical. Iā€™m really looking forward to the next firmware release and further improvements in jitter and noise floor.

Weā€™re chasing small improvements here, hence youā€™ll understand the query abut USB processors and SQ. (Iā€™ll try to be less colourful in terms of language!). High speed processors tend to generate high frequency hash, which is hard to contain and hard to predict in terms of effect. I take the points about USB power supply isolation and also software side effects. Perhaps an opportunity will arise at some point to make a bench test.

Lonan

The leakage inductance of the transformer is a part of the output filter. The lower leakage of a better transformer isnā€™t necessarily good. There is a physical space problem when changing transformers. I donā€™t believe that any Jensen transformer will directly fit. Some might with a klugy mounting system. The Edcor 4400 (https://www.edcorusa.com/xs4400) is a pin compatible but better transformer which fits the space. I havenā€™t tried it, but it was one of the transformers that the DS was originally designed to accommodate.

Be careful of possible shorting, the space probably wonā€™t accommodate both a shield and upgraded transformers. Shielding even part of the output transformers with iron will muffle the sound.

Sure, but unsoldering the old connectors isnā€™t easy and mounting and soldering the new connectors wonā€™t be easy either. There are many different board mountable footprints for RCA connectors.

Shouldnā€™t be too hard.

No. There are no signal carrying wires. Everything is board mount. There is are ribbon cables between some of the card sets, but they need approx. 100 Ohms of differential impedance so replacing them with isolated wires would be a bad idea. I donā€™t know if there are compatible ribbon cables made with silver wire - if so the one between the digital and analog card would be the most important one to change (but keep the length the same.) There are two wires from the power supply to the analog card. To a first approximation they only carry DC so I wouldnā€™t count on too much help from silver.

People have many options on better fuses - I donā€™t have any specific recommendations, but as long as the fuse has the same ratings as the current fuse, no problem.

Everything on the digital and analog boards is surface mount - specific recommendations are higher in this thread, but in general the four input filtering capacitors on the analog card can be replaced fairly safely, but not many or even any others. I chose good quality caps with specific requirements of ESR, ESL, capacitance, voltage rating, current handling, etc. Replacing any with different ratings can cause problems (like power supply instability, or inferior filtering, ā€¦ The resistors arenā€™t cheap and the thin film resistors are already oversized 0.1% quality resistors with 25 ppm/degree C specs. Resistors that donā€™t have the same footprint would be bad (ESL and capacitance, etc.) I donā€™t cheap out anywhere.

Iā€™d just put a cover over the USB, you certainly donā€™t want to short the USB VBUS or ground to anything else. Shorting XLR inputs may help or it may hurt. Youā€™ll have to try each way.

Thereā€™s a thread around here somewhere with ECT placement recommendations by me and some results of various placements by users.

Youā€™ll need a supply with three one amp 5V rails and one one amp 12 volt rail. The last is the most important for the audio quality. Corect grounding is important.

Line input isolators arenā€™t appropriate for the digital inputs (digital needs pulse transformers.)
So I assume you are talking about the analog outputs? RCA connections are already one half of the line input transformers used as output transformers. Iā€™m not sure how adding another line input transformer would help.

See earlier posts in this thread and others. Searching for ā€œmodificationā€ or ā€œmodificationsā€ would probably find them.

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Thank you, Ted.

It was very kind of you to go through the questions and present this level of detail.

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Definitely the power supplies are the most readily available points of modifications. Some here have reported great results with only replacing the 12V analog supply. One has replaced it with a rechargeable battery with good results, but keeping the battery near 12V might be a problem for some battery technologies.
You can also search for results of people who tried various shielding approaches. I only vaguely remember one such post.
The lower level power supplies are discrete regulators around the boards. They are already better than most chip regulators. But itā€™s not easy to replace them individually.
If you want extra credit, physically separating the analog and digital would make a difference, but some lengths of ribbon cable wonā€™t work so some experimentation may be needed.

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I think Ted has more or less made it clear: Diminishing returns. The way mine is currently performing I would have no want to upgrade it. I might as well look to modify my loaded select DAC ii with mono power bases. I drive a 2019 GT-R Nismo(among other things). People do modify the heck out of these. I see no reason. It is plenty capable of getting you in trouble as is. I do not mean with the law. I mean like dead. Does it really need to go faster than 248 miles per hour from the factory? Sometimes I just enjoy things the way they are but that is just me. YMMV.

I say if you want a better DAC then just buy a better DAC. However the DSS is no slouch at all. My current streaming rig is outperforming the finest CD transports in the world. I own the Burmester 069 for reference. It is arguably the best CD player ever made. I feel my current DSS streaming rig actually bests it on Flac radio from across the world. What more do you want? There is really not much to upgrade in the DSS. I personally feel that it is not worth my time. I doubt a better power Xformer is going to make some huge difference and that is pretty much the extent of the upgrades. I am sorry to spoil the party. Ted does not do poop work. He did it right first.

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Some folks do it for fun and the diy chops, but I think they mostly hang out on different forums.

The Nismo will not even break 200 MPH; it has insufficient power.

Back to your regularly scheduled programming.