eziitis
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- Mar 5, 2019
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The major issue I can see is those DIP OPs. SOIC is much better.
just wonder, what is the SOIC superiority audio wise?
The major issue I can see is those DIP OPs. SOIC is much better.
What kind of piece is this ? Perhaps voltage regulator, from 5,3v to 5.0v ?
Of what? They show a THD of -60 dB. What DAC do you know that has that performance? DX3 Pro clocks at -105 dB. No way what you are reading there is a typical measurement or circuit.Those curves are valid measurement data.
No, I meant capacitors for power OPA1612.
just wonder, what is the SOIC superiority audio wise?
Huston, we have a problem! to me that 5V testpoint rings to VREF and VDD and AVDD pins. would that mean there is just one reg for all these +5V? it is a must to have VREF innocently clean for these AK beauties. if that is the case, then shame on you Topping!
Of what? They show a THD of -60 dB. What DAC do you know that has that performance? DX3 Pro clocks at -105 dB. No way what you are reading there is a typical measurement or circuit.
In which case the differences are -140 dB down. In other words, it is beyond the realm of audibility. On that front, I suggest reading this article I wrote: https://www.audiosciencereview.com/...-digest-audio-capacitors-myth-or-reality.176/The paper stated that there's a 80.5db total gain. You have to deduct the values by 80.5db. The general shape of the curves look right to me. Have seen those in too many reports.
In which case the differences are -140 dB down. In other words, it is beyond the realm of audibility. On that front, I suggest reading this article I wrote: https://www.audiosciencereview.com/...-digest-audio-capacitors-myth-or-reality.176/
They are not valid data when you cut off even the label under the graph let alone the link to the paper. The piezoelectric effects are known and nothing new. The focus of the paper is also on acoustic interference from what I can gather. It certainly has no bearing on headphone listening.
What problem? THD+N is -106 dB. 2nd harmonic distortion is at -110 dB.But as the output coupling cap for DX3's 4493 output, it can be a problem.
The only ones that showed a "problem" were those affected by piezoelectric effect. There is no such factor here.If all the caps are tested in exactly the same way and shows a difference. Don't you think there is really a difference between the caps?
Huston, we have a problem! to me that 5V testpoint rings to VREF and VDD and AVDD pins. would that mean there is just one reg for all these +5V? it is a must to have VREF innocently clean for these AK beauties. if that is the case, then shame on you Topping!
View attachment 23082
basically this means we are facing VREF pin lifting and putting a buffer something like below to make VREF happy:
View attachment 23083
The only ones that showed a "problem" were those affected by piezoelectric effect. There is no such factor here.
signal integrity wise, it is much better. shorter feedback path as there are a lot of HF signals going through.
Go ahead check out the layout guidelines in those high performance OPs datasheets
Thanks for the link to Murata part. Have you ever tried it? It can only do 1w though.
Some SOIC/DIP adapters would put silver mica across the +- lines but this may not work all the time.
Another concern is the feedback loop. The adapter will pull the line too long. I like SMD parts much better. Easier to work with, too.
This weekend I will replace the XOs. Probably add a 1.5A 15V linear power supply later then that will be it. I will be done with DX3. This thing already sounds much better than most $1k DACs. The machine has been running non-stop for over 60 hours now. Solid stable. The sound keeps getting better and better. Warm and smooth. Lovely vocals. The biggest steal in 2019!
I have read some early feedback on Topping's D70, pretty much in line with what I heard from DX3.
After looking into DX7, most likely I will skip D70 - I see the same bad 100uf SMD caps again.
This one seems to be a good candidate. The implementation looks good, at least it follows whatever 4497 datasheet asks for, the four big caps around 4497 are good. The output stage looks correct. The major issue I can see is those DIP OPs. SOIC is much better.
The only ones that showed a "problem" were those affected by piezoelectric effect. There is no such factor here.
Ummm... at the risk of putting my foot in it, can I, rather timidly, once again as I did a few pages back ask @finneybear and others modding their units to send them to @amirm for measurement and comparison to stock units? Brighter minds than mine can then debate the findings, but can there first be findings to debate?
Also, two points if I can dip my little toe into the debate...
1. This is a forum that is founded on measurement. There actually has been a very tactful avoidance of the discussion as to whether the measurable differences are actually audible. I don’t believe this forum was established to deal with that issue. It is about identifying how well a product was engineered - and no product is perfect. There are other forums such as SBAF and Head-fi for more subjective evaluations. Folks shouldn’t be surprised when “measurement” keeps coming up. When you are in Church, God comes up, when you are in a bar, whiskey comes up. Comes with the territory.
2. I think that there is no doubt that better components and cleaner engineering would result in a better product than the DX3PRO... it is a product with a budget trying to hit a particular set of marketing and engineering constraints, and even then mistakes and sub-optimizations occur... Many, many posts back @finneybear said his changes to date would result in a $500 product that would compete well with $1000-$2000 products. I would think everyone would grant that makes sense in concept, add $300 underlying value to a $200 product, and it probably does get better! But, there is a desire to actually measure the results of those modifications.
So, going back to my original suggestion... can some modified units be provided to @amirm for measurement so we can have the discussion about the resulting measurements?
As I tell my wife all the time, sometimes people fall into the trap of talking about the talking rather than talking about the issues...