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In Reply to: RE: Power supplies in dacs posted by beppe61 on July 19, 2015 at 23:37:30
Many DACs and cdp's can be improved by enhancing the grounding schemes. See the Archives at Hi-Rez Highway for ideas, especially as regards the Sony SCD-1 and 777ES. That might give you a jumping off point for working on other brands and designs.
Follow Ups:
Hi and thanks a lot for the very valuable advice.
I have a question about " enhancing the grounding schemes "
Does this have the effect of reducing noise ?
Lately i have come to the conclusion that noise is a very bad beast for audio. It tends to cover the details (i.e. low level signals) so important for instance for a good 3D effect.
Another point, but off topic, is the usually poor quality of connectors.
However that can be solved quite easily. And it gives benefits also.
I will search for these mods.
Thanks again.
Kind regards,
bg
Edits: 07/21/15
enhancing the ground scheme should have the effect of reducing noise. With the Sony devices I mentioned, which were built to a cost-no-object level not seen since, the "problem" is that essentially everything is grounded to everything. Unclestu points out that separate power supplies for each element of a CDP is desirable, and the Sony flagship products were built that way. But by redundantly grounding each section to every other section and to the chassis, some of the benefits of separate PSs were lost. Isolating the grounds had a noticeable benefit.
Hi and thanks again
I have indeed a lot to learn before attempting any mod
I find quite surprising that Sony engineers have made some debatable design choices anyway. Not that i doubt the efficacy of the mods.
Actually the contrary.
Thanks again.
Kind regards,
bg
(in audiophile terms) Harman Kardon CD players in the 90's employed extensive ground planing but kept the planes for analog, DAC, Power supply and the board for the focus motors and timing separate.
The planes met at only one single point to minimize cross contamination. Analog stages like many top end multi format players had a shielding box built over the semiconductors and the ground plane on the bottom pof the board.
In addition many players now have extensive shielding across the front faceplate. One of the early top line Wadia machines had a chassis made of two inch billet aluminum with four machined wells to separate the four typical sections of a DAC....
Hi ! thanks again for the very interesting advice.
I have a further question ... after deciding for a single ground on the board would it be beneficial to use pieces of good quality wire (like hook-up wire) to connect that point with different grounds on the board ?
Not very elegant, but effective ?
Thanks again.P.S. sorry for the poor English ...
Kind regards,
bg
Edits: 07/21/15
As I inferred, but did not describe very well, the issue with the Sony CDPs was that "everything was grounded to everything". Plus, the circuit was connected to chassis ground at many different points. The modifications essentially converted the grounding system to "star ground". This is well described in the Hi-Rez Highway thread. As to using "good wire", no audiophile would ever advise another to use "bad wire", so, yes, use good wire. For connection to ground at the star ground point, heavy gauge is de rigeur, copper or silver. Interestingly, once these mods are completed, the circuit works better. The time interval required for loading and reading a CD is reduced, etc.
There must be something wrong! IK understand why this tweak works, how it can be applied, and it would not be hard to implement. What kind of tweak is that?!! Just kidding! Thank you for the very clear explanation.
Dave
Hi actually i do not understand why the designers do not take care of this aspect during the design of the lay-out.
It should be a very well known issue.
Another thing i do not understand.
Sometimes some newer products appear on the market that sound worse than previous models ... this is insane for me.
One step forward and 2 o 3 backwards. Why ?
I remember for instance an amp, the Pioneer a400.
The successor, the a400X, was less convincing soundwise.
Unbelievable ...
Sorry for the outburst.
Thanks again.
Kind regards,
bg
For Sony, the grounding scheme of the original SCD1, etc, may have been a byproduct of their perceived need for modular construction. Thus having the ground for each separate PCB connect to every other PCB ground and to chassis ground requires less thinking on the part of a tech who may be replacing one or another module. But that's just a guess. Surely they knew about star grounding.
Re the fact that new products are not always superior to the products they replace, this happens a lot, all the time, in most markets (cars, audio, washing machines, etc). Some who prefer vintage equipment may view the entire last 40 years in the audio marketplace as a gradual decline in quality. "They don't make them like they used to". Some of this is generated by the need to keep prices under control while also incorporating advances in technology into commercial products. And yet, if you take the long view, I do think "things" we can buy get better over time; it's just not a linear upgoing curve.
HI and thanks a lot for the very helpful reply.
Still when the scope is a TOTL unit excellence in performance should come first and so the design should be not reproachable i guess
Regarding the second point i think that price of parts tends to increase
I do not know a specific case but it could be that they use a weaker transformer ... cheaper parts to keep the price down.
I believe that present TOTL units have very good parts, probably much better than vintage units. But the price is very very high indeed.
I see dacs costing tenths of thousands of USD without any problem.
Thanks a lot again.
Kind regards,
bg
Not to beat a dead horse, but the chips in modern megabuck DACs are certainly "better" by most criteria than the analogous chips of 10 or more years ago (or even last year, in some cases), but the cost differences may often be in the opposite direction; newer technology chips may also be cheaper, or if more expensive, not enough to account even remotely for the differences in pricing of the assembled products. Those stratospheric prices are more aimed at those who have the bucks to play in an exclusive league and who believe at some level that if the item is not super costly, it cannot be good enough for them. This is only my opinion, of course.
Hi and i would think the same if it were not for this multi-bit discussion going around.
Those vintage multi-bit dac chips are object of cult almost.
However i see that TOTL and very expensive newer dacs use sigma-delta chips. They cannot be that bad i guess.
Someone say that there is no comparison with the old dac chips anyway.
Like dacs have reached the top of sound quality in the 90 and then they started to get worse.
For me this is quite difficult to accept.
Thanks again.
Kind regards,
bg
Edits: 07/30/15
since CDPs like the Sony SCD1 and SCD777ES (essentially the same unit but without balanced outputs) still have their cult followers. I always wondered why that was the case, apart from the fact that both ARE built to battleship quality levels almost unheard of these days except at the megabuck level. (In my previous rant I forgot to mention that a large part of the justification for megabuck DACs is based on their elaborate and beautifully made chassis', IMO.) But it's also true that the main chips in the Sony units are superb still by modern standards. The problem is that if those chips fail, the unit becomes about as useful as a doorstop or boat anchor; you'd need an entirely new audio board, because it is near impossible to de-solder and then install just a replacement chip even assuming you could find one. (I get this info from a very skilled professional who worked on my SCD777ES.) I went from a very tweaked SCD777ES to an Oppo BDP105, skipping about 15 years of technological development, yet the Oppo is not superior to the Sony in terms of pure sonics.
Philips in issuing their Crown chipset, the venerable 1541, with only 16 bit 44.1 sampling, claimed why ask for more when all you need is a "perfect" DAC chip for the information at hand?WHile very popular, that did not stop the tidal wave of higher bit rate sets which entered the market, claiming better high frequency filtering because of the higher bit rate.
In essence, DAC's become part of the computer race. Higher numbers as being seen as better. I do not believe the algebraic manipulation of these numbers has improved much though, nor the addressing of certain particular issues as it pertains to music and digital
Edits: 07/31/15
there's no question in my mind that modern cdp's and DACs are far far superior in sonics to the first wave of "perfect sound forever" products, all of which were 16/44. So, something got better. Whether there is continuous linear improvement over time up to the present is quite another matter, however, IMO.
a large part of the issue is in mastering. In analog, its ok to use low level recordings. Not true in digital. You need the bits to get detail and the number of bits is also correlated to volume , unfortunately.
Over the years I notice my discs are getting louder and louder. And they do sound better.
Also, although it receives very little mention, the analog sections are greatly improving. employing judicious filtering to roll off the RFI edginess, although I believe the pendulum has swung a bit too far in that direction.
Apparently some of the sonic improvement has to do with the appreciation of the jitter phenomenon and how to fix it, or so we are led to believe (or beleive).
What was interesting is, as an former HK dealer. I had access to service manuals . In the early 1990's their top line models ( 7500, 7600) had jitter figures in the very low teens ( 12-14), much lower than any separate stand alone DAC and transport. Makes you wonder, and I used all the tricks: reclockers, upwards dithering, trick cables and such.
Hi and thanks a lot again. Very interesting indeed.
I will limit myself only to some caps replacement with better parts and some testing with different transformer.
The risk to do more harm than good is very high for me.
Thanks again for the very valuable advice.
Kind regards,
bg
Hi thanks again and again very very interesting
The importance of a well designed lay-out seems a little underestimated
While i can understand in a cheap mass market product it is more difficult to accept for a flagship model ... and especially from highly famous Brands ...
However ... i will read the thread you mentioned hoping to understand something
I am very slow to catch things and this is one very complex issue indeed.
Amazing the fact that the modded players worked better as well !
Thanks again.
Kind regards,
bg
Edits: 07/22/15
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