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RE: MacMini vs Bryston BDP-1 Compared-It's

And you've measured this and have screen shots from your oscilloscope and spectrum analyzer . . .

Of course not - I no more have a spectrum analyser to illustrate my point than you do to disprove it. If you had, you'd have shown us all your measurements and screenshots. Would you not?

As it happens, I do have a 'scope but it's broken so I have to look for answers to the many reports, screenshots etc etc to be found on the net for those who trouble to look. I also use my ears - you might try the same though I doubt you will.

. . . stock power supplies are junk and need to be replaced

I said no such thing. The SMPS in a typical desktop computer is well engineered and, as anyone who remembers linear PSUs from the mini-computer days well knows, far better suited to general computing tasks than any linear PSU on weight, cost, efficiency and cooling grounds. And they're getting better all the time.

But, in some situations, the picture is less clear cut. Any digital machine performing precision tasks in realtime is sensitive to noise, not just audio boxes.

Someone earlier in the thread made the scornful remark that "I've heard that different computers print to the same printer much differently . . .".

Very droll - but silly with it. I worked for years with high-resolution imagesetters and platemakers (which are essentially large-format laserprinters) in the graphics arts industry where output resolutions are typically 2540 dpi and tolerances much tighter than are called for by the average office printer where ink and toner helpfully cover a multitude of sins. An error of a few microns in the placing of a single line of pixels on a printing plate (and there can be over 200,000 lines on a large plate) can render it useless because the error is readily apparent to the eye.

Manufacturers of top-end imaging kit must therefore pay attention to issues of noise, ground integrity and so on and ensure that their power supplies and the mains power lines that feed them are up to the mark. In short, different computers can and do print differently to the same printer whatever the engineering philistine may think. I'm sure similar points apply in dozens of engineering fields outwith my experience.

. . . you had better check every other electronic gadget in your home and replace their noisy power supplies, too.

As do others, I power my audio kit from a couple of dedicated spurs (one for analogue, one for digital) with no "gadgets" on them, an approach I first encountered in the early 1970s, those halycon days of "clean lines" that suppliers would inspect before delivering kit.

As a parlour trick to illustrate the point, try connecting a commodity-level TV set first to the workaday mains supply then to a proper "clean" line. The difference in picture quality is very marked. I didn't bother installing spurs for years but took the opportunity of other work being done to install them. Yes, they make a difference and, yes, I wish I'd done it earlier.

Not to diminish the quality of Swenson's power supply design but it is basically just a pi network (been around for several decades) in front of a 3-terminal regulator.

Thank you but I do know how it works. Well enough in fact to note that you miss the point that it's a well implemented design, not just any old rework from text books.

I seem to recall from the original discussion that you struggled with some of its basics. Whatever, as JS noted at the time, "I never stated that this was a new, unique, never-seen-before power supply design, just that it was a carefully optimized design targeting parameters I have found to be important for audio purposes".

My experience with it (I've built a couple - have you?) is that John seems to have got it about right.

And as you know, it won't power a Mac or PC which is what we are talking about.

It's not easy to get them to power a conventional motherboard but more than one list member has done so and reports good results. Others report good results from comparable though (IMHO at least) less refined circuits.

I accept that the Mac does not readily lend itself to that sort of approach. In fact, it's one of the reasons I find it hard to take Macs very seriously as devices for decent domestic audio reproduction despite their undoubted merits in other fields.


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  • RE: MacMini vs Bryston BDP-1 Compared-It's - Ryelands 10:56:02 04/12/12 (0)

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