dorkus;167384 Wrote: > i just came across that last night... it looks pretty similar to the > other ones on the market, for better or worse (a little of both > actually). but the price, while still too high IMO, is more reasonable > than the alternatives. > > i'm currently in the process of building a SB PSU from scratch. have > been researching my design options for a few months now... but more on > that later. > > > > sorry, but a SB supply that costs 4 digits is nothing short idiotic. > for that amount you should be able to build a no-holds-barred power > supply for a power amplifier. or as you rightly point out, a > Transporter... > > +5V @ 2A with good regulation, low noise, low broadband impedance and > good transient response, while not as easy as some may think, is not > complete rocket science. and as Mr. Adams has pointed out, the fruits > of your labor are ultimately limited by the internal supply rails > anyway. i also wouldn't be surprised if the $2500 supply does not > really do a better job in these respects than a well-designed > commercial supply, as your listening bore out... a lot of "audiophile" > supplies actually have terrible, terrible design flaws... > > like dpac it also irks me to see the $750 supplies which use the most > run-of-the-mill parts like a LT1086 in totally generic implementations > straight out of a datasheet/DIY forum. as if that weren't bad enough, > they throw in some total faux pas warned against in said datasheet, > like putting a 2 meter wire between the regulator and load > (squeezebox), or adding undamped "designer" film bypass caps which are > pretty much guaranteed to add a nice ringing to the line when exposed > to the high-speed load transients of a digital device like the SB. yet > people seem to be happily snapping these things up, probably for lack > of better options... oh well. > > anyway, enough bashing, and on to a more constructive note. i think i > am close to selecting a regulator... unfortunately the Jung-based > "super regs" are too low in current (most top out around 300mA), and > i'm too lazy/unskilled to figure out how to modify it for increased > current capacity without degrading performance. so i might go with the > LT1963, which has an improved topology compared to the typical LMx17 > stuff, and much better noise performance than the LT1086 (40uV max vs. > 130uV, specified over a wider band too). only downside is reduced > ripple rejection, so i might look into a choke filter. i will probably > make the main box an unregulated supply, and put the regulator in a > little dongle at the very end of the DC power cable to the squeezebox. > if you guys are interested i will keep you updated on my progress... > > happy new year! :)
I like that idea very much. Placing the reg right there is very appropriate. Depending on the remaining volume of the SB in that area you can fit some local capacitance, post reg. Having the xfrmr and diodes and main cap in the remote box very cool. THis is another trade off in general b/t industrial design (cool little box with far away power supply) or one like the transporter with internal (improved functional layout) supply where you can place the reg right next to the load circuits. I guess the SB has an internal smps of some surface mount type for the digital pwr, but a separate liner reg for the analog. You would think that as long as the main supply has enough stability with transient loads (such as the SB) putting the money there would not pay off as much as much better supplies/regulators directly before the circuits they are powering. I bought that welborne PS with such skepticism in mind, and as such it is more for experimentation and a decent platform with which to stage follow on work. I intend to use the SB3 (eventually) to drive an external DAC like a bel canto dac 2 or some equivalent. Keep us posted of your work! -- dpac996 ------------------------------------------------------------------------ dpac996's Profile: http://forums.slimdevices.com/member.php?userid=9407 View this thread: http://forums.slimdevices.com/showthread.php?t=19822 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
