I investigated the fault on Octavian's ps and found that one of the pair of 7805 three-terminal regulators had failed. That meant that the remaining regulator was unable to maintain 5 volts at the current demand of the SB, and the voltage collapsed to around 2v. Whether the SB had blown the ps or vice-versa is unknown, but more probably the former. Interestingly the no-load output voltage was still 5v, which fooled me for a while!
However I was not impressed by the use of two 7805 regs which were connected in parallel, with no provision for load sharing between the devices. I decided to repair the ps, using a single LT1085CT5 (5v,3A) three term reg in place of the two 7805s. At the same time I replaced the 1N5402 diodes with IR MBR360 Shottky diodes, and the reservoir cap and the o/p stabilising cap with better electrolytics. I found the original supply had run very hot under load, so I modified the case to allow a better airflow across the internal regulator's heatsink. The audible results was surprising and immediate. The improvement in the sound over my original CPC ps was as great as the original CPC ps had been over Slimdevice's switch-mode ps. It is much quieter electrically (lower ripple and noise), which has revealed the micro details previously hidden in the noise floor, and which in turn has increased the dynamic range of the output. The dimensions of the reproduced sound stage have increased noticeably, and the performers now operate their own clearly defined spaces, with an extended decay to the notes they are playing or singing. It is now very much easier to 'hear' the recording venue. I think this was a worthwile exercise, and I have now modified my own (CPC) ps as well. All the components were sourced from CPC. Now I am wondering how much more can be extracted from the SB if I build a proper 'no-holds-barred' supply, or source one of Bolder's power supplies from the US. Maybe one of Andrew Weeks' Super Regulators feeding a series-pass power transistor might be the answer? It just goes to confirm, to me anyway, that any bit of hi-fi kit is really only as good as its power supply. -- afblaster ------------------------------------------------------------------------ afblaster's Profile: http://forums.slimdevices.com/member.php?userid=1643 View this thread: http://forums.slimdevices.com/showthread.php?t=26937 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
