sandyk Posted July 24, 2016 Share Posted July 24, 2016 r_w With many USB devices the shield is connected internally to the 0 volts ("earth") wire. Where the P.C. is connected to Mains Earth, this may mean that the earth return is less than optimum, and may even be a noisy earth .( Ground loop) Are you sure that your return path isn't now via the shield ? Regards Alex How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file. PROFILE UPDATED 13-11-2020 Link to comment
sandyk Posted July 24, 2016 Share Posted July 24, 2016 I've been told that USB isn't supposed to work without a ground connection, but it does in my system... But your system isn't a P.C. which needs to see an earth return. If the resistance of the earth exceeds a certain limit, the connection may drop out after a while. With the Peachtree DAC it for example, the connection would start to be lost at around 50 ohms in the earth return. How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file. PROFILE UPDATED 13-11-2020 Link to comment
sandyk Posted July 24, 2016 Share Posted July 24, 2016 If I was building any USB device now I would put a mechanism in to drop ground after handshake, either auto or manual. You keep stating that as if it's a universal remedy. It isn't , and won't work with USB from Windows PCs in general, or probably the later Mac Minis without the connection dropping out sooner or later, and the USB device no longer showing up in "My Computer" This even happens with USB memory sticks ! Yes, USB Audio does benefit from the highest possible quality power supply, with the least coupling back to Mains Earth. Even the type of transformer used in a Linear PSU matters, with Toroidal transformers the worst due to their high capacitance between Primary and Secondary windings. R-Core transformers are better, but the best type is the split bobbin type with their side by side windings. How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file. PROFILE UPDATED 13-11-2020 Link to comment
sandyk Posted July 25, 2016 Share Posted July 25, 2016 I'm no evangelist, just saying it's well worth trying it for yourself. Did you read what John Swenson posted about how USB functions with a Computer ? Sometimes a USB port isn't recognised after switch on, and you may need to do a Restart for it to show in My Computer. USB on a Computer can be highly temperamental, and incorrect protocols can result in the USB port being used , BLOCKED as FAULTY after several failed attempts to be correctly identified. It isn't always easy to unblock the marked USB port either, but one method that works for me with W7,8 and 10, is to use System Restore.Even if System Restore isn't successful, the Fault Counters are written back, and the blocked USB port becomes functional again. How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file. PROFILE UPDATED 13-11-2020 Link to comment
sandyk Posted July 25, 2016 Share Posted July 25, 2016 I suspect that the 50V quoted by John may be considerably higher in 230V AC 50HZ countries .? How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file. PROFILE UPDATED 13-11-2020 Link to comment
sandyk Posted July 25, 2016 Share Posted July 25, 2016 The moment you have ANY two pronged PS or something whose negative DC rail is NOT connected to that star ground point you can develop significant voltage due to leakage current. An exception will of course be John's own JS2 Linear PSU !!! How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file. PROFILE UPDATED 13-11-2020 Link to comment
sandyk Posted July 29, 2016 Share Posted July 29, 2016 r_w Looks pretty good to me. Regards Alex How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file. PROFILE UPDATED 13-11-2020 Link to comment
sandyk Posted October 12, 2018 Share Posted October 12, 2018 Quote Connect ground and +5V to the external supply. Also connect ground to the PC during the handshake. - mansr I presume that you mean 0 Volts of the external +5V supply. It doesn't need to be earthed as the +5V supply can even come from a battery with a possible further improvement due to isolation from mains earth. Also make sure that the incoming shield from the USB port isn't connected through . It may be connected internally to mains earth. rikhav 1 How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file. PROFILE UPDATED 13-11-2020 Link to comment
sandyk Posted October 12, 2018 Share Posted October 12, 2018 7 minutes ago, mansr said: I mean what I said. Connect USB ground and +5V to the corresponding terminals of the power supply. Connecting only one would be rather pointless. I think we may be talking at cross purposes here. Perhaps a simple diagram also showing a USB ground switch may help the less experienced members ? rikhav 1 How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file. PROFILE UPDATED 13-11-2020 Link to comment
sandyk Posted October 12, 2018 Share Posted October 12, 2018 29 minutes ago, mansr said: DAC PSU +------+ +-----+ | +5V |---------------| +5V | | GND |-----+---------| GND | | D+/- |==# | +-----+ +------+ | | | | | | PC | | +------+ | +--<SW>---| GND | #============| D+/- | +------+ Thanks. That should assist quite a few members. Incidentally, anything further on the USB Widget ? Also, a front panel like the attached also has the advantage of the USB shield not being connected through at the front panel, which gives the possibility of a separate earth shield from the device end, as well as shielding of the actual internal cabling in the Computer. (Click on the photo of the USB Widget for a much larger photo.) rikhav 1 How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file. PROFILE UPDATED 13-11-2020 Link to comment
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