- Dec 5, 2012
USB errors are more common than you think, because there is no error correction in isochronous transfer. So the quality matters and so is the distance.USB signal is passing without errors, as errors on the USB connection are very rare. With asynchronous transfers a source frequency and timing is no problem as USB clock is slaved to the internal clock - as long as there are no receiving errors, but again errors are very rare. 5V is not used, no problem. Problem is with a noise on the ground wire. It creates a current flow inside a DAC through the internal power supply for the Amanero module. It creates EMI spreading inside a DAC. There is also interference between other sections of a power supply, and finally a galvanic isolation which is placed between Amanero and FPGA core logic is not perfect. Any capacitance (even very small) between components of a dirty side and a core logic create leak.
In other words, USB give perfect bit transfers, therefore any USB reclockers do not make any sense, the only concern is a noise entering inside a DAC.
You can try running on 3m USB cable, and a 1m cable, with the same contruction, the difference will be obvious. Then if you add a reclocker you won't be able to hear the difference between a 3m or 1m one.