I need someone cleverer than me ( almost everyone ) to decode this for me, to me it sounds like more BS, and an admittance that his most expensive dac isn’t immune to power supply vagaries,
Quote,
‘Yes all sources create RF noise. We have two ways of coupling RF noise - via the cables, or electromagnetically. This mode is stopped with Dave being made from a solid block of aluminium - it is extremely well screened. The mains, and the outputs are RF filtered too. On the USB, we have galvanic isolation, but that will not completely isolate Dave from the source, as it has 2pF of coupling capacitance on the galvanic isolation (all isolators have some level of coupling capacitance).
Now this coupling capacitance is important, as RF noise voltages from the source will inject a small current into Dave's ground plane - and due to the ground plane having a 0.5 ohms per square and about 1 nH inductance per square will create small internal RF voltages that is picked up by the analogue electronics which will then induce a tiny amount of IM distortion, and so noise floor modulation will increase - even though Dave has immeasurably small amounts of RF noise modulation, the small extra amount is audible.
But if you run the source from batteries, and have no ground connected to the lap-top, then there are no net currents flowing into Dave, as the isolation capacitance of the lap top to ground is much smaller than the 2 pF from the isolators; in effect you are now completely isolating the source from Dave via the direct USB connection and so no RF currents from the source can be injected into Dave's ground plane. That's why this mode sounds a bit smoother and warmer than mains powering the lap-top.
Having said all that, we are talking about very minor stuff here; it's not the icing on the cake but making sure the icing is flat to 1 micron rather than 0.1 mm...Before the galvanic isolation I used to get huge differences from sources if they were mains powered - now we are talking about a small change that is only audible on AB tests. When I listen to music I don't bother disconnecting the lap-top - only when doing serious testing.
I wait with baited breath,
Keith
Quote,
‘Yes all sources create RF noise. We have two ways of coupling RF noise - via the cables, or electromagnetically. This mode is stopped with Dave being made from a solid block of aluminium - it is extremely well screened. The mains, and the outputs are RF filtered too. On the USB, we have galvanic isolation, but that will not completely isolate Dave from the source, as it has 2pF of coupling capacitance on the galvanic isolation (all isolators have some level of coupling capacitance).
Now this coupling capacitance is important, as RF noise voltages from the source will inject a small current into Dave's ground plane - and due to the ground plane having a 0.5 ohms per square and about 1 nH inductance per square will create small internal RF voltages that is picked up by the analogue electronics which will then induce a tiny amount of IM distortion, and so noise floor modulation will increase - even though Dave has immeasurably small amounts of RF noise modulation, the small extra amount is audible.
But if you run the source from batteries, and have no ground connected to the lap-top, then there are no net currents flowing into Dave, as the isolation capacitance of the lap top to ground is much smaller than the 2 pF from the isolators; in effect you are now completely isolating the source from Dave via the direct USB connection and so no RF currents from the source can be injected into Dave's ground plane. That's why this mode sounds a bit smoother and warmer than mains powering the lap-top.
Having said all that, we are talking about very minor stuff here; it's not the icing on the cake but making sure the icing is flat to 1 micron rather than 0.1 mm...Before the galvanic isolation I used to get huge differences from sources if they were mains powered - now we are talking about a small change that is only audible on AB tests. When I listen to music I don't bother disconnecting the lap-top - only when doing serious testing.
I wait with baited breath,
Keith