How is a battery powered SD card reader the nearest thing to a digital source.
It is also quite funny to read that a lot of engineers are stuck in the past, LOL, all designs have to pass EMC testing for one. For another, unless you have had your head in the sand (or audio forums) for the past 30 years, you may have notices some little changes in digital devices, such as speed, rise time, size of packaging etc etc, i am quite shocked that all this has passed designers by and they are allowing this evil RF into their products to corrupt the sound to such an extent.
It is also quite funny to read that a lot of engineers are stuck in the past, LOL, all designs have to pass EMC testing for one. For another, unless you have had your head in the sand (or audio forums) for the past 30 years, you may have notices some little changes in digital devices, such as speed, rise time, size of packaging etc etc, i am quite shocked that all this has passed designers by and they are allowing this evil RF into their products to corrupt the sound to such an extent.
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Is there a word missing? Its the nearest thing to a perfect digital source in the sense that its isolated and hence can't send any CM noise into the DAC. Well isolation isn't perfect for sure because as soon as a cable's connected to a digital device then that cable's an antenna. But given that its only got to read an SD card then it doesn't have to be high power and hence can be relatively low noise, RF-wise. Compared to something spinning a hard drive or even an optical disk.
As soon as they let that poisonous digital stuff into their analog designs they've already swallowed the evil RF. So you're suggesting that digital designs shouldn't be digital after all? Or should run at clock rates of a few 100Hz so they generate nothing beyond audio frequencies?
I read that 20
years go. But I will still stick to my comment and get some support doing it from Julf above /
No I am suggesting that in all other walks of life digital and analogue can be made to work together, it only seems to be consumer audio where the digital demons are so bad.RF is only RF if it is transmitted, most digital systems dont actually ransmit RF (esky EMC compatability again). As to the noise that is present at frequecies far higher than audio, how much of a problem is it, can we here 100MHz noise (and if the analogue end is getting upset by it, filter it, isolate it or change the design).
I could make a sound recording of the current CM noise issue I have (and yet to solve) but where could I post the file? Or would it be enough just to paste a screenshot from Audacity? It only happens when the laptop is feeding the DAC via a USB-SPDIF (HAinfo) box. When the laptop's isolated from the mains, nothing audible at all so its a textbook example of common-mode noise.
Screenshot with laptop on and off mains would probably be enough.
I assume the USB-SPDIF converter is powered by the USB connection, and your DAC doesn't have an isolated S/PDIF input? Have you verified if either device actually uses an isolation transformer?
Too expensive and too bulky. A murata choke does it much smaller (0805) size and cheaper ($0.10)
But the murata choke doesn't equalize the bio-energy on a sub-atomic level in accordance with the principles of quantum physics.
Yes its powered by USB bus power and yes there is an isolation trafo in there (Pulse Engineering, forgot the part no. but can find out if you want it). I should check though that I haven't inadvertently violated the isolation barrier before I run this. The USB adapter doesn't have a trafo but the DAC does (I installed it myself).
The transformer should take care of any CM noise, and cut down any possible HF as well.
Well, yes, considering people manage to get class D amps and heavily oversampling DACs to work, despite the presence of significant HF...
Yes I had thought that too which was why I was surprised I got such an audible effect on connecting the laptop - nothing audible when the DAC's fed with a cheap DVD player (noisy SMPSU) over S/PDIF.
I rather think the audible effect arises from the ground lifting inductor (a custom one) I installed in the amp - that's the only LF path back to mains earth in the system at present. Probably if I put a smaller damping resistor across that the effect will diminish or cease entirely.
I rather think the audible effect arises from the ground lifting inductor (a custom one) I installed in the amp - that's the only LF path back to mains earth in the system at present. Probably if I put a smaller damping resistor across that the effect will diminish or cease entirely.
Screenshot would be nice. You can use Soundcloud to post the actual .wav (or whatever format) file.
Since we've got the brains trust together and on topic how about a few moments to look over a block diagram of my DAC build
Any thoughts on this? I have doubts over the need for using the NVE at output of the WaveIO, though it can't hurt so I'm going to use it anyway.
The only thing that slightly bugs me is that there will be some coupling via the toroid that will bypass the Si8650 isolator.
Each psu indicated with have separate secondary winding dedicated to that part of the circuit.
This is the planned build at least and all parts are en-route already.
Any thoughts on this? I have doubts over the need for using the NVE at output of the WaveIO, though it can't hurt so I'm going to use it anyway.
The only thing that slightly bugs me is that there will be some coupling via the toroid that will bypass the Si8650 isolator.
Each psu indicated with have separate secondary winding dedicated to that part of the circuit.
This is the planned build at least and all parts are en-route already.
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I dont think hes asking for comment on the component choices... and actually if its the board I think, its a very well executed PSU of its type and works quite well, particularly on fairly undemanding class A circuits. and the headphone amp has excellent overkill local decoupling and very high PSRR, so with that very same supply 'the wire' is bouncing off the measurement floor of an AP2 and another equally high end distortion analyser
its very popular to hate on LM317/337 here and its also very popular to just throw shunt regs at everything whether they are needed, or even desirable.
yes its the fifo, but what looks strange anyway? isolate, then reclock to kill the jitter from the isolation method, pretty logical
its very popular to hate on LM317/337 here and its also very popular to just throw shunt regs at everything whether they are needed, or even desirable.
yes its the fifo, but what looks strange anyway? isolate, then reclock to kill the jitter from the isolation method, pretty logical
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