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Computer Audiophile


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About JohnSwenson

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  1. The answer is "I don't know". That is why I am doing the research, to find out what is going. Before I do that, ANYTHING is purely a guess. Six months to a year from now I will be able to answer that question, but as of now, no idea. John S.
  2. I know it seems like a long time ago, but it was just this week! I did in two days, Tuesday and Wednesday this week. John S.
  3. No, I have not done that recently, it is a little difficult to do right now, the connector on the starquad DC cable won't fit the JS-2. I would have to build another one with a different connector to try that. John S.
  4. Hi All, I finally had some time to take a production LPS-1.2 into the listening room and try it out! I have an ultraRendu powered by an LPS-1 (powered by a JS-2), feeding a Bottlehead DAC (DAC I designed about 5 years ago), The DAC was powered by the new LPS-1.2 (which was powered from the same JS-2). I was not prepared for this. It was jaw dropping. I've been alternately crying, smiling like an idioot, and getting goose bumps. I thought I had this system sounding incredibly lifelike, wonderful to listen to, as good as it was going to get. Boy was I wrong! Just this addition of the new power supply on the DAC transformed it yet again. First off was the bass, WOW, this has all got to be just perception but it seems like it is shaking the room much more, with less "boominess", that I didn't even realize was there. Not only does it sound "more there there" but I can now hear subtleties in the bass line I never noticed before. Like one song has TWO bass players, I never realized that before, now it is obvious. The whole sound field seems much richer now. The transformation over time as my system improved, went from a kind of haze over the whole space which got energized by instruments and voices, like looking in fog, the light sources tend to light up the whole space, but individual source are spread out and indistinct. Then the fog went away and I could hear individual instruments and voices, but they were kind of grainy and the whole thing felt a little "thread bare". The previous incarnation, was filling out the sound field and the graininess was gone. But with the LPS-1.2 the whole sound field is much richer and full and each sound source has so much more detail and finesse, like going to 4K HDR from DVD. But it's not "etched" or hard or any other form of hyper detail, it is just organically "there", not hidden but not pushed forward either. And this is just CD rips. Summary: WOW. John S.
  5. GMR is magnetic, but is different than a transformer. A transformer passes change in a magnetic field, thus it cannot properly pass a steady high or low, just something changing. Thus all transformer based isolators have to send a more complicated series of changes to define a steady state signal. GMR works differently, it has a coil that generates a magnetic field, and magnetically sensitive resistors. They change resistance with differing magnetic fields applied. Thus they inherently handle steady state signals as well as changing ones. They can run pretty fast, but are still fairly expensive. The common optocouplers are fairly large and can't go very fast. The LPS-1 uses optocouplers all over the place to get signals between power domains. They work well for this because the signals are slow (32KHz) and the couplers are dirt cheap (40 cents per channel). GMRs are much faster (150MHz) but are much more expensive ($3 per channel). I use GMRs when I am isolating I2S signals. Both optocouplers and GMRs have very low cpacitance, hence very good leakage isolation. The problem with the ISO REGEN was not the isolation technology per se, but that for some reason the chip didn't work when there was a very rapidly changing voltage between the two sides. It turns out this can easily happen with older style SMPS supplies, particularly those used for residential networking equipment. Since most of you guys are using this with computer audio where residential networks are used, this happens a lot. The only way to deal with this is to put a filter across the "moat" which slows down the edges, but also lets high impedance leakage through. In REALLY bad cases that isn't even enough which is what the switch is for. John S.
  6. The reason you use an isolator is that you want to isolate the ground. The ground is where the leakage current travels so it is the critical path to isolate. The problem is that without the ground connection normal signals will not pass, since they use the ground for return current. This is where the digital isolator comes into play, it transfers digital signals across a ground break. There are many types of digital isolators, the most famous is the optocoupler, (LED pointing at photostransistor), there are many others: transformers, capacitively coupled, radio transmitters and my favorite, GMR (Giant MagnetoResistive). There are two things that make high speed USB difficult: 1): high speed -- HS USB runs at 480 Megabit per second (Mbps), most digital isolators do not run anywhere near that fast. Some do, but they are not easy to come by and are very expensive. 2): HS USB is a bidirectional bus, all of the digital isolators are uni-directional, you need two, one for each direction. The hard part is that the isolators need to know which end is driving the bus, the isolator or what is at the other end. There is no wire in the bus that specifies which direction the data is going in at any given time. The ONLY way to do this is a full blown USB protocol engine that follows the commands on the bus and can thus figure out which direction the bus is going at any given time. #2 is not easy, none of the big chip companies has a chip that does this, anybody that wants to to isolate HS mode has to do this themselves, very few companies have been successful at this. Things get more complicated for capacitive and transformer coupled isolators. Neither of these transfers a steady state, they only transfer a CHANGE in signal. This means more complex encoding so they can handle the state of a signal not just that it changed. This limits the data rate they can handle. I don't know for sure what the Sillana uses, but I think it is capacitively coupled. That is the overview, if you want more detail, let me know. John S.
  7. SMPS and grounding

    The ISO REGEN has the same issue, it only blocks low impedance leakage. That means it is effective if whatever drives it does not have any high impedance leakage going through its USB output. I have never tried shunting high impedance leakage through the USB ground connection, it MAY work, but it may not. I have just followed the practice of making sure that whatever is feeding the USB going into the ISO REGEN has had its SMPS negative output grounded. That works for sure, trying to do it with the USB ground may or may not work. John S.
  8. First off I would get the data sheets for the original and the new clock board and make sure the output voltage for both. Most oscillators are 3.3V output, but there are a few chips that use a lower voltage clock. If you feed such a clock input with a 3.3V clock you COULD fry it. (don't ask me how I know this!) Do you have a scope? My next debugging would be to check the signals going into the DAC chip look good, then look at the outputs and see if they look reasonable. You can try tracing the clock signal from the oscillator to the DAC chip and see if there is anything in-between (chip, resistors etc). If there is, THAT might have been damaged by the new board. Swapping that DAC chip is not an easy task if you are not familiar with the process. Make SURE nothing else is wrong before tackling it. If you don't have a scope, now would be a very good time to get one! John S.
  9. Mutec REF 10 Masterclock

    As noted above Pasternack is the place to go for custom RF cables. I recently had some 2 ft 50 ohm cables made using LMR-200-UF (thats the UltraFlex version) I wouldn't call it limp but it is quite a bit more flexible than other cables with similar specs. They cost $50 each for the custom cables. You can get them in any length you want and over 200 different coax types and MANY different connector combinations. I had to call them up to get what I wanted, for some reason the web page wouldn't get me what I wanted. Their people on the phone are very knowledgeable and got me what I wanted right away. If you want good RF cables, just go to Pasternack. John S.
  10. Is the oscillator in the picture the original one? It clearly shows 100MHz, but the one you linked to is 16.9344. That seems like it could cause some significant malfunction, but that should not cause anything to be permanently damaged. Adding an AC powered board in parallel to a transformer powering another AC powered board should not inherently cause a problem. It could cause the voltage on the transformer to droop which might have caused a problem with some circuitry not working properly, but again that will not usually permanently harm something. Given you have a display that shows messages etc it sounds like there is a processor of some sort, it is theoretically possible that a low voltage on the processor could cause it corrupt its firmware. It's unlikely but it IS possible. If that is the case you would need to reload the firmware. I have no idea if that is even possible with your DAC. John S.
  11. SMPS and grounding

    You just want to shunt the SMPS feeding the LPS-1, the LPS-1 will isolate its output from the ground of the feeder. So in your case, shunt the feeder to the LPS-1 and DON'T ground the negative of the LPS-1 output. John S.
  12. I don't know what SoTM does in any of these situations. The Ref10 has clock output of the appropriate impedance (some 50 some 75) so they will drive a coax properly. The ref inputs on the clock synthesizer chips are designed for low voltage, so they can handle reduces signal amplitude from the properly terminated source. I presume the ref input on the SoTM board has the proper termination resistor for the connector being used. I have no idea what is on the clock interface board, but it is probably some form of termination and maybe a conversion chip. I presume they did it right so it will work driving standard CMOS inputs. I was writing the post to people that want to do their own clock distribution scheme to let them know it is not so simple to do it right. John S.
  13. The ISO REGEN does not have a clock synthesizer chip. The hub chip is directly connected to the output of the 575. Custom 575 chips are used which have the correct frequency for the hub chip. There are 5 LT3042 regulators powering different circuits. John S.
  14. Its already sitting on a ground plane. John S.
  15. SMPS and grounding

    Just to clarify, the Mean Well was connected to the adapter, then the adapter was connected to the LPS-1? Did the LED on the LPS-1 ever come on? Did it come on red then go off? Did it go read, then amber then sometime during amber go to red? Did it flashing red? Something else? The sequence of events is very critical to trying to figuring what is going on. Thanks, John S.