Popular Post One and a half Posted April 26, 2020 Popular Post Share Posted April 26, 2020 Rather than getting bogged down in too much detail, the input impedance on 'scopes are best 9M Ohms. Differential types off the shelf at Keysight are worse impedance If the noise we are measuring between equipment, say a PC and a DAC is in the microvolts at mutliples of SMPS frequencies of 100kHz-22kHz, adding s a scope lead will bring these values to zero and nothing can be seen, makes sense to observe, but it's not right. Unless input impedance of probes approach that of GigOhms, then hey. that's closer to reality and there will be noise to measure. Just trying to relate to what I heard on different USB cables now three years ago. Summary of the results Curious USB cable in my system dropped the sound stage height significantly and introduced (audible) distortion Generic printer cable removed the distortion, but didn't add any height and not very exciting Nordost blue Heaven cable restored the balance of height and (little if any) distortion The Nordost A cable connector measured closer to the USB standard than the Curious and was a tighter fit (less of a loss) Anecdotal reports from some 'early' USB cables not working at all with DACs (stutter, droputs, no sound) leading to the whole cable impedance and length of USB cabling debate. Here's a practical and important application of the right cable that matches the spec of a phono cartridge. So each cable has its unique properties of L, C, and R. That looks like a filter formula does it not? When it comes to phono stage cabling (between the cartridge and the phono pre-amp), the more capacitance will roll off the highs considerably. The spec for my Ortofon 2M Blue MM cart recommends 150-300pf of loading and I thought OK, I could use RG-6 for the length was 63pf, plus the cable in the tonearm already (?) should be OK. Well not quite right (maybe too low), noted sibilants on some records, and swapped out the RG6 with an Accuphase AL10 which has 260pf/m. Sibilants are now under control gone, that was today's task. Here's the spec, one manufacturer that publishes data (and not afraid to). sandyk, Audiophile Neuroscience and Teresa 1 2 AS Profile Equipment List Say NO to MQA Link to comment
Popular Post One and a half Posted May 24, 2020 Popular Post Share Posted May 24, 2020 1 hour ago, sandyk said: NO ! It definitely is NOT !!! Virtually all NOS large value electros for example , benefit from further forming, and many DIY Audio members even use a " Cap Rack" to help quickly stabilise larger value electrolytic capacitors. Many hundreds of DIY Audio and other forum members who have constructed the John Linsley Hood designed PSU Add-on from the >800 PCBs made available for this project have found that the resulting SQ varies dramatically in SQ for around 72 hours as the large value Capacitance Multiplier electros reach stabilisation with the typically low 600mV across them. When using 2 parallel 4,700uF in that area some constructors found that the Current Limiter transistor often became quite warm initially. Agreed, NOS electrolytic caps need to be reformed before use. I have seen evidence of applying full volts on old caps, it's like the effect from the film Alien, where the creature came from within. The cap juice spreads everywhere, it's a horrid job to clean. Reforming avoids a lot of hard work, and cap juice is conductive, so it really needs to be removed carefully. Most caps, the large electros have a build date on them, they should be powered on within two years of the build date at full volts, if not reform them, the above method is ok, there are many others, current limiting is another, variable voltage over a period of time is another one or a combo of both, the electrons have to go back on the film in the cap and stay there, needs a time period which is not milliseconds. John Dyson and sandyk 1 1 AS Profile Equipment List Say NO to MQA Link to comment
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