Oh, I missed that, but it was 10 years ago and I haven't read everything on the board since I signed up. I'll read through more carefully, and may want to start a new thread similar to that.
I'm thinking the reason this technique was never used outside of magnetic tape recording) is it's usually "too complicated" (too much extra circuitry) and not enough benefit, though it was clearly needed for magnetic tape.
Yet another thought, dithering noise for lower bit depth ADCs was common to reduce sampling distortion before delta-sigma took over everything. AC bias does a similar thing, and I'm wondering if such noise (probably filtered so that it's all ultrasonic) could be used in tape recording as well as other magnetic-related applications. This seems off-topic for an oscillator, but maybe not.
Another check of another 15K and a Yaego. The Dales are clearly defective. Both distortion and noise. The second 15K noise was 30 dB higher than the Vishay foil. The Yaego was about 10 dB higher than the Vishay, all measured at .1W. The noise problem suggest a real manufacturing problem, most likely termination but it could be flaws inthe laser trimming.
These instruments were created to weed out bad parts for high reliability applications, not for audio nuts BUT they are great for checking nonsense audio claims.
These instruments were created to weed out bad parts for high reliability applications, not for audio nuts BUT they are great for checking nonsense audio claims.
Thanks for running the quick test. Will be interesting to see the rest particularly the ones that seem to measure clean.
Correction: The Holsworthy are the YR1B. I think all of my previous posts had the series part number reversed.
Wow.
Not bad for the Yageo considering the "60 dB" difference in price. IIRC the Vishay S102 is at or near the noise floor?
I believe so. Unfortunately I have never found a manual for this version of the 315. Its quite different from the older version. However Noise index is a standard https://eepower.com/resistor-guide/resistor-fundamentals/resistor-noise/# and the S102 are at the low end on the chart. I think I have a 10K wirewound in my collection which will also have very low current noise. I'll also look for a carbon comp 10K.
Here is an interesting thought- carbon comp resistors could have noise modulation with the signal, particularly at low frequencies. Maybe thats a euphonic thing some people like?
Here is an interesting thought- carbon comp resistors could have noise modulation with the signal, particularly at low frequencies. Maybe thats a euphonic thing some people like?
Resistor noise index:
INDEX, the unit of measurement, as defined in the NBS report is “the ratio of the rms noise voltage, in
microvolts, to the applied dc voltage, in volts, expressed in decibels, when the associated pass band
for the noise is one frequency decade.” Or simply pV/V/Dec in dB.
INDEX, the unit of measurement, as defined in the NBS report is “the ratio of the rms noise voltage, in
microvolts, to the applied dc voltage, in volts, expressed in decibels, when the associated pass band
for the noise is one frequency decade.” Or simply pV/V/Dec in dB.