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Re: Burning in hi-pass capacitors
Here are some measurements that may shed some quantitative light on the Cross-Cap vs Superior Z-Cap discussion.
Luckily, I had a 4.7 uF Jantzen MKP 400 V Cross-Cap and a 3.9 uF Jantzen 800 V Superior Z-Cap to test. I ran some special tests with my WT2. Not a megabuck test instrument, but a very effective one just the same. The test methodology is the subject of a forthcoming article in audioXpress magazine.
Screenshots of the test output are below (thanks to some help from bkeane..). The test measures Capacitive reactance, phase, ESR and Capacitance from 10 to 20 kHz over 31 data points. The plots in the left window are impedance (red line) and phase (blue line) The best caps I've tested show phase at a nice flat line at the -90 deg level. Both of these do. I've seen full or 1/2 smile profiles in the blue line with vintage NPE's and other caps. Secondly, variation in the reading of phase and capacitance over the test freq. range is minimal in very good caps. To evaluate this, basic statistics are run on the phase and capacitance columnar data. I like to use coeficient of variation (st'd dev./ave) express as a % to quantify the variability. The cross cap phase was 0.52%, capacitance COV was 0.404%. The Superior Z-Cap was 0.28% and 0.38% - a little better. COV's on vintage NPE's and others's were typically well over 1% and some as high as 5%.
Measurements taken with my TENMA LCR meter were 3.908 uF and 0.1% D.F. for the Superior Z-Cap and 4.805 uF and 0.1% D.F.
The bottom line here is that both caps, though not identical in their capacitance, voltage values are never-the-less very close with respect to their variability.
Originally posted by bkeane1259
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Luckily, I had a 4.7 uF Jantzen MKP 400 V Cross-Cap and a 3.9 uF Jantzen 800 V Superior Z-Cap to test. I ran some special tests with my WT2. Not a megabuck test instrument, but a very effective one just the same. The test methodology is the subject of a forthcoming article in audioXpress magazine.
Screenshots of the test output are below (thanks to some help from bkeane..). The test measures Capacitive reactance, phase, ESR and Capacitance from 10 to 20 kHz over 31 data points. The plots in the left window are impedance (red line) and phase (blue line) The best caps I've tested show phase at a nice flat line at the -90 deg level. Both of these do. I've seen full or 1/2 smile profiles in the blue line with vintage NPE's and other caps. Secondly, variation in the reading of phase and capacitance over the test freq. range is minimal in very good caps. To evaluate this, basic statistics are run on the phase and capacitance columnar data. I like to use coeficient of variation (st'd dev./ave) express as a % to quantify the variability. The cross cap phase was 0.52%, capacitance COV was 0.404%. The Superior Z-Cap was 0.28% and 0.38% - a little better. COV's on vintage NPE's and others's were typically well over 1% and some as high as 5%.
Measurements taken with my TENMA LCR meter were 3.908 uF and 0.1% D.F. for the Superior Z-Cap and 4.805 uF and 0.1% D.F.
The bottom line here is that both caps, though not identical in their capacitance, voltage values are never-the-less very close with respect to their variability.
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