Just as not all audible differences are measurable, not all measurable differences are audible.
The following is quoted from a post I made on 4-8-2016 in this thread:
https://forum.audiogon.com/discussions/quality-and-security-of-littelfuse-products?page=2
Regards,
-- Al
The following is quoted from a post I made on 4-8-2016 in this thread:
https://forum.audiogon.com/discussions/quality-and-security-of-littelfuse-products?page=2
Regarding the measurements described in the HFT paper (which Nonoise was kind enough to link to earlier in the thread) which purport to support the notion of fuse directionality:
1)Resistance measurements related to directionality were provided for 16 different HFT fuses, having current ratings ranging from 1.6 amps to 20 amps, as well as for a few competitive fuses and standard glass and ceramic fuses (the specific make of the "standard" fuses being unspecified). The differences in resistance for the HFT fuses in the two directions ranged from 0.000002 ohms to 0.000120 ohms. The differences in resistance for the competitive fuses were a bit greater in some cases, with the worst cases generally being the standard fuses, for which there was one isolated case having a measured difference of 0.005200 ohms.
IMO those numbers are so miniscule as to be:
(a)Laughable.
(b)Very possibly attributable to changes in the voltage of the battery in the measurement meter, from measurement to measurement (each measurement imposing a slight drain on the battery), and from minute to minute. Or if the meter was AC powered, to the very slight differences in AC line voltage that may occur from minute to minute, as various loads are turned on and off at nearby locations.
(c)Very possibly attributable to differences in contact pressure and contact area between the meter’s probe tips and the contacts on the fuse. The paper presents separate measurements of fuse resistance as measured in a fuseholder (for just one direction), indicating that the direction-related measurements were performed by touching the meter leads directly to the contacts on the fuse.
(d)Perhaps even contributed to by differences in the resistance of the measurer’s body, that would have been paralleled with the resistance of the fuse if he or she had fingers on the probe tips and/or the fuse contacts while the measurements were being taken.
(e)If Geoff’s comments about all wires being significantly directional are to be believed, then these differences would be totally swamped by both the resistances and the alleged direction-related resistance differences of the vastly longer associated wiring. In the case of mains fuses, that would include the power transformer and the power wiring in the component, as well as the power cord and the AC wiring in and outside of the house.
I’ll say also that the comments I provided on the HFT paper in the "Fuses That Matter" thread (linked to in one of my posts earlier in this thread) do nothing to provide confidence that these measurements were performed in a methodologically scrupulous manner, that would rule out the kinds of extraneous variables described in (b), (c), and (d) above.
Regards,
-- Al