QUALITY AND SECURITY OF "LITTELFUSE" PRODUCTS

Peter, you’ve probably seen various references I’ve made to Littelfuse datasheets in the thread on SR fuses. And yes, Littelfuse is definitely to be commended for the very comprehensive, technically unimpeachable, and confidence inspiring information they provide on their fuses.

I have no doubt that Littelfuses of the same current ratings, voltage ratings, fast/slow ratings, and physical size as the ones in your equipment would provide proper protection, and would also not blow when they shouldn’t. As to how the resulting sonics would compare with either the stock fuses that are used in your components or with SR or other audiophile-oriented fuses, in the absence of reports from a variety of users who have performed careful, thorough, and unbiased direct comparisons in a variety of components and circuit applications (e.g., both AC mains fuses and DC rail fuses), I don’t think anyone can do more than speculate. And I think it can be expected that more often than not audiophile speculation will be in the direction of assuming that solid engineering and low price = inferior sonics.

Best regards,
-- Al

Yes, that's correct Yogiboy.  See my posts dated 3-14-2016 in the SR fuse thread.

Regards,
-- Al
 

Thom and Bdp24, thanks for providing those inputs and perspectives.  For those who may be interested in the meaning of "breaking capacity," also known as "interrupting rating," those terms are defined on pages 6 and 7 (pdf pages 10 and 11) of the following Littelfuse document:

http://www.littelfuse.com/~/media/electronics/product_catalogs/littelfuse_fuse_catalog.pdf.pdf

Regards,
-- Al
 

Geoff, searching for the terms "direction," "directional," and "directionality" in the 294 page fuse catalog/design guide I linked to above, as well as in the search box provided at the Littelfuse home page, returns nothing that is relevant to your question.

Regards,
-- Al
 

Nonoise, thanks for providing the link. As some here will recall, the HiFi Tuning measurements were discussed extensively several years ago in the very lengthy "Fuses That Matter" thread. I provided comments on those measurements in a number of posts in that thread, most notably in my post about 3/4 of the way down on this page, dated 5-14-2012, 11:24 am EDT.

Thom, in addition to his comments above about power cord resistance/voltage drop, in a number of past threads Ralph has also emphasized that a power cord should provide bandwidth extending up into the tens of kHz, especially in the case of power amplifiers (since as I’m sure you realize their current draw typically consists of narrow spikes of high amplitude during a relatively small fraction of the 60 Hz cycle). And as you mentioned shielding also figures to be a significant factor in many cases.

I would add, though, that low resistance and hence low voltage drop, wide bandwidth, and good shielding in a power cord can be obtained at much less than kilobuck prices.

Regards,
-- Al

P.S: BTW, Thom, I like your taste in speakers :-) (Mine are Daedalus Ulysses, which when I was last aware were your reference speakers).

+1 to the comments just above by Ralph (Atmasphere) and Mapman.

Regarding "Does components with best spec sounds the best?":

As you appear to be implying, the answer is "of course not."  Sometimes "better" specs can even be an indication that the component will sound worse, because they indicate a misplaced priority in the design. But a more expensive component doesn't necessarily sound better than a less expensive component, either. And that is particularly true when it comes to cables and power cords, IMO. As you've probably seen, the degree of correlation between cable price and cable performance has been discussed in many prior threads, such as this one.

An excerpt from one of my posts in that thread, which relates to the point Ralph made just above:

It seems to be generally agreed by most audiophiles that cable performance cannot be either fully explained or fully predicted based on generally recognized science. It follows from that, however, that the cable designers have no way to accurately predict the point of demarcation between optimization of a given cable parameter or design characteristic and what may be overkill of that parameter or design characteristic, which will accomplish nothing in most or all applications. Therefore it can be expected that what is likely to be a significant driver of the cost of many very expensive cables is overkill of some or all of their design parameters and characteristics, which will accomplish nothing in most or all applications.

Regards,
-- Al

The following was composed prior to seeing Bdp24’s post just above:

Regarding Bdp24’s statement which Joecasey quoted above, according to Stereophile’s review of the RM9 the amplifier’s main B+ supply is 450 volts. That would be DC of course. Although Bdp24’s reference to the HFT fuses not being "suitable for use in a DC circuit" was perhaps worded a bit ambiguously, I suspect that what he was alluding to is that the HFT fuses didn’t blow when they should have because they did not have sufficient "breaking capacity" for a 450 volt application. NOT that those or other audiophile-oriented fuses are unsuitable for use in **any** DC application (which appears to be what Joe interpreted the statement to mean).

If that same fuse (or a similar fuse differing only in its current rating) had been used in an AC mains application, it would only have had to deal with 120 volts (in the USA and other 120 volt countries), rather than 450 volts, which it presumably/hopefully would have been able to "break" reliably.

See the Littelfuse link in one of my earlier posts in this thread for the definition of "breaking capacity."

Regards,
-- Al

I myself am not comfortable installing fuses designed by someone unfamiliar with the concept of breaking capacity into my $5000 amplifier....

My sentiments exactly.  :-)

Best regards,
-- Al
 

Geoffkait 4-8-2016 8:11am EDT
If fuses were not directional in AC circuits then we wouldn’t be getting all these reports of directionality. The data sheets provided on the HiFi Tuning web site contain the statement that even for AC - Resistance measurements directionality of fuses was noted. Case closed.

Regarding the measurements described in the HFT paper (which Nonoise was kind enough to link to earlier in this 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.

Regarding the anecdotal reports Geoff refers to, such as those provided by various A’gon members in the current SR fuse thread, those are the one reason for which my mind remains somewhat open on this issue. Particularly given that some of those reports emanate from sources I consider to be particularly credible, such as Charles1dad among a few others. But while in those particular cases I certainly don’t question the reported perceptions, I also don’t rule out the possibility that subtle and non-obvious effects may have been in play which resulted in attribution of the perceived effect to something other than the variable that was actually responsible. Perhaps even differences in contact integrity.

If as Geoff indicated the case is indeed closed, I hereby submit a petition for "certiorari" to the highest judicial body having appropriate jurisdiction, namely the individual judgment of each reader of this thread, who can and will decide for themselves. :-)

Regards,
-- Al

Ralph, yes, that is very conceivable to me, even in the cases of the most astute and sincere listeners. As you’ve probably seen, I’ve mentioned in many past threads how easy it is in audio to attribute a perceived change to the wrong variable. And even if steps are taken to assure that comparisons are made under equal states of warmup, just the fact that power has been cycled could conceivably result in perceptible differences, especially if the component includes significant digital circuitry. We all know how the behavior of a computer can often change when it is rebooted, usually for the better. And unlike a computer the sonics of an audio component may additionally be susceptible to differences in the levels and characteristics of internally generated digital noise that might result from re-initialization of the circuitry.

Best regards,
-- Al

I'll add my thanks to Roger as well, for an excellent elucidation of fuse fundamentals that unfortunately are not widely understood.

Best regards,
-- Al