truly 'scientific' A/B tests comparing film caps from different manuf?

[mxrshiver]

are there any actually 'scientific' tests out there evaluating the sound of Sozo vs Mallory vs whatever caps of the same value, with recordings posted?? i put 'scientific' in quotes because at the end of the process, it's still just your subjective ear evaluating the recordings... but that's even more reason why the process needs to be as clinical as possible for the results to have any significance at all. there's tons of youtube videos and threads about this, but all of them i've been able to find fall short of meeting all the following criteria, which i think are necessary to prove that any differences heard aren't due to other factors:

- capacitance must be actually MEASURED and verified to match within a tight tolerance between caps being swapped out, so that the 'differences' between 22nF's from different manufacturers aren't just because one's an 18nF and the other is a 27nF... stunning to me that i haven't been able to find a single test (with accessible recordings) that mentions doing this
- recordings must be taken from the SAME AMP, not 'two identical amps' as then other component tolerances could easily create the difference
- recordings must use the SAME EXACT INPUT, if someone's a really tight player and can produce studio identical takes of the same exact riff then that's passable, but ideally re-amping would be used so the signal is actually identical

additional criteria which aren't as strictly necessary, but i think would help ensure the results are significant and easily analyzed by ear:
- riffs should be short in length (around 5 sec ideal, no longer than 10 sec), and different riffs should use as many different styles and pickup types/positions as possible
- for comparison, recordings from different manufacturers should be randomized with the key hidden from the evaluator, and played directly back to back with no gaps in between
- tube amps only... if there are differences, they might reveal themselves in a guitar, but they should be more pronounced with much larger signal swings and DC voltages, so a tube amp would be the best method to evaluate whether differences truly exist
- coupling caps only for max DC drop and AC swing, see previous point
- ideally all the coupling caps in the amp would be replaced at once

i feel like anyone willing and able to go through the trouble to set up a test like this properly, doesn't, because they already know they're not going to find any difference, and value their time and money more than that. i'm all but convinced there's no difference, but i am immensely curious and very willing to be proven wrong, so i'd do it if i had the opportunity... but buying an entire amp's worth of fancy caps from multiple manufacturers just isn't in the cards for me haha.

[jbrrrrr]

I think the short answer is that there's just too many variables to satisfy all inquiries.  Besides the actual capacitance of the capacitor in question vs. the dielectric, capacitors also have a series resistance and series inductance that need to be taken into account, and that can spawn a whole other side conversation about whether that actually has any meaningful impact, requiring its own a/b testing and reporting, and then the variance of all the properties even between two similarly rated, same composition capacitors from the same manufacturer and establishing whether there is a tolerable variance... and that's just the capacitor.  We haven't even begun to speak about how that particular capacitor's properties might be influencing some other particular property, like tube type, power amp configuration, negative feedback, etc., when it's reported to have certain "improved properties" in a particular amp.

I think for as long as internet forums have existed for people to debate about this in real time, not to mention the age of magazine articles before that and reader submitted letters - this has been an argument, and there will always be some weird quirk to explain why someone hears something one way that justifies spending 10x for a part vs. buying the common, inexpensive variety.  And lack of experience will always make people curious if they'd be more skilled if they spent more money on parts, which will keep the machine chugging along into the sunset.

That's my $0.02, which is probably devalued to less than a penny with inflation.  YMMV. 

[tubeswell]

What’s the aim of your scientific testing?


Reliability? (At different voltages?, temperatures?)
Longevity?
Capacitance value?


Sonically, there’s no audible difference between a 16uF e-cap and a 20uF e-cap (or between a 22uF and 25uF etc) when used in the type of circuits in a guitar amplifier because the filter corner/rolloff frequencies are a product of (2 or more of) the values of capacitance, resistance and inductance (depending on the circuit).


Brand reliability is something you would want to do extensive and recurring sample testing for, to get some statistical information with a stated confidence interval to be able to make inferences about the general brand reliability.


Having said that, all IC caps are bad LoL

[shooter]

https://el34world.com/Forum/index.php?topic=19534.0

[Merlin]

You're unlikely to find such a test, since there will be no audible difference. The distortion properties of caps is well established now, you can at least find plenty of published information on that.

[JPK]

I swapped out Sprage orange drop coupling caps on my 5E3 from 0.1uF to 0.022 uF (reduce boomy bass) and could barely hear the difference. Yes I know it should make an audible difference. Point is I can barely hear it. You might. Not me. Different film caps from different manuf? Fagetaboutit.