Capacitor value substitution

[goraman]

Would substituting a 3.9 uf for a 4.0 uf film cap alter the cross over point enough to make any real audible difference?

[Reid Malenfant]

Not really no... Most capacitors are rated at 5 or 10% tolerance.

[goraman]

Not really no... Most capacitors are rated at 5 or 10% tolerance.

Good enough for me then!
Thanks, Mark

[goraman]

I wonder why they don't just call them all 4.0 uf caps then,why 3.9 ,4.0 ?

[Reid Malenfant]

Jeff, some do manufacture closer tolerance components. 39 or 3.9 or 390 is in line with the resistor values so not too far out of whack :eyebrows:

The 4uf capacitors are more out of line of standard values in reality ;)

[goraman]

Jeff, some do manufacture closer tolerance components. 39 or 3.9 or 390 is in line with the resistor values so not too far out of whack :eyebrows:

The 4uf capacitors are more out of line of standard values in reality ;)

Now i'm really confused,the caps uf value needs to correspond with the resistor value?
As you can tell other than swapping one same value part for another I know nothing about how a crossover works.

[Reid Malenfant]

Now i'm really confused,the caps uf value needs to correspond with the resistor value?
As you can tell other than swapping one same value part for another I know nothing about how a crossover works.
No Jeff, don't worry about it m8 ;) There are what is know as 'standard values' in most components, but there are also much closer tolerance components available.

3.9uf is much more in line should I say than a 4.0uf capacitor. If the 4.0uf capacitor is more than a few years old it really won't be precisely 4.0uf, it'll likely be between 3.8uf & 4.2uf & that is going on a 5% tolerance. 10% = 3.6 & 4.4uf ;)

With standard values you'll get a good enough replacement as 3.9uf is as you can see pretty close to the mark.

The same standard values are applied to both resistors, capacitors & as a third inductors. You want something that doesn't come in those then it'll cost you...

[Rare Bird]

Jeff:

i'll send you some notes regarding value Standardization

:)

[goraman]

Thanks guys,
I get it now,Andre after reading a little it makes sense not to have a whole lot of caps just a 10th of a percent apart from each other.
I just don't get why they didn't use nice round numbers like 1.0 1.5 2.0 2.5 ect....
But that's ok.
How long will film caps stay in spec?
I know electrolytics can begin to drop after 10 years.

[Reid Malenfant]

I doubt a film cap will likely go out of spec in your lifetime Jeff, unless it was subjected to more than it's voltage rating or other forms of abuse ;)

[goraman]

I doubt a film cap will likely go out of spec in your lifetime Jeff, unless it was subjected to more than it's voltage rating or other forms of abuse ;)

Thanks, Thats good news.

[Rare Bird]

self healing is a good point

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