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

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

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