[sdiy] Wanted: non mathematical description of the function ofRC-filters

[cheater00 .]

Hi Neil,

>> the one thing that wasn't addressed in the explanations here, and is
>> confusing, is that you're not talking about the frequency of the
>> signal (as some have said), but the frequency of a partial.
>
> Umm, no, I think that would just confuse people even more, since now
> you need to split a simple-to-understand continuous frequency spectrum
> into lots of discrete partials.

OK, let's do a short thought experiment and see how that pans out.

"""
My resistor-capacitor divider depends on the frequency of my signal.
It's the little man moving a cross-fader, looking at the frequency of
the signal. It will let half the sound disappear at 400 Hz and it will
let a quarter of it disappear at 200 Hz. (*)

So if I play an A440, then half of it should disappear? So it just
changes loudness. So notes that are higher should just be quieter. But
that's not how filters work. They don't only change the loudness, they
also change the timbre.

Now I'm confused. But I'm probably too stupid to follow this text, so
I'll just learn this by heart, and maybe one day I'll understand it.
"""

The thing is, I've spoken with quite a few musicians who gave exactly
the (*) asterisk explanation for filters. They didn't understand them.
And it's been a definition they've been using for a long time by then.
This specific misconception is not an uncommon occurrence. If you use
your authority to tell people untruths, they will go through life
burdened by them. Best not to tell any. Bear in mind many people are
able to accept things coming from the ivory tower as true without
being able to validate them, because they're not broadly technical,
and can't validate most of the things said about life surrounding
them.

A more knowledgeable musician might continue the thought with:

"""
>From my harmony lessons, I remember about overtones. This is like a
string ensemble playing lots of separate notes, each called an
overtone, that come together to form the timbre of the sound.

But the author mentioned the filter depends on the frequency of the
sound itself, not of the overtones. This article is needlessly
confusing.
"""

I find it's important to point in the right direction, even if it's
through a tiny cue. For example, instead of saying "the divider ratio
depends on the frequency of the signal going through it", just say
"the divider ratio depends on the frequency of the overtone going
through it", even without having used the word "overtone" before in
the article. All musicians know what overtones are. Any introduction
is just going to be a re-hash or reminder. However, by using the right
word for the concept you challenge the reader to go back in his mind
and actually bring up that concept, rather than build his mental model
with the wrong building blocks, as in the quotes above.


Hi Dan,

Dan Snazelle wrote:
>> Electronics is math.  The sooner
>> noobies understand that, the faster they can learn it properly.
>
> Geez....thats a pretty rough statement!!
> So does that mean that my 9 yr old son shouldnt try learning electronics
> because his math is too basic?

There are different levels of learning. In order to understand an
article at the level Florian is talking about, a lot of other
knowledge is required. For example, you need to know what a filter is
and what it does at all, how sounds filter through it etc. Then
there's the question of what resistors are, do experiments with light
bulbs, and so on. They're things that we find obvious, but your son
needs to learn them as well, and it's a lot of work. That, and other
things he needs, are about 4 years of casual learning for a 9 year
old. Once he's 13 his algebra is likely to be better. But you have to
challenge him with mathematics repeatedly for this to happen.

> Just because you are scared of math doesnt mean you dont want to learn
> electronics.
> and there are different needs and motivations among people

Just because I'm scared of the weights doesn't mean I don't want to be
a body builder? Buckle up and bite through a few books, that's what I
had to do. I've had really serious mental blocks when starting out
with higher math. Took years to clear. It was really fun but also very
challenging. However, math really is indispensable if you want to know
what's going on inside the wires - just like weights are indispensable
for building muscle. I can only encourage you to pick up some weights.
Anyone can do it, but it takes a lot of time to get anywhere.

Cheers,
D.