Subtractive synthesis on FL

M

mornview

New member
I have a question about the Sim Synth Live plugin for FL Studio; perhaps those without FL would be able to answer it as well, but either way, I hope there's an easy answer to this question.

First off, while I realize it's not really a close enough screen shot to be of much use, here's a picture of the synth:

plugin_gen_simsynth.gif


Now, the problem I'm having is finding a low-pass filter, since I want to create a bass sound. From what I understand, a low-pass filter is pretty much standard on subtractive synths, right? Now, the filter section of the synth offers four paramaters (this is quoted from the help manual):

Cut Off Frequency wheel (CUT) – The base cutoff frequency of the filter, from 0% to 100%.

Filter Emphasis wheel (EMPH) – Also called resonance and Q. Emphasizes the frequencies near the cutoff. A little emphasis is useful for general purpose synthesis. A lot of emphasis sounds highly electronic and is useful for techno or special effects (together with cutoff frequency variations).

High Pass Frequency wheel (HIGH) – Sets the high pass frequency of the filter. Note that this knob reduces low pass output as high pass output is increased. Set to 50% to produce a notch filter.

Band Pass Frequency wheel (BAND) – Sets the band pass frequency of the filter. Note that this knob reduces low pass (or high pass as specified by the high knob), as band pass output is increased.

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That's the part that confuses me ... it looks like all the filters will only cut out low frequencies - they all have a range of 0% to 100%, and they all seem to cut out low-pass when they're turned up, at least, from those descriptions. But that "notch filter" thing in the high-pass filter is what confuses me ... does this mean that settings from 0-49% affect low pass and 51-100% affect high pass?

In addition to that, I've been looking into harmonics a bit, and what I need to know is - how do you know when a harmonic series ends? Like, I was looking at one synth and it said that it was an "8 Voice Synth" - does this mean it goes from "F" to "8F"? Most of the time I see people talking about harmonics they usually go through "8F".

Thanks for reading, and a huge thanks in advance if anyone can help me with this ... this particular plug-in I've found to be extremely useful for learning subsynthesis, but these are some things I just can't figure out on my own ...
 
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You got it the other way around with the LPFs. A low-pass filter will cut *higher* frequencies starting at the cutoff frequency. think of it as "low frequency passes through". tweak the cutoff knob to around 1/3 from 0%, leave highpass at 0 and turn all filter modulation off (envelopes and lfos - the two knobs right above filter settings, I guess). you should hear as the signal is filtered to a pure bass tone. :)

As for the number of voices, it regards polyphony, as in the number of simultaneous notes (voices) it will play. Harmonics are a whole different ball game and will be treated more directly when setting up the the oscilator section.

I hope I'm making myself clear. there's a lot more to be said but rambling on is inevitable lol
 
dedo nervoso said:
You got it the other way around with the LPFs. A low-pass filter will cut *higher* frequencies starting at the cutoff frequency. think of it as "low frequency passes through". tweak the cutoff knob to around 1/3 from 0%, leave highpass at 0 and turn all filter modulation off (envelopes and lfos - the two knobs right above filter settings, I guess). you should hear as the signal is filtered to a pure bass tone. :)

As for the number of voices, it regards polyphony, as in the number of simultaneous notes (voices) it will play. Harmonics are a whole different ball game and will be treated more directly when setting up the the oscilator section.

I hope I'm making myself clear. there's a lot more to be said but rambling on is inevitable lol
Click to expand...

I think I see what you're saying ... I set the cutoff to 1/3 so that I'm pretty much only getting the bottom third of the sound; the bass part. But the thing that's confusing me is, how does it know if I want to cut the frequencies above the 1/3 mark or below it?

What I'm saying is, the cutoff knob only sets where I want to cut-off frequencies, right? I need a low-pass or high-pass filter to then actually cut out those frequencies, correct?

I hope I'm making myself clear enough ... I just really want to know how this stuff works! :)
 
how does it know if I want to cut the frequencies above the 1/3 mark or below it?
Click to expand...
This depends on the filter type. The cutoff is not a separate entity, but a parameter to the filter itself. It doesn't know which frequency you want to cut, but you do, so it's up to you to choose the right filter for the job.

That means the so-called highpass knob controls also a cutoff frequency, except it is applied to a different highpass filter.

This applies to the way every filter handles a sound... a cutoff frequency will always be the point where the frequency cut is applied in whatever ways, which will depend on the filter type. An additional usual parameter in filters is the resonance knob you see, which will boost the level at the cutoff frequency point and so adding a new dimension for sculpting the sound.

Once you get past the jargon it really is cool to understand the workings of these machines so keep it up.

peace
 
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