Origineel geplaatst door krz
Olaf,
zou je wat Hordijk tips met ons willen sharen? 
ok je hebt er om gevraagd, hier ff een outtake van postings die ik zo snel kon vinden..lang niet alles is natuurlijk toe te passen op een fixed architecture synth, maar met wat inventiviteit kom je al een heel eind, en het levert ook nieuwe inzichten op.....alles dus copyright rob hordijk:
The different looking waveforms don't necessarily have to sound that
different. They are undoubtedly sampled at the line output of the synths and
had to go through all the other circuits as well.
In fact at the internal outputs of the oscillators the waves in general are
pretty accurate, unless they are made by one of those dreaded DCOs that make
little stairs instead of smooth ramps. Then the signal goes through at least
a filter, a VCA and some output buffer. The AC coupling used between these
circuits acts as a highpass filter causing slight frequencyshifts that can
dramatically alter the appearance of a waveform without significantly
altering the harmonic content. Then there is the dreaded (or blessed)
nonlinearities of the OTA circuits used in both filters and the VCA. Often
there are clipping diodes in the filter to reduce the high level of the
resonant peak. Also there might be small feedback capacitors in both filters
and VCA to prevent the circuit from radiofrequency oscillations, these work
as lp filters. Some synths have bass/treble controls or equalizers on their
output, you don't want to know how those can affect a waveform. Then there
might be overdrive present, e.g. the Rogue has an overdrive range on its
output level slider but others have it without printing it on the box.
On the MS20 square waveform you can see the effect of the HP part of its
HP/LP filter on the waveform.
The thing that imho makes the most difference is that the Modular has much
more high in its waveforms. The transients (corners) in the NM waveforms are
slightly enhanced, which makes the NM sound ultrabright. This little
enhancement makes the filters excite more with high resonances. But it can
also make the NM sound colder.
The trick I use to make the NM sound much warmer and much more analog is to
use a filter with a notch at 12kHz. Such a filter is patched by a static
12dB filter set to around 6.64kHz and adding a bit of the HP output to the
LP output (mixersettings LP:127 HP:90-102). This suppresses the transient
enhancements, masking the ultrabright very high harmonics and instantly
giving more depth to the sound.
Using a bit of feedback on this filter will boost the lower frequencies a
bit, you can even add a clipper in this feedback path to create a subtle
'korny' overdrive effect in the low.
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Perhaps you mean the high buzzy sound if the resonance is set high and the
filter is open. That effect is because digital oscillators contain
relatively much energy above 10kHz. Most analog oscillators have less energy
in this region, as the analog circuitry itself filters part of it away.
Imagine a sawtooth set to 200 Hz, then the overtones are 200 Hz apart from
each other. This means that in the area between 10 kHz and 20 kHz there are
50 overtones present, but its within a single octave. When using e.g. 3
slightly detuned oscillators you're talking about 3 * 50 = 150 overtones in
that one high octave, all phasing fast with each other. The amplitudes of
these overtones are very small, but there are a lot of them and very high
sounds are perceived quite well, so there is a distinct buzz in the high.
If, with high resonance, the cutoff frequency is set to this area it is
increased even more by the resonance. The resonance band of a 12 dB filter
is a bit broader than that of a 24 dB filter, so the 12 dB filter suffers a
bit more from the buzz.
The problem with this buzz is that it can mess up those other sounds that
have by nature lots of energy in the same band, notably hihats and cymbals
and some dipthongs in the vocals. E.g. its a good thing to filter everything
above 10kHz away from all instruments when there are hihats and cymbals in
the rhythm track or if you use vocals from someone with a clear voice. Else
these hihats and the s's and t's will drown in the high of the other
instruments. Mostly its done by ear on the mixing desk with a parametric eq,
but when recording several tracks at once or without a good mixing desk its
best to get the right sound before recording. A 'de-esser' can help as well.
Its even worse if the 10kHz+ area gets in a reverb with a very bright tail.
That will start to produce lots of noise.
For most synth sounds, especially strings, its not the 10kHz+ area which is
important, but the area between 3.5kHz and 10 kHz. E.g. filtering away all
above 10kHz but slightly emphasising the 3.5 to 8 kHz area greatly improves
the warmth and depth of stringsounds. A single 6 dB LP filter set to 10kHz
won't do the job, it should be set to 2.5 kHz or less to effectively remove
the buzz, even a 24 dB filter should be set to something like 5kHz. But in
both cases you would also loose part of the important 3.5 to 8 kHz area. The
most useful solution imho is to use a dipfilter with a notch around 12 kHz.
Perhaps you didn't notice but I posted several patches last couple of months
with such a dip filter, when we were discussing 'Analog warmth'. I think
only Dave Peck picked it up.
Listen to the attached patch for a couple of minutes and you 'feel' what I
mean. Without the notch on the strings it sounds 'tense' and the HH drowns
in the stringsound, with the notch it sounds open and the tension is gone.
There is also a slight formant effect you can hear, if the sound sounds
slightly more like 'aah' or 'uuh' its generally felt pleasant, if it sounds
more 'ooh' or 'iih'-ish it has a bit more tension. The 'uuh' formant makes
the sound neutral, an 'aah' effect asks for attention, 'ooh' makes it severe
and 'iih' is like a conclusion.
This all just to make clear that there happens so much in sound. This has
lots to do with harmonicity, an obscure subject at first, but basically if
too many overtones of different sounds and notes start to conflict with each
other it starts to feel tense. By filtering away a conflicting band in one
of the sounds, especially if that band is emphasized in another sound, you
can get much more control. In fact thats what most of postproduction is
about and why multiband compressors have become so important. And why
professional records sound so good. E.g. you don't have to like the songs on
that latest Kylie Minogue album, but listen to its sound and how its
produced, its a production masterpiece. There's hardly ever a moment when a
sound is soundwise conflicting with another sound, instead they all seem to
emphasize each other to get that snappy drive.
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