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| chorus ch-1 |
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- Updated [16/12/2005]
The development of this plug-in has been discontinued, in favour of the newest
and improved Chorus CH-2. Check it out!
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I needed a versatile chorus effect for my guitar recordings, so I made this plugin which
produces a rich sound by recreating up to 10 voices.
I've spent much time analyzing the output of some chorus effects with my
SG-1, to make an idea about the technology they use:
most of them show off signal reductions in the high frequency range, and produce messed harmonics around the
modulated signals. Most of these plugins use linear interpolation for frequency modulation.
My CH-1 uses instead an allpass interpolation.
It's computationally slower, but it doesn't reduce the high frequency components, and the
unwanted harmonics introduced are minimized, in a certain manner as some analog devices do.
Notice: CH-1 hasn't a GUI yet, it uses the graphics provided by your host.
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| details |
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Figure 1
This is the circuit diagram for Chorus CH-1, reffering to
the processing of a single, mono voice; it actually uses twenty
of these circuits in parallel.
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CH-1 can produce a wide stereo effect out of a mono track.
This is achieved by leading the frequency modulator with different phases:
each generated voice and each channel of the voice can have their own modulation by
tweaking the phase (L/R) and the phase (voices) parameters.
Furthermore, the stereo width parameter regulates the voices disposition in
the stereo field, ranging from 0%, which means all voices panned to center,
to 100%, which spreads the voices over the entire stereo field.
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Figure 2
Spectral difference between the allpass interpolation of CH-1 (left)
and the linear interpolation of most commercial plugins (right) -
the analysis was made with SG-1.
The test was conducted with a pure 5kHz sine as source, a
modulation rate of 1Hz and a modulation depth of 20ms.
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All-pass interpolation produces less unwanted harmonics than its linear sister.
Guitar sounds and human voices will be brighter, because CH-1 doesn't filter high frequencies
as many other choruses do: as a guitar player I always looked for choruses which produced a sound as
clean and clear as possible.
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Figure 3
Linear interpolation is a time varying LP filter, while all-pass interpolation
(as its name implies) lets the entire frequency range pass.
This test was conducted by feeding 10 seconds of white noise into CH-1 and
into a famous commercial chorus: I analyzed a single wet voice from both, set with a 0.1
modulation rate and a 20ms depth.
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CH-1 comes with varied presets that you can apply to guitars, voices and other instruments in
order to obtain rich, wide or weird sounds.
Below you can listen to some mp3 samples I made using CH-1 only.
Credit and admiration go to Jon Dattorro for his great articles about effect design.
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| sound samples |
I recorded these short samples using my Ibanez electric guitar played through my 200W Marshall
amp only.
The first is the dry, mono recording; the following clips contain the same arpeggio processed
by CH-1, with some of its presets.
The processed ones are in stereo format because, as you will notice, CH-1 can produce a nice
stereo image out of a mono track.
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| download |
Last updates:
- [16/12/2005] CH-1 v1.0 Final Released
Before downloading, please read the license agreement carefully.
This product is given to you for free.
CH-1 was downloaded by
5350 users since beta release (21/09/2005).
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| future development |
The development of Chorus CH-1 has been discontinued, in favour of the newest
and improved Chorus CH-2. Check it out!
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