                                Rez Synth


Rez Synth allows you to "play" bandpass resonant filter banks that are 
applied to the audio input signal.  The the center frequency of the base 
filter in any bank is controlled by MIDI notes.  The rest of the filters 
in each bank (if any) have center frequencies that ascend from the base 
frequency according to linear or octaval increments.  You can have up to 
3,000,000 filter banks active.

In Cubase, the way to make Rez Synth work is to first insert it as an 
effect & activate it.  Now it will be included as a MIDI device in 
Cubase's MIDI output devices list.  Select "dfx Rez Synth" as the output 
device for one of your MIDI tracks & now that MIDI track's output will be 
fed into Rez Synth & allow you to "play" Rez Synth.  You can either do 
that with a prearranged MIDI track or live with a keyboard when that 
particular MIDI track is selected.

I am told that Fruity Loops, Nuendo, Buzz, & Orion know how to send MIDI 
to plugins as well, but I've never tried those out & therefore can't tell 
you how to set my plugins up in those programs.  SynthEdit makes no 
distinctions between synths & effects.



bandwidth:

The bandwidth parameter controls the bandwidth of each resonant filter, 
in Hz.


bands per note:

This is how many bands there will be in each filter bank.  Each MIDI note 
that you play creates a new filter bank on top of any other banks that are 
already playing.


band separation:

This controls the separation width between each band in a filter bank.  
The way that it operates depends one which band separation mode you are 
working in.  If you are working in "octaval" separation mode, then band 
separation controls the separation width in semitones.  If you are in 
"linear" mode, then it controls the separation as a multiplier of the base 
frequency.

In addition to using the slider to adjust this parameter, you can also 
click on this parameter's value display & type a value in manually in case 
you need a precise value.


separation mode:

The band separation mode defines how the band sep. parameter operates.  
Separation mode can be set to "linear" or "octaval" (logarithmic separation).


attack & release:

These adjust the attack & release durations for each note, in milliseconds.


pitchbend range:

This lets you adjust your MIDI pitchbend wheel's range in semitones.


velocity curve:

This lets you adjust the key velocity response curve of your MIDI keyboard.


velocity influence:

This controls how much of an influence key velocity will have on the 
volume of each note.  A value of 0 means that key velocity is completely 
ignored & a value 1 means that key velocity is fully effective.


input gain scaling:

This parameter allows you to scale the gain of the input signal in the 
resonant filter operations.  It can be scaled according to the RMS of the 
resonant feedback or the peak of the resonant feedback, or you can disable 
scaling.


filtered output gain:

This allows you to control the level of the output signal after all other 
processing has taken place.


between gain:

This control the volume of the unprocessed audio input when no notes are 
sounding.


dry/wet mix:

This lets you adjust the balance of the input audio (unprocessed) & the 
output audio (processed).  100% is all processed.


legato:

Turning this on puts Rez Synth into legato mode (i.e. no polyphony, no 
space between notes, & no note envelopes).
Note that, while attack & release settings are inaffectual in legato mode, 
the fade mode is still relevant.  There are very short fades during each 
note transition in legato mode.  They are too short for the fade mode to 
make any audible difference, so you are best off setting the fade mode to 
the mode that is most efficient with your particular CPU.


fades:

Calculating the fades for attack & release takes a little extra processing 
power.  With this parameter, you can choose between "nicer" & "cheap" 
fades.  On my G3, the difference between cheap fades & nicer fades is 
approximately 1% extra CPU vs. 2%, but for some reason on my Pentium II, 
cheap fades use about 2% extra CPU during attacks & releases & nicer fades
 use about 25% extra.  The nicer fades, of course, sound smoother, but if 
you have a PC & are only using really short attack & release times or you 
need to conserve processing power, you probably ought to use cheap fades.


mistakes:

Because you are playing banks of resonant filters that ascend in center 
frequencies, it is possible to get filters in your bank that have center 
frequencies above what your digital sampling resolution can handle.  When 
this happens, frequencies "foldover" the maximum possible frequency & your 
filters start sounding rather odd.  I personally like that, so I have left 
the option up to the user whether or not to "allow" or "resist" these 
impossible bands.


careful:

The volume of the output of resonant bandpass filters is totally erratic.  
With careful mode enabled, Rez Synth tries to keep a handle on this & 
keep your output within a narrow range.  Whether you use this mode or not, 
I still recommend following Rez Synth with a limiter, & perhaps a 
compressor before that, too.



parameter adjustment tricks:  You can make fine adjustments by holding the 
shift key while adjusting a parameter with your mouse.  You can also reset 
a parameter to its default value by holding the ctrl key when clicking on it.



   important notes about compatibility:
Right now Cubase, Nuendo, SynthEdit, Fruity Loops, Orion, & Buzz are, to 
the best of my knowledge, the only VST hosts that support sending MIDI 
notes to non-synth audio-processing plugins.
If you load Rez Synth in other hosts, the host will basically behave as 
though it is ignoring every parameter except for between gain & dry/wet 
mix, making Rez Synth nothing more than a very fancy volume plugin.  
I am told that version 5 of Logic (due out January 2002) will support 
this kind of plugin.



            by Marc Poirier ~ destroyfx@smartelectronix.com
                         January/February 2001

                             Destroy FX #8
                     smartelectronix.com/~destroyfx

              comments, suggestions, & feedback are adored
