Casio MZ-2000 - Manual (Page 31)

30
MZ-2000 MIDI Implementation
* System Noise Gate
1. System Noise Gate
4.8.3.2 Effect Connections
Monaural/Stereo
Effects include monaural and stereo types, so signal flow must be considered when making con-
nections.
There is one monaural type input terminal and two stereo type input terminals, and two terminals
each for monoaural and stereo outputs. This means that the monaural/stereo type of the effect is
determined by the input type. In the case of a monaural effect, the same signal is ouput from both
of the output terminals.
[=========]----->
--> [ Mono FX ]
[=========]----->
--> [===========]----->
[ Stereo FX ]
--> [===========]----->
Monaural Effect and Stereo Effect Connection
Connecting a stereo effect after a monaural effect outputs two monaural effects, each of which is
connected to the two stereo effect inputs.
[=========]----> [===========]----->
--> [ Mono Fx ] [ Stereo FX ]
[=========]----> [===========]----->
Stereo Effect and Monaural Effect Connection
Connecting a monaural effect after a stereo effect causes a signal that mixes the two stereo effect
outputs to be sent to the monaural effect.
--> [===========]---->+ [=========]----->
[ Stereo FX ]----> [ Mono Fx ]
--> [===========]---->+ [=========]----->
Assingment of a Stereo Effect to a DSP
Assigning a stereo effect to DSP1 connects two input lines to DSP1, without any signal being sent
to DSP2.
-----+--->[DSP1]---->
-----+ x-[DSP2]---->
Conversely, no signal is sent to DSP1 when a stereo effect is assigned to DSP2.
The above also holds true for DSP3 and DSP4.
Parallel Use of Two Monoaural Effects
Selecting A + B as the input line when monaural effects are assigned to DSP1 and DSP2 causes
Part L output to be sent to DSP1, and Part R output to be sent to DSP2. Selecting the same effect
for both outputs in this configuration produces a stereo effect.
+--->[DSP1]---->
=====
+--->[DSP2]---->
4.8.3.3 Resource Problem
The DSP resource problem is the point that requires most attention when loading effects.
MZ-2000 effects are produced using Digital Signal Processors (DSP), but the DSPs to not possess
sufficient resources to allow discretionary assignment of effects to all effect parts at the same
time. Simultaneous assignment of a number of effects makes use of further effects impossible.
Because of this, a dynamic resource allocation system for DSP effects is employed in order to
ensure efficient use of DSP resources.
More concretely, the same resources are used by DSP1 and B, and by DSP3 and D, so when DSP1
uses up all the available resources, Insertion B is undable to use effects. This does not, however,
effect DSP3 or D, System Chorus, Reverb, Master, or other effects.
Modification or addition of effect assignments by DSP1 causes DSP1 signal flow to be tempo-
rarily muted. Due to the resource sharing relationship, the DSP signal is also temporarily muted.
The same relationship applies to DSP3 and D. Though the actual mute time depends of the makeup
of the effect, it can be anywhere in the range of 20 to 100 milliseconds.
Be sure to keep all of this in mind when changing effect assignments while playing.
If resources are insufficient for sequential assignment of effects to each DSP segment, further
assignment of effects becomes impossible. Th extremely complex decision making process re-
quired to determine what combination of resources leads to a shortage is beyond the scope of this
document. Probably the easiest and most practical way to determine whether a particular combi-
nation can be used is to try it out on the MZ-2000 and see what happens. If a shortage of resources
occurs after receipt of an effect assignment instruction, you can determine whether an effect has
not been loaded by re-setting the DSP line effect to Thru on the MZ-2000.
In addition, when switching effects of DSP multiple segments, all of the semgnets must be cleared.
Let us say, for example that effects A, B, and C are assigned respectively to DSP 1, 2, and 3, and
you want to change the assignments of DSP 2 and 3 to effects D and E. The new effects could be
assigned in the sequence 2, 3 or 3, 2, but the number of resources consumed by effect A assigned
to DSP 1 can cause a shortage of resources when you try to assign effects D or E to DSP 2 or 3.
Because of this, you must clear DSP 2 and 3 first.
[A]--[B]--[C]
V
[A]--[D]--[C] This combination may be impossible.
[A]--[B]--[C]
V
[A]--[-]--[C] Clear [2].
V
[A]--[-]--[-] Clear [3].
V
[A]--[D]--[-] Replace [2].
V
[A]--[D]--[E] Replace [3].
The clear operation is achieved by changing the patch parameter effect select block parameter of
the applicable part to execute a NOFX (No Effect) effect select instruction.
MdevID=2F00H
TypeID=0000H
Number=0000H
For details about send messages, see "4.5 Selecting Patch Effects."
4.8.3.4 Distortion
Distortion can be caused by changing the parameters of the effectors so signal level related set-
tings cause the amplification factor to be greater than the sound source, and then using thoses
effects in combination. Since this is basically unavoidable, you need check your settings and
avoid setups that cause distortion to be generated.