While real circuitry can process a signal within a few nanoseconds, digital models calculate per
sample, adding about a million times as much latency to each iteration. The cumulative effect of
feedback latency in digital emulations is very noticeable. Oversampling and higher sample rates
help reduce the latency, but conventional digital filters always “smear” at high resonance levels.
Methods of addressing the latency have been available for many years, but the implementations
either 1) don’t model the complex distortion inherent in real circuitry, or 2) aren’t suitable for
realtime processing. Common to all methods is that they predict output values and use that
prediction in the current calculation.
Of course we can’t see into the future either, but our routines are fast enough to deliver at least
a few voices in realtime. We calculate the filter with a few test samples and look at the deviation
between the prediction and the result, then we use that deviation to calculate a better prediction.
The goal, of course, is to close the gap as quickly as possible!
Diva applies a classic trial-and-error principle but includes a rather intelligent way (or so we like
to think) of learning from mistakes. As a rule of thumb, Diva’s filters only need to be calculated
once or twice in succession. However, it can take up to 15 cycles if the resonance is very high
and/or the input is very complex, for instance noise.
Accuracy
Click on the MAIN button at the bottom of the window. In the panel above the button are two
selectors called Accuracy and OfflineAcc. These are global parameters, they remain fixed
across all presets per loaded instance:
draft CPU-friendly, but FM will sound rough and resonance is primitive (not ‘zero delay’)"..........
fast Fine for older computers and/or when you need more polyphony in acceptable quality"............
great The best compromise between quality and polyphony on high-power computers"........
divine Top-quality zero delay feedback filters – but can your computer can handle it? .......
OfflineAcc selects the resolution at which Diva instances are rendered to audio (offline). The
two options are same (same as the Accuracy setting) and best. Some hosts have trouble
rendering at the selected accuracy, while the better ones include an “inform plug-ins of offline
rendering status” or similarly named option.
Control Bar
Save
First, right-click on the [save] button to check (or change) the format you will be using. Standard
is .h2p, which has the great advantage of being cross-platform compatible. The .h2p extended
format is the same but also allows per-line comments.
Important: If you have set the Save Presets To preference from the default user folder to the
other option, selected folder, make sure that the folder in which you want to store your preset is
already selected – if not, click on it first.
Click on the [save] button, give your preset a name and enter any other details. Preset
description, playing tips etc. – anything you would like to appear in the PRESET INFO panel of
the browser. Finally, confirm by clicking on the apply button. If you have loaded Diva as VST2,
you will also see the option .nksf. See the NKS chapter.
MIDI activity
Small indicator which flashes whenever MIDI data is received.!