Parallel equalization
The original machine that Pulsar Massive emulates is a parallel equalizer. If we were to take a
quick look at the electronic structure of the unit, we would see that:
The overall structure consists of two passive filtering networks (Boost and Cut) in series
(processed one after the other), followed by two amplification circuits: one for positive gain
filters and one for negative gain filters.
Within each of the Boost and Cut structures, the filter blocks corresponding to the 4 bands
of the EQ are wired in parallel, which essentially means that they all filter the same input
signal, and the filtered signals are then summed. By constrast, in most other modern
equalizers, the filters are successively applied to the signal and they are said to be in
series.
Here is a quick example of parallel equalization. Let's take two bell filters of about 20 dB of gain,
placed at about 600 Hz and 1 kHz. You can see the frequency responses below:
Two bell filters at close frequencies.
Now, take a look at the combination of these two bell filters performed with a series equalizer (in
yellow), and with a parallel equalizer (in blue). You can see that with filters of 20dB maximum
gain, the series equalizer gives a response that can reach up to 40dB. With a parallel equalizer,
on the other hand, the response never exceeds 20 dB in total.
Difference between the combination of bell-shaped filters in series and in parallel.
Pulsar Massive - User Manual - page 13 / 35
