User Manual

VII. EQ Filter Sections in Depth

We’ve put a large amount of time, effort, money, and listening tests into the research and development of the

analog stages of the Bettermaker EQ232P. We feel that it represents one of the best values, highest delity, and

newest methods of working available in audio today. We set out to make a product that broke new ground, an

equalizer with the highest sonic quality, ease of use, and a full pallet of sound shaping tools to allow engineers to

make the best-sounding record. In the following pages, we’ll share this knowledge, show how the lters work and

interact to provide a complete sound-sculpting system.

The following measurements illustrate a precision of lter implementation rarely seen in any analog equalizer.

These were taken at 96 K sample rate so they do not extend to the full 100 kHz bandwidth of the EQ232P. As

the curves approach the Nyquist frequency of 48 kHz they will appear slightly deformed (though in real life they

extend symmetrically and smoothly to 100 kHz). Also, since human hearing is generally limited to under 20 kHz,

you should pay attention to how the curves look within the audible spectrum. For viewing clarity, we began our

measurement sweep at around 20 Hz and stopped it at 20 kHz or as high as 40 kHz.

HPF

The HPF is electrically connected before the EQ1/2 and PEQ section and can be completely hardware

bypassed by unpressing its engage button. It is a second order RC high pass lter with a 12 dB per octave slope

and a -3 dB point at the selected frequency. The corner frequency can be selected from 18 Hz to 200 Hz in precise

1 Hz increments, never before seen in a commercial analog equalizer (but remember, a rapid rotation of the

frequency knob quickly arrives at your desired frequency). As the rst lter following input, it is very useful to

clear out sub-sonic gunk and low frequency trash prior to the EQ1/2 and P-Filter sections. If the unit appears to

be clipping but with only moderate signal level, use the HPF to improve headroom. Like most of the lters in the

EQ232P, the HPF is relatively gentle (as opposed to surgical) and so can be used as an additional shelving lter

to supplement and interact with the shelves in the unit. This is explored in detail in the P-Filter discussion found

below.

Four examples of the high pass lter: 18 Hz, 30 Hz, 50 Hz, 100 Hz

EQ 1/2

The EQ1/2 lter section contains two bands of fully parametric EQ, featuring a large +/-15 dB gain range

in 0.1 dB steps, and the ability to cover 3 octaves at its widest setting. It is placed after the HPF, and before the

P-Filter section. So cutting or boosting with the EQ1/2 lters will change the signal response going into the P-

Filter section. Likewise, changing the HPF lter will shelve out lows from getting into the EQ1/2 lters.