EQ Section

Click the “EQ” switch on an Input Strip to expose the EQ controls:

EQ Mode

The EQ ‘mode’ switch allows selection of either the Harrison 32C equalizer, or the SSL 9000J equalizer (Mixbus Pro only)

Harrison 32C Channelstrip EQ & Filters

The default setting for the channelstrip EQ emulates the famous Harrison 32Series EQ, which was used on countless popular albums.

The Channelstrip EQ provides a very wide range of frequency and gain changes ( up to 15dB! ) to help tame your tracks. The high and low bands are shelving filters for general tone sculpting, while the 2 middle bands are “proportional Q” design. Optionally, the High and Low bands may be switched to “bell” ( peaking ) shape with the small mode switches at top and bottom.

*The proportional-Q design was used in the original Harrison consoles to allow an engineer to use the EQ as either a subtle tone shaping tool, or a steep filter problem-solver, with only 2 knobs. As the gain is progressively increased (or cut), the bandwidth becomes progressively narrower (the Q increases).

*NOTE: In the original 32C EQ, and the Mixbus emulation of it, the frequency and gain knobs are labeled as if the “bell” knob were engaged, however the default mode is shelving. In shelving mode, the available gain is +/-18dB and the frequencies are different (because it is a filter corner freq, not a bell center freq). We have decided to keep the labeling of the knob the same as on the actual 32C console. Please note that the knob is labeled for a mode that is not the default, and the text display does not match the tick marks around the knob.

Specifications:

Separate “In” buttons for 4-band EQ; 2-band Filter section.

Gain Range +/- 15dB

Frequency Ranges (adjustable):

• HI: approx 900 Hz to 13,000 Hz
• HI MID : approx 400 Hz to 6,000 Hz
• LOW MID: 200 Hz to 3,100 Hz
• LO: 40 Hz to 600 Hz
  

Filter Frequencies:
LPF 12 dB/octave, frequency range (approx) 160 to 20,000 Hz
HPF 12 dB/octave, frequency range (approx) 20 to 3,100 Hz

NOTE that the filters have a generous frequency overlap. It is possible to adjust the frequency knobs on the filters such that there is NO signal coming through! This was also possible on the original 32C analog console, and was a favorite tactic of control room pranksters.

*Care was taken to model the performance of the analog circuit, and variations in the knob resistor values are used to drive the model, rather than more typical “frequency” settings. Due to that, and also the resulting interaction between bands, you will notice that the reported band frequency can change with the gain setting, and vice versa…particularly in the “shelving” mode.

SSL 9000J Channelstrip EQ & Filters

Mixbus Pro users may select the SSL 9000J equalizer as an alternative to the Harrison 32C equalizer.

The SSL 9000 console was introduced in 1995 and uses SSL’s newly introduced “Superanalogue” circuitry to provide an extended and clean frequency response for the era of high-resolution digital recording and playback.

The SSL 9000J Channelstrip EQ provides a very wide range of frequency and gain changes (up to 20dB) to help tame your tracks. The high and low bands are shelving filters for general tone sculpting, while the 2 middle bands have a “proportional Q” design. Additionally, the 2 middle bands also have a dedicated Q (sharpness) knob. At its widest setting,the proportional-q has little effect, while at the tightest (leftmost) setting, the curve is noticeably sharper and becomes more sensitive to the gain, introducing a noticeably sharper eq when boosted or cut.

Optionally, the High and Low shelving bands may be switched to “bell” ( peaking ) shape with the small mode switches at top and bottom.

By default, the 9KJ shelving bands have a slight resonance which causes an inverse ‘cut’ just before a shelving boost. The “E” button decreases this resonance, making the curves more like the 32C shelves.

*Care was taken to model the performance of the analog circuit, and variations in the knob resistor values are used to drive the model. Just like the physical console, the frequency and gain indications on the knobs may not match the measured behavior, but these variations are retained to emulate the experience of using the analog console.

Differences between the EQ modes

While similar in many ways to the 32C equalizer, the SSL version has some notable differences.

While both equalizers have 2 sweepable mid-bands, the middle bands of the 9kJ equalizer have more gain (20dB) available than 32C (15dB).

At its default settings, the SSL EQ’s midrange bandwidth is significantly wider than the 32C, and at wider Q settings it is much wider than the 32C, making it suitable for very gentle wide-band tone control. Only at its tightest Q settings and highest boost does the SSL exceed the sharpness of the 32C circuit. Conversely, when switched to Bell mode, the 32C has a wider bandwidth than the SSL bell shapes! These small differences are indicative of their different designers’ goals, and might lead you to choose a different EQ depending on the job at hand.

*You can copy EQ settings from one track to another by dragging the EQ processor (in the processor list at the top of the channelstrip) onto another channel’s EQ processor.

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