HEX PHASER

Besides being a stupendously good name for a comic-book villain, Hex Phaser takes the standard phaser effect and adds features out the proverbial wazoo. Though it vaguely resembles a classic 70s phaser effect, its unique feature set allows endless colors and tonal variations. These include individually switchable stages and feedback insert point, as well as extensive modulation, taking it waaay beyond the standard "two-knob special" stomp box. 

A Little Background

In order to get the most from phaser, let's talk a bit about how phaser effects work. Phasers make use of a special type of filter called an "all-pass" filter. Unlike low-, high-, or band-pass filters, an all-pass filters allows all frequencies to pass through. So what good is that? Though it passes all frequencies, it alters the phase relationship of part of the audio spectrum. By itself, you wouldn't hear any audible difference, but when the signal is inverted and combined with the dry signal, phase cancellation occurs in regions of the audio spectrum. Varying the center frequency of the all-pass filter (i.e. where the phase cancellation occurs) results in the familiar swooshing sound we know as "phasing."

If a single all-pass filter is used, the effect is rather subtle. Engineers found that stacking multiple all-pass filter stages created a deeper, more pronounced swooshing effect. This is why phaser effects are sometimes referred to as four-stage, six-stage, etc. (Most of the classic stomp box phaser effects use four stages.) Another way phasing effects are intensified is by feeding back an inverted version of the phased part of the signal (i.e. not the unaffected dry signal) back into one of the stages. 

In a typical hardware unit, the number of stages and feedback routing are fixed and unalterable. Hex Phaser allows all six of its stages to be enabled or disabled in any combination, and also lets you select the stage where the feedback routing occurs. This results in a lot of different sounds, especially in combination with the Feedback and Q Width controls.  

Inputs, Outputs and Controls

We'll be jumping around a little bit in order to make the most sense of the control layout. 

In L(M) and In R jacks- These are the mono or stereo audio inputs. Though it only has one set of controls, Hex Phaser is actually a true-stereo effect "under the hood." Unlike a typical stereo effect (e.g., reverb), it's desirable to have both channels share settings and have their modulation cycles related to each other (see the Stereo Offset control section for more on this). 

  • Mono in/mono outUse In L (M) and Out L (M). The Stereo Offset control won't have any useful effect (it's setting won't matter). 
  • Stereo in/mono out Use In L (M) and both outputs. The dry signal remains mono; the phased signal modulation is offset according to the Stereo Offset control setting. Hex Phaser is a great way to stereo-ize mono signals. 
  • Mono in/mono out - Use In L (M) and Out L (M). The Stereo Offset control won't have any useful effect (it's setting won't matter). 

Stages- Hex Phaser features six all-pass filter stages (hence the name). Each of these can be enabled or disabled using the numbered buttons. As a general rule, more stages = lusher phase, but there are plenty of interesting tones to be had using very few stages. Note that the center frequency for each stage is slightly different - this was done because it actually sounds a little "larger" on the whole when multiple stages are used, and has the side benefit of sounding slightly different when individual stages are used. 

If all stages are disabled, the unaffected dry signal is fed through - the equivalent of a bypass button. 

Feedback, Feedback Path buttons and Feedback CV mod input/attenuator- The feedback knob adjusts the amount of inverted effect-only signal that gets mixed with the existing signal. This creates a more colorful and intense effect. The Feedback Path buttons let you specify which phaser stage receives the feedback signal, resulting in different tonalities. 

Keep in mind that the signal always travels through the stages from left to right, so there are some non-tragic caveats to be aware of. In the example below, since stages 2 and 3 are disabled, Feedback Path "skips" stages 2 and 3 and is effectively the same as setting Feedback Path to stage 4. 

In the screenshot below, the feedback signal is inserted after the enabled phaser stages, so it wouldn't result in any change in the phase sound (just an overall volume increase, and potentially loud, not-cool-sounding feedback mess). If the feedback path is routed after any enabled stages, the feedback path is automatically disabled. It won't void your warranty or anything like that, but it's something to be aware of. 

The Feedback CV mod input and attenuator allow negative or positive CV control of feedback. The center setting correlates to no modulation.  

Rate and Rate CV mod input/attenuator- Sets the phaser speed modulation from 0.01 Hz to 7.5 Hz. You'll note that the knob is calibrated so that slower speeds occupy the first half of the knob travel. The Rate CV mod input and attenuator allow negative or positive CV control of rate. The center setting correlates to no modulation.  

Depth and Depth CV mod input/attenuator- Adjusts the depth of the phase modulation, i.e. how far the all-pass filters sweep back and forth. The Depth CV mod input and attenuator allow negative or positive CV control of phase depth. The center setting correlates to no modulation.  

Q Width and Q CV mod input/attenuator- Sets the nominal frequency spread size or "bandwidth" of the all-pass filters. This control will really noticeably alter the overall tone and character - be sure to try it when experimenting with stage and feedback settings. The Q CV mod input and attenuator allow negative or positive CV control of Q width. The center setting correlates to no modulation.  

Stereo Offset and Offset CV mod input/attenuator- Though it only has one set of controls, Hex Phaser is actually a true-stereo effect "under the hood," with two triangle-wave LFO's modulating two sets of all-pass filters. The LFO's always run at the same rate, and are phase-locked to each other 

(When we say "phase-locked," we're not referring to the phaser effect itself, but rather the relationship of the two modulation waves. Sorry for the same-y and potentially confusing verbiage.)

If the Stereo Offset control is set to 0°, both modulation LFO's are exactly in phase, i.e. exactly the same, as shown the diagram below (we actually shifted the two waves a wee bit so they'd be visible, but you get the idea). This translates to the exact same phasing mod for both the left and right channels, resulting in a mono effect. 

If the the Stereo Offset knob is set to +90°, the left channel mod wave moves -45° to the left, and the right channel mod wave moves 45° to the right (for a total of 90° of phase offset as shown below). 

Setting the Stereo Offset knob to negative values moves the mod waves in opposite directions. This "simultaneous movement" (as opposed to only shifting one channel) results in more interesting sound animation, especially when using CV control. 

The Offset CV mod input jack and attenuator allow negative or positive CV control of stereo offset. The center setting correlates to no modulation.  

Out L (M) and Out R jacks- These are the module's stereo output jacks. If the Stereo Offset control is set to 0°, the signal will be identical on both jacks. At any setting other than 0°, the outputs will be shifted apart dependent on the setting of the Stereo Offset control (and any mod applied to it). 

Ext Mod/LFO Bypass button, knob and bypass jack- This bypasses Hex Phaser's internal LFOs and allows an external LFO, or any other mod source to modulate the allpass filter frequencies. Clicking the button disables the internal LFOs, and the attenuator allows negative or positive modulation. This is particularly useful if you'd like to use a tempo-synced LFO or a stepped sequencer. 

Disabling the internal LFOs with the button also allows Hex Phaser to be used as a fixed filter, which can yield a lot of useful sounds. The Rate, Depth, and Stereo Offset knobs won't do anything, but the Stage buttons and Feedback controls will still work. If you really want to get crazy with fixed settings, try connecting a DC Module to the Ext Mod/LFO Bypass jack for manual control of the all-pass filter frequencies with its DC voltage knob (make sure to set the CV attenuator to a non-zero value).