Pulsar

Classic phaser with a nice technology update

 

   

 

The GT Pulsar phaser rack effect module compares to the Earthquaker Devices Grand Orbiter phaser, which is an updated version of the classic MXR Phase 90 phaser pedal.  In addition to a technology update in the phaser circuit, the updated design includes more controls for dialing in a variety of tweaked phaser effects.

 

Description

The GT Pulsar compares to the EarthQuaker Devices four-stage Grand Orbiter phaser.  In rough terms, it is a technology update of an MXR Phase 90 design, but with several more controls to let you dial in a much broader range of phaser and non-phaser effects, including vibrato and cocked wah.

This circuit doesn't use matched transistors or optical components in the phasing stages, as most phasers do.  Instead, it uses OTA, or "operational transconductance amplifier" chips.   Wow… WT???  Thankfully the details of that aren't really important.  What it means in practical terms is that it utilizes chips to do the phasing.  These OTA chips each contain multiple circuits, one of which is used for each of the four phasing stages.  Because of the way they are manufactured, the differences in the circuits in those chips are usually very, very small.  Due to that, whoever is building this circuit can save a lot of time and money trying to find enough closely matched components.  Instead of sorting through dozens and dozens of transistors to find a closely matched set of four, you just use the OTA chips without even having to measure them.  In the end, that means it costs less to build them, plain and simple.  Not that it is cheap to build, but it costs less than many of the alternatives.  This is especially true as the particular types of transistors used in phasers begin to get scarce and expensive.  And also due to the chip manufacturing process, there is less noise, that annoying swooshing you get from a phaser that's turned up, even when you aren't playing.  That's basically the deal.  In this circuit "OTA" means "save some money and get less noise from a great phaser".

The features and controls are about what you expect for a nicely designed phaser.  

There is a Range switch with three settings.  Two of the settings are Fast and Slow, which give two different speed ranges for the Rate control to operate within.  The third switch setting turns off the phasing movement, leaving only the filters operating.  That's very similar to leaving a wah pedal in a fixed position, a "cocked wah".  The Rate control won't have any effect on that switch setting, but the other controls can still be utilized to adjust the fixed wah sound.

The Depth control adjusts the mix of wet and dry signal, to manage the intensity of the phasing.

Sweep controls the peak frequency of the filter.  One way for a lower bass peak, the other way for a higher treble peak.

Resonance controls the feedback or regeneration in the phasing.  This is a different way to change the intensity of the phasing.

Finally, there is the Phase/Vibrato switch.  If you set it to Vibrato, the dry signal is cut off, leaving only the pitch-shifted phasing signal, which is another way of saying vibrato.  Of course, the Depth control won't do anything useful for phasing without a dry signal to mix, although it does allow for some volume control.

Due to the range of control, you can use this phaser in many settings for different types of music.  Keep it subtle and "always on" to add some of that extra something-something to avoid stale tones.  Or crank it up and swoosh away on those 80's rock anthems.

The Pulsar probably sounds a little closer to the MXR Phase 90 than any other phaser you may know, but has more controls and options to change it up.  The Pulsar design includes pretty much all the controls you would likely want for a phaser, so only a single configuration is offered.  Somehow, we forgot to add a blinking rate LED in our first version, so that may be added in the future, so no configuration options for now.

Configurations

  • Pulsar - compares to EarthQuaker Devices Grand Orbiter

 

 

Options

  • None

 

Front Panel

  • On/Off indicator LED
  • Rate
  • Depth
  • Resonance
  • Sweep
  • Range switch
  • Phaser/Vibrato switch

 

Rear Panel

  • Audio In
  • Audio Out
  • On/Off Footswitch
  • On/Off Override
  • DC Power
  • DC Power LED

 

Module Width

  • 2" standard 
  • left or right wing configuration may be available

 

Power Consumption (aprox)

17-22mA

 

Base Configurations

Part # Description List Price
MOD-PULSAR Pulsar module $250

 

Options

 N/A