The Deluxe Electric Mistress XO is a compact flanger pedal from Electro-Harmonix, announced in January 2014 and reaching shops in spring 2015. It packs the analog circuit of the classic Deluxe Electric Mistress into a compact die-cast package, keeping the same Color, Range and Rate controls plus the Filter Matrix switch12.
MusicRadar described the intent plainly when the pedal was announced: it was built to "deliver all the syrupy flange, chorus and filter chimes that made its 1976 predecessor such a widely used unit in studio" settings2. Like other Mistress-family pedals, it produces traditional sweeping flanging and lush chorus effects from the same circuit, with the Filter Matrix mode as the odd extra voice3.
What it does: syrupy flange, chorus and filter chimes
The XO is an analog flanger, and Premier Guitar's announcement stressed that "the circuit remains true to its roots" rather than being a redesign1. What that means in practice is the Mistress sound: a flanger that also leans into chorus territory. Guitar World's history of the Electric Mistress notes that the circuit "generates traditional sweeping flanging and lush chorus effects equally well"3, and EarthQuaker Devices' pedalboard guide calls the Mistress "a classic pedal with flange and chorus effect options"5.
The three voices break down like this:
- Flange: the classic jet-like sweep, with the Color knob setting how intense and resonant it gets3.
- Chorus: a lush, watery modulation available at the gentler end of the control range3.
- Filter Matrix: a frozen, non-sweeping bank of comb filters that produces metallic and chime-like tones1.
The Filter Matrix mode is the Mistress family's signature trick. In that mode, the modulation waveform is disconnected from the flanger circuit, freezing the flanger and creating a matrix of filters. Electro-Harmonix says it "enables a musician to achieve effects like the sound of chimes being played in unison with his or her instrument"1. Guitar World describes it from the player's side: the switch "stops the LFO and 'freezes' the flanging effect's frequency cancellations in mid-sweep, creating unusual metallic tones that can be 'tuned' with the Range knob"3. Guitar.com's modulation guide points out that the filter matrix setting is also a useful way to hear comb filtering on its own, before flanging is applied6.
"In that mode the modulation waveform is disconnected from the flanger circuit, freezing the flanger and creating a matrix of filters."
The controls: Color, Range, Rate and the Filter Matrix switch
The XO carries the same four controls as the larger Deluxe Electric Mistress: Color, Range, Rate and the Filter Matrix switch27.
| Control | What it does |
|---|---|
| Color | Dials in the intensity of the effect, also known as feedback, regeneration or resonance3 |
| Range | Sets where the sweep sits; also tunes the frozen filter points in Filter Matrix mode3 |
| Rate | Covers a wide range, from slow sweeps to vibrato-style fast warbles3 |
| Filter Matrix switch | Stops the LFO and freezes the flanger's frequency cancellations in mid-sweep3 |
One change from the original: an LED was added to indicate when the effect is engaged1.
Power and connections: 9V, flanged and dry outputs
The XO runs on a 9 volt battery or on the standard EHX 9.6-200mA power supply, which comes in the box with the pedal1. That is a change from the older big-box Mistress pedals, which drew power in ways that made battery operation awkward; the XO was part of EHX's move to put its vintage circuits in compact, pedalboard-friendly housings with conventional power.
On the back of the pedal are two outputs: flanged out and dry out2. The dry out carries the unprocessed signal, so you can send the effect to one amp and the clean signal to another, or blend them at the mixer.
The XO is a mono pedal. Players who want a true stereo Mistress should look at the Stereo Electric Mistress, which EHX lists as a Flanger/Chorus with stereo audio and separate Flanger Depth and Chorus Depth knobs8.
Where it came from and where it went
The Electric Mistress dates back to the 1970s, and the Deluxe version added the Filter Matrix function, activated with a switch9. The XO, announced in 2014, was the compact die-cast reissue of that circuit, available in spring 2015 at a US suggested list price of $204.2712.
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Questions
Does the Deluxe Electric Mistress XO take a battery?
Yes. The pedal runs on a 9 volt battery or on the standard EHX 9.6-200mA power supply that comes in the box. The battery route makes it usable on a board without a dedicated power tap, though the included adapter is the everyday option.
Is the Deluxe Electric Mistress XO true bypass?
Yes. Electro-Harmonix fitted true bypass switching so the signal path stays intact when the effect is switched off. An LED was also added to show when the effect is engaged, something the original larger version did not have.
Is the Deluxe Electric Mistress XO stereo?
No. It is a mono pedal, but it has two outputs: a flanged out jack carrying the effect and a dry out jack carrying the unprocessed signal. Splitting the two gives a kind of pseudo-stereo spread across two amps.
What does Filter Matrix mode do on the Electric Mistress?
It stops the pedal's internal modulation and freezes the flanger's frequency cancellations in mid-sweep, leaving a static matrix of filters. The result is unusual metallic tones that can be tuned with the Range knob, including chime-like sounds that track what you play.
Is the Deluxe Electric Mistress still made?
No. Electro-Harmonix lists the Deluxe Electric Mistress as discontinued in 2023. The XO was the compact 2015 version of that circuit, and the Mistress line's controls and Filter Matrix mode live on in other EHX flangers.
Sources (9)
- New Deluxe Electric Mistress XO by Electro-Harmonix, Premier Guitar, 2015-01-12
- NAMM 2015: Electro-Harmonix reveals Deluxe Electric Mistress XO flanger pedal, MusicRadar, 2015-01-12
- How the Electro-Harmonix Electric Mistress became the go-to flanger for David Gilmour and Andy Summers, and remained a pedalboard staple for nearly 50 years, Guitar World, 2024-01-23
- Deluxe Electric Mistress, Electro-Harmonix
- A Beginners Guide To Pedalboards Pt. 1: Choosing Your Pedals, EarthQuaker Devices, 2021-12-06
- All About… Modulation, Guitar.com, 2016-04-18
- Best Electro-Harmonix pedals, Guitar World, 2023-04-25
- Stereo Electric Mistress, Electro-Harmonix
- Deluxe Elastic Mattress, PastFx, 2026
