Skip to Content

MXR Phase 90 M101 Pedal Review

MXR Phase 90 M101 Pedal Review

The phaser is a modulation effect that has become very popular among musicians since the 70s. People have been using them on several instruments, but the ones that are most frequently paired with this effect are guitars and keyboards.

This MXR Phase 90 M101 pedal review will tell you everything you need to know about this iconic stompbox, one of the most famous phasers in the history of music. Aside from going deep into its features, we will also discuss other phasers that might suit your preferences better in case you are looking for something that this one does not offer.

Bottom Line Up Front:

In my personal experience, the MXR Phase 90 M101 is the perfect guitar phaser for someone to get into this partiular effect. It is reliable, well-built, very simple to operate, and you’re almost guaranteed to get a great tone out of it without having to spend too much time trying different settings. You have heard it on so many records before that the classic phaser sound it produces will instantly feel familiar and easy to play with.

Even if you have already played and owned other phaser pedals before, I would still say that having one of these in your collection is always a good idea for so many reasons. Many famous guitar players have used this model during their careers, such as Eddie Van Halen and David Gilmour. If you ever want to record a guitar part that features a similar phasing effect to the one they have in their records, this is an inexpensive and efficient way of achieving just that!

What is a Phaser?

MXR Phase 90

Image by Gustavo Pereira

In summary, to achieve the phaser effect, you have a circuit that splits your signal into two paths. One of them remains exactly the same, and the other one is out of phase. Depending on the phaser you use, you have control over more or fewer parameters.

The bare minimum is to be able to control the rate of the LFO, which translates into the speed of the phasing effect. Other guitar pedals might allow you to control the intensity of the effect, how many phase stages the signal goes through, among others.

Some of the most famous examples of the phaser circuit are the MXR Phase 90, as well as its variants (Phase 45, EVH Phase 90, Phase 100, etc.), the Electro-Harmonix Small Stone and the Electro-Harmonix Bad Stone.

MXR Phase 90 Main Features

Since its release in 1974, the MXR Phase 90 has always been a very simple pedal, so there are not many features that we can discuss.

Apart from the version we are looking at here, the M101 Block Logo, you can also find the Script Logo version, easily distinguishable by the “MXR” written with swirly letters. The other variations by MXR include additional controls such as an intensity control, a switch to change between two and four-stage phasing, among other features.

This iconic pedal can be bought for less than $100, which is a steal for a classic sounding effect housed in a rugged enclosure that will endure years of constant playing.

Sweetwater Music – MXR M101 Phase 90 Phaser Pedal

Sweetwater Music - MXR M101 Phase 90 Phaser Pedal

Image by Gustavo Pereira


With this pedal, you can get anything from a subtle, slow whooshing effect to a high-speed swirl that stands out much more but might compel you to play with a different approach.

If you compare the Block Logo and the Script Logo Phase 90 pedals side by side, you will most likely notice that the Block Logo has a significantly more pronounced sound that is more noticeable than the Script Logo. This one tends to stay a little bit more in the background.

It really is not possible to say that one is objectively superior to the other, it all comes down to your personal taste in regards to your phaser tone. It is also possible to mod these pedals to achieve the sound of their other counterpart.

While it is not possible to customize your sound a lot with the Phase 90, the fact that you have heard it multiple times in countless records makes it easy to dial a sound that feels familiar and musical in just a few seconds. In my experience, people tend to prefer slower speeds, but you should try to explore it as much as you can.

Personally, I love to use this pedal with a clean sound and a low speed. It gives it a subtle atmospheric feel that fits in perfectly in many different scenarios across various music genres. I don’t use it as much with distorted sounds, but I obviously engage it whenever I’m playing my favorite Eddie Van Halen riffs!

I also have mine after all of my dirt pedals in the signal chain. Since my main amplifier does not feature an effects loop, I can’t do that, but many people like to run their modulation effects that way.

Design and Build Quality

MXR Phase 90 from the side

Image by Gustavo Pereira

The MXR Phase 90 takes a very simple and straightforward approach. It features a bright orange finish that is guaranteed to be noticed anywhere, one knob on which you can place a cover that will allow you to easily adjust it with your foot while playing, and an LED to let you know when the pedal is on or off.

Just like all MXR pedals, this thing is built to last you for a very long time. It is sturdy and durable, but not too heavy, making it the perfect addition for any guitar pedalboard that is missing a phaser. I have had mine for a little over 7 years, and I never had to worry about anything. It never made any irregular noise, no audible clicks when engaging the pedal, and the enclosure itself looks amazing even though I’ve taken it with me on dozens of gigs.

True Bypass Switching

While the earlier versions of the MXR Phase 90 were buffered bypass pedals, the ones that you will find today at music stores are true bypass, which means that your guitar tone will remain unaffected when the pedal is not engaged.

Some people still like to have a couple of buffered bypass pedals at the start or end of their signal chain to compensate for some of the high frequency loss that happens when you run very long cables in your rig.

In my case, I like the fact that this pedal features true bypass switching. The pedalboard I have at home has a bunch of pedals on it, a lot of cables, and if I can mitigate the loss of high frequencies or “tone suck” that typically happens in these cases, I will take that opportunity gladly.

Complete Specifications of the MXR Phase 90

Sweetwater Music - MXR M101 Phase 90 Phaser Pedal

Image by Gustavo Pereira

You can check the full specifications of the MXR Phase 90 below.

  • Pedal Type: Phaser
  • Analog/Digital: Analog
  • Inputs: 1 x 1/4″
  • Outputs: 1 x 1/4″
  • Bypass Switching: True Hardwire (true bypass)
  • Power Source: 9V DC power supply (not included)
  • 9V Battery Option: Yes
  • Input Impedance: 1 MΩ
  • Output Impedance: 10 kΩ
  • Current Draw: 5 mA
  • Nominal Input Level: -20 dBV
  • Nominal Output Level: -20dBV
  • Noise Floor: -96 dBV
  • Dimensions: 1.25″ x 2.25″ x 4.25″ (H x W x D)
  • Weight: 0.84lbs

Pros and Cons of the MXR Phase 90

MXR Phase 90 from the side

Image by Gustavo Pereira


Classic Tones

One of the biggest advantages of using a Phase 90 is that it is very easy to dial a great phaser tone. Every parameter has a fixed value and you only control the rate (speed), so if you have a specific sound in mind, it should not be very challenging to recreate it.


Since this pedal is not very complex in terms of circuitry, knobs and switches, there aren’t as many things that could potentially go wrong with time as there are with other more intricate pedals.

Apart from that, since it is very well built, it should withstand a lifetime of abuse and still deliver flawlessly every time you engage it. Just make sure to power it with a nice power supply with good isolation.


Limited Controls

If you would like to explore the phasing effect as much as possible, this might not be the right pedal for you, since it only allows you to adjust the rate of the phaser’s LFO.

There are other options in the market that give you a higher degree of control over the effect, and these might be more adequate to your needs. A great example of this would be the Walrus Audio Lillian Phaser.

Other Phaser Pedals to Check Out as Alternatives to the MXR Phase 90

Fortunately for us guitarists, we live in a time in which the effect pedal market is full of different options that cater to all tastes and preferences. If you think that the MXR Phase 90 might not be the best phaser for you, don’t worry, as there is plenty to choose from.

Here are some of my favorite phaser pedals besides the MXR Phase 90.

MXR M290 Mini Phase 95

MXR M290 Mini Phase 95

The MXR M290 Mini Phase 95 is an amazing option for the players who love the original Phase 90 but feel like it could have a few more sounds available.

This model comes in a slightly smaller enclosure, but it still manages to fit a few more options than its older cousins. Apart from the usual Speed knob, you have a switch that toggles between the Block Logo and Script Logo variants, and another one that toggles between the Phase 90 and the Phase 45 circuits.

The original Phase 90 is a four-stage phaser circuit, while the Phase 45 is a two-stage phaser. This one has a somewhat smoother, softer sound that doesn’t feel as “in your face” as the first one.

You can generally find the MXR Phase 95 for around $100, which is still very affordable for the pedal you are getting.

MXR M107 Phase 100

MXR M107 Phase 100

The MXR M107 Phase 100 takes the iconic Phase 90 and goes even further, allowing you to switch between four distinct intensity presets, instead of only allowing you to control the rate.

This opens up a very wide range of possibilities that you can explore. You can get very subtle phasing that sits nicely in the mix, all the way up to aggressive, warbly phasing.

The pedal’s enclosure is slightly bigger than the original Phase 90, so take that into account if your pedalboard is becoming a bit crowded.

This interesting take on a classic circuit is usually sold for around $120.

Boss PH-3 Phase Shifter

Boss PH-3 Phase Shifter

The Boss PH-3 might come in a compact enclosure, but it is housing lots of interesting features that set it apart from the most phasers that you usually see.

The basic controls are Rate, Depth and Resonance, and there’s also a Stage knob that switches between several phaser types. This is probably the most notable feature of the pedal, since it gives you access to multiple sounds that can be easily accessed.

You have 4, 8, 10 and 12-stage phasing, as well as a “Fall”, a “Rise” and a “Step” mode. Having this kind of variety makes this pedal an excellent choice to keep on your pedalboard, since it can efficiently adapt itself to different scenarios. It even has a Tap Tempo feature, something that is rarely seen on phaser pedals.

Additionally, you can get even more out of this pedal by connecting an expression pedal to it. This will allow you to control different parameters of the phaser with your foot while you are playing.

This pedal can typically be found for a price of around $150.

Walrus Audio Lillian Analog Phaser

Walrus Audio Lillian Analog Phaser

Walrus Audio is known for making some of the most interesting effect pedals in the market nowadays. Aside from having gorgeous designs on every pedal, their sound and build quality are notable. Not only that, but they also offer a lifetime warranty on their products, which is a big plus if you’re planning to keep them for a long time.

The Lillian is a phaser that can do 4 and 6-stage phasing, allowing you to carefully control how present the effect will sound with its “D-P-V” knob. Turn it all the way to the left and there will be no effect whatsoever. As you start turning it to the right, you will start blending in the phaser, which gets more intense until it turns into a vibrato.

You can adjust the Rate, Width and Feedback with the 3 knobs at the top of the pedal, and toggle between 4 and 6-stage phasing with the toggle switch on the left side.

This pedal features true bypass switching, and you can power it either with a 9V battery, or with a 9V DC power supply. You can usually find it for a price of around $200.

FAQ: Frequently Asked Questions About the MXR Phase 90

Question: Is the MXR Phase 90 true bypass?

Answer: The answer to this question depends on the version of the MXR Phase 90 you have. The most recent ones are all true bypass, sometimes referred to as true hardwire by Dunlop. If you have a model that was built before 2000, it is most likely to feature buffered bypass switching.

Question: Which guitarists use the MXR Phase 90?

Answer: The MXR Phase 90 has been a popular pedal among guitarists since its release in the 70s. Many musicians picked it up and used it on several occasions. Here are a few examples that you will surely recognize:

• Eddie Van Halen
• Paul Gilbert
• Johnny Winter
• David Gilmour
• Zakk Wylde
• Jimmy Page
• John Frusciante
• John Mayer

You can find countless examples of this pedal in records of pretty much every music genre. People have been using it on everything from guitar, bass, keyboards and even vocals.

Question: What are some good alternatives to the MXR Phase 90?

Answer: If you feel like the MXR Phase 90 is lacking something and it is making you think twice before pulling the trigger, there are other pedals that you might enjoy more. Here are a few examples that contain different features across a variety of price ranges.

Sweetwater Music – MXR M290 Mini Phase 95 Pedal
Sweetwater Music – MXR M107 Phase 100 Phaser Pedal
Sweetwater Music – Electro-Harmonix Nano Small Stone Phase Shifter Pedal
Sweetwater Music – Electro-Harmonix Bad Stone Phase Shifter Pedal
Sweetwater Music – Boss PH-3 Phase Shifter Pedal
Sweetwater Music – Walrus Audio Lillian Analog Phaser Pedal

As always, the best way to approach this question is to try out a bunch of different phaser pedals side by side and get your conclusions there and then.

Question: Can you power the MXR Phase 90 with a 9v battery?

Answer: Yes, if you do not want to power your MXR Phase 90 with a 9V DC adapter or an effects power supply such as the MXR Iso Brick, you can unscrew the backplate of the pedal and connect a 9V battery to it.

Remember to unplug the pedal when you are not playing in order to avoid draining the battery unnecessarily.

Question: Is the MXR Phase 90 worth it?

Answer: Taking into account that this is a pedal that you can get for less than $100 and easily gives you classic tones that you have heard in more situations than you can count, it is almost a must-have pedal for any guitarist. It is simple to use, versatile, durable, visually appealing, and it is an iconic piece of music history.

Closing Considerations About the MXR Phase 90

The MXR Phase 90 is a legendary pedal that put MXR on the map in the 70s, and it has made its way to the pedalboards of countless artists around the globe.

It is easy to use, well built, durable, and it will deliver classic tones such as the ones you have heard on records all the time without breaking a sweat.

If you would like to have more control over the parameters of your phaser, you might want to explore other options as this one is somewhat limited in regards to what you can adjust.

I know for a fact that I will keep this pedal for a very long time, even if it is not in my main pedalboard all the time. It is a great tool to have, besides being an iconic pedal that any collector would appreciate having.