Please help with MXR Phase 90 distortion problem

[DC-Choppah]

I need help figuring out if my MXR Phase 90 distortion pedal can be made clean. Is it broken?

I just got it on the used market. Looks to be in fine condition. But perhaps it is defective. Or just not what I expected.

Plugging the guitar directly into the pedal, and then directly into my mixing board, I can verify that the mixing board is not clipping from the meters. Sound is clean with the pedal off.

The distortion comes from the pedal itself. Like the pedal is both a phaser, and a fuzz box.

I am using my DC power brick from my pedal board to power the pedal. The same DC power cord works with my other MXR pedal no problem.

Here is a clip of what I am hearing as I play and turn the phasor on/off.
https://drive.google.com/file/d/1oywYRw ... sp=sharing

This was recorded with my Tascam handheld digital recorder listening to what comes out of the Adam studio monitors. Nothing is clipping in the monitor chain. The fuzz you hear comes from the pedal.

I was hoping more for the sound of Grant Geissman on Chuck Mangione's Feel so Good. They say he used a MXR Phase 90.

Grant's solos starts about 5 1/2 minutes in...
https://www.youtube.com/watch?v=NDSBV0vTfTo

[Watchmaker]

That's definitely not how mine sounds. God only knows what's causing it. Actually I bet one of the forum members will identify the problem post haste but I can't recall his name atm. Have you opened it up to see if someone monkeyed with it?

[DC-Choppah]

A few photos of the guts

https://drive.google.com/file/d/18qWN_C ... sp=sharing

https://drive.google.com/file/d/1GdzGbq ... sp=sharing

https://drive.google.com/file/d/1XEaUrY ... sp=sharing

Nothing obvious to me

[resistorman]

Have you tried it with a battery? Have you turned that trimpot on the board yet

[DC-Choppah]

Sounds identical when powered from the 9v battery.

[DC-Choppah]

Playing with the trim pot, does not help with the fuzz.

Turning the pot too much in either direction takes the depth of the phase away. A sweet spot in the middle gives it the full range of depth. This is like a weird depth control. Sounds like a phaser in one position only.

Unfortunately it is still a fuzz box at any setting.

[DC-Choppah]

If I turn the guitar volume knob down to 3 or 4, then the pedal no longer distorts.

But then when I turn the pedal off, there is a big (15 dB?) jump lower in volume.

The pedal is acting like it has a big boost of gain in front of it when you turn it on. And this is too much, and causes it to distort badly.

[forumuser931182]

It doesn't look like anyone has tried to modify it. Last owner may have plugged in an incorrect power supply perhaps.
You can find details about the circuit here: https://www.electrosmash.com/mxr-phase90
but only of use if you are electronically minded.

[Hugh Robjohns]

If it sounds like it's phasing properly when you lower the input level, then the chances are it's a problem either with the input buffer opamp, the output transistor, or the one of the power supply voltages (Vref or the 9V supply).

There's a good talk through the circuit and fault-finding process here:

https://www.circuitbenders.co.uk/forum/index.php?topic=1532.15

[Watchmaker]

No to be critical of your purchase decision...This is why I almost always buy anything with electronics new. You never know what the last person, or the one before them, did. Unless you have a drawer full of spare parts, some free time, and like to solve this kind of puzzle, imo the difference between 20 bucks for a used item and 100 bucks for a new one pays for itself instantaneously.

Oddly, I have no problem buying used rack mounted gear and hate the idea of spending for new compressors. fwiw, I use the script version with LED (model CSP101SL) and mine has served faithfully for years.

Good luck with the project, I hope you find a happy, easy solution!

[DC-Choppah]

Thanks for the info!

The voltages all check out. Thanks for the link to the circuit walkthrough Hugh.

So I clipped the R28 resistor (feedback resistor) that they note many people do. This is known as the 'R28 mod'.

This helped considerably. Still a bit dirty. But if I roll back the volume to 8 it cleans up.

New audio file after the R28 mod and guitar on 8.
https://drive.google.com/file/d/12ak3R8 ... sp=sharing

I can work with this now.

[Hewesy]

The R28 mod is essential for any new Phase 90, no idea why they thought adding that boost in was a good idea.

What's the signal upstream of the Phase 90, just guitar or any other FX pedals?

What's the guitar, and pickups? If it cleans up when you dial back the volume I wonder if you're clipping the input.

Hewesy

[DC-Choppah]

The R28 mod is essential for any new Phase 90, no idea why they thought adding that boost in was a good idea.

What's the signal upstream of the Phase 90, just guitar or any other FX pedals?

What's the guitar, and pickups? If it cleans up when you dial back the volume I wonder if you're clipping the input.

Hewesy

Well, for the recording I posted, the Phase 90 is all that was in between my guitar and the clean mixer. Not clipping on the mixer.

Situation is the same for all my guitars. All guitars need some roll off to not distort this pedal. My main axe these days is my Gibson 195. But they all need a roll off to not clip this pedal.

Yes, it sounded like the input was clipped - and not in a good way to my ear. With the mod and guitar rolled off to 8 it is acceptable.

I am learning something here. I really wanted the Grant Geissman 'Feels so good tone'. It appears that to get that you have to have a different phasor pedal than the one I have?!?

Oh man. This music stuff can be endless sometimes.

I mean I read that Grant used a Phase 90. But now I realize there are lots of these pedals.

[The Elf]

I've never understood why the Phase 90 has gone down in legend, while the superior Phase 100 is a forgotten gem!

[Martin Walker]

I've never understood why the Phase 90 has gone down in legend, while the superior Phase 100 is a forgotten gem!

Perhaps it's because the Phase 90 is easier for guitarists to use, whereas the Phase 100 is more a keyboard player's delight?

Runs for cover

Martin

[DC-Choppah]

I've never understood why the Phase 90 has gone down in legend, while the superior Phase 100 is a forgotten gem!

Is the Phase 100 clean?

I am looking for a clean phasor - One that Feels So Good!

[DC-Choppah]

I have sold the modified Phasor 90. So I am looking for a different one now (clean, not dirty).

Any recommendations are appreciated.

[Martin Walker]

As I understand it, the MXR Phase 100 simply has more stages for a potentially deeper effect, along with an extra 'depth' control so you can vary it, whereas the Phase 90 simply supplies a speed control.

Apart from that I don't think they sound very different.

Martin

[Martin Walker]

Any recommendations are appreciated.

Have a listen here - something might catch your fancy!

That Pedal Show – Six Fantastic Phasers!

https://www.youtube.com/watch?v=7kpkbT2bbb8

Martin

[DC-Choppah]

Two hundred thousand dollar phasor pedal!

https://reverb.com/item/35916309-maestr ... phaser-70s

[DC-Choppah]

Solved!

I found that my Lexicon MX200 that is in my rack has a phasor in it! I used it for chorus and reverb only before.

The phasor It sounds great. Pure and clean and faithfully can do the Feels So Good thing.

I got a foot controller so I can activate the MIDI program change from my pedal board.

[resistorman]

Two hundred thousand dollar phasor pedal!

https://reverb.com/item/35916309-maestr ... phaser-70s

Hmmm. Miami. Isn’t that where they sell duct taped bananas for around the same price?

[Drew Stephenson]

Seller has 73 five-star reviews though...

[Martin Walker]

But 73 five-star reviews isn't nuanced enough for SOS readers - we need more in-depth discussions that point out all the benefits and downsides of each sale

Martin

[Hewesy]

Well, for the recording I posted, the Phase 90 is all that was in between my guitar and the clean mixer. Not clipping on the mixer.

Situation is the same for all my guitars. All guitars need some roll off to not distort this pedal. My main axe these days is my Gibson 195. But they all need a roll off to not clip this pedal.

Yes, it sounded like the input was clipped - and not in a good way to my ear. With the mod and guitar rolled off to 8 it is acceptable.

I am learning something here. I really wanted the Grant Geissman 'Feels so good tone'. It appears that to get that you have to have a different phasor pedal than the one I have?!?

Oh man. This music stuff can be endless sometimes.

I mean I read that Grant used a Phase 90. But now I realize there are lots of these pedals.

Thanks for confirming. I have a modern Phase 90 and it doesn't clip like that with any of my own guitars (including some fairly output humbuckers). It did add a boost which is why I did the same R28 mod. After that it is rather chewy as you'd expect - which is a good thing!

So, I suspect that sadly yours has some issue causing it to clip the input gain. Two choices here, either send it off to someone who can check it over for you or buy a replacement.

There are various iterations of the Phase 90, Grant apparently used a classic Script logo so my suggestion would be to try a clone rather than either risk another 2ndhand unit or spend £££ buying the MXR reissue, unless you want too of course

A Mooer Ninety Orange has a vintage mode which supposedly copes this sound, usually Mooer stuff is actually very good at replicating classic gear so worth a punt for the price. Their Yelliw Comp is a very nice replication of a Diamond Compressor too.

Hewesy