Name:Chris Goodson
Build Report:Another successful build! I can't say enough about the quality of the boards sold here. They make everything go so smoothly you feel like your cheating. Ordered my parts from Small Bear and got 25 FET's to select from. I breadboarded the Improved JFET Matcher @ and it went well. I went with 1.210, 1.211,1.234 and 1.234. I don't know if that's really optimum but to my ears this is the best sounding phaser I've ever owned!

Name:Mark Monteverdi
Build Report:What's up guys? Props from Portland, Oregon USA! Francisco, great site and thx for the wonderful PCB's you got going on. Makes the projects so much easier. Built the Phase 90 to spec; no special mod except the 22K feedback. I matched all the fets and biased as specified. Fired right up first time! Sounds effin amazing. A little smoother without the feedback resistor, but great either way. Looking forward to getting started on the reboot delay next. Take care man!

Name:David Million
Build Report:Previously built a Ross Compressor and Dynacomp (I seem to like pedals that go squish or woosh....) and moved onto the Phas 90. I am building confidence as I tackle each new project and working with Francisco's excellent PCB's makes everything so much easier. Still fiddling with the settings but already, I am in love with my Phase 90 - amazing effect and very usable throughout its range. The various mods mentioned here all sound worth a lookbut for now, I am enjoying whacking it through a Marshall Vintage Modern and will link it up tomorrow with my BB Preamp to see what happens.

I can;t wait to start the next project!

Build Report:OK      my best phaser ,great sound, I love it, thanks tonepad.

bye masters    

Build Report:Wonderful phaser. Does exactly what it's supposed to do and does it really good too. I built mine with a switchable feedback resistor, the difference in sound is fairly subtle but clearly noticeable. I favour the slighty more mellow sound with the feedback resistor disconnected best.

One note though, make sure you either wire the bypass switch in such a way that the input of the board is grounded when bypassed or connect a large (>1Mohm) pull down-resistor from ground to the input. This solved my problem with an occasional loud pop when switched on.

Name:n kirkwood
Build Report:i did as suggested use the fet matching thingy.
bought 45 from smallbear.
go 2 the same and the other two pretty close.i think they were all around -1.656
i used 5v1 zener and did the intensity mod that every one else here was doing.
i noticed the phase works ok with any old fets, although i did notice the improvement with the matched ones.i even did the flahing light lfo thing which was easy and great.i tinkingered with all the trim post etc but found my phase sounded good but not as good as examples of the mxr ones. Then at a last resort i tried different zener diodes, and this made a huge difference i had to change the trim pots again but found the sound excellent if you are going to do this then do it only if you do ther following.
1. match fets from smallbear see matching schematic geofx.
2. try different value zeners, ie 4.7,, 5,1 ,5.6 etc.
3. reverse log pot!, it will still work with a normal log pot, but the sweep of the phase doesnt do much for most of the turning of the pot but only at the very end . which makes it difficult tochange sweep acurately.
i also did a volume pot replacing the last resistor with a 250k pot i think.
my pedal has 3 knobs up the top , looks sort of like a retro sonic chorus, in terms of hoe the pedal is positioned. i have an led above the right hand side bypass switch, indicating theb function of the phase. and on the left hand side i have another footswitch whichis wired to the speed pot at 0 ohms , which gives a vibrato effect.when pressed it goes straight to the fastest speed setting and when pressed again reverts back to the setting what ever the speed pot is on . i couldnt fit a battery in my pedal due to my not so neat work and just runs of external power.. all in all very happy!

Build Report:First, don't make an excuse if you don't know how to build or use the JFET matcher because this only takes minutes to build.

I test 15 JFETs on hand(2N5458 and J113{salvaged from several DOD's FET switching}). And finally ended with the ff:2N5458 @ 1.44V, 1.45V, 1.48V, and a J113 at 1.53V.

Man, this phaser is sweet if only matched FETs are to be used. It pretty nails the original sound of the ones i saw in youtube. I did try replacing 1M fixed resistor into a linear pot to control its depth and a switch to lift off/on the 22K feedback resistor. A REVERSE LOG pot is a must. I already build the ross which is kinda excellent but this one is just kinda superb..(philippines)

Build Report:My first DIY project... and I love it!!! I etched the board myself, used matched BF245A instead of 2N5952, and 2N3906 instead of 2N4125. And I had to use 0.047uF instead of 0.05uF, cause I didn't found them :)
But it sounds great!
Here is a picture of my EVH Phase 90:

Name:Doug Hammond
Build Report:I just finished this a week or two ago. Fired right up and was really easy to build, thanks to the excellent Tonepad PCB.

I omitted the feedback loop (22k) for the milder sound which I prefer. I also increased the 150k "feedback" resistor in the output stage to 180k to even out the bypass/wet signal levels.

I used 4 matched J201's for the JFET control elements. Their pinout is the exact opposite of the specified 2n5457's, so installation was real easy and they work real well. I also used a 2n5087 for the output stage. It sounds great, just what I remember a 70's era Phase 90 sounding like. Just gigged with it for the first time the other day and I'm really happy with it!

Name:Bob Iles
Build Report:WOW!! Just finished building this for the other guitarist in my band. As with my previous 5 Tonepad projects, this one fired up right away, with no problems. I used a DPDT switch to bypass the 22k resistor to get a more classic, warmer tone. I added a 250K Log pot in place of the 150K output resistor to adjust the volume, and 500K Log pot in series with the 1M resistor for intensity adjustment. This pedal will be hard to give up, but I do plan to build one for myself, so all is not lost! LOL....As usual, a great project. Thanks, Francisco!!

Name:William Fernandes

The pedal that I've made have become better than the orginal.
I've put a potenciometer where the trimpot were to control the intensity of the modulation.

Mods: I've used bf245 instead of 2N5952.
The most important observation is to use matched FETS (with the same Vgs)

Build Report:first: great site!

i build this one with no problems and added the feedback mod. i use it on bass and i build a second one for our bands guitarist. we're both very happy with the effect! no problems encountered when building this sweet baby.

Build Report:thanks francisco!!!!! This is the best stompboxes that i have built! I'm using 2n3906 for pnp, bf245 (matched with geofx jfet matcher) instead the 5259, tl082 instead tl072! A lot of substitution, i know... but it sounds pretty good! I mod it with depth mod, (1Mohm pot with a 680 ohm resistor in series with it), rate led, classic-modern switch! I painted the enclosure with vh style stripes, so i like it very much! A very good pedal! Phase it up!!!!

Build Report:Just finished build this lovely pedal yesterday, along with a Tube Screamer and Smal Clone. Very warm analog sounding, I love it!!

Mods I've done: 22K resistor out and the intensity control replacing the 1M resistor with a 470K resistor in series with a 500K pot. Lot better because the versatility I've achieved.

Muchas gracias Francisco, muy buenos diseos. Saludos desde Lima - Per.

Name:Groove Electronics
Build Report:Very Very cool.

This phaser is absolutely amazing! I build a couple so far and they just sound better than the original. Build this phaser instead of the "phase 45". 90 has more stages that clearly will make a subtle but noticeable transition of the highs and lows of the range.

I did a couple of mods:

1) Depth Pot: Replace the 1M resistor wich is in series with the trim pot, and add a 1M linear pot in series with a 680 ohm resistor. This is a better mod than the "mix mod", because in lets you control the amount of phasing signal perfectly.

2) Classic - Modern Switch: Add a DPDT switch in place of the "feedback resistor". One half of the DPDT is connected with the fdbk resistor and the other half leave it empty. Very cool and cheap mod.

3) Vibrato Mod: This mod is tricky and hard to explain. if you find info about this mod, here is a good tip for you: To make the pedal acts like a vibrato, the "speed pot" should be at its maximun speed, otherwise it would not vibe. Use a DPDT to give the "speed pot" a "0 ohm" between terminals.

4) Rate LED: Yes, its absolutely amazing and is very very easy. On IC1 (TL072), connect the positive side of the led to the "7th pin" and the negative side to ground (be sure to use a resistor, about 1K, in series with the led)

I recommend using a 500KC (rev log) pot for speed.

Do the matching of the fets, because the wave will be uniform.

Thanks a lot FP.

Saludos desde CHILE.

Build Report:Let me start by saying that I have a few of the original MXR phase 90s in the BUD boxes - I'm addicted to these things. This one sounds really close to the original.

The build was pretty easy; I etched the board using the layout given here, matched the FETs using the shematic from GeoFx (didn't need the feedback resistor), soldered it all up & voila a great sounding effect.

One note - the Fairchild 2N5952s that I used had to be rotated 180 degrees from what is shown on the layout.

Build this it's great!

Build Report: Great sounding phaser!! I've never heard how the original MXR phase 90 sounds like but, this circuit works for me. At first I used unmatchet 2N5457 for jfets. I've been changing severel (it was easy because I used sockets for them) untill I got the right sound (tweaking the trimer is very imortant too). Also, I removed the feedback resistor, replased the 150K resistor with 180K because of the little volume drop when effect is on, and added 500K pot (as a variable resistor) in series with 1M resistor for intesity control (as I've read in earlier reports).
After a while I menaged to understend what it means to match fets so I did it (useing BF245A) and
placed those fets in the circuit - waaay better sound. Cool phaser is what I have now.
BIG THANX to Tonepad and FP!

Build Report:Easy enough to build and sounds good, I also built the Ross Phaser and I feel that the Ross sounds smoother and has more use . This is a good phaser just depends on what you want.

Name:Insane guitar
Build Report:WOW... THE BEST PHASER EVER!!!!

I have problems to do it... I was using matched bf245... really... dont use it... it causes irregulatiom with the bias diode and principally with the LFO.. I mean it.. dont use bf245... use another like mpf102.. theyre good

I have found probally the best modification ever... i was playing and the oscillation stoped... in the midlle of the effect.. lets say about 73%..

It was a problem with the wire.. fixed it and it broked again... but in another value of the effect.. a bit more bassy and fat sound.. wow.. beautfull.. i was playng with.. stoping the LFO in every points..

Its just like you get every type of sound by selecting when you 'pause' the LFO

sorry I cant explain very much but... try it... put a footswitch in one wire of the speed POT and go playing...

this modification I called it 'Stop speed' ugly.. lol

its beautyfull.. probably the best modification of phase 90.. giving you TOTALLY control of the pedal..

didnt made de intensity pot.. its almost useless..

good effect... really good..
didnt liked phasing effects until know this phaser..

Thanx tonepad! and thanx broken wire!

Name:Bas Stottelaar
Build Report:Really nice project!

I've built 3 of them. The first one was working after using an NPN (2n3904) instead of an PNP (2n3906/2n4125). The second one still doesn't work and I don't know how. The third one which I made some hours ago wasn't working either due wrong FET biasing. It was oscilating at my favorite sweep point. I corrected that by using a 5V6 zener instead of a 5V1 or a 4V7. I used J201 FETs.

The first 2 were made on pre-drilled boards, the last one I etched.

Build Report:Very nice effect! I like it without the 22k feedback resistor. I had to rotate the FETs 180, too.

Build Report:what a great phaser!I used matched 2n5952,and removed the feedback resistor,wich caused distortion.Use the trimmer to set your favourite "sound",mine have a great "swooossshhh"!Soon sound sample and picks!!!
As usual,great layout at Tonepad!!!!

Build Report:very nice phase effect. very similar to the phase 90. I had to flip my fets the other direction as well to make it work.

Build Report:well, after a little mistake (bad solder joint on the fet matcher :P ) and a little playing with zener values i've got this one working
this is my first modulation stompbox... and the second one i've built classified as "advanced" (the other one was the sansamp gt2... so much easier as you don't need to tweak any comonent value or things like that...)
well, i don't think it's a very useful effect for my style, but is very cool any way! great organ/hammond like sounds using clean with highest rate to me...
another stompbox in my case :)
thanks francisco! your layouts are the best ever, i hope some day i'd could do such nice little and clean designs..
now i think i'll try some mods... i'll let you know

Name:Felipe Sanchez
Build Report:Que bello y tentador es el pez 90, lo construi con fets J309 matcheados y solo compr 10 y eleg los mas cercanos: 3 eran de 1,4 volt y uno era de 1,2 , pero suena genial limpio o con distorcin. Gracias Pancho Pea este fue el tercer pedal que constru.

Build Report:I could only get hold of the bf245 FETs in the uk. These sound perfectly good to me. I had some problems with the pinouts for the PNP transistor but once these were sorted it worked like a dream. The trim pot creates a big difference on my circuit and adjusting it to about centre gives a nice mix to the effect. You can get some really very flangy sounds out of it with some fiddling on the trim. As some other people have mentioned im not sure that the pot is really the best value. Mine is far too sensitive.

Build Report:Built this one with self-etched pcb and 4 matched BF245 FETs. A really nice effect, recommended!

Build Report:An update to my earlier review...
Whilst it appears that any 4 fets will work, using 4 matched ones gives a much tighter phase sound.

I love this effect - especially the fact that at high speeds it does an excellent leslie simulation !!

Name:Jeff Jonsson
Build Report:This is the second pedal I've built from the Tonepad plans. The first was a Tube Screamer which worked great.

For this one, I followed all of the directions carefully. I went over to and grabbed the test circuit for the JFETs and bought a hundred of them, and tested them all on a breadboard. I found four that were within 3 millivolts, registering at 1.509, 1.511, 1.511, and 1.512. So I thought I was golden. I etched my own PC Board with Press-n-peel blue. (After trying the iron-on about 11 times! ...Maybe it's my laser printer. I dunno.) And then I assembled it.

At first I got nothing. I thought maybe i detected some phasing, but it mostly just sounded like a treble booster. I was wracking my brains when i read the build reports on this project, and then I realized that the circuit layout has the flat side of the 2N5952 wrong. Look at the little G on the design and insert your FETs accordingly, with the flat side to the right when looking at the diagram. As soon as I flipped the FETs, (I had to desolder them, as I didn't figure I'd need sockets when I matched them so perfectly.) It worked first shot out of the gate. The 500K Pot seems a little off though, because I get to the slowest sweep somewhere near 10 O'clock on the knob. I'm gonna fiddle with that before I declare it a success, but it sounds great.

Build Report:Hi!! The Phase 90 is the second pedal that Ive built using Tonepad. I etched my board, populated it and tested it. Didnt work at first and it took me a while to de-bug. Turned out to be a couple of tracks joined by sloppy soldering (doh!). Works fine now though. Goes from a fast watery effect to a nice slow "swoosh". I used 2N5845 as 2n5952 are very pricy in the uk. The first 4 I tried worked but, after testing them, they are not matched (??). I tested several other combinations and they all sounded fine but they shouldnt work as they are not matched. Can some one explain this to me?? I assume if you do use a matched set you'll get a tighther sound. I give this project 10/10. Very useful phasor and sounds just like the MXR.

Name:Matti Kari
Build Report:Since I was unable to get any other FET's, I tried to the Phase 90 using the four MPF102's I had in my box, without matching (I had only five of them). It worked straight away!

The sound is pretty damn good! Much dirtier and warmer than my Boss Super Phaser (which is now for sale ;). I use the pedal with my Rhodes Suitcase 73 electric piano. Now I'm able to play No Quarter with very authentic sounds! :)

Highly recommened!

Name:Paolo from ITALY
Build Report:I have build two phase 90. As I didn't find all the 4 jfet (sorry for my english) I used similar (BC264) but much expensive: each 1,5 euro. I initially had only two 2n5952, so I used those with other 2 bc264, but the fx was imperceptible. The trim didn't let me to listen any variation of the sound. I don't know why. Instead when I used all four BC264 the fx worked fine. Just a little change to the trimmer and the fx was better than the original. Now I'll try to mod and decrease a bit the gain.

Name:Urban Osterman
Build Report:I just finnished building the Pez90, or a clone of
the mxr90 phaser.
This thing sounds great.
Beacuse it does not have that over-the-top-swooishooiiish
that some other phasers have,
it phases in the midrange somehow,
I dont like when phasers swooishes in the top frequencies, allmost
removing the bottom.
You can trim this a bit and I did not set it on the
top position because of this.

I got a pcb from Francisco, and it was the B version
or the B2 version as I beleive it does
exists 2 types of the B version.

I got 100 2N5952:s from SmallBear
and I selected several groups of matched sets.

I actually build two Pez90:s,
one in a HammondStompBox for gigs,
and one for my effectsrack for recording.
My effectsrack has panels that is 4x19 cm big.
and then I can stack several effects using the same power supply.

The 2N5952:s I selected, had a matching value
for the first pez90 of 4 FETs at -1.610 V
and the second group was 3 FETs 1,637V and 1 with 1,636V
pretty close matchings......

I really dont know how close the matching must be
but I do beleive that if theyre within a 1/100 of a volt
should be ok....

I dont think that MXR themselves had this close matching....
anyone have any Ideas.....!!!

I used a log 100K pot for the speed and I wired it
backwards, meaning slower setting clockwise, and fastest value ccw.
I think I'll try a 250K or even the 500K pot
as I think that the faster settings are not that usefull.
2/3 of the pot is to fast for me...
(actually where most of the log part is)

I tend to set the Speed pot in the highest positions (in my case cw).

I also added a Volume pot instead of the last 150K resistor
as the pez90 has a small volumeboost,
as someone discussed in these building reports.
I think that you need to lower the volume a bit, to have an even
outputvolume when you use the effect with other effects.

I also added a 500K pot in series with the 1M resistor
for an INTENSITY control, a very subtle change,
but still noticeable.

The 15uF cap is not a standard value, so I used a 10uF in one of my
pez90 and a 22uF in the other..

I added a switch to add the 22K feedbackresistor in and out..
but this does not sound good, it made the curcuit 'klick'.
Maybe its because I got so closematched FETs..

So I intend to use that switch for a ADD-input switch instead
meaning that I can remove the direct link from IC1a pin 1
to the 150K resistor.
giving me the option to just use the delayline.

I also used a 200K multiturn trim pot for the 250K trim
it makes easier to find a good trim position.
The easiest way to trim this is to set the speed pot to fast,
where you hear the Swooishing effect better in the higher frequencies.
And then trim yout pot.

I used a 5,1 Zener for D2.
I used Tl072:s for the OP amps.
and 1% mtallresistors.


Build Report:I just completed the "B" version of the phase 90 it works great!before you build this version take notice that there is a visible mistake on the drawings,the picture shows all the 2N5952's on the board in the wrong direction, they in fact need to be placed 180 in the opposit direction to how it is showned.Other than that i also removed the 22k feedback resistor and decreased the 500k varible to 100k ,improved tremondousley although will still decrease to 50k. this being said it is a fine phase 90 and if can pry my son away from if for about an hour i may be able to enclose it! thanks!!!!

Name:Julio Novetti
Build Report:It worked!

I built my phaser 90 using BF245 for the fets.The first 4 i tried were matched.
I got a cold solder joint in the output section of the PCB, s as soon as i fixed it and Dooh, i was using the fets in the wrong position, it was wooshing...
I had to use a 50K pot(reversed) for the rate control, because in my circuit, the 500K was too large, too sensitive within the smallest movement.

I don't know if it's something wrong but with this fets or something else,the trim pot position isn't making too much perceptive. I think with it's adjust the sound is getting a bassy-trebly touch.
Great effect! Recomended!

Build Report:WoW! Great project! Thanx Fp!

I used the Ver.1 layout and it worked the first time, but you must follow certain steps for a successful build.

I may sound like a parrot here BUT I want to make sure everybody understands: The matching of the JFETs is essential! GEO has a great article and a simple circuit to match JFETs, Thanks again as always R.G.!


"The Master" Rob Strand also has a pretty good matching circuit, a few more parts but it gives "actual" results.


I tried both and either one will give you good results. If all you are doing is matching JFETs for the Phase 90 (or 45), R.G.'s works great and you can breadboard it in 10 minutes.

I used 2n5952 JFETs from Small Bear. Make sure you get at least a dozen and find 4 that closely match.

Leave the 22k feedback resistor off the board. I think this is only here to compensate for poorly matched JFETs. Comments? The 4 JFETs I used were so tightly matched I was able to achieve a jet-swooshing sound with the trim-pot set at a certain point. To me this was WAY too much for a phase effect. I had to back it off a little.

Mine worked fine with either a 5.1W Zener or a 4.7W Zener.

This project works best with a 500k reverse audio pot, thank Steve at Small Bear for this one. In a pinch you can use a 50k (yes, 50k) linear wired backwards. Be sure to put a 3.3k or 5k resistor in series with the pot. This will get rid of that dreaded dead spot at the fully CW position.

I was able to fit this safely into a Hammond 1590B box. It's true! Really!


I put a 500k linear pot in series with the 1M resistor which ties to the 250k trim-pot. This is a great mod, it gives an external "Intensity" control. RECOMMENDED!

I also put a 100k resistor in series with a 100k linear pot in place of the 150k resistor which connects between the collector and base of the output transistor (2n4125). This gives you a subtle "Level" control. This allows you to dial-in unity gain at all times. You kind of need this if you like tweaking the intensity frequently.

Rock On!
- HB

Build Report:This is a great layout for the phase 90.The only mod I had to make was to change the feedback resistor and it was swooshing like a champion!

Build Report:Layout was perfect!
the notes about having matched JFETS is VITAL.
You may also have to play with the value of the zener diode in order to get the biasing right for the JFets.
I found a TL062 opamp to work the best for the project over TL072 in my case due to the biasing requirements of the JFETS I used in order to avoid 'clicks' and 'pops' with the oscilator. This is probably again due to the biasing requirements of the JFETS that I selected.
The 500k pot for speed would be best if a reverse log taper was used (or in a pinch, a regular audio/log taper pot, wired backwards --i.e. as you turn the knob 'up' the speed decreases).
I also modded mine with a small resistor in series with the speed pot in order to eliminate the 'dead spot' at the max. end of the speed knob.