MXR Phase 90 mods?

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MXR Phase 90 mods?

Postby nagshay1818 » 24 Jul 2008, 21:49

Anyone know any mod for these cheap bad boys?
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Re: MXR Phase 90 mods?

Postby Silent Fly » 24 Jul 2008, 23:23

nagshay1818 wrote:Anyone know any mod for these cheap bad boys?


C input: from 0.01uF to 0.1uF
C output: from 0.05uF to 0.47uF

it is much better for bass guitar.
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Re: MXR Phase 90 mods?

Postby JiM » 25 Jul 2008, 02:11

Univibe cap ratio ! :thumbsup

You can get inspiration here :
http://www.lynx.bc.ca/~jc/pedalsPhase45.html
http://www.lynx.bc.ca/~jc/pedalsSmallStone.html
http://www.moosapotamus.net/THINGS/frankenstone.htm
I did it on both Phase45 and SmallStone clones, and it works great for changing the overall frequency balance, especially on the P45. I did not build a P90 (yet), but i remember quickly breadboarding two additional stages for the P45, also with switchable caps. It had a wide range of sounds, but did not fit in the intended enclosure (along with a Tube Driver). I might try again ...

'found some soundclips (there are more in the same folder) :
http://www.indyguitarist.com/soundclips ... -stock.mp3
http://www.indyguitarist.com/soundclips ... nivibe.mp3
http://www.indyguitarist.com/soundclips ... ibe-pv.mp3

You can also vary the mix of the delayed signal with the dry signal. Stock it is a fixed 50% for maximum phaser effect, but 100% is a vibrato, and around 50% you can vary the intensity of the phaze. Use a switch or better, a pot.

You can also mess with the feedback, for example like that : http://www.home-wrecker.com/ross_phaser_orange2.png
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Re: MXR Phase 90 mods?

Postby Bremt » 12 Oct 2009, 11:37

JiM wrote:You can also vary the mix of the delayed signal with the dry signal. Stock it is a fixed 50% for maximum phaser effect, but 100% is a vibrato, and around 50% you can vary the intensity of the phaze. Use a switch or better, a pot.


I just discovered this thread, and this sounds quite nice, can you give any info on how to do this?
(I'm quite new in the guitar effects world :) )
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Re: MXR Phase 90 mods?

Postby JiM » 12 Oct 2009, 21:08

Bremt wrote:
JiM wrote:You can also vary the mix of the delayed signal with the dry signal. Stock it is a fixed 50% for maximum phaser effect, but 100% is a vibrato, and around 50% you can vary the intensity of the phaze. Use a switch or better, a pot.

I just discovered this thread, and this sounds quite nice, can you give any info on how to do this?

It's just a matter of replacing a pair of fixed mixing resistors with a pot. Here is the example of the Phase45, but every phaser work that way.
Before, two 10k resistors : http://www.freeinfosociety.com/electron ... php?id=566
After (mod #5), one 22k pot : http://www.lynx.bc.ca/~jc/phase45modded.gif

Another example : for the Ross Phaser linked above, it's R27 and R28.
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Re: MXR Phase 90 mods?

Postby lolbou » 12 Oct 2009, 21:17

Just a note: I mod the feedback resistor in a new unit. Desoldering was a pain in the ass (double sided)... Be sue you're ok with it or you may ruin your pcb... :wink:
- Are you a mod or a rocker?
- Uh, no, I'm a mocker.
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Re: MXR Phase 90 mods?

Postby diggum12 » 13 Oct 2009, 14:15

For those double sided ones, flow a tiny bit of fresh solder in. Then use some flux on both sides and wick it all out with desoldering braid. I've had really good luck with that method.
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ayayay! on the other site
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Re: MXR Phase 90 mods?

Postby astrobass » 06 Apr 2014, 06:44

I'm going to post my findings here because I just did a Phase 90 mod and I'm very pleased with how it turned out.

I added two On-Off-On SPST switches:
The one on the left replaces R28. The Off position obviously gives you 1/2 of the very popular "Script" mod (which I do not care for much), and the switch down position gives 24K ohm, the stock value. Switch up position gives 12K. Why 12K? Because it increases the depth. The pedal becomes much more aggressive, much more interesting this way. Below 8K or so you just get feedback. 10K seemed like I was losing too much of the note and just getting the phase sound.

The one on the right replaces C11. Off position is the other 1/2 of the Script mod, and it drops the highs. Down position is the stock 0.01 uF value, and switch up is 0.033 uF. That significantly increases your highs and gives you almost an overdriven, dirty sounding phaser. This combined with the other switch in the up position yields a hairy, gnarly phase sweep.

I used switches because I had limited internal space to work with. If I were to do a re-house into a 1590DD or a clone, I'd replace C11 with a SP12T rotary switch, leave position 1 open, position 2 at 0.01uF, and then values all the way up to 2.2 uF. I'd also add a volume control however, as going to 0.1 uF even substantially increases the volume of the effect. Swapping the first switch for a 10K ohm resistor in series with a 100K pull-dpdt pot with the pull position used to bypass that control completely would also be pretty slick.

Anyhow, these are the best mods to do. R21 is a garbage mod, leave it stock. Does nothing useful. Replacing the resistor under the rate pot with either a trimmer or a second pot might be neat too. Haven't looked too closely at the schem, don't know if you could just reduce it and increase the pot value to extend the range.
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Re: MXR Phase 90 mods?

Postby rats_eyes » 11 May 2014, 18:22

The rate can be altered by changing the value of components. I slowed the minimum rate by change c10 from 15uf to 22uf. The maximum rate can be apparently be increased by reducing the value of the 10k resistor by the rate pot, 4k7 is recommended elsewhere on the forum. I only tried the first of these mods, I've no need for a faster phase.
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Re: MXR Phase 90 mods?

Postby POTL » 22 Jan 2017, 22:10

Hello
I do not want to create a new topic, this revives this)
Can I use the J113 as a substitute for 2N5457 and J201
in my country, and J201 2N5457 is only in the form of SMD or cost 10 times more expensive J113 and delivery a few months
or transistors which models also work with this effect.
The main thing that the body was TO-92 I am not yet ready to work with smd
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