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Phase 90 distortion

Started by james, January 08, 2015, 07:10:50 PM

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james

Is it normal to get distortion from the MXR Phase 90 when you're playing harmonically complex chords? This is the first time I've ever had the chance to use one, and the results seem pretty dirty...
Web Designer/Developer, Webmaster & Co-Creator
The Rhodes Super Site since 1996
1977 Mark I Stage 73 + Vintage Vibe Stereo Vibe

Tim W

Yes this is normal for a stock Phase 90.  It needs to be modded to handle a Rhodes without distorting.

Tim
Retrolinear.com

james

#2
Is the R28 mod the one I want?

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Web Designer/Developer, Webmaster & Co-Creator
The Rhodes Super Site since 1996
1977 Mark I Stage 73 + Vintage Vibe Stereo Vibe

Tim W

You can do the R28 mod as a simple place to start and see if it helps.  We have had to sometimes modify the overall gain of the preamp stage in the pedal by changing some resistors to handle a higher input signal without clipping the phasing stages.

There are several different versions of MXR Phase 90s with different amounts of ICs (single/dual opamps, etc.) and components (some are even now surface mount) so we generally figure out what to do on the fly based on what is in front of us.  All versions of the P90 circuits are basically or mostly the same (except mainly for R28 as you pointed out, LEDs, and DC power jacks), but they changed how they built them over the years.

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Tim
retrolinear.com

pianotuner steveo

Tim,

slightly off topic, but I have a similar problem with my old surround sound unit for my stereo. (1970's Sony) I think I need to add resistors to the audio input- my Blu Ray player audio seems to be too hot for the input. The rear channels distort. The front channels are fine( more modern front amp)

Any suggestions for what value resistors to try? 10k? 20k? Less?

1960 Wurlitzer model 700 EP
1968 Gibson G101 Combo organ
1975 Rhodes Piano Bass
1979 Wurlitzer 206A EP
1980 Wurlitzer 270 Butterfly Grand
2009 73A Rhodes Mark 7
2009 Korg SV-1 73
2017 Yamaha P255
2020 Kawai CA99
....and a few guitars...