I've finally found a decent 'swirly Rhodes' sound, using keyboard and an effects pedal. The problem is now that when recording, or on stage, I prefer to go stereo, as that gives other sounds - strings, Hammond, etc.- a much better airing. Trouble is, the phaser pedal, really designed for guitar (mono) only works with one channel. So, the effect isn't so, well, effective. How have other keys players got around this. Do I go out with a phaser on each channel, or make do with the not-so-good mono from one speaker?
I wouldn't try anything like trying to synch two MXR Phase 90s. There are several phasers with stereo outputs, presumably with each output 180 degrees out of phase in their respective cycles?
One idea is to simply have the Phase 90 in one channel. From recording experience I've found that a phaser on one side of the stereo field can still sound like it is effecting the other side of the stereo field, because you are hearing the dry signal in reference with a signal with a constantly changing phase effect applied to it.
The stereo effect applied to a Rhodes quite commonly on records comes from the tremolo built into some Rhodes models, which basically pans between two channels. From memory this effect is utilised on some Pink Floyd and Jeff Beck records (there will be countless others).
Be careful over stereo on stage. Even if the PA is stereo, few of the audience will receive the intended effect. And be careful over stereo even when recording. Are keyboards SO important to the song that they should take up the full soundstage?
If you're sub-mixing your keyboards on stage, and have your own stereo monitoring, you could put the phaser as a send effect and feed it back to both channels. You can then get off on the sound! But don't be surprised if a good sound guy narrows the stereo image you send him considerably, so as to give ALL the band members some space.
I've been searching for the same thing for my Rhodes. I am very partial to putting a Phase 90 on just one channel as mentioned by ABragg. But for less subtle effect I sometimes put a mid-speed Phase 45 on one channel and a low-speed Phase 100 on the other. This interview with Don Fagen of Steely Dan fame describes using 2 Phase 90's in parallel.
For a 1-pedal solution, there's the MXR Phase 99 - two phase 90's with independent speed controls and outputs, built into one box. It's mono in, stereo out, so it'll need to be the first pedal in the stereo portion of your effects chain. I just bought one but haven't received it yet so can't comment on sound. The pedal has a "parallel/stereo" feature, which is cool but I'm only interested in the "parallel" mode. It was a limited release and most retailers only have a few left in stock, FYI.