MXR Phase 90

dazzlindino · 09-01-2007, 07:03 PM

Is it possible to modify the mxr phase 90 not to sweep, just use it as a booster pedal?
Or madify it to where it sweeps much slower and lower?
Thanks

Mark Hammer · 09-06-2007, 04:10 PM

To the first question, no.
To the second question, yes. The range of where the notches are is given partly by the .05(.047uf) caps in each of the 4 phase shift stages. If you wanted the pedal to have its lowest sweep point even lower than it currently is, you will want to increase that capacitance. You could do this by replacing those 4 caps with .068uf caps, or perhaps soldering a .01uf cap in parallel with the existing ones on the copper side of the board.

The speed is partly given by an electrolytic capacitor in the LFO subcircuit. It is supposed to be 15uf. If you increase it to 22uf, you will likely be able to achieve slower sweep rates, although at the cost of fastest sweep rates.

09-01-2007, 07:03 PM	#1
dazzlindino Member Join Date: Jan 2007 Posts: 77	MXR Phase 90 Is it possible to modify the mxr phase 90 not to sweep, just use it as a booster pedal? Or madify it to where it sweeps much slower and lower? Thanks

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09-06-2007, 04:10 PM	#2
Mark Hammer Senior Member Join Date: May 2006 Posts: 1,122	To the first question, no. To the second question, yes. The range of where the notches are is given partly by the .05(.047uf) caps in each of the 4 phase shift stages. If you wanted the pedal to have its lowest sweep point even lower than it currently is, you will want to increase that capacitance. You could do this by replacing those 4 caps with .068uf caps, or perhaps soldering a .01uf cap in parallel with the existing ones on the copper side of the board. The speed is partly given by an electrolytic capacitor in the LFO subcircuit. It is supposed to be 15uf. If you increase it to 22uf, you will likely be able to achieve slower sweep rates, although at the cost of fastest sweep rates.

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