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Help me with a clicking/popping sound from MXR Phase 90 RI

PWGuy

Member
Messages
187
I bought an MXR Phase 90 RI (CSP-026) shortly after it was "re-released" a few years back. I have it sitting in the middle of my chain - after O/Ds and before delay. I plan on moving it to sit after the tuner and compressor, BEFORE the O/Ds but haven't done so yet.

The pedal sounds wonderful but when I have it anywhere on my board, it makes a clicking/popping sound when I engage the pedal on or off. When on the board, the pedal is powered using a Voodoo Labs Pedal Power 2+ and the 9V tap, since the pedal doesn't have a 9v jack.

I swapped a 9v battery in for the 9v tap, put it back on the board but have the same issue - regardless of where I put the pedal.

I then left the battery in the pedal, pulled it off the board, connected my guitar directly to it and the pedal output directly to the amp: noise is more or less gone.

I swap in the 9v tap, connect guitar through pedal and into amp: noise is still more or less gone.

So what gives on the board?


My chain:

Guitar > TU-2 (acts as a buffer before VP) > EB VPJr > Comp > Bad Monkey O/D > Monte Allums BD-2 H20 > MXR Phase 90 > DD-5 > DL-4 > PRRI

HELP THIS IS KILLING ME! I can't use the effect well when playing live because stacking a delay on top is HORRIBLE! :( :(

:mad:
 

drgonzoguitar

Member
Messages
4,709
One quick fix is soldering a 1meg resistor from the input to the ground in the pedal. You could probably do it on the backside of the pedal PCB.
 

Youngpedals

Member
Messages
313
The majority of switch popping problems come from differing DC voltages between opposite contacts of the switch. This difference creates the pop when you engage it. It can come from leaky coupling caps, no terminating in/out resistors, a bad switch, inadequate wiring techniques, etc. etc.

Since you removed it from your chain and the problem stops, i suspect you're removing some problem DC voltage coming from other pedals. But this is only one of many scenarios and i'm speculating. I don't know if the RI phase 90's are "true bypass," but if it is, one solution is to see if its wired for "input grounded" true bypass, and to check the value/ existence of terminating resistors that could possibly aid in draining any DC voltage from the switch terminals.
 

PWGuy

Member
Messages
187
The majority of switch popping problems come from differing DC voltages between opposite contacts of the switch. This difference creates the pop when you engage it. It can come from leaky coupling caps, no terminating in/out resistors, a bad switch, inadequate wiring techniques, etc. etc.

Since you removed it from your chain and the problem stops, i suspect you're removing some problem DC voltage coming from other pedals. But this is only one of many scenarios and i'm speculating. I don't know if the RI phase 90's are "true bypass," but if it is, one solution is to see if its wired for "input grounded" true bypass, and to check the value/ existence of terminating resistors that could possibly aid in draining any DC voltage from the switch terminals.
They are not "true bypass" they are "hard bypass". Analogman modifies these for TB - would that potentially solve the issue?
 

Youngpedals

Member
Messages
313
They are not "true bypass" they are "hard bypass". Analogman modifies these for TB - would that potentially solve the issue?
Maybe, still hard to say without having a look. Email Mike/ see if there is FAQ about the Phase 90 RI. He's real good about getting back to folks.
 




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