Finally Fixed : Purple Plexi + Boost excessive noise (ground hum)

[gearJunkie]

I received the Purple Plexi + Boost pedal today and although it sounds fantastic, there is a constant loud ground hum present when the Plexi side is engaged.

I have checked all my cables and have tried powering it with both the internal battery and an external Cioks DC7 with the same result.

Guitar > Purple Plexi > amplifier (Fillmore 50 or JVM 410H)

Touching the input jack seems to ground the pedal minimizing (and sometimes eliminating) the noise temporarily.

I am hoping this is not the intended behavior of this pedal. Does anyone have any insight and/or troubleshooting tips to address this issue?

Thanks.

 

[Achilles]

Starting with post #4 there's a number of complaints about excessive noise. Never owned one myself.

Who Didn’t Get Along With Their Purple Plexi?

I’ve been thinking about picking up one of those for a while now, as I like MAIBs, and this one seems especially well regarded. That said, nothing is for everyone. If you tried one and it didn’t work for you, why not? Or if you want to pontificate about how great the pedal is, that’s cool too...

www.thegearpage.net

 

[gearJunkie]

Starting with post #4 there's a number of complaints about excessive noise. Never owned one myself.

Who Didn’t Get Along With Their Purple Plexi?

I’ve been thinking about picking up one of those for a while now, as I like MAIBs, and this one seems especially well regarded. That said, nothing is for everyone. If you tried one and it didn’t work for you, why not? Or if you want to pontificate about how great the pedal is, that’s cool too...

www.thegearpage.net

Thanks for the link. From what I read, most are complaining about gain related noise.

The noise I am experiencing is present with the guitar volume on zero and even with nothing plugged into the input.

If I bridge the ground sleeves on the input and output cables with my finger the hum disappears, even with the gain and volume maxed.

 

[la szum]

Bummer! Is there a battery in it now? I know you said you tested with a battery.

 

[gearJunkie]

Yes, it arrived with a battery installed. I'm getting ready to open it up to have a look. I'll pull the battery and try it with an isolated power supply sans battery.

 

[gearJunkie]

Wow! Talk about customer service. I sent an email to the lovepedal address on their website and Sean responded within 10 minutes.

He suggested it's a ground lift problem. I'm going to follow his advice by tightening the foot switches and the jacks.

 

[la szum]

That's awesome.

 

[DrewJD82]

Shit, I still haven't plugged in that multi-tap!

 

[gearJunkie]

I noticed that the noise disappears completely when the gain is maxed, but gradually appears as I turn the gain knob counterclockwise maxing out about 2/3 of the way down and reducing slightly, but still very audible with the gain at 0.

Maybe a bad pot or cold solder joint?

 

[la szum]

Is the nut tight around that pot? If it is tight, then still trying to loosen it and retighten it.

 

[gearJunkie]

Is the nut tight around that pot? If it is tight, then still trying to loosen it and retighten it.

Good idea. I'll give it a shot in the AM. Getting ready to shut it down for the night.

 

[gearJunkie]

Decided to completely disassemble the pedal to inspect the pcb.

Everything looked fine.

Carefully reassembled making sure the ground spring on the boost potentiometer was making contact with the chassis.

Plugged it into the Fillmore 50 combo and the noise was completely gone. Loving this pedal

 

[Alex Kenivel]

Decided to completely disassemble the pedal to inspect the pcb.

Everything looked fine.

View attachment 15024
View attachment 15025
View attachment 15026

Carefully reassembled making sure the ground spring on the boost potentiometer was making contact with the chassis.

Plugged it into the Fillmore 50 combo and the noise was completely gone. Loving this pedal

View attachment 15027

Great Satan, that's tidy AF!

 

[DrewJD82]

Decided to completely disassemble the pedal to inspect the pcb.

Everything looked fine.

View attachment 15024
View attachment 15025
View attachment 15026

Carefully reassembled making sure the ground spring on the boost potentiometer was making contact with the chassis.

Plugged it into the Fillmore 50 combo and the noise was completely gone. Loving this pedal

View attachment 15027

When I saw the circuit flipped upside down I thought you depopulated the whole board at first.

Glad that worked!! I've been eyeing this one but....no more fuckin' dirt pedals!

 

[gearJunkie]

False alarm

Ground noise is back.

 

[Achilles]

ITEM RETURN: FREIGHT PRE-PAID BY SELLER

 

[jellodog]

False alarm

Ground noise is back.

Does that ground spring just need teasing out a bit more so that it's more extended? Could it have lost contact again?

 

[gearJunkie]

Does that ground spring just need teasing out a bit more so that it's more extended? Could it have lost contact again?

It's a possibility, but I'm going to wait until I hear back from Sean before I disassemble the pedal again.

Last night Sean wrote he was going to look if he had another PP+B already built.

 

[gearJunkie]

ITEM RETURN: FREIGHT PRE-PAID BY SELLER

I'm sure Sean will make it right.

 

[gearJunkie]

I think I've got it sorted out now. I noticed that when I tapped on the pedal it sounded like something was shorting out on the input side. Thus, I decided to disassemble once again to ensure the ground spring was still making contact.

After pulling the pcb, I lightly pulled on the ground spring to make it longer. Also, for good measure, inserted a small dome-top set screw into the tip of the spring, adding a few millimeters.

Everything is now reassembled and functioning properly after an hour or so of playing, switching, tweaking, and patching into and out of the pedal.

Hopefully this is the last time I need to adjust the thread title.